/* vi: set sw=4 ts=4: */
/*
 * Command line editing.
 *
 * Copyright (c) 1986-2003 may safely be consumed by a BSD or GPL license.
 * Written by:   Vladimir Oleynik <dzo@simtreas.ru>
 *
 * Used ideas:
 *      Adam Rogoyski    <rogoyski@cs.utexas.edu>
 *      Dave Cinege      <dcinege@psychosis.com>
 *      Jakub Jelinek (c) 1995
 *      Erik Andersen    <andersen@codepoet.org> (Majorly adjusted for busybox)
 *
 * This code is 'as is' with no warranty.
 */
/*
 * Usage and known bugs:
 * Terminal key codes are not extensive, more needs to be added.
 * This version was created on Debian GNU/Linux 2.x.
 * Delete, Backspace, Home, End, and the arrow keys were tested
 * to work in an Xterm and console. Ctrl-A also works as Home.
 * Ctrl-E also works as End.
 *
 * The following readline-like commands are not implemented:
 * CTL-t -- Transpose two characters
 *
 * lineedit does not know that the terminal escape sequences do not
 * take up space on the screen. The redisplay code assumes, unless
 * told otherwise, that each character in the prompt is a printable
 * character that takes up one character position on the screen.
 * You need to tell lineedit that some sequences of characters
 * in the prompt take up no screen space. Compatibly with readline,
 * use the \[ escape to begin a sequence of non-printing characters,
 * and the \] escape to signal the end of such a sequence. Example:
 *
 * PS1='\[\033[01;32m\]\u@\h\[\033[01;34m\] \w \$\[\033[00m\] '
 *
 * Unicode in PS1 is not fully supported: prompt length calulation is wrong,
 * resulting in line wrap problems with long (multi-line) input.
 */
#include "busybox.h"
#include "NUM_APPLETS.h"
#include "unicode.h"
#ifndef _POSIX_VDISABLE
# define _POSIX_VDISABLE '\0'
#endif


#ifdef TEST
# define ENABLE_FEATURE_EDITING 0
# define ENABLE_FEATURE_TAB_COMPLETION 0
# define ENABLE_FEATURE_USERNAME_COMPLETION 0
#endif


/* Entire file (except TESTing part) sits inside this #if */
#if ENABLE_FEATURE_EDITING


#if !ENABLE_SHELL_ASH && !ENABLE_SHELL_HUSH
/* so far only shells use these features */
# undef ENABLE_FEATURE_EDITING_FANCY_PROMPT
# undef ENABLE_FEATURE_TAB_COMPLETION
# undef ENABLE_FEATURE_USERNAME_COMPLETION
# define ENABLE_FEATURE_EDITING_FANCY_PROMPT 0
# define ENABLE_FEATURE_TAB_COMPLETION       0
# define ENABLE_FEATURE_USERNAME_COMPLETION  0
#endif


#define ENABLE_USERNAME_OR_HOMEDIR \
        (ENABLE_FEATURE_USERNAME_COMPLETION || ENABLE_FEATURE_EDITING_FANCY_PROMPT)
#if ENABLE_USERNAME_OR_HOMEDIR
# define IF_USERNAME_OR_HOMEDIR(...) __VA_ARGS__
#else
# define IF_USERNAME_OR_HOMEDIR(...) /*nothing*/
#endif


#undef CHAR_T
#if ENABLE_UNICODE_SUPPORT
# define BB_NUL ((wchar_t)0)
# define CHAR_T wchar_t
static bool BB_isspace(CHAR_T c)
{
        return ((unsigned)c < 256 && isspace(c));
}
# if ENABLE_FEATURE_EDITING_VI
static bool BB_isalnum_or_underscore(CHAR_T c)
{
        return ((unsigned)c < 256 && isalnum(c)) || c == '_';
}
# endif
static bool BB_ispunct(CHAR_T c)
{
        return ((unsigned)c < 256 && ispunct(c));
}
# undef isspace
# undef isalnum
# undef ispunct
# undef isprint
# define isspace isspace_must_not_be_used
# define isalnum isalnum_must_not_be_used
# define ispunct ispunct_must_not_be_used
# define isprint isprint_must_not_be_used
#else
# define BB_NUL '\0'
# define CHAR_T char
# define BB_isspace(c) isspace(c)
# if ENABLE_FEATURE_EDITING_VI
static bool BB_isalnum_or_underscore(CHAR_T c)
{
        return isalnum(c) || c == '_';
}
# endif
# define BB_ispunct(c) ispunct(c)
#endif
#if ENABLE_UNICODE_PRESERVE_BROKEN
# define unicode_mark_raw_byte(wc)   ((wc) | 0x20000000)
# define unicode_is_raw_byte(wc)     ((wc) & 0x20000000)
#else
# define unicode_is_raw_byte(wc)     0
#endif


#define ESC "\033"

#define SEQ_CLEAR_TILL_END_OF_SCREEN  ESC"[J"
//#define SEQ_CLEAR_TILL_END_OF_LINE  ESC"[K"


enum {
        MAX_LINELEN = CONFIG_FEATURE_EDITING_MAX_LEN < 0x7ff0
                      ? CONFIG_FEATURE_EDITING_MAX_LEN
                      : 0x7ff0
};

/* We try to minimize both static and stack usage. */
struct lineedit_statics {
        line_input_t *state;

        unsigned cmdedit_termw; /* = 80; */ /* actual terminal width */

        unsigned cmdedit_x;        /* real x (col) terminal position */
        unsigned cmdedit_y;        /* pseudoreal y (row) terminal position */
        unsigned cmdedit_prmt_len; /* on-screen length of last/sole prompt line */

        unsigned cursor;
        int command_len; /* must be signed */
        /* signed maxsize: we want x in "if (x > S.maxsize)"
         * to _not_ be promoted to unsigned */
        int maxsize;
        CHAR_T *command_ps;

        const char *cmdedit_prompt;
        const char *prompt_last_line;  /* last/sole prompt line */

#if ENABLE_USERNAME_OR_HOMEDIR
        char *user_buf;
        char *home_pwd_buf;
        smallint got_user_strings;
#endif

#if ENABLE_FEATURE_TAB_COMPLETION
        unsigned num_matches;
        char **matches;
#endif

#if ENABLE_FEATURE_EDITING_WINCH
        unsigned SIGWINCH_saved;
        volatile unsigned SIGWINCH_count;
        volatile smallint ok_to_redraw;
#endif

#if ENABLE_FEATURE_EDITING_VI
# define DELBUFSIZ 128
        smallint newdelflag;     /* whether delbuf should be reused yet */
        CHAR_T *delptr;
        CHAR_T delbuf[DELBUFSIZ];  /* a place to store deleted characters */
#endif
#if ENABLE_FEATURE_EDITING_ASK_TERMINAL
        smallint sent_ESC_br6n;
#endif

#if ENABLE_FEATURE_EDITING_WINCH
        /* Largish struct, keeping it last results in smaller code */
        struct sigaction SIGWINCH_handler;
#endif
};

/* See lineedit_ptr_hack.c */
extern struct lineedit_statics *BB_GLOBAL_CONST lineedit_ptr_to_statics;

#define S (*lineedit_ptr_to_statics)
#define state            (S.state           )
#define cmdedit_termw    (S.cmdedit_termw   )
#define cmdedit_x        (S.cmdedit_x       )
#define cmdedit_y        (S.cmdedit_y       )
#define cmdedit_prmt_len (S.cmdedit_prmt_len)
#define cursor           (S.cursor          )
#define command_len      (S.command_len     )
#define command_ps       (S.command_ps      )
#define cmdedit_prompt   (S.cmdedit_prompt  )
#define prompt_last_line (S.prompt_last_line)
#define user_buf         (S.user_buf        )
#define home_pwd_buf     (S.home_pwd_buf    )
#define got_user_strings (S.got_user_strings)
#define num_matches      (S.num_matches     )
#define matches          (S.matches         )
#define delptr           (S.delptr          )
#define newdelflag       (S.newdelflag      )
#define delbuf           (S.delbuf          )

#define INIT_S() do { \
        XZALLOC_CONST_PTR(&lineedit_ptr_to_statics, sizeof(S)); \
} while (0)

static void deinit_S(void)
{
#if ENABLE_FEATURE_EDITING_FANCY_PROMPT
        /* This one is allocated only if FANCY_PROMPT is on
         * (otherwise it points to verbatim prompt (NOT malloced)) */
        free((char*)cmdedit_prompt);
#endif
#if ENABLE_USERNAME_OR_HOMEDIR
        free(user_buf);
        free(home_pwd_buf);
#endif
        free(lineedit_ptr_to_statics);
}
#define DEINIT_S() deinit_S()


#if ENABLE_USERNAME_OR_HOMEDIR
/* Call getpwuid() only if necessary.
 * E.g. if PS1=':', no user database reading is needed to generate prompt.
 * (Unfortunately, default PS1='\w \$' needs it, \w abbreviates homedir
 * as ~/... - for that it needs to *know* the homedir...)
 */
static void get_user_strings(void)
{
        struct passwd *entry;

        got_user_strings = 1;
        entry = getpwuid(geteuid());
        if (entry) {
                user_buf = xstrdup(entry->pw_name);
                home_pwd_buf = xstrdup(entry->pw_dir);
        }
}

static NOINLINE const char *get_homedir_or_NULL(void)
{
        const char *home;

# if ENABLE_SHELL_ASH || ENABLE_SHELL_HUSH
        home = state && state->sh_get_var ? state->sh_get_var("HOME") : getenv("HOME");
# else
        home = getenv("HOME");
# endif
        if (home != NULL && home[0] != '\0')
                return home;

        if (!got_user_strings)
                get_user_strings();
        return home_pwd_buf;
}
#endif

#if ENABLE_FEATURE_EDITING_FANCY_PROMPT
static const char *get_username_str(void)
{
        if (!got_user_strings)
                get_user_strings();
        return user_buf ? user_buf : "";
        /* btw, bash uses "I have no name!" string if uid has no entry */
}
#endif

#if ENABLE_UNICODE_SUPPORT
static size_t load_string(const char *src)
{
        if (unicode_status == UNICODE_ON) {
                ssize_t len = mbstowcs(command_ps, src, S.maxsize - 1);
                if (len < 0)
                        len = 0;
                command_ps[len] = BB_NUL;
                return len;
        } else {
                unsigned i = 0;
                while (src[i] && i < S.maxsize - 1) {
                        command_ps[i] = src[i];
                        i++;
                }
                command_ps[i] = BB_NUL;
                return i;
        }
}
static unsigned save_string(char *dst, unsigned maxsize)
{
        if (unicode_status == UNICODE_ON) {
# if !ENABLE_UNICODE_PRESERVE_BROKEN
                ssize_t len = wcstombs(dst, command_ps, maxsize - 1);
                if (len < 0)
                        len = 0;
                dst[len] = '\0';
                return len;
# else
                unsigned dstpos = 0;
                unsigned srcpos = 0;

                maxsize--;
                while (dstpos < maxsize) {
                        wchar_t wc;
                        int n = srcpos;

                        /* Convert up to 1st invalid byte (or up to end) */
                        while ((wc = command_ps[srcpos]) != BB_NUL
                            && !unicode_is_raw_byte(wc)
                        ) {
                                srcpos++;
                        }
                        command_ps[srcpos] = BB_NUL;
                        n = wcstombs(dst + dstpos, command_ps + n, maxsize - dstpos);
                        if (n < 0) /* should not happen */
                                break;
                        dstpos += n;
                        if (wc == BB_NUL) /* usually is */
                                break;

                        /* We do have invalid byte here! */
                        command_ps[srcpos] = wc; /* restore it */
                        srcpos++;
                        if (dstpos == maxsize)
                                break;
                        dst[dstpos++] = (char) wc;
                }
                dst[dstpos] = '\0';
                return dstpos;
# endif
        } else {
                unsigned i = 0;
                while ((dst[i] = command_ps[i]) != 0)
                        i++;
                return i;
        }
}
/* I thought just fputwc(c, stderr) would work. But no... */
static void BB_PUTCHAR(wchar_t c)
{
        if (unicode_status == UNICODE_ON) {
                char buf[MB_CUR_MAX + 1];
                mbstate_t mbst = { 0 };
                ssize_t len = wcrtomb(buf, c, &mbst);
                if (len > 0) {
                        buf[len] = '\0';
                        fputs(buf, stderr);
                }
        } else {
                /* In this case, c is always one byte */
                bb_putchar_stderr(c);
        }
}
# if ENABLE_UNICODE_COMBINING_WCHARS || ENABLE_UNICODE_WIDE_WCHARS
static wchar_t adjust_width_and_validate_wc(unsigned *width_adj, wchar_t wc)
# else
static wchar_t adjust_width_and_validate_wc(wchar_t wc)
#  define adjust_width_and_validate_wc(width_adj, wc) \
        ((*(width_adj))++, adjust_width_and_validate_wc(wc))
# endif
{
        int w = 1;

        if (unicode_status == UNICODE_ON) {
                if (wc > CONFIG_LAST_SUPPORTED_WCHAR) {
                        /* note: also true for unicode_is_raw_byte(wc) */
                        goto subst;
                }
                w = wcwidth(wc);
                if ((ENABLE_UNICODE_COMBINING_WCHARS && w < 0)
                 || (!ENABLE_UNICODE_COMBINING_WCHARS && w <= 0)
                 || (!ENABLE_UNICODE_WIDE_WCHARS && w > 1)
                ) {
 subst:
                        w = 1;
                        wc = CONFIG_SUBST_WCHAR;
                }
        }

# if ENABLE_UNICODE_COMBINING_WCHARS || ENABLE_UNICODE_WIDE_WCHARS
        *width_adj += w;
#endif
        return wc;
}
#else /* !UNICODE */
static size_t load_string(const char *src)
{
        safe_strncpy(command_ps, src, S.maxsize);
        return strlen(command_ps);
}
# if ENABLE_FEATURE_TAB_COMPLETION
static void save_string(char *dst, unsigned maxsize)
{
        safe_strncpy(dst, command_ps, maxsize);
}
# endif
# define BB_PUTCHAR(c) bb_putchar_stderr(c)
/* Should never be called: */
int adjust_width_and_validate_wc(unsigned *width_adj, int wc);
#endif


/* Put 'command_ps[cursor]', cursor++.
 * Advance cursor on screen. If we reached right margin, scroll text up
 * and remove terminal margin effect by printing 'next_char' */
#define HACK_FOR_WRONG_WIDTH 1
static void put_cur_glyph_and_inc_cursor(void)
{
        CHAR_T c = command_ps[cursor];
        unsigned width = 0;
        int ofs_to_right;

        if (c == BB_NUL) {
                /* erase character after end of input string */
                c = ' ';
        } else {
                /* advance cursor only if we aren't at the end yet */
                cursor++;
                if (unicode_status == UNICODE_ON) {
                        IF_UNICODE_WIDE_WCHARS(width = cmdedit_x;)
                        c = adjust_width_and_validate_wc(&cmdedit_x, c);
                        IF_UNICODE_WIDE_WCHARS(width = cmdedit_x - width;)
                } else {
                        cmdedit_x++;
                }
        }

        ofs_to_right = cmdedit_x - cmdedit_termw;
        if (!ENABLE_UNICODE_WIDE_WCHARS || ofs_to_right <= 0) {
                /* c fits on this line */
                BB_PUTCHAR(c);
        }

        if (ofs_to_right >= 0) {
                /* we go to the next line */
#if HACK_FOR_WRONG_WIDTH
                /* This works better if our idea of term width is wrong
                 * and it is actually wider (often happens on serial lines).
                 * Printing CR,LF *forces* cursor to next line.
                 * OTOH if terminal width is correct AND terminal does NOT
                 * have automargin (IOW: it is moving cursor to next line
                 * by itself (which is wrong for VT-10x terminals)),
                 * this will break things: there will be one extra empty line */
                puts("\r"); /* + implicit '\n' */
#else
                /* VT-10x terminals don't wrap cursor to next line when last char
                 * on the line is printed - cursor stays "over" this char.
                 * Need to print _next_ char too (first one to appear on next line)
                 * to make cursor move down to next line.
                 */
                /* Works ok only if cmdedit_termw is correct. */
                c = command_ps[cursor];
                if (c == BB_NUL)
                        c = ' ';
                BB_PUTCHAR(c);
                bb_putchar_stderr('\b');
#endif
                cmdedit_y++;
                if (!ENABLE_UNICODE_WIDE_WCHARS || ofs_to_right == 0) {
                        width = 0;
                } else { /* ofs_to_right > 0 */
                        /* wide char c didn't fit on prev line */
                        BB_PUTCHAR(c);
                }
                cmdedit_x = width;
        }
}

/* Move to end of line (by printing all chars till the end) */
static void put_till_end_and_adv_cursor(void)
{
        while (cursor < command_len)
                put_cur_glyph_and_inc_cursor();
}

/* Go to the next line */
static void goto_new_line(void)
{
        put_till_end_and_adv_cursor();
        /* "cursor == 0" is only if prompt is "" and user input is empty */
        if (cursor == 0 || cmdedit_x != 0)
                bb_putchar_stderr('\n');
}

static void beep(void)
{
        bb_putchar_stderr('\007');
}

/* Full or last/sole prompt line, reset edit cursor, calculate terminal cursor.
 * cmdedit_y is always calculated for the last/sole prompt line.
 */
static void put_prompt_custom(bool is_full)
{
        /* https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
         * says that shells must write $PSn to stderr, not stdout.
         */
        fputs((is_full ? cmdedit_prompt : prompt_last_line), stderr);
        cursor = 0;
        cmdedit_y = cmdedit_prmt_len / cmdedit_termw; /* new quasireal y */
        cmdedit_x = cmdedit_prmt_len % cmdedit_termw;
}

#define put_prompt_last_line() put_prompt_custom(0)
#define put_prompt()           put_prompt_custom(1)

/* Move back one character */
/* (optimized for slow terminals) */
static void input_backward(unsigned num)
{
        if (num > cursor)
                num = cursor;
        if (num == 0)
                return;
        cursor -= num;

        if ((ENABLE_UNICODE_COMBINING_WCHARS || ENABLE_UNICODE_WIDE_WCHARS)
         && unicode_status == UNICODE_ON
        ) {
                /* correct NUM to be equal to _screen_ width */
                int n = num;
                num = 0;
                while (--n >= 0)
                        adjust_width_and_validate_wc(&num, command_ps[cursor + n]);
                if (num == 0)
                        return;
        }

        if (cmdedit_x >= num) {
                cmdedit_x -= num;
                if (num <= 4) {
                        /* This is longer by 5 bytes on x86.
                         * Also gets miscompiled for ARM users
                         * (busybox.net/bugs/view.php?id=2274).
                         * fprintf(("\b\b\b\b" + 4) - num, stderr);
                         * return;
                         */
                        do {
                                bb_putchar_stderr('\b');
                        } while (--num);
                        return;
                }
                fprintf(stderr, ESC"[%uD", num);
                return;
        }

        /* Need to go one or more lines up */
        if (ENABLE_UNICODE_WIDE_WCHARS) {
                /* With wide chars, it is hard to "backtrack"
                 * and reliably figure out where to put cursor.
                 * Example (<> is a wide char; # is an ordinary char, _ cursor):
                 * |prompt: <><> |
                 * |<><><><><><> |
                 * |_            |
                 * and user presses left arrow. num = 1, cmdedit_x = 0,
                 * We need to go up one line, and then - how do we know that
                 * we need to go *10* positions to the right? Because
                 * |prompt: <>#<>|
                 * |<><><>#<><><>|
                 * |_            |
                 * in this situation we need to go *11* positions to the right.
                 *
                 * A simpler thing to do is to redraw everything from the start
                 * up to new cursor position (which is already known):
                 */
                unsigned sv_cursor;
                /* go to 1st column; go up to first line */
                fprintf(stderr, "\r" ESC"[%uA", cmdedit_y);
                cmdedit_y = 0;
                sv_cursor = cursor;
                put_prompt_last_line(); /* sets cursor to 0 */
                while (cursor < sv_cursor)
                        put_cur_glyph_and_inc_cursor();
        } else {
                int lines_up;
                /* num = chars to go back from the beginning of current line: */
                num -= cmdedit_x;
                /* num=1...w: one line up, w+1...2w: two, etc: */
                lines_up = 1 + (num - 1) / cmdedit_termw;
                cmdedit_x = (cmdedit_termw * cmdedit_y - num) % cmdedit_termw;
                cmdedit_y -= lines_up;
                /* go to 1st column; go up */
                fprintf(stderr, "\r" ESC"[%uA", lines_up);
                /* go to correct column.
                 * xterm, konsole, Linux VT interpret 0 as 1 below! wow.
                 * need to *make sure* we skip it if cmdedit_x == 0 */
                if (cmdedit_x)
                        fprintf(stderr, ESC"[%uC", cmdedit_x);
        }
}

/* See redraw and draw_full below */
static void draw_custom(int y, int back_cursor, bool is_full)
{
        if (y > 0) /* up y lines */
                fprintf(stderr, ESC"[%uA", y);
        bb_putchar_stderr('\r');
        put_prompt_custom(is_full);
        put_till_end_and_adv_cursor();
        fputs(SEQ_CLEAR_TILL_END_OF_SCREEN, stderr);
        input_backward(back_cursor);
}

/* Move y lines up, draw last/sole prompt line, editor line[s], and clear tail.
 * goal: redraw the prompt+input+cursor in-place, overwriting the previous */
#define redraw(y, back_cursor) draw_custom((y), (back_cursor), 0)

/* Like above, but without moving up, and while using all the prompt lines.
 * goal: draw a full prompt+input+cursor unrelated to a previous position.
 * note: cmdedit_y always ends up relating to the last/sole prompt line */
#define draw_full(back_cursor) draw_custom(0, (back_cursor), 1)

/* Delete the char in front of the cursor, optionally saving it
 * for later putback */
#if !ENABLE_FEATURE_EDITING_VI
static void input_delete(void)
#define input_delete(save) input_delete()
#else
static void input_delete(int save)
#endif
{
        int j = cursor;

        if (j == (int)command_len)
                return;

#if ENABLE_FEATURE_EDITING_VI
        if (save) {
                if (newdelflag) {
                        delptr = delbuf;
                        newdelflag = 0;
                }
                if ((delptr - delbuf) < DELBUFSIZ)
                        *delptr++ = command_ps[j];
        }
#endif

        memmove(command_ps + j, command_ps + j + 1,
                        /* (command_len + 1 [because of NUL]) - (j + 1)
                         * simplified into (command_len - j) */
                        (command_len - j) * sizeof(command_ps[0]));
        command_len--;
        put_till_end_and_adv_cursor();
        /* Last char is still visible, erase it (and more) */
        fputs(SEQ_CLEAR_TILL_END_OF_SCREEN, stderr);
        input_backward(cursor - j);     /* back to old pos cursor */
}

#if ENABLE_FEATURE_EDITING_VI
static void put(void)
{
        int ocursor;
        int j = delptr - delbuf;

        if (j == 0)
                return;
        ocursor = cursor;
        /* open hole and then fill it */
        memmove(command_ps + cursor + j, command_ps + cursor,
                        (command_len - cursor + 1) * sizeof(command_ps[0]));
        memcpy(command_ps + cursor, delbuf, j * sizeof(command_ps[0]));
        command_len += j;
        put_till_end_and_adv_cursor();
        input_backward(cursor - ocursor - j + 1); /* at end of new text */
}
#endif

/* Delete the char in back of the cursor */
static void input_backspace(void)
{
        if (cursor > 0) {
                input_backward(1);
                input_delete(0);
        }
}

/* Move forward one character */
static void input_forward(void)
{
        if (cursor < command_len)
                put_cur_glyph_and_inc_cursor();
}

#if ENABLE_FEATURE_TAB_COMPLETION

//FIXME:
//needs to be more clever: currently it thinks that "foo\ b<TAB>
//matches the file named "foo bar", which is untrue.
//Also, perhaps "foo b<TAB> needs to complete to "foo bar" <cursor>,
//not "foo bar <cursor>...

static void free_tab_completion_data(void)
{
        if (matches) {
                while (num_matches)
                        free(matches[--num_matches]);
                free(matches);
                matches = NULL;
        }
}

static void add_match(char *matched)
{
        unsigned char *p = (unsigned char*)matched;
        while (*p) {
                /* ESC attack fix: drop any string with control chars */
                if (*p < ' '
                 || (!ENABLE_UNICODE_SUPPORT && *p >= 0x7f)
                 || (ENABLE_UNICODE_SUPPORT && *p == 0x7f)
                ) {
                        free(matched);
                        return;
                }
                p++;
        }
        matches = xrealloc_vector(matches, 4, num_matches);
        matches[num_matches] = matched;
        num_matches++;
}

# if ENABLE_FEATURE_USERNAME_COMPLETION
/* Replace "~user/..." with "/homedir/...".
 * The parameter is malloced, free it or return it
 * unchanged if no user is matched.
 */
static char *username_path_completion(char *ud)
{
        struct passwd *entry;
        char *tilde_name = ud;
        const char *home = NULL;

        ud++; /* skip ~ */
        if (*ud == '/') {       /* "~/..." */
                home = get_homedir_or_NULL();
        } else {
                /* "~user/..." */
                ud = strchr(ud, '/');
                *ud = '\0';           /* "~user" */
                entry = getpwnam(tilde_name + 1);
                *ud = '/';            /* restore "~user/..." */
                if (entry)
                        home = entry->pw_dir;
        }
        if (home) {
                ud = concat_path_file(home, ud);
                free(tilde_name);
                tilde_name = ud;
        }
        return tilde_name;
}

/* ~use<tab> - find all users with this prefix.
 * Return the length of the prefix used for matching.
 */
static NOINLINE unsigned complete_username(const char *ud)
{
        struct passwd *pw;
        unsigned userlen;

        ud++; /* skip ~ */
        userlen = strlen(ud);

        setpwent();
        while ((pw = getpwent()) != NULL) {
                /* Null usernames should result in all users as possible completions. */
                if (/* !ud[0] || */ is_prefixed_with(pw->pw_name, ud)) {
                        add_match(xasprintf("~%s/", pw->pw_name));
                }
        }
        endpwent(); /* don't keep password file open */

        return 1 + userlen;
}
# endif  /* FEATURE_USERNAME_COMPLETION */

enum {
        FIND_EXE_ONLY = 0,
        FIND_DIR_ONLY = 1,
        FIND_FILE_ONLY = 2,
};

static unsigned path_parse(char ***p)
{
        unsigned npth;
        const char *pth;
        char *tmp;
        char **res;

# if EDITING_HAS_path_lookup
        if (state->flags & WITH_PATH_LOOKUP)
                pth = state->path_lookup;
        else
# endif
                pth = getenv("PATH");

        /* PATH="" or PATH=":"? */
        if (!pth || !pth[0] || LONE_CHAR(pth, ':'))
                return 1;

        tmp = (char*)pth;
        npth = 1; /* path component count */
        while (1) {
                tmp = strchr(tmp, ':');
                if (!tmp)
                        break;
                tmp++;
                npth++;
        }

        *p = res = xzalloc((npth + 1) * sizeof(res[0]));
        res[0] = tmp = xstrdup(pth);
        npth = 1;
        while (1) {
                tmp = strchr(tmp, ':');
                if (!tmp)
                        break;
                *tmp++ = '\0'; /* ':' -> '\0' */
                res[npth++] = tmp;
        }
        /* special case: "match subdirectories of the current directory" */
        /*res[npth] = NULL; - filled by xzalloc() */
        return npth + 1;
}

/* Complete command, directory or file name.
 * Return the length of the prefix used for matching.
 */
static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
{
        char *path1[1];
        char **paths = path1;
        unsigned npaths;
        unsigned i;
        unsigned baselen;
        const char *basecmd;
        char *dirbuf = NULL;

        npaths = 1;
        path1[0] = (char*)".";

        basecmd = strrchr(command, '/');
        if (!basecmd) {
                if (type == FIND_EXE_ONLY)
                        npaths = path_parse(&paths);
                basecmd = command;
        } else {
                /* point to 'l' in "..../last_component" */
                basecmd++;
                /* dirbuf = ".../.../.../" */
                dirbuf = xstrndup(command, basecmd - command);
# if ENABLE_FEATURE_USERNAME_COMPLETION
                if (dirbuf[0] == '~')   /* ~/... or ~user/... */
                        dirbuf = username_path_completion(dirbuf);
# endif
                path1[0] = dirbuf;
        }
        baselen = strlen(basecmd);

        if (type == FIND_EXE_ONLY && !dirbuf) {
# if ENABLE_FEATURE_SH_STANDALONE && NUM_APPLETS != 1
                const char *p = applet_names;
                while (*p) {
                        if (strncmp(basecmd, p, baselen) == 0)
                                add_match(xstrdup(p));
                        while (*p++ != '\0')
                                continue;
                }
# endif
# if ENABLE_SHELL_ASH || ENABLE_SHELL_HUSH
                if (state->get_exe_name) {
                        i = 0;
                        for (;;) {
                                const char *b = state->get_exe_name(i++);
                                if (!b)
                                        break;
                                if (strncmp(basecmd, b, baselen) == 0)
                                        add_match(xstrdup(b));
                        }
                }
# endif
        }

        for (i = 0; i < npaths; i++) {
                DIR *dir;
                struct dirent *next;
                struct stat st;
                char *found;
                const char *lpath;

                if (paths[i] == NULL) { /* path_parse()'s last component? */
                        /* in PATH completion, current dir's subdir names
                         * can be completions (but only subdirs, not files).
                         */
                        type = FIND_DIR_ONLY;
                        paths[i] = (char *)".";
                }

                lpath = *paths[i] ? paths[i] : ".";
                dir = opendir(lpath);
                if (!dir)
                        continue; /* don't print an error */

                while ((next = readdir(dir)) != NULL) {
                        unsigned len;
                        const char *name_found = next->d_name;

                        /* .../<tab>: bash 3.2.0 shows dotfiles, but not . and .. */
                        if (!basecmd[0] && DOT_OR_DOTDOT(name_found))
                                continue;
                        /* match? */
                        if (strncmp(basecmd, name_found, baselen) != 0)
                                continue; /* no */

                        found = concat_path_file(lpath, name_found);
                        /* NB: stat() first so that we see is it a directory;
                         * but if that fails, use lstat() so that
                         * we still match dangling links */
                        if (stat(found, &st) && lstat(found, &st))
                                goto cont; /* hmm, remove in progress? */

                        /* Save only name */
                        len = strlen(name_found);
                        found = xrealloc(found, len + 2); /* +2: for slash and NUL */
                        strcpy(found, name_found);

                        if (S_ISDIR(st.st_mode)) {
                                /* skip directories if searching PATH */
                                if (type == FIND_EXE_ONLY && !dirbuf)
                                        goto cont;
                                /* name is a directory, add slash */
                                found[len] = '/';
                                found[len + 1] = '\0';
                        } else {
                                /* skip files if looking for dirs only (example: cd) */
                                if (type == FIND_DIR_ONLY)
                                        goto cont;
                        }
                        /* add it to the list */
                        add_match(found);
                        continue;
 cont:
                        free(found);
                }
                closedir(dir);
        } /* for every path */

        if (paths != path1) {
                free(paths[0]); /* allocated memory is only in first member */
                free(paths);
        }
        free(dirbuf);

        return baselen;
}

/* build_match_prefix:
 * On entry, match_buf contains everything up to cursor at the moment <tab>
 * was pressed. This function looks at it, figures out what part of it
 * constitutes the command/file/directory prefix to use for completion,
 * and rewrites match_buf to contain only that part.
 */
#define dbg_bmp 0
/* Helpers: */
/* QUOT is used on elements of int_buf[], which are bytes,
 * not Unicode chars. Therefore it works correctly even in Unicode mode.
 */
#define QUOT (UCHAR_MAX+1)
static void remove_chunk(int16_t *int_buf, int beg, int end)
{
        /* beg must be <= end */
        if (beg == end)
                return;

        while ((int_buf[beg] = int_buf[end]) != 0)
                beg++, end++;

        if (dbg_bmp) {
                int i;
                for (i = 0; int_buf[i]; i++)
                        bb_putchar_stderr((unsigned char)int_buf[i]);
                bb_putchar_stderr('\n');
        }
}
/* Caller ensures that match_buf points to a malloced buffer
 * big enough to hold strlen(match_buf)*2 + 2
 */
static NOINLINE int build_match_prefix(char *match_buf)
{
        int i, j;
        int command_mode;

        int16_t *int_buf = (int16_t*)match_buf;

        if (dbg_bmp) printf("\n%s\n", match_buf);

        /* Copy in reverse order, since they overlap */
        i = strlen(match_buf);
        do {
                int_buf[i] = (unsigned char)match_buf[i];
                i--;
        } while (i >= 0);

        /* Mark every \c as "quoted c" */
        for (i = 0; int_buf[i]; i++) {
                if (int_buf[i] == '\\') {
                        remove_chunk(int_buf, i, i + 1);
                        int_buf[i] |= QUOT;
                }
        }
        /* Quote-mark "chars" and 'chars', drop delimiters */
        {
                int in_quote = 0;
                i = 0;
                while (int_buf[i]) {
                        int cur = int_buf[i];
                        if (!cur)
                                break;
                        if (cur == '\'' || cur == '"') {
                                if (!in_quote || (cur == in_quote)) {
                                        in_quote ^= cur;
                                        remove_chunk(int_buf, i, i + 1);
                                        continue;
                                }
                        }
                        if (in_quote)
                                int_buf[i] = cur | QUOT;
                        i++;
                }
        }

        /* Remove everything up to command delimiters:
         * ';' ';;' '&' '|' '&&' '||',
         * but careful with '>&' '<&' '>|'
         */
        for (i = 0; int_buf[i]; i++) {
                int cur = int_buf[i];
                if (cur == ';' || cur == '&' || cur == '|') {
                        int prev = i ? int_buf[i - 1] : 0;
                        if (cur == '&' && (prev == '>' || prev == '<')) {
                                continue;
                        } else if (cur == '|' && prev == '>') {
                                continue;
                        }
                        remove_chunk(int_buf, 0, i + 1 + (cur == int_buf[i + 1]));
                        i = -1;  /* back to square 1 */
                }
        }
        /* Remove all `cmd` */
        for (i = 0; int_buf[i]; i++) {
                if (int_buf[i] == '`') {
                        for (j = i + 1; int_buf[j]; j++) {
                                if (int_buf[j] == '`') {
                                        /* `cmd` should count as a word:
                                         * `cmd` c<tab> should search for files c*,
                                         * not commands c*. Therefore we don't drop
                                         * `cmd` entirely, we replace it with single `.
                                         */
                                        remove_chunk(int_buf, i, j);
                                        goto next;
                                }
                        }
                        /* No closing ` - command mode, remove all up to ` */
                        remove_chunk(int_buf, 0, i + 1);
                        break;
 next: ;
                }
        }

        /* Remove "cmd (" and "cmd {"
         * Example: "if { c<tab>"
         * In this example, c should be matched as command pfx.
         */
        for (i = 0; int_buf[i]; i++) {
                if (int_buf[i] == '(' || int_buf[i] == '{') {
                        remove_chunk(int_buf, 0, i + 1);
                        i = -1;  /* back to square 1 */
                }
        }

        /* Remove leading unquoted spaces */
        for (i = 0; int_buf[i]; i++)
                if (int_buf[i] != ' ')
                        break;
        remove_chunk(int_buf, 0, i);

        /* Determine completion mode */
        command_mode = FIND_EXE_ONLY;
        for (i = 0; int_buf[i]; i++) {
                if (int_buf[i] == ' ' || int_buf[i] == '<' || int_buf[i] == '>') {
                        if (int_buf[i] == ' '
                         && command_mode == FIND_EXE_ONLY
                         && (char)int_buf[0] == 'c'
                         && (char)int_buf[1] == 'd'
                         && i == 2 /* -> int_buf[2] == ' ' */
                        ) {
                                command_mode = FIND_DIR_ONLY;
                        } else {
                                command_mode = FIND_FILE_ONLY;
                                break;
                        }
                }
        }
        if (dbg_bmp) printf("command_mode(0:exe/1:dir/2:file):%d\n", command_mode);

        /* Remove everything except last word */
        for (i = 0; int_buf[i]; i++) /* quasi-strlen(int_buf) */
                continue;
        for (--i; i >= 0; i--) {
                int cur = int_buf[i];
                if (cur == ' ' || cur == '<' || cur == '>' || cur == '|' || cur == '&' || cur == '=') {
                        remove_chunk(int_buf, 0, i + 1);
                        break;
                }
        }

        /* Convert back to string of _chars_ */
        i = 0;
        while ((match_buf[i] = int_buf[i]) != '\0')
                i++;

        if (dbg_bmp) printf("final match_buf:'%s'\n", match_buf);

        return command_mode;
}

/*
 * Display by column (original idea from ls applet,
 * very optimized by me [Vladimir] :)
 */
static void showfiles(void)
{
        int ncols, row;
        int column_width = 0;
        int nfiles = num_matches;
        int nrows = nfiles;
        int l;

        /* find the longest file name - use that as the column width */
        for (row = 0; row < nrows; row++) {
                l = unicode_strwidth(matches[row]);
                if (column_width < l)
                        column_width = l;
        }
        column_width += 2;              /* min space for columns */
        ncols = cmdedit_termw / column_width;

        if (ncols > 1) {
                nrows /= ncols;
                if (nfiles % ncols)
                        nrows++;        /* round up fractionals */
        } else {
                ncols = 1;
        }
        for (row = 0; row < nrows; row++) {
                int n = row;
                int nc;

                for (nc = 1; nc < ncols && n+nrows < nfiles; n += nrows, nc++) {
                        fprintf(stderr, "%s%-*s", matches[n],
                                (int)(column_width - unicode_strwidth(matches[n])), ""
                        );
                }
                if (ENABLE_UNICODE_SUPPORT)
                        puts(printable_string(matches[n]));
                else
                        puts(matches[n]);
        }
}

static const char *is_special_char(char c)
{
        // {: It's mandatory to escape { only if entire name is "{"
        // (otherwise it's not special. Example: file named "{ "
        // can be escaped simply as "{\ "; "{a" or "a{" need no escaping),
        // or if shell supports brace expansion
        // (ash doesn't, hush optionally does).
        // (): unlike {, shell treats () specially even in contexts
        // where they clearly are not valid (e.g. "echo )" is an error).
        // #: needs escaping to not start a shell comment.
        return strchr(" `'\"\\#$~?*[{()&;|<>", c);
        // Used to also have %^=+}]: but not necessary to escape?
}

static char *quote_special_chars(char *found)
{
        int l = 0;
        char *s = xzalloc((strlen(found) + 1) * 2);

        while (*found) {
                if (is_special_char(*found))
                        s[l++] = '\\';
                s[l++] = *found++;
        }
        /* s[l] = '\0'; - already is */
        return s;
}

/* Do TAB completion */
static NOINLINE void input_tab(smallint *lastWasTab)
{
        char *chosen_match;
        char *match_buf;
        size_t len_found;
        /* Length of string used for matching */
        unsigned match_pfx_len = match_pfx_len;
        int find_type;
# if ENABLE_UNICODE_SUPPORT
        /* cursor pos in command converted to multibyte form */
        int cursor_mb;
# endif
        if (!(state->flags & TAB_COMPLETION))
                return;

        if (*lastWasTab) {
                /* The last char was a TAB too.
                 * Print a list of all the available choices.
                 */
                if (num_matches > 0) {
                        /* cursor will be changed by goto_new_line() */
                        int sav_cursor = cursor;
                        goto_new_line();
                        showfiles();
                        draw_full(command_len - sav_cursor);
                }
                return;
        }

        *lastWasTab = 1;
        chosen_match = NULL;

        /* Make a local copy of the string up to the position of the cursor.
         * build_match_prefix will expand it into int16_t's, need to allocate
         * twice as much as the string_len+1.
         * (we then also (ab)use this extra space later - see (**))
         */
        match_buf = xmalloc(MAX_LINELEN * sizeof(int16_t));
# if !ENABLE_UNICODE_SUPPORT
        save_string(match_buf, cursor + 1); /* +1 for NUL */
# else
        {
                CHAR_T wc = command_ps[cursor];
                command_ps[cursor] = BB_NUL;
                save_string(match_buf, MAX_LINELEN);
                command_ps[cursor] = wc;
                cursor_mb = strlen(match_buf);
        }
# endif
        find_type = build_match_prefix(match_buf);

        /* Free up any memory already allocated */
        free_tab_completion_data();

# if ENABLE_FEATURE_USERNAME_COMPLETION
        /* If the word starts with ~ and there is no slash in the word,
         * then try completing this word as a username. */
        if (state->flags & USERNAME_COMPLETION)
                if (match_buf[0] == '~' && strchr(match_buf, '/') == NULL)
                        match_pfx_len = complete_username(match_buf);
# endif
        /* If complete_username() did not match,
         * try to match a command in $PATH, or a directory, or a file */
        if (!matches)
                match_pfx_len = complete_cmd_dir_file(match_buf, find_type);

        /* Account for backslashes which will be inserted
         * by quote_special_chars() later */
        {
                const char *e = match_buf + strlen(match_buf);
                const char *s = e - match_pfx_len;
                while (s < e)
                        if (is_special_char(*s++))
                                match_pfx_len++;
        }

        /* Remove duplicates */
        if (matches) {
                unsigned i, n = 0;
                qsort_string_vector(matches, num_matches);
                for (i = 0; i < num_matches - 1; ++i) {
                        //if (matches[i] && matches[i+1]) { /* paranoia */
                                if (strcmp(matches[i], matches[i+1]) == 0) {
                                        free(matches[i]);
                                        //matches[i] = NULL; /* paranoia */
                                } else {
                                        matches[n++] = matches[i];
                                }
                        //}
                }
                matches[n++] = matches[i];
                num_matches = n;
        }

        /* Did we find exactly one match? */
        if (num_matches != 1) { /* no */
                char *cp;
                beep();
                if (!matches)
                        goto ret; /* no matches at all */
                /* Find common prefix */
                chosen_match = xstrdup(matches[0]);
                for (cp = chosen_match; *cp; cp++) {
                        unsigned n;
                        for (n = 1; n < num_matches; n++) {
                                if (matches[n][cp - chosen_match] != *cp) {
                                        goto stop;
                                }
                        }
                }
 stop:
                if (cp == chosen_match) { /* have unique prefix? */
                        goto ret; /* no */
                }
                *cp = '\0';
                cp = quote_special_chars(chosen_match);
                free(chosen_match);
                chosen_match = cp;
                len_found = strlen(chosen_match);
        } else {                        /* exactly one match */
                /* Next <tab> is not a double-tab */
                *lastWasTab = 0;

                chosen_match = quote_special_chars(matches[0]);
                len_found = strlen(chosen_match);
                if (chosen_match[len_found-1] != '/') {
                        chosen_match[len_found] = ' ';
                        chosen_match[++len_found] = '\0';
                }
        }

# if !ENABLE_UNICODE_SUPPORT
        /* Have space to place the match? */
        /* The result consists of three parts with these lengths: */
        /* cursor + (len_found - match_pfx_len) + (command_len - cursor) */
        /* it simplifies into: */
        if ((int)(len_found - match_pfx_len + command_len) < S.maxsize) {
                int pos;
                /* save tail */
                strcpy(match_buf, &command_ps[cursor]);
                /* add match and tail */
                sprintf(&command_ps[cursor], "%s%s", chosen_match + match_pfx_len, match_buf);
                command_len = strlen(command_ps);
                /* new pos */
                pos = cursor + len_found - match_pfx_len;
                /* write out the matched command */
                redraw(cmdedit_y, command_len - pos);
        }
# else
        {
                /* Use 2nd half of match_buf as scratch space - see (**) */
                char *command = match_buf + MAX_LINELEN;
                int len = save_string(command, MAX_LINELEN);
                /* Have space to place the match? */
                /* cursor_mb + (len_found - match_pfx_len) + (len - cursor_mb) */
                if ((int)(len_found - match_pfx_len + len) < MAX_LINELEN) {
                        int pos;
                        /* save tail */
                        strcpy(match_buf, &command[cursor_mb]);
                        /* where do we want to have cursor after all? */
                        strcpy(&command[cursor_mb], chosen_match + match_pfx_len);
                        len = load_string(command);
                        /* add match and tail */
                        stpcpy(stpcpy(&command[cursor_mb], chosen_match + match_pfx_len), match_buf);
                        command_len = load_string(command);
                        /* write out the matched command */
                        /* paranoia: load_string can return 0 on conv error,
                         * prevent passing pos = (0 - 12) to redraw */
                        pos = command_len - len;
                        redraw(cmdedit_y, pos >= 0 ? pos : 0);
                }
        }
# endif
 ret:
        free(chosen_match);
        free(match_buf);
}

#endif  /* FEATURE_TAB_COMPLETION */


line_input_t* FAST_FUNC new_line_input_t(int flags)
{
        line_input_t *n = xzalloc(sizeof(*n));
        n->flags = flags;
        n->timeout = -1;
#if MAX_HISTORY > 0
        n->max_history = MAX_HISTORY;
#endif
        return n;
}


#if MAX_HISTORY > 0

unsigned FAST_FUNC size_from_HISTFILESIZE(const char *hp)
{
        int size = MAX_HISTORY;
        if (hp) {
                size = atoi(hp);
                if (size <= 0)
                        return 1;
                if (size > MAX_HISTORY)
                        return MAX_HISTORY;
        }
        return size;
}

static void save_command_ps_at_cur_history(void)
{
        if (command_ps[0] != BB_NUL) {
                int cur = state->cur_history;
                free(state->history[cur]);

# if ENABLE_UNICODE_SUPPORT
                {
                        char tbuf[MAX_LINELEN];
                        save_string(tbuf, sizeof(tbuf));
                        state->history[cur] = xstrdup(tbuf);
                }
# else
                state->history[cur] = xstrdup(command_ps);
# endif
        }
}

/* state->flags is already checked to be nonzero */
static int get_previous_history(void)
{
        if ((state->flags & DO_HISTORY) && state->cur_history) {
                save_command_ps_at_cur_history();
                state->cur_history--;
                return 1;
        }
        beep();
        return 0;
}

static int get_next_history(void)
{
        if (state->flags & DO_HISTORY) {
                if (state->cur_history < state->cnt_history) {
                        save_command_ps_at_cur_history(); /* save the current history line */
                        return ++state->cur_history;
                }
        }
        beep();
        return 0;
}

/* Lists command history. Used by shell 'history' builtins */
void FAST_FUNC show_history(const line_input_t *st)
{
        int i;

        if (!st)
                return;
        for (i = 0; i < st->cnt_history; i++)
                fprintf(stderr, "%4d %s\n", i, st->history[i]);
}

# if ENABLE_FEATURE_EDITING_SAVEHISTORY
void FAST_FUNC free_line_input_t(line_input_t *n)
{
        if (n) {
                int i = n->cnt_history;
                while (i > 0)
                        free(n->history[--i]);
                free(n);
        }
}
# else
/* #defined to free() in libbb.h */
# endif

# if ENABLE_FEATURE_EDITING_SAVEHISTORY
/* We try to ensure that concurrent additions to the history
 * do not overwrite each other.
 * Otherwise shell users get unhappy.
 *
 * History file is trimmed lazily, when it grows several times longer
 * than configured MAX_HISTORY lines.
 */

/* state->flags is already checked to be nonzero */
static void load_history(line_input_t *st_parm)
{
        char *temp_h[MAX_HISTORY];
        char *line;
        FILE *fp;
        unsigned idx, i, line_len;

        /* NB: do not trash old history if file can't be opened */

        fp = fopen_for_read(st_parm->hist_file);
        if (fp) {
                /* clean up old history */
                for (idx = st_parm->cnt_history; idx > 0;) {
                        idx--;
                        free(st_parm->history[idx]);
                        st_parm->history[idx] = NULL;
                }

                /* fill temp_h[], retaining only last MAX_HISTORY lines */
                memset(temp_h, 0, sizeof(temp_h));
                idx = 0;
                st_parm->cnt_history_in_file = 0;
                while ((line = xmalloc_fgetline(fp)) != NULL) {
                        if (line[0] == '\0') {
                                free(line);
                                continue;
                        }
                        free(temp_h[idx]);
                        temp_h[idx] = line;
                        st_parm->cnt_history_in_file++;
                        idx++;
                        if (idx == st_parm->max_history)
                                idx = 0;
                }
                fclose(fp);

                /* find first non-NULL temp_h[], if any */
                if (st_parm->cnt_history_in_file) {
                        while (temp_h[idx] == NULL) {
                                idx++;
                                if (idx == st_parm->max_history)
                                        idx = 0;
                        }
                }

                /* copy temp_h[] to st_parm->history[] */
                for (i = 0; i < st_parm->max_history;) {
                        line = temp_h[idx];
                        if (!line)
                                break;
                        idx++;
                        if (idx == st_parm->max_history)
                                idx = 0;
                        line_len = strlen(line);
                        if (line_len >= MAX_LINELEN)
                                line[MAX_LINELEN-1] = '\0';
                        st_parm->history[i++] = line;
                }
                st_parm->cnt_history = i;
                if (ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
                        st_parm->cnt_history_in_file = i;
        }
}

#  if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
void save_history(line_input_t *st)
{
        FILE *fp;

        if (!st || !st->hist_file)
                return;
        if (st->cnt_history <= st->cnt_history_in_file)
                return;

        fp = fopen(st->hist_file, "a");
        if (fp) {
                int i, fd;
                char *new_name;
                line_input_t *st_temp;

                for (i = st->cnt_history_in_file; i < st->cnt_history; i++)
                        fprintf(fp, "%s\n", st->history[i]);
                fclose(fp);

                /* we may have concurrently written entries from others.
                 * load them */
                st_temp = new_line_input_t(st->flags);
                st_temp->hist_file = st->hist_file;
                st_temp->max_history = st->max_history;
                load_history(st_temp);

                /* write out temp file and replace hist_file atomically */
                new_name = xasprintf("%s.%u.new", st->hist_file, (int) getpid());
                fd = open(new_name, O_WRONLY | O_CREAT | O_TRUNC, 0600);
                if (fd >= 0) {
                        fp = xfdopen_for_write(fd);
                        for (i = 0; i < st_temp->cnt_history; i++)
                                fprintf(fp, "%s\n", st_temp->history[i]);
                        fclose(fp);
                        if (rename(new_name, st->hist_file) == 0)
                                st->cnt_history_in_file = st_temp->cnt_history;
                }
                free(new_name);
                free_line_input_t(st_temp);
        }
}
#  else
static void save_history(char *str)
{
        int fd;
        int len, len2;

        if (!state->hist_file)
                return;

        fd = open(state->hist_file, O_WRONLY | O_CREAT | O_APPEND, 0600);
        if (fd < 0)
                return;
        xlseek(fd, 0, SEEK_END); /* paranoia */
        len = strlen(str);
        str[len] = '\n'; /* we (try to) do atomic write */
        len2 = full_write(fd, str, len + 1);
        str[len] = '\0';
        close(fd);
        if (len2 != len + 1)
                return; /* "wtf?" */

        /* did we write so much that history file needs trimming? */
        state->cnt_history_in_file++;
        if (state->cnt_history_in_file > state->max_history * 4) {
                char *new_name;
                line_input_t *st_temp;

                /* we may have concurrently written entries from others.
                 * load them */
                st_temp = new_line_input_t(state->flags);
                st_temp->hist_file = state->hist_file;
                st_temp->max_history = state->max_history;
                load_history(st_temp);

                /* write out temp file and replace hist_file atomically */
                new_name = xasprintf("%s.%u.new", state->hist_file, (int) getpid());
                fd = open(new_name, O_WRONLY | O_CREAT | O_TRUNC, 0600);
                if (fd >= 0) {
                        FILE *fp;
                        int i;

                        fp = xfdopen_for_write(fd);
                        for (i = 0; i < st_temp->cnt_history; i++)
                                fprintf(fp, "%s\n", st_temp->history[i]);
                        fclose(fp);
                        if (rename(new_name, state->hist_file) == 0)
                                state->cnt_history_in_file = st_temp->cnt_history;
                }
                free(new_name);
                free_line_input_t(st_temp);
        }
}
#  endif
# else
#  define load_history(a) ((void)0)
#  define save_history(a) ((void)0)
# endif /* FEATURE_COMMAND_SAVEHISTORY */

static void remember_in_history(char *str)
{
        int i;

        if (!(state->flags & DO_HISTORY))
                return;
        if (str[0] == '\0')
                return;
        i = state->cnt_history;
        /* Don't save dupes */
        if (i && strcmp(state->history[i-1], str) == 0)
                return;

        free(state->history[state->max_history]); /* redundant, paranoia */
        state->history[state->max_history] = NULL; /* redundant, paranoia */

        /* If history[] is full, remove the oldest command */
        /* we need to keep history[state->max_history] empty, hence >=, not > */
        if (i >= state->max_history) {
                free(state->history[0]);
                for (i = 0; i < state->max_history-1; i++)
                        state->history[i] = state->history[i+1];
                /* i == state->max_history-1 */
# if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
                if (state->cnt_history_in_file)
                        state->cnt_history_in_file--;
# endif
        }
        /* i <= state->max_history-1 */
        state->history[i++] = xstrdup(str);
        /* i <= state->max_history */
        state->cur_history = i;
        state->cnt_history = i;
# if ENABLE_FEATURE_EDITING_SAVEHISTORY && !ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
        save_history(str);
# endif
}

#else /* MAX_HISTORY == 0 */
# define remember_in_history(a) ((void)0)
#endif /* MAX_HISTORY */


#if ENABLE_FEATURE_EDITING_VI
/*
 * vi mode implemented 2005 by Paul Fox <pgf@foxharp.boston.ma.us>
 */
static void
vi_Word_motion(int eat)
{
        CHAR_T *command = command_ps;

        while (cursor < command_len && !BB_isspace(command[cursor]))
                input_forward();
        if (eat) while (cursor < command_len && BB_isspace(command[cursor]))
                input_forward();
}

static void
vi_word_motion(int eat)
{
        CHAR_T *command = command_ps;

        if (BB_isalnum_or_underscore(command[cursor])) {
                while (cursor < command_len
                 && (BB_isalnum_or_underscore(command[cursor+1]))
                ) {
                        input_forward();
                }
        } else if (BB_ispunct(command[cursor])) {
                while (cursor < command_len && BB_ispunct(command[cursor+1]))
                        input_forward();
        }

        if (cursor < command_len)
                input_forward();

        if (eat) {
                while (cursor < command_len && BB_isspace(command[cursor]))
                        input_forward();
        }
}

static void
vi_End_motion(void)
{
        CHAR_T *command = command_ps;

        input_forward();
        while (cursor < command_len && BB_isspace(command[cursor]))
                input_forward();
        while (cursor < command_len-1 && !BB_isspace(command[cursor+1]))
                input_forward();
}

static void
vi_end_motion(void)
{
        CHAR_T *command = command_ps;

        if (cursor >= command_len-1)
                return;
        input_forward();
        while (cursor < command_len-1 && BB_isspace(command[cursor]))
                input_forward();
        if (cursor >= command_len-1)
                return;
        if (BB_isalnum_or_underscore(command[cursor])) {
                while (cursor < command_len-1
                 && (BB_isalnum_or_underscore(command[cursor+1]))
                ) {
                        input_forward();
                }
        } else if (BB_ispunct(command[cursor])) {
                while (cursor < command_len-1 && BB_ispunct(command[cursor+1]))
                        input_forward();
        }
}

static void
vi_Back_motion(void)
{
        CHAR_T *command = command_ps;

        while (cursor > 0 && BB_isspace(command[cursor-1]))
                input_backward(1);
        while (cursor > 0 && !BB_isspace(command[cursor-1]))
                input_backward(1);
}

static void
vi_back_motion(void)
{
        CHAR_T *command = command_ps;

        if (cursor <= 0)
                return;
        input_backward(1);
        while (cursor > 0 && BB_isspace(command[cursor]))
                input_backward(1);
        if (cursor <= 0)
                return;
        if (BB_isalnum_or_underscore(command[cursor])) {
                while (cursor > 0
                 && (BB_isalnum_or_underscore(command[cursor-1]))
                ) {
                        input_backward(1);
                }
        } else if (BB_ispunct(command[cursor])) {
                while (cursor > 0 && BB_ispunct(command[cursor-1]))
                        input_backward(1);
        }
}
#endif /* ENABLE_FEATURE_EDITING_VI */

/* Modelled after bash 4.0 behavior of Ctrl-<arrow> */
static void ctrl_left(void)
{
        CHAR_T *command = command_ps;

        while (1) {
                CHAR_T c;

                input_backward(1);
                if (cursor == 0)
                        break;
                c = command[cursor];
                if (c != ' ' && !BB_ispunct(c)) {
                        /* we reached a "word" delimited by spaces/punct.
                         * go to its beginning */
                        while (1) {
                                c = command[cursor - 1];
                                if (c == ' ' || BB_ispunct(c))
                                        break;
                                input_backward(1);
                                if (cursor == 0)
                                        break;
                        }
                        break;
                }
        }
}
static void ctrl_right(void)
{
        CHAR_T *command = command_ps;

        while (1) {
                CHAR_T c;

                c = command[cursor];
                if (c == BB_NUL)
                        break;
                if (c != ' ' && !BB_ispunct(c)) {
                        /* we reached a "word" delimited by spaces/punct.
                         * go to its end + 1 */
                        while (1) {
                                input_forward();
                                c = command[cursor];
                                if (c == BB_NUL || c == ' ' || BB_ispunct(c))
                                        break;
                        }
                        break;
                }
                input_forward();
        }
}


/*
 * read_line_input and its helpers
 */

#if ENABLE_FEATURE_EDITING_ASK_TERMINAL
static void ask_terminal(void)
{
        /* Ask terminal where is the cursor now.
         * lineedit_read_key handles response and corrects
         * our idea of current cursor position.
         * Testcase: run "echo -n long_line_long_line_long_line",
         * then type in a long, wrapping command and try to
         * delete it using backspace key.
         * Note: we print it _after_ prompt, because
         * prompt may contain CR. Example: PS1='\[\r\n\]\w '
         */
        /* Problem: if there is buffered input on stdin,
         * the response will be delivered later,
         * possibly to an unsuspecting application.
         * Testcase: "sleep 1; busybox ash" + press and hold [Enter].
         * Result:
         * ~/srcdevel/bbox/fix/busybox.t4 #
         * ~/srcdevel/bbox/fix/busybox.t4 #
         * ^[[59;34~/srcdevel/bbox/fix/busybox.t4 #  <-- garbage
         * ~/srcdevel/bbox/fix/busybox.t4 #
         *
         * Checking for input with poll only makes the race narrower,
         * I still can trigger it. Strace:
         *
         * write(1, "~/srcdevel/bbox/fix/busybox.t4 # ", 33) = 33
         * poll([{fd=0, events=POLLIN}], 1, 0) = 0 (Timeout)  <-- no input exists
         * write(1, "\33[6n", 4) = 4  <-- send the ESC sequence, quick!
         * poll([{fd=0, events=POLLIN}], 1, -1) = 1 ([{fd=0, revents=POLLIN}])
         * read(0, "\n", 1)      = 1  <-- oh crap, user's input got in first
         */
        struct pollfd pfd;

        pfd.fd = STDIN_FILENO;
        pfd.events = POLLIN;
        if (safe_poll(&pfd, 1, 0) == 0) {
                S.sent_ESC_br6n = 1;
                fputs(ESC"[6n", stderr);
                fflush_all(); /* make terminal see it ASAP! */
        }
}
#else
# define ask_terminal() ((void)0)
#endif

/* Note about multi-line PS1 (e.g. "\n\w \u@\h\n> ") and prompt redrawing:
 *
 * If the prompt has any newlines, after we print it once we use only its last
 * line to redraw in-place, which makes it simpler to calculate how many lines
 * we should move the cursor up to align the redraw (cmdedit_y). The earlier
 * prompt lines just stay on screen and we redraw below them.
 *
 * Use cases for all prompt lines beyond the initial draw:
 * - After clear-screen (^L) or after displaying tab-completion choices, we
 *   print the full prompt, as it isn't redrawn in-place.
 * - During terminal resize we could try to redraw all lines, but we don't,
 *   because it requires delicate alignment, it's good enough with only the
 *   last line, and doing it wrong is arguably worse than not doing it at all.
 *
 * Terminology wise, if it doesn't mention "full", then it means the last/sole
 * prompt line. We use the prompt (last/sole line) while redrawing in-place,
 * and the full where we need a fresh one unrelated to an earlier position.
 *
 * If PS1 is not multiline, the last/sole line and the full are the same string.
 */

/* Called just once at read_line_input() init time */
#if !ENABLE_FEATURE_EDITING_FANCY_PROMPT
static void parse_and_put_prompt(const char *prmt_ptr)
{
        const char *p;
        cmdedit_prompt = prompt_last_line = prmt_ptr;
        p = strrchr(prmt_ptr, '\n');
        if (p)
                prompt_last_line = p + 1;
        cmdedit_prmt_len = unicode_strwidth(prompt_last_line);
        put_prompt();
}
#else
static void parse_and_put_prompt(const char *prmt_ptr)
{
        int prmt_size = 0;
        char *prmt_mem_ptr = xzalloc(1);
        char *cwd_buf = NULL;
        char flg_not_length = '[';
        char cbuf[2];

        /*cmdedit_prmt_len = 0; - already is */

        cbuf[1] = '\0'; /* never changes */

        while (*prmt_ptr) {
                char timebuf[sizeof("HH:MM:SS")];
                char *free_me = NULL;
                char *pbuf;
                char c;

                pbuf = cbuf;
                c = *prmt_ptr++;
                if (c == '\\') {
                        const char *cp;
                        int l;
/*
 * Supported via bb_process_escape_sequence:
 * \a   ASCII bell character (07)
 * \e   ASCII escape character (033)
 * \n   newline
 * \r   carriage return
 * \\   backslash
 * \nnn char with octal code nnn
 * Supported:
 * \$   if the effective UID is 0, a #, otherwise a $
 * \w   current working directory, with $HOME abbreviated with a tilde
 *      Note: we do not support $PROMPT_DIRTRIM=n feature
 * \W   basename of the current working directory, with $HOME abbreviated with a tilde
 * \h   hostname up to the first '.'
 * \H   hostname
 * \u   username
 * \[   begin a sequence of non-printing characters
 * \]   end a sequence of non-printing characters
 * \T   current time in 12-hour HH:MM:SS format
 * \@   current time in 12-hour am/pm format
 * \A   current time in 24-hour HH:MM format
 * \t   current time in 24-hour HH:MM:SS format
 *      (all of the above work as \A)
 * Not supported:
 * \!   history number of this command
 * \#   command number of this command
 * \j   number of jobs currently managed by the shell
 * \l   basename of the shell's terminal device name
 * \s   name of the shell, the basename of $0 (the portion following the final slash)
 * \V   release of bash, version + patch level (e.g., 2.00.0)

 * \d   date in "Weekday Month Date" format (e.g., "Tue May 26")
 * \D{format}
 *      format is passed to strftime(3).
 *      An empty format results in a locale-specific time representation.
 *      The braces are required.
 * Mishandled by bb_process_escape_sequence:
 * \v   version of bash (e.g., 2.00)
 */
                        cp = prmt_ptr;
                        c = *cp;
                        if (c != 't') /* don't treat \t as tab */
                                c = bb_process_escape_sequence(&prmt_ptr);
                        if (prmt_ptr == cp) {
                                if (*cp == '\0')
                                        break;
                                c = *prmt_ptr++;

                                switch (c) {
                                case 'u':
                                        pbuf = (char*)get_username_str();
                                        break;
                                case 'H':
                                case 'h':
                                        pbuf = free_me = safe_gethostname();
                                        if (c == 'h')
                                                strchrnul(pbuf, '.')[0] = '\0';
                                        break;
                                case '$':
                                        c = (geteuid() == 0 ? '#' : '$');
                                        break;
                                case 'T': /* 12-hour HH:MM:SS format */
                                case '@': /* 12-hour am/pm format */
                                case 'A': /* 24-hour HH:MM format */
                                case 't': /* 24-hour HH:MM:SS format */
                                        /* We show all of them as 24-hour HH:MM */
                                        strftime_HHMMSS(timebuf, sizeof(timebuf), NULL)[-3] = '\0';
                                        pbuf = timebuf;
                                        break;
                                case 'w': /* current dir */
                                case 'W': /* basename of cur dir */
                                        if (!cwd_buf) {
                                                const char *home;
# if EDITING_HAS_sh_get_var
                                                cwd_buf = state && state->sh_get_var
                                                        ? xstrdup(state->sh_get_var("PWD"))
                                                        : xrealloc_getcwd_or_warn(NULL);
# else
                                                cwd_buf = xrealloc_getcwd_or_warn(NULL);
# endif
                                                if (!cwd_buf)
                                                        cwd_buf = (char *)bb_msg_unknown;
                                                else if ((home = get_homedir_or_NULL()) != NULL && home[0]) {
                                                        char *after_home_user;

                                                        /* /home/user[/something] -> ~[/something] */
                                                        after_home_user = is_prefixed_with(cwd_buf, home);
                                                        if (after_home_user
                                                         && (*after_home_user == '/' || *after_home_user == '\0')
                                                        ) {
                                                                cwd_buf[0] = '~';
                                                                overlapping_strcpy(cwd_buf + 1, after_home_user);
                                                        }
                                                }
                                        }
                                        pbuf = cwd_buf;
                                        if (c == 'w')
                                                break;
                                        cp = strrchr(pbuf, '/');
                                        if (cp)
                                                pbuf = (char*)cp + 1;
                                        break;
// bb_process_escape_sequence does this now:
//                              case 'e': case 'E':     /* \e \E = \033 */
//                                      c = '\033';
//                                      break;
                                case 'x': case 'X': {
                                        char buf2[4];
                                        for (l = 0; l < 3;) {
                                                unsigned h;
                                                buf2[l++] = *prmt_ptr;
                                                buf2[l] = '\0';
                                                h = strtoul(buf2, &pbuf, 16);
                                                if (h > UCHAR_MAX || (pbuf - buf2) < l) {
                                                        buf2[--l] = '\0';
                                                        break;
                                                }
                                                prmt_ptr++;
                                        }
                                        c = (char)strtoul(buf2, NULL, 16);
                                        if (c == 0)
                                                c = '?';
                                        pbuf = cbuf;
                                        break;
                                }
                                case '[': case ']':
                                        if (c == flg_not_length) {
                                                /* Toggle '['/']' hex 5b/5d */
                                                flg_not_length ^= 6;
                                                continue;
                                        }
                                        break;
                                } /* switch */
                        } /* if */
                } /* if */
                cbuf[0] = c;
                {
                        int n = strlen(pbuf);
                        prmt_size += n;
                        if (c == '\n')
                                cmdedit_prmt_len = 0;
                        else if (flg_not_length != ']') {
# if ENABLE_UNICODE_SUPPORT
                                if (n == 1) {
                                        /* Only count single-byte characters and the first of multi-byte characters */
                                        if ((unsigned char)*pbuf < 0x80  /* single byte character */
                                         || (unsigned char)*pbuf >= 0xc0 /* first of multi-byte characters */
                                        ) {
                                                cmdedit_prmt_len += n;
                                        }
                                } else {
                                        cmdedit_prmt_len += unicode_strwidth(pbuf);
                                }
# else
                                cmdedit_prmt_len += n;
# endif
                        }
                }
                prmt_mem_ptr = strcat(xrealloc(prmt_mem_ptr, prmt_size+1), pbuf);
                free(free_me);
        } /* while */

        if (cwd_buf != (char *)bb_msg_unknown)
                free(cwd_buf);
        /* see comment (above this function) about multiline prompt redrawing */
        cmdedit_prompt = prompt_last_line = prmt_mem_ptr;
        prmt_ptr = strrchr(cmdedit_prompt, '\n');
        if (prmt_ptr)
                prompt_last_line = prmt_ptr + 1;
        put_prompt();
}
#endif /* FEATURE_EDITING_FANCY_PROMPT */

#if ENABLE_FEATURE_EDITING_WINCH
static void cmdedit_setwidth(void)
{
        int new_y;

        cmdedit_termw = get_terminal_width(STDIN_FILENO);
        /* new y for current cursor */
        new_y = (cursor + cmdedit_prmt_len) / cmdedit_termw;
        /* redraw */
        redraw((new_y >= cmdedit_y ? new_y : cmdedit_y), command_len - cursor);
}

static void win_changed(int nsig UNUSED_PARAM)
{
        if (S.ok_to_redraw) {
                /* We are in read_key(), safe to redraw immediately */
                int sv_errno = errno;
                cmdedit_setwidth();
                fflush_all();
                errno = sv_errno;
        } else {
                /* Signal main loop that redraw is necessary */
                S.SIGWINCH_count++;
        }
}
#endif

static int lineedit_read_key(char *read_key_buffer, int timeout)
{
        int64_t ic;
#if ENABLE_UNICODE_SUPPORT
        char unicode_buf[MB_CUR_MAX + 1];
        int unicode_idx = 0;
#endif

        fflush_all();
        for (;;) {
                /* Wait for input. TIMEOUT = -1 makes read_key wait even
                 * on nonblocking stdin, TIMEOUT = 50 makes sure we won't
                 * insist on full MB_CUR_MAX buffer to declare input like
                 * "\xff\n",pause,"ls\n" invalid and thus won't lose "ls".
                 *
                 * If LI_INTERRUPTIBLE, return -1 if got EINTR in poll()
                 * inside read_key and bb_got_signal became != 0,
                 * or if bb_got_signal != 0 (IOW: if signal
                 * arrived before poll() is reached).
                 *
                 * Note: read_key sets errno to 0 on success.
                 */
                for (;;) {
                        if ((state->flags & LI_INTERRUPTIBLE) && bb_got_signal) {
                                errno = EINTR;
                                return -1;
                        }
//FIXME: still races here with signals, but small window to poll() inside read_key
                        IF_FEATURE_EDITING_WINCH(S.ok_to_redraw = 1;)
                        /* errno = 0; - read_key does this itself */
                        ic = read_key(STDIN_FILENO, read_key_buffer, timeout);
                        IF_FEATURE_EDITING_WINCH(S.ok_to_redraw = 0;)
                        if (errno != EINTR)
                                break;
                        /* It was EINTR. Repeat read_key() unless... */
                        if (state->flags & LI_INTERRUPTIBLE) {
                                /* LI_INTERRUPTIBLE bails out on EINTR
                                 * if bb_got_signal became nonzero.
                                 * (It may stay zero: for example, our SIGWINCH
                                 * handler does not set it. This is used for signals
                                 * which should not interrupt line editing).
                                 */
                                if (bb_got_signal != 0)
                                        goto ret; /* will return -1 */
                        }
                }

                if (errno) {
#if ENABLE_UNICODE_SUPPORT
                        if (errno == EAGAIN && unicode_idx != 0)
                                goto pushback;
#endif
                        break;
                }

#if ENABLE_FEATURE_EDITING_ASK_TERMINAL
                if ((int32_t)ic == KEYCODE_CURSOR_POS
                 && S.sent_ESC_br6n
                ) {
                        S.sent_ESC_br6n = 0;
                        if (cursor == 0) { /* otherwise it may be bogus */
                                int col = ((ic >> 32) & 0x7fff) - 1;
                                /*
                                 * Is col > cmdedit_prmt_len?
                                 * If yes (terminal says cursor is farther to the right
                                 * of where we think it should be),
                                 * the prompt wasn't printed starting at col 1,
                                 * there was additional text before it.
                                 */
                                if ((int)(col - cmdedit_prmt_len) > 0) {
                                        /* Fix our understanding of current x position */
                                        cmdedit_x += (col - cmdedit_prmt_len);
                                        while (cmdedit_x >= cmdedit_termw) {
                                                cmdedit_x -= cmdedit_termw;
                                                cmdedit_y++;
                                        }
                                }
                        }
                        continue;
                }
#endif

#if ENABLE_UNICODE_SUPPORT
                if (unicode_status == UNICODE_ON) {
                        wchar_t wc;

                        if ((int32_t)ic < 0) /* KEYCODE_xxx */
                                break;
                        // TODO: imagine sequence like: 0xff,<left-arrow>: we are currently losing 0xff...

                        unicode_buf[unicode_idx++] = ic;
                        unicode_buf[unicode_idx] = '\0';
                        if (mbstowcs(&wc, unicode_buf, 1) != 1) {
                                /* Not (yet?) a valid unicode char */
                                if (unicode_idx < MB_CUR_MAX) {
                                        timeout = 50;
                                        continue;
                                }
 pushback:
                                /* Invalid sequence. Save all "bad bytes" except first */
                                read_key_ungets(read_key_buffer, unicode_buf + 1, unicode_idx - 1);
# if !ENABLE_UNICODE_PRESERVE_BROKEN
                                ic = CONFIG_SUBST_WCHAR;
# else
                                ic = unicode_mark_raw_byte(unicode_buf[0]);
# endif
                        } else {
                                /* Valid unicode char, return its code */
                                ic = wc;
                        }
                }
#endif
                break;
        }
 ret:
        return ic;
}

#if ENABLE_UNICODE_BIDI_SUPPORT
static int isrtl_str(void)
{
        int idx = cursor;

        while (idx < command_len && unicode_bidi_is_neutral_wchar(command_ps[idx]))
                idx++;
        return unicode_bidi_isrtl(command_ps[idx]);
}
#else
# define isrtl_str() 0
#endif

/* leave out the "vi-mode"-only case labels if vi editing isn't
 * configured. */
#define vi_case(caselabel) IF_FEATURE_EDITING_VI(case caselabel)

/* convert uppercase ascii to equivalent control char, for readability */
#undef CTRL
#define CTRL(a) ((a) & ~0x40)

enum {
        VI_CMDMODE_BIT = 0x40000000,
        /* 0x80000000 bit flags KEYCODE_xxx */
};

#if ENABLE_FEATURE_REVERSE_SEARCH
/* Mimic readline Ctrl-R reverse history search.
 * When invoked, it shows the following prompt:
 * (reverse-i-search)'': user_input [cursor pos unchanged by Ctrl-R]
 * and typing results in search being performed:
 * (reverse-i-search)'tmp': cd /tmp [cursor under t in /tmp]
 * Search is performed by looking at progressively older lines in history.
 * Ctrl-R again searches for the next match in history.
 * Backspace deletes last matched char.
 * Control keys exit search and return to normal editing (at current history line).
 */
static int32_t reverse_i_search(int timeout)
{
        char match_buf[128]; /* for user input */
        char read_key_buffer[KEYCODE_BUFFER_SIZE];
        const char *matched_history_line;
        const char *saved_prompt;
        unsigned saved_prmt_len;
        int32_t ic;

        matched_history_line = NULL;
        read_key_buffer[0] = 0;
        match_buf[0] = '\0';

        /* Save and replace the prompt */
        saved_prompt = prompt_last_line;
        saved_prmt_len = cmdedit_prmt_len;
        goto set_prompt;

        while (1) {
                int h;
                unsigned match_buf_len = strlen(match_buf);

//FIXME: correct timeout? (i.e. count it down?)
                ic = lineedit_read_key(read_key_buffer, timeout);

                switch (ic) {
                case CTRL('R'): /* searching for the next match */
                        break;

                case '\b':
                case '\x7f':
                        /* Backspace */
                        if (unicode_status == UNICODE_ON) {
                                while (match_buf_len != 0) {
                                        uint8_t c = match_buf[--match_buf_len];
                                        if ((c & 0xc0) != 0x80) /* start of UTF-8 char? */
                                                break; /* yes */
                                }
                        } else {
                                if (match_buf_len != 0)
                                        match_buf_len--;
                        }
                        match_buf[match_buf_len] = '\0';
                        break;

                default:
                        if (ic < ' '
                         || (!ENABLE_UNICODE_SUPPORT && ic >= 256)
                         || (ENABLE_UNICODE_SUPPORT && ic >= VI_CMDMODE_BIT)
                        ) {
                                goto ret;
                        }

                        /* Append this char */
# if ENABLE_UNICODE_SUPPORT
                        if (unicode_status == UNICODE_ON) {
                                mbstate_t mbstate = { 0 };
                                char buf[MB_CUR_MAX + 1];
                                int len = wcrtomb(buf, ic, &mbstate);
                                if (len > 0) {
                                        buf[len] = '\0';
                                        if (match_buf_len + len < sizeof(match_buf))
                                                strcpy(match_buf + match_buf_len, buf);
                                }
                        } else
# endif
                        if (match_buf_len < sizeof(match_buf) - 1) {
                                match_buf[match_buf_len] = ic;
                                match_buf[match_buf_len + 1] = '\0';
                        }
                        break;
                } /* switch (ic) */

                /* Search in history for match_buf */
                h = state->cur_history;
                if (ic == CTRL('R'))
                        h--;
                while (h >= 0) {
                        if (state->history[h]) {
                                char *match = strstr(state->history[h], match_buf);
                                if (match) {
                                        state->cur_history = h;
                                        matched_history_line = state->history[h];
                                        command_len = load_string(matched_history_line);
                                        cursor = match - matched_history_line;
//FIXME: cursor position for Unicode case

                                        free((char*)prompt_last_line);
 set_prompt:
                                        prompt_last_line = xasprintf("(reverse-i-search)'%s': ", match_buf);
                                        cmdedit_prmt_len = unicode_strwidth(prompt_last_line);
                                        goto do_redraw;
                                }
                        }
                        h--;
                }

                /* Not found */
                match_buf[match_buf_len] = '\0';
                beep();
                continue;

 do_redraw:
                redraw(cmdedit_y, command_len - cursor);
        } /* while (1) */

 ret:
        if (matched_history_line)
                command_len = load_string(matched_history_line);

        free((char*)prompt_last_line);
        prompt_last_line = saved_prompt;
        cmdedit_prmt_len = saved_prmt_len;
        redraw(cmdedit_y, command_len - cursor);

        return ic;
}
#endif /* ENABLE_FEATURE_REVERSE_SEARCH */

#if ENABLE_FEATURE_EDITING_WINCH
static void sigaction2(int sig, struct sigaction *act)
{
        // Grr... gcc 8.1.1:
        // "passing argument 3 to restrict-qualified parameter aliases with argument 2"
        // dance around that...
        struct sigaction *oact FIX_ALIASING;
        oact = act;
        sigaction(sig, act, oact);
}
#endif

/* maxsize must be >= 2.
 * Returns:
 * -1 on read errors or EOF, or on bare Ctrl-D,
 * 0  on ctrl-C (the line entered is still returned in 'command'),
 * (in both cases the cursor remains on the input line, '\n' is not printed)
 * >0 length of input string, including terminating '\n'
 */
int FAST_FUNC read_line_input(line_input_t *st, const char *prompt, char *command, int maxsize)
{
        int len, n;
        int timeout;
#if ENABLE_FEATURE_TAB_COMPLETION
        smallint lastWasTab = 0;
#endif
        smallint break_out = 0;
#if ENABLE_FEATURE_EDITING_VI
        smallint vi_cmdmode = 0;
#endif
        struct termios initial_settings;
        struct termios new_settings;
        char read_key_buffer[KEYCODE_BUFFER_SIZE];

        INIT_S();
        //command_len = 0; - done by INIT_S()
        //cmdedit_y = 0;  /* quasireal y, not true if line > xt*yt */
        cmdedit_termw = 80;
        IF_FEATURE_EDITING_VI(delptr = delbuf;)

        n = get_termios_and_make_raw(STDIN_FILENO, &new_settings, &initial_settings, 0
                | TERMIOS_CLEAR_ISIG /* turn off INTR (ctrl-C), QUIT, SUSP */
        );
        if (n != 0 || (initial_settings.c_lflag & (ECHO|ICANON)) == ICANON) {
                /* Happens when e.g. stty -echo was run before.
                 * But if ICANON is not set, we don't come here.
                 * (example: interactive python ^Z-backgrounded,
                 * tty is still in "raw mode").
                 */
                parse_and_put_prompt(prompt);
                fflush_all();
                if (fgets(command, maxsize, stdin) == NULL)
                        len = -1; /* EOF or error */
                else
                        len = strlen(command);
                DEINIT_S();
                return len;
        }

        init_unicode();

// FIXME: audit & improve this
        if (maxsize > MAX_LINELEN)
                maxsize = MAX_LINELEN;
        S.maxsize = maxsize;

        timeout = -1;
        /* Make state->flags == 0 if st is NULL.
         * With zeroed flags, no other fields are ever referenced.
         */
        state = (line_input_t*) &const_int_0;
        if (st) {
                state = st;
                timeout = st->timeout;
        }
#if MAX_HISTORY > 0
        if (state->flags & DO_HISTORY) {
# if ENABLE_FEATURE_EDITING_SAVEHISTORY
                if (state->hist_file)
                        if (state->cnt_history == 0)
                                load_history(state);
# endif
                state->cur_history = state->cnt_history;
        }
#endif

        /* prepare before init handlers */
#if ENABLE_UNICODE_SUPPORT
        command_ps = xzalloc(maxsize * sizeof(command_ps[0]));
#else
        command_ps = command;
        command[0] = '\0';
#endif
#define command command_must_not_be_used

        tcsetattr_stdin_TCSANOW(&new_settings);

#if 0
        for (i = 0; i <= state->max_history; i++)
                bb_error_msg("history[%d]:'%s'", i, state->history[i]);
        bb_error_msg("cur_history:%d cnt_history:%d", state->cur_history, state->cnt_history);
#endif

        /* Get width (before printing prompt) */
        cmdedit_termw = get_terminal_width(STDIN_FILENO);
        /* Print out the command prompt, optionally ask where cursor is */
        parse_and_put_prompt(prompt);
        ask_terminal();

#if ENABLE_FEATURE_EDITING_WINCH
        /* Install window resize handler (NB: after *all* init is complete) */
        S.SIGWINCH_handler.sa_handler = win_changed;
        S.SIGWINCH_handler.sa_flags = SA_RESTART;
        sigaction2(SIGWINCH, &S.SIGWINCH_handler);
#endif
        read_key_buffer[0] = 0;
        while (1) {
                /*
                 * The emacs and vi modes share much of the code in the big
                 * command loop.  Commands entered when in vi's command mode
                 * (aka "escape mode") get an extra bit added to distinguish
                 * them - this keeps them from being self-inserted. This
                 * clutters the big switch a bit, but keeps all the code
                 * in one place.
                 */
                int32_t ic, ic_raw;
#if ENABLE_FEATURE_EDITING_WINCH
                unsigned count;

                count = S.SIGWINCH_count;
                if (S.SIGWINCH_saved != count) {
                        S.SIGWINCH_saved = count;
                        cmdedit_setwidth();
                }
#endif
                ic = ic_raw = lineedit_read_key(read_key_buffer, timeout);

#if ENABLE_FEATURE_REVERSE_SEARCH
 again:
#endif
#if ENABLE_FEATURE_EDITING_VI
                newdelflag = 1;
                if (vi_cmdmode) {
                        /* btw, since KEYCODE_xxx are all < 0, this doesn't
                         * change ic if it contains one of them: */
                        ic |= VI_CMDMODE_BIT;
                }
#endif

                switch (ic) {
                case '\n':
                case '\r':
                vi_case('\n'|VI_CMDMODE_BIT:)
                vi_case('\r'|VI_CMDMODE_BIT:)
                        /* Enter */
                        goto_new_line();
                        break_out = 1;
                        break;
                case CTRL('A'):
                vi_case('0'|VI_CMDMODE_BIT:)
                        /* Control-a -- Beginning of line */
                        input_backward(cursor);
                        break;
                case CTRL('B'):
                vi_case('h'|VI_CMDMODE_BIT:)
                vi_case('\b'|VI_CMDMODE_BIT:) /* ^H */
                vi_case('\x7f'|VI_CMDMODE_BIT:) /* DEL */
                        input_backward(1); /* Move back one character */
                        break;
                case CTRL('E'):
                vi_case('$'|VI_CMDMODE_BIT:)
                        /* Control-e -- End of line */
                        put_till_end_and_adv_cursor();
                        break;
                case CTRL('F'):
                vi_case('l'|VI_CMDMODE_BIT:)
                vi_case(' '|VI_CMDMODE_BIT:)
                        input_forward(); /* Move forward one character */
                        break;
                case '\b':   /* ^H */
                case '\x7f': /* DEL */
                        if (!isrtl_str())
                                input_backspace();
                        else
                                input_delete(0);
                        break;
                case KEYCODE_DELETE:
                        if (!isrtl_str())
                                input_delete(0);
                        else
                                input_backspace();
                        break;
#if ENABLE_FEATURE_TAB_COMPLETION
                case '\t':
                        input_tab(&lastWasTab);
                        break;
#endif
                case CTRL('K'):
                        /* Control-k -- clear to end of line */
                        command_ps[cursor] = BB_NUL;
                        command_len = cursor;
                        fputs(SEQ_CLEAR_TILL_END_OF_SCREEN, stderr);
                        break;
                case CTRL('L'):
                vi_case(CTRL('L')|VI_CMDMODE_BIT:)
                        /* Control-l -- clear screen */
                        /* cursor to top,left; clear to the end of screen */
                        fputs(ESC"[H" ESC"[J", stderr);
                        draw_full(command_len - cursor);
                        break;
#if MAX_HISTORY > 0
                case CTRL('N'):
                vi_case(CTRL('N')|VI_CMDMODE_BIT:)
                vi_case('j'|VI_CMDMODE_BIT:)
                        /* Control-n -- Get next command in history */
                        if (get_next_history())
                                goto rewrite_line;
                        break;
                case CTRL('P'):
                vi_case(CTRL('P')|VI_CMDMODE_BIT:)
                vi_case('k'|VI_CMDMODE_BIT:)
                        /* Control-p -- Get previous command from history */
                        if (get_previous_history())
                                goto rewrite_line;
                        break;
#endif
                case CTRL('U'):
                vi_case(CTRL('U')|VI_CMDMODE_BIT:)
                        /* Control-U -- Clear line before cursor */
                        if (cursor) {
                                command_len -= cursor;
                                memmove(command_ps, command_ps + cursor,
                                        (command_len + 1) * sizeof(command_ps[0]));
                                redraw(cmdedit_y, command_len);
                        }
                        break;
                case CTRL('W'):
                vi_case(CTRL('W')|VI_CMDMODE_BIT:)
                        /* Control-W -- Remove the last word */
                        while (cursor > 0 && BB_isspace(command_ps[cursor-1]))
                                input_backspace();
                        while (cursor > 0 && !BB_isspace(command_ps[cursor-1]))
                                input_backspace();
                        break;
                case KEYCODE_ALT_D: {
                        /* Delete word forward */
                        int nc, sc = cursor;
                        ctrl_right();
                        nc = cursor - sc;
                        input_backward(nc);
                        while (--nc >= 0)
                                input_delete(1);
                        break;
                }
                case KEYCODE_ALT_BACKSPACE: {
                        /* Delete word backward */
                        int sc = cursor;
                        ctrl_left();
                        while (sc-- > cursor)
                                input_delete(1);
                        break;
                }
#if ENABLE_FEATURE_REVERSE_SEARCH
                case CTRL('R'):
                        ic = ic_raw = reverse_i_search(timeout);
                        goto again;
#endif

#if ENABLE_FEATURE_EDITING_VI
                case 'i'|VI_CMDMODE_BIT:
                        vi_cmdmode = 0;
                        break;
                case 'I'|VI_CMDMODE_BIT:
                        input_backward(cursor);
                        vi_cmdmode = 0;
                        break;
                case 'a'|VI_CMDMODE_BIT:
                        input_forward();
                        vi_cmdmode = 0;
                        break;
                case 'A'|VI_CMDMODE_BIT:
                        put_till_end_and_adv_cursor();
                        vi_cmdmode = 0;
                        break;
                case 'x'|VI_CMDMODE_BIT:
                        input_delete(1);
                        break;
                case 'X'|VI_CMDMODE_BIT:
                        if (cursor > 0) {
                                input_backward(1);
                                input_delete(1);
                        }
                        break;
                case 'W'|VI_CMDMODE_BIT:
                        vi_Word_motion(1);
                        break;
                case 'w'|VI_CMDMODE_BIT:
                        vi_word_motion(1);
                        break;
                case 'E'|VI_CMDMODE_BIT:
                        vi_End_motion();
                        break;
                case 'e'|VI_CMDMODE_BIT:
                        vi_end_motion();
                        break;
                case 'B'|VI_CMDMODE_BIT:
                        vi_Back_motion();
                        break;
                case 'b'|VI_CMDMODE_BIT:
                        vi_back_motion();
                        break;
                case 'C'|VI_CMDMODE_BIT:
                        vi_cmdmode = 0;
                        /* fall through */
                case 'D'|VI_CMDMODE_BIT:
                        goto clear_to_eol;

                case 'c'|VI_CMDMODE_BIT:
                        vi_cmdmode = 0;
                        /* fall through */
                case 'd'|VI_CMDMODE_BIT: {
                        int nc, sc;

                        ic = lineedit_read_key(read_key_buffer, timeout);
                        if (errno) /* error */
                                goto return_error_indicator;
                        if (ic == ic_raw) { /* "cc", "dd" */
                                input_backward(cursor);
                                goto clear_to_eol;
                                break;
                        }

                        sc = cursor;
                        switch (ic) {
                        case 'w':
                        case 'W':
                        case 'e':
                        case 'E':
                                switch (ic) {
                                case 'w':   /* "dw", "cw" */
                                        vi_word_motion(vi_cmdmode);
                                        break;
                                case 'W':   /* 'dW', 'cW' */
                                        vi_Word_motion(vi_cmdmode);
                                        break;
                                case 'e':   /* 'de', 'ce' */
                                        vi_end_motion();
                                        input_forward();
                                        break;
                                case 'E':   /* 'dE', 'cE' */
                                        vi_End_motion();
                                        input_forward();
                                        break;
                                }
                                nc = cursor;
                                input_backward(cursor - sc);
                                while (nc-- > cursor)
                                        input_delete(1);
                                break;
                        case 'b':  /* "db", "cb" */
                        case 'B':  /* implemented as B */
                                if (ic == 'b')
                                        vi_back_motion();
                                else
                                        vi_Back_motion();
                                while (sc-- > cursor)
                                        input_delete(1);
                                break;
                        case ' ':  /* "d ", "c " */
                                input_delete(1);
                                break;
                        case '$':  /* "d$", "c$" */
 clear_to_eol:
                                while (cursor < command_len)
                                        input_delete(1);
                                break;
                        }
                        break;
                }
                case 'p'|VI_CMDMODE_BIT:
                        input_forward();
                        /* fallthrough */
                case 'P'|VI_CMDMODE_BIT:
                        put();
                        break;
                case 'r'|VI_CMDMODE_BIT:
//FIXME: unicode case?
                        ic = lineedit_read_key(read_key_buffer, timeout);
                        if (errno) /* error */
                                goto return_error_indicator;
                        if (ic < ' ' || ic > 255) {
                                beep();
                        } else {
                                command_ps[cursor] = ic;
                                bb_putchar_stderr(ic);
                                bb_putchar_stderr('\b');
                        }
                        break;
                case '\x1b': /* ESC */
                        if (state->flags & VI_MODE) {
                                /* insert mode --> command mode */
                                vi_cmdmode = 1;
                                input_backward(1);
                        }
                        break;
#endif /* FEATURE_COMMAND_EDITING_VI */

#if MAX_HISTORY > 0
                case KEYCODE_UP:
                        if (get_previous_history())
                                goto rewrite_line;
                        beep();
                        break;
                case KEYCODE_DOWN:
                        if (!get_next_history())
                                break;
 rewrite_line:
                        /* Rewrite the line with the selected history item */
                        /* change command */
                        command_len = load_string(state->history[state->cur_history] ?
                                        state->history[state->cur_history] : "");
                        /* redraw and go to eol (bol, in vi) */
                        redraw(cmdedit_y, (state->flags & VI_MODE) ? 9999 : 0);
                        break;
#endif
                case KEYCODE_RIGHT:
                        input_forward();
                        break;
                case KEYCODE_LEFT:
                        input_backward(1);
                        break;
                case KEYCODE_CTRL_LEFT:
                case KEYCODE_ALT_LEFT: /* bash doesn't do it */
                        ctrl_left();
                        break;
                case KEYCODE_CTRL_RIGHT:
                case KEYCODE_ALT_RIGHT: /* bash doesn't do it */
                        ctrl_right();
                        break;
                case KEYCODE_HOME:
                        input_backward(cursor);
                        break;
                case KEYCODE_END:
                        put_till_end_and_adv_cursor();
                        break;

                default:
                        if (initial_settings.c_cc[VINTR] != 0
                         && ic_raw == initial_settings.c_cc[VINTR]
                        ) {
                                /* Ctrl-C (usually) - stop gathering input */
                                command_len = 0;
                                break_out = -1; /* "do not append '\n'" */
                                break;
                        }
                        if (initial_settings.c_cc[VEOF] != 0
                         && ic_raw == initial_settings.c_cc[VEOF]
                        ) {
                                /* Ctrl-D (usually) - delete one character,
                                 * or exit if len=0 and no chars to delete */
                                if (command_len == 0) {
                                        errno = 0;

                case -1: /* error (e.g. EIO when tty is destroyed) */
 IF_FEATURE_EDITING_VI(return_error_indicator:)
                                        break_out = command_len = -1;
                                        break;
                                }
                                input_delete(0);
                                break;
                        }
//                      /* Control-V -- force insert of next char */
//                      if (c == CTRL('V')) {
//                              if (safe_read(STDIN_FILENO, &c, 1) < 1)
//                                      goto return_error_indicator;
//                              if (c == 0) {
//                                      beep();
//                                      break;
//                              }
//                      }
                        if (ic < ' '
                         || (!ENABLE_UNICODE_SUPPORT && ic >= 256)
                         || (ENABLE_UNICODE_SUPPORT && ic >= VI_CMDMODE_BIT)
                        ) {
                                /* If VI_CMDMODE_BIT is set, ic is >= 256
                                 * and vi mode ignores unexpected chars.
                                 * Otherwise, we are here if ic is a
                                 * control char or an unhandled ESC sequence,
                                 * which is also ignored.
                                 */
                                break;
                        }
                        if ((int)command_len >= (maxsize - 2)) {
                                /* Not enough space for the char and EOL */
                                break;
                        }

                        command_len++;
                        if (cursor == (command_len - 1)) {
                                /* We are at the end, append */
                                command_ps[cursor] = ic;
                                command_ps[cursor + 1] = BB_NUL;
                                put_cur_glyph_and_inc_cursor();
                                if (unicode_bidi_isrtl(ic))
                                        input_backward(1);
                        } else {
                                /* In the middle, insert */
                                int sc = cursor;

                                memmove(command_ps + sc + 1, command_ps + sc,
                                        (command_len - sc) * sizeof(command_ps[0]));
                                command_ps[sc] = ic;
                                /* is right-to-left char, or neutral one (e.g. comma) was just added to rtl text? */
                                if (!isrtl_str())
                                        sc++; /* no */
                                put_till_end_and_adv_cursor();
                                /* to prev x pos + 1 */
                                input_backward(cursor - sc);
                        }
                        break;
                } /* switch (ic) */

                if (break_out)
                        break;

#if ENABLE_FEATURE_TAB_COMPLETION
                if (ic_raw != '\t')
                        lastWasTab = 0;
#endif
        } /* while (1) */

#if ENABLE_FEATURE_EDITING_ASK_TERMINAL
        if (S.sent_ESC_br6n) {
                /* "sleep 1; busybox ash" + hold [Enter] to trigger.
                 * We sent "ESC [ 6 n", but got '\n' first, and
                 * KEYCODE_CURSOR_POS response is now buffered from terminal.
                 * It's bad already and not much can be done with it
                 * (it _will_ be visible for the next process to read stdin),
                 * but without this delay it even shows up on the screen
                 * as garbage because we restore echo settings with tcsetattr
                 * before it comes in. UGLY!
                 */
                usleep(20*1000);
// MAYBE? tcflush(STDIN_FILENO, TCIFLUSH); /* flushes data received but not read */
        }
#endif

/* End of bug-catching "command_must_not_be_used" trick */
#undef command

#if ENABLE_UNICODE_SUPPORT
        command[0] = '\0';
        if (command_len > 0)
                command_len = save_string(command, maxsize - 1);
        free(command_ps);
#endif

        if (command_len > 0) {
                remember_in_history(command);
        }

        if (break_out > 0) {
                command[command_len++] = '\n';
                command[command_len] = '\0';
        }

#if ENABLE_FEATURE_TAB_COMPLETION
        free_tab_completion_data();
#endif

        /* restore initial_settings */
        tcsetattr_stdin_TCSANOW(&initial_settings);
#if ENABLE_FEATURE_EDITING_WINCH
        /* restore SIGWINCH handler */
        sigaction_set(SIGWINCH, &S.SIGWINCH_handler);
#endif
        fflush_all();

        len = command_len;
        DEINIT_S();

        return len; /* can't return command_len, DEINIT_S() destroys it */
}

#else  /* !FEATURE_EDITING */

#undef read_line_input
int FAST_FUNC read_line_input(const char* prompt, char* command, int maxsize)
{
        /* https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
         * says that shells must write $PSn to stderr, not stdout.
         */
        fputs(prompt, stderr);
        fflush_all();
        if (!fgets(command, maxsize, stdin))
                return -1;
        return strlen(command);
}

#endif  /* !FEATURE_EDITING */


/*
 * Testing
 */

#ifdef TEST

#include <locale.h>

const char *applet_name = "debug stuff usage";

int main(int argc, char **argv)
{
        char buff[MAX_LINELEN];
        char *prompt =
#if ENABLE_FEATURE_EDITING_FANCY_PROMPT
                "\\[\\033[32;1m\\]\\u@\\[\\x1b[33;1m\\]\\h:"
                "\\[\\033[34;1m\\]\\w\\[\\033[35;1m\\] "
                "\\!\\[\\e[36;1m\\]\\$ \\[\\E[m\\]";
#else
                "% ";
#endif

        while (1) {
                int l;
                l = read_line_input(prompt, buff);
                if (l <= 0 || buff[l-1] != '\n')
                        break;
                buff[l-1] = '\0';
                printf("*** read_line_input() returned line =%s=\n", buff);
        }
        printf("*** read_line_input() detect ^D\n");
        return 0;
}

#endif  /* TEST */