/* vi: set sw=4 ts=4: */
/*
 * Mini grep implementation for busybox using libc regex.
 *
 * Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
 * Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
/* BB_AUDIT SUSv3 defects - unsupported option -x "match whole line only". */
/* BB_AUDIT GNU defects - always acts as -a.  */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/grep.html */
/*
 * 2004,2006 (C) Vladimir Oleynik <dzo@simtreas.ru> -
 * correction "-e pattern1 -e pattern2" logic and more optimizations.
 * precompiled regex
 *
 * (C) 2006 Jac Goudsmit added -o option
 */
//config:config GREP
//config:       bool "grep (8.6 kb)"
//config:       default y
//config:       help
//config:       grep is used to search files for a specified pattern.
//config:
//config:config EGREP
//config:       bool "egrep (7.8 kb)"
//config:       default y
//config:       help
//config:       Alias to "grep -E".
//config:
//config:config FGREP
//config:       bool "fgrep (7.8 kb)"
//config:       default y
//config:       help
//config:       Alias to "grep -F".
//config:
//config:config FEATURE_GREP_CONTEXT
//config:       bool "Enable before and after context flags (-A, -B and -C)"
//config:       default y
//config:       depends on GREP || EGREP || FGREP
//config:       help
//config:       Print the specified number of leading (-B) and/or trailing (-A)
//config:       context surrounding our matching lines.
//config:       Print the specified number of context lines (-C).

//applet:IF_GREP(APPLET(grep, BB_DIR_BIN, BB_SUID_DROP))
//                APPLET_ODDNAME:name   main  location    suid_type     help
//applet:IF_EGREP(APPLET_ODDNAME(egrep, grep, BB_DIR_BIN, BB_SUID_DROP, egrep))
//applet:IF_FGREP(APPLET_ODDNAME(fgrep, grep, BB_DIR_BIN, BB_SUID_DROP, fgrep))

//kbuild:lib-$(CONFIG_GREP) += grep.o
//kbuild:lib-$(CONFIG_EGREP) += grep.o
//kbuild:lib-$(CONFIG_FGREP) += grep.o

#include "libbb.h"
#include "common_bufsiz.h"
#include "xregex.h"

//usage:#define grep_trivial_usage
//usage:       "[-HhnlLoqvsrRiwFE"
//usage:        IF_EXTRA_COMPAT("z")
//usage:       "] [-m N] "
//usage:        IF_FEATURE_GREP_CONTEXT("[-A|B|C N] ")
//usage:       "{ PATTERN | -e PATTERN... | -f FILE... } [FILE]..."
//usage:#define grep_full_usage "\n\n"
//usage:       "Search for PATTERN in FILEs (or stdin)\n"
//usage:     "\n        -H      Add 'filename:' prefix"
//usage:     "\n        -h      Do not add 'filename:' prefix"
//usage:     "\n        -n      Add 'line_no:' prefix"
//usage:     "\n        -l      Show only names of files that match"
//usage:     "\n        -L      Show only names of files that don't match"
//usage:     "\n        -c      Show only count of matching lines"
//usage:     "\n        -o      Show only the matching part of line"
//usage:     "\n        -q      Quiet. Return 0 if PATTERN is found, 1 otherwise"
//usage:     "\n        -v      Select non-matching lines"
//usage:     "\n        -s      Suppress open and read errors"
//usage:     "\n        -r      Recurse"
//usage:     "\n        -R      Recurse and dereference symlinks"
//usage:     "\n        -i      Ignore case"
//usage:     "\n        -w      Match whole words only"
//usage:     "\n        -x      Match whole lines only"
//usage:     "\n        -F      PATTERN is a literal (not regexp)"
//usage:     "\n        -E      PATTERN is an extended regexp"
//usage:        IF_EXTRA_COMPAT(
//usage:     "\n        -z      NUL terminated input"
//usage:        )
//usage:     "\n        -m N    Match up to N times per file"
//usage:        IF_FEATURE_GREP_CONTEXT(
//usage:     "\n        -A N    Print N lines of trailing context"
//usage:     "\n        -B N    Print N lines of leading context"
//usage:     "\n        -C N    Same as '-A N -B N'"
//usage:        )
//usage:     "\n        -e PTRN Pattern to match"
//usage:     "\n        -f FILE Read pattern from file"
//usage:
//usage:#define grep_example_usage
//usage:       "$ grep root /etc/passwd\n"
//usage:       "root:x:0:0:root:/root:/bin/bash\n"
//usage:       "$ grep ^[rR]oo. /etc/passwd\n"
//usage:       "root:x:0:0:root:/root:/bin/bash\n"
//usage:
//usage:#define egrep_trivial_usage NOUSAGE_STR
//usage:#define egrep_full_usage ""
//usage:#define fgrep_trivial_usage NOUSAGE_STR
//usage:#define fgrep_full_usage ""

/* -e,-f are lists; -m,-A,-B,-C have numeric param */
#define OPTSTR_GREP \
        "lnqvscFiHhe:*f:*LorRm:+wx" \
        IF_FEATURE_GREP_CONTEXT("A:+B:+C:+") \
        "E" \
        IF_EXTRA_COMPAT("z") \
        "aI"
/* ignored: -a "assume all files to be text" */
/* ignored: -I "assume binary files have no matches" */
enum {
        OPTBIT_l, /* list matched file names only */
        OPTBIT_n, /* print line# */
        OPTBIT_q, /* quiet - exit(EXIT_SUCCESS) of first match */
        OPTBIT_v, /* invert the match, to select non-matching lines */
        OPTBIT_s, /* suppress errors about file open errors */
        OPTBIT_c, /* count matches per file (suppresses normal output) */
        OPTBIT_F, /* literal match */
        OPTBIT_i, /* case-insensitive */
        OPTBIT_H, /* force filename display */
        OPTBIT_h, /* inhibit filename display */
        OPTBIT_e, /* -e PATTERN */
        OPTBIT_f, /* -f FILE_WITH_PATTERNS */
        OPTBIT_L, /* list unmatched file names only */
        OPTBIT_o, /* show only matching parts of lines */
        OPTBIT_r, /* recurse dirs */
        OPTBIT_R, /* recurse dirs and symlinks to dirs */
        OPTBIT_m, /* -m MAX_MATCHES */
        OPTBIT_w, /* -w whole word match */
        OPTBIT_x, /* -x whole line match */
        IF_FEATURE_GREP_CONTEXT(    OPTBIT_A ,) /* -A NUM: after-match context */
        IF_FEATURE_GREP_CONTEXT(    OPTBIT_B ,) /* -B NUM: before-match context */
        IF_FEATURE_GREP_CONTEXT(    OPTBIT_C ,) /* -C NUM: -A and -B combined */
        OPTBIT_E, /* extended regexp */
        IF_EXTRA_COMPAT(            OPTBIT_z ,) /* input is NUL terminated */
        OPT_l = 1 << OPTBIT_l,
        OPT_n = 1 << OPTBIT_n,
        OPT_q = 1 << OPTBIT_q,
        OPT_v = 1 << OPTBIT_v,
        OPT_s = 1 << OPTBIT_s,
        OPT_c = 1 << OPTBIT_c,
        OPT_F = 1 << OPTBIT_F,
        OPT_i = 1 << OPTBIT_i,
        OPT_H = 1 << OPTBIT_H,
        OPT_h = 1 << OPTBIT_h,
        OPT_e = 1 << OPTBIT_e,
        OPT_f = 1 << OPTBIT_f,
        OPT_L = 1 << OPTBIT_L,
        OPT_o = 1 << OPTBIT_o,
        OPT_r = 1 << OPTBIT_r,
        OPT_R = 1 << OPTBIT_R,
        OPT_m = 1 << OPTBIT_m,
        OPT_w = 1 << OPTBIT_w,
        OPT_x = 1 << OPTBIT_x,
        OPT_A = IF_FEATURE_GREP_CONTEXT(    (1 << OPTBIT_A)) + 0,
        OPT_B = IF_FEATURE_GREP_CONTEXT(    (1 << OPTBIT_B)) + 0,
        OPT_C = IF_FEATURE_GREP_CONTEXT(    (1 << OPTBIT_C)) + 0,
        OPT_E = 1 << OPTBIT_E,
        OPT_z = IF_EXTRA_COMPAT(            (1 << OPTBIT_z)) + 0,
};

#define PRINT_LINE_NUM              (option_mask32 & OPT_n)
#define BE_QUIET                    (option_mask32 & OPT_q)
#define SUPPRESS_ERR_MSGS           (option_mask32 & OPT_s)
#define PRINT_MATCH_COUNTS          (option_mask32 & OPT_c)
#define FGREP_FLAG                  (option_mask32 & OPT_F)
#define NUL_DELIMITED               (option_mask32 & OPT_z)

struct globals {
        int max_matches;
#if !ENABLE_EXTRA_COMPAT
        int reflags;
#else
        RE_TRANSLATE_TYPE case_fold; /* RE_TRANSLATE_TYPE is [[un]signed] char* */
#endif
        smalluint invert_search;
        smalluint print_filename;
        smalluint open_errors;
#if ENABLE_FEATURE_GREP_CONTEXT
        smalluint did_print_line;
        int lines_before;
        int lines_after;
        char **before_buf;
        IF_EXTRA_COMPAT(size_t *before_buf_size;)
        int last_line_printed;
#endif
        /* globals used internally */
        llist_t *pattern_head;   /* growable list of patterns to match */
        const char *cur_file;    /* the current file we are reading */
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { \
        setup_common_bufsiz(); \
        BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
} while (0)
#define max_matches       (G.max_matches         )
#if !ENABLE_EXTRA_COMPAT
# define reflags          (G.reflags             )
#else
# define case_fold        (G.case_fold           )
/* http://www.delorie.com/gnu/docs/regex/regex_46.html */
# define reflags           re_syntax_options
# undef REG_NOSUB
# undef REG_EXTENDED
# undef REG_ICASE
# define REG_NOSUB    bug:is:here /* should not be used */
/* Just RE_SYNTAX_EGREP is not enough, need to enable {n[,[m]]} too */
# define REG_EXTENDED (RE_SYNTAX_EGREP | RE_INTERVALS | RE_NO_BK_BRACES)
# define REG_ICASE    bug:is:here /* should not be used */
#endif
#define invert_search     (G.invert_search       )
#define print_filename    (G.print_filename      )
#define open_errors       (G.open_errors         )
#define did_print_line    (G.did_print_line      )
#define lines_before      (G.lines_before        )
#define lines_after       (G.lines_after         )
#define before_buf        (G.before_buf          )
#define before_buf_size   (G.before_buf_size     )
#define last_line_printed (G.last_line_printed   )
#define pattern_head      (G.pattern_head        )
#define cur_file          (G.cur_file            )


typedef struct grep_list_data_t {
        char *pattern;
/* for GNU regex, matched_range must be persistent across grep_file() calls */
#if !ENABLE_EXTRA_COMPAT
        regex_t compiled_regex;
        regmatch_t matched_range;
#else
        struct re_pattern_buffer compiled_regex;
        struct re_registers matched_range;
#endif
#define ALLOCATED 1
#define COMPILED 2
        int flg_mem_allocated_compiled;
} grep_list_data_t;

#if !ENABLE_EXTRA_COMPAT
#define print_line(line, line_len, linenum, decoration) \
        print_line(line, linenum, decoration)
#endif
static void print_line(const char *line, size_t line_len, int linenum, char decoration)
{
#if ENABLE_FEATURE_GREP_CONTEXT
        /* Happens when we go to next file, immediately hit match
         * and try to print prev context... from prev file! Don't do it */
        if (linenum < 1)
                return;
        /* possibly print the little '--' separator */
        if ((lines_before || lines_after) && did_print_line
         && last_line_printed != linenum - 1
        ) {
                puts("--");
        }
        /* guard against printing "--" before first line of first file */
        did_print_line = 1;
        last_line_printed = linenum;
#endif
        if (print_filename)
                printf("%s%c", cur_file, decoration);
        if (PRINT_LINE_NUM)
                printf("%i%c", linenum, decoration);
        /* Emulate weird GNU grep behavior with -ov */
        if ((option_mask32 & (OPT_v|OPT_o)) != (OPT_v|OPT_o)) {
#if !ENABLE_EXTRA_COMPAT
                puts(line);
#else
                fwrite(line, 1, line_len, stdout);
                putchar(NUL_DELIMITED ? '\0' : '\n');
#endif
        }
}

#if ENABLE_EXTRA_COMPAT
/* Unlike getline, this one removes trailing '\n' */
static ssize_t FAST_FUNC bb_getline(char **line_ptr, size_t *line_alloc_len, FILE *file)
{
        ssize_t res_sz;
        char *line;
        int delim = (NUL_DELIMITED ? '\0' : '\n');

        res_sz = getdelim(line_ptr, line_alloc_len, delim, file);
        line = *line_ptr;

        if (res_sz > 0) {
                if (line[res_sz - 1] == delim)
                        line[--res_sz] = '\0';
        } else {
                free(line); /* uclibc allocates a buffer even on EOF. WTF? */
        }
        return res_sz;
}
#endif

static int grep_file(FILE *file)
{
        smalluint found;
        int linenum = 0;
        int nmatches = 0;
#if !ENABLE_EXTRA_COMPAT
        char *line;
#else
        char *line = NULL;
        ssize_t line_len;
        size_t line_alloc_len;
# define rm_so start[0]
# define rm_eo end[0]
#endif
#if ENABLE_FEATURE_GREP_CONTEXT
        int print_n_lines_after = 0;
        int curpos = 0; /* track where we are in the circular 'before' buffer */
        int idx = 0; /* used for iteration through the circular buffer */
#else
        enum { print_n_lines_after = 0 };
#endif

        while (
#if !ENABLE_EXTRA_COMPAT
                (line = xmalloc_fgetline(file)) != NULL
#else
                (line_len = bb_getline(&line, &line_alloc_len, file)) >= 0
#endif
        ) {
                llist_t *pattern_ptr = pattern_head;
                grep_list_data_t *gl = gl; /* for gcc */

                linenum++;
                found = 0;
                while (pattern_ptr) {
                        gl = (grep_list_data_t *)pattern_ptr->data;
                        if (FGREP_FLAG) {
                                char *match;
                                char *str = line;
 opt_f_again:
                                match = ((option_mask32 & OPT_i)
                                        ? strcasestr(str, gl->pattern)
                                        : strstr(str, gl->pattern)
                                        );
                                if (match) {
                                        if (option_mask32 & OPT_x) {
                                                if (match != str)
                                                        goto opt_f_not_found;
                                                if (str[strlen(gl->pattern)] != '\0')
                                                        goto opt_f_not_found;
                                        } else
                                        if (option_mask32 & OPT_w) {
                                                char c = (match != line) ? match[-1] : ' ';
                                                if (!isalnum(c) && c != '_') {
                                                        c = match[strlen(gl->pattern)];
                                                        if (!c || (!isalnum(c) && c != '_'))
                                                                goto opt_f_found;
                                                }
                                                str = match + 1;
                                                goto opt_f_again;
                                        }
 opt_f_found:
                                        found = 1;
 opt_f_not_found: ;
                                }
                        } else {
#if ENABLE_EXTRA_COMPAT
                                unsigned start_pos;
#else
                                int match_flg;
#endif
                                char *match_at;

                                if (!(gl->flg_mem_allocated_compiled & COMPILED)) {
                                        gl->flg_mem_allocated_compiled |= COMPILED;
#if !ENABLE_EXTRA_COMPAT
                                        xregcomp(&gl->compiled_regex, gl->pattern, reflags);
#else
                                        memset(&gl->compiled_regex, 0, sizeof(gl->compiled_regex));
                                        gl->compiled_regex.translate = case_fold; /* for -i */
                                        if (re_compile_pattern(gl->pattern, strlen(gl->pattern), &gl->compiled_regex))
                                                bb_error_msg_and_die("bad regex '%s'", gl->pattern);
#endif
                                }
#if !ENABLE_EXTRA_COMPAT
                                gl->matched_range.rm_so = 0;
                                gl->matched_range.rm_eo = 0;
                                match_flg = 0;
#else
                                start_pos = 0;
#endif
                                match_at = line;
 opt_w_again:
//bb_error_msg("'%s' start_pos:%d line_len:%d", match_at, start_pos, line_len);
                                if (
#if !ENABLE_EXTRA_COMPAT
                                        regexec(&gl->compiled_regex, match_at, 1, &gl->matched_range, match_flg) == 0
#else
                                        re_search(&gl->compiled_regex, match_at, line_len,
                                                        start_pos, /*range:*/ line_len,
                                                        &gl->matched_range) >= 0
#endif
                                ) {
                                        if (option_mask32 & OPT_x) {
                                                found |= (gl->matched_range.rm_so == 0
                                                         && match_at[gl->matched_range.rm_eo] == '\0');
                                        } else
                                        if (!(option_mask32 & OPT_w)) {
                                                found = 1;
                                        } else {
                                                char c = ' ';
                                                if (match_at > line || gl->matched_range.rm_so != 0) {
                                                        c = match_at[gl->matched_range.rm_so - 1];
                                                }
                                                if (!isalnum(c) && c != '_') {
                                                        c = match_at[gl->matched_range.rm_eo];
                                                }
                                                if (!isalnum(c) && c != '_') {
                                                        found = 1;
                                                } else {
                        /*
                         * Why check gl->matched_range.rm_eo?
                         * Zero-length match makes -w skip the line:
                         * "echo foo | grep ^" prints "foo",
                         * "echo foo | grep -w ^" prints nothing.
                         * Without such check, we can loop forever.
                         */
#if !ENABLE_EXTRA_COMPAT
                                                        if (gl->matched_range.rm_eo != 0) {
                                                                match_at += gl->matched_range.rm_eo;
                                                                match_flg |= REG_NOTBOL;
                                                                goto opt_w_again;
                                                        }
#else
                                                        if (gl->matched_range.rm_eo > start_pos) {
                                                                start_pos = gl->matched_range.rm_eo;
                                                                goto opt_w_again;
                                                        }
#endif
                                                }
                                        }
                                }
                        }
                        /* If it's a non-inverted search, we can stop
                         * at first match and report it.
                         * If it's an inverted search, we can move on
                         * to the next line of input, ignoring the
                         * rest of the patterns.
                         */
                        if (found) {
                                //if (invert_search)
                                //      goto do_not_found;
                                //goto do_found;
                                break; // this accomplishes both
                        }
                        pattern_ptr = pattern_ptr->link;
                } /* while (pattern_ptr) */

                if (found ^ invert_search) {
 //do_found:
                        /* keep track of matches */
                        nmatches++;

                        /* quiet/print (non)matching file names only? */
                        if (option_mask32 & (OPT_q|OPT_l|OPT_L)) {
                                free(line); /* we don't need line anymore */
                                if (BE_QUIET) {
                                        /* manpage says about -q:
                                         * "exit immediately with zero status
                                         * if any match is found,
                                         * even if errors were detected" */
                                        exit(EXIT_SUCCESS);
                                }
                                /* -l "print filenames with matches": stop after the first match */
                                if (option_mask32 & OPT_l) {
                                        puts(cur_file);
                                        return 1;
                                }
                                /* -L "print filenames without matches": return early too */
                                return 0; /* 0: we do not print fname, hence it's "not a match" */
                        }

#if ENABLE_FEATURE_GREP_CONTEXT
                        /* Were we printing context and saw next (unwanted) match? */
                        if ((option_mask32 & OPT_m) && nmatches > max_matches)
                                break;
#endif

                        /* print the matched line */
                        if (PRINT_MATCH_COUNTS == 0) {
#if ENABLE_FEATURE_GREP_CONTEXT
                                int prevpos = (curpos == 0) ? lines_before - 1 : curpos - 1;

                                /* if we were told to print 'before' lines and there is at least
                                 * one line in the circular buffer, print them */
                                if (lines_before && before_buf[prevpos] != NULL) {
                                        int first_buf_entry_line_num = linenum - lines_before;

                                        /* advance to the first entry in the circular buffer, and
                                         * figure out the line number is of the first line in the
                                         * buffer */
                                        idx = curpos;
                                        while (before_buf[idx] == NULL) {
                                                idx = (idx + 1) % lines_before;
                                                first_buf_entry_line_num++;
                                        }

                                        /* now print each line in the buffer, clearing them as we go */
                                        while (before_buf[idx] != NULL) {
                                                print_line(before_buf[idx], before_buf_size[idx], first_buf_entry_line_num, '-');
                                                free(before_buf[idx]);
                                                before_buf[idx] = NULL;
                                                idx = (idx + 1) % lines_before;
                                                first_buf_entry_line_num++;
                                        }
                                }

                                /* make a note that we need to print 'after' lines */
                                print_n_lines_after = lines_after;
#endif
                                if (option_mask32 & OPT_o) {
                                        if (FGREP_FLAG) {
                                                /* -Fo just prints the pattern
                                                 * (unless -v: -Fov doesn't print anything at all) */
                                                if (found)
                                                        print_line(gl->pattern, strlen(gl->pattern), linenum, ':');
                                        } else while (1) {
                                                unsigned start = gl->matched_range.rm_so;
                                                unsigned end = gl->matched_range.rm_eo;
                                                unsigned len = end - start;
                                                char old = line[end];
                                                line[end] = '\0';
                                                /* Empty match is not printed: try "echo test | grep -o ''" */
                                                if (len != 0)
                                                        print_line(line + start, len, linenum, ':');
                                                if (old == '\0')
                                                        break;
                                                line[end] = old;
                                                if (len == 0)
                                                        end++;
#if !ENABLE_EXTRA_COMPAT
                                                if (regexec(&gl->compiled_regex, line + end,
                                                                1, &gl->matched_range, REG_NOTBOL) != 0)
                                                        break;
                                                gl->matched_range.rm_so += end;
                                                gl->matched_range.rm_eo += end;
#else
                                                if (re_search(&gl->compiled_regex, line, line_len,
                                                                end, line_len - end,
                                                                &gl->matched_range) < 0)
                                                        break;
#endif
                                        }
                                } else {
                                        print_line(line, line_len, linenum, ':');
                                }
                        }
                }
#if ENABLE_FEATURE_GREP_CONTEXT
                else { /* no match */
 //do_not_found:
                        /* if we need to print some context lines after the last match, do so */
                        if (print_n_lines_after) {
                                print_line(line, strlen(line), linenum, '-');
                                print_n_lines_after--;
                        } else if (lines_before) {
                                /* Add the line to the circular 'before' buffer */
                                free(before_buf[curpos]);
                                before_buf[curpos] = line;
                                IF_EXTRA_COMPAT(before_buf_size[curpos] = line_len;)
                                curpos = (curpos + 1) % lines_before;
                                /* avoid free(line) - we took the line */
                                line = NULL;
                        }
                }

#endif /* ENABLE_FEATURE_GREP_CONTEXT */
#if !ENABLE_EXTRA_COMPAT
                free(line);
#endif
                /* Did we print all context after last requested match? */
                if ((option_mask32 & OPT_m)
                 && !print_n_lines_after
                 && nmatches == max_matches
                ) {
                        break;
                }
        } /* while (read line) */

        /* special-case file post-processing for options where we don't print line
         * matches, just filenames and possibly match counts */

        /* grep -c: print [filename:]count, even if count is zero */
        if (PRINT_MATCH_COUNTS) {
                if (print_filename)
                        printf("%s:", cur_file);
                printf("%d\n", nmatches);
        }

        /* grep -L: "print filenames without matches" */
        if (option_mask32 & OPT_L) {
                /* nmatches is zero, no need to check it:
                 * we return 0 early if -L and we detect a match
                 */
                puts(cur_file);
                return 1; /* 1: we printed fname, hence it's "a match" */
        }

        return nmatches != 0; /* we return not a count, but a boolean */
}

#if ENABLE_FEATURE_CLEAN_UP
#define new_grep_list_data(p, m) add_grep_list_data(p, m)
static char *add_grep_list_data(char *pattern, int flg_used_mem)
#else
#define new_grep_list_data(p, m) add_grep_list_data(p)
static char *add_grep_list_data(char *pattern)
#endif
{
        grep_list_data_t *gl = xzalloc(sizeof(*gl));
        gl->pattern = pattern;
#if ENABLE_FEATURE_CLEAN_UP
        gl->flg_mem_allocated_compiled = flg_used_mem;
#else
        /*gl->flg_mem_allocated_compiled = 0;*/
#endif
        return (char *)gl;
}

static void load_regexes_from_file(llist_t *fopt)
{
        while (fopt) {
                char *line;
                FILE *fp;
                llist_t *cur = fopt;
                char *ffile = cur->data;

                fopt = cur->link;
                free(cur);
                fp = xfopen_stdin(ffile);
                while ((line = xmalloc_fgetline(fp)) != NULL) {
                        llist_add_to(&pattern_head,
                                new_grep_list_data(line, ALLOCATED));
                }
                fclose_if_not_stdin(fp);
        }
}

static void load_pattern_list(llist_t **lst, char *pattern)
{
        char *p;
        while ((p = strsep(&pattern, "\n")) != NULL)
                llist_add_to(lst, new_grep_list_data(p, 0));
}

static int FAST_FUNC file_action_grep(struct recursive_state *state UNUSED_PARAM,
                const char *filename,
                struct stat *statbuf)
{
        FILE *file;

        /* If we are given a link to a directory, we should bail out now, rather
         * than trying to open the "file" and hoping getline gives us nothing,
         * since that is not portable across operating systems (FreeBSD for
         * example will return the raw directory contents). */
        if (S_ISLNK(statbuf->st_mode)) {
                struct stat sb;
                if (stat(filename, &sb) != 0) {
                        if (!SUPPRESS_ERR_MSGS)
                                bb_simple_perror_msg(filename);
                        return 0;
                }
                if (S_ISDIR(sb.st_mode))
                        return 1;
        }

        file = fopen_for_read(filename);
        if (file == NULL) {
                if (!SUPPRESS_ERR_MSGS)
                        bb_simple_perror_msg(filename);
                open_errors = 1;
                return 0;
        }
        cur_file = filename;
        *(int*)state->userData |= grep_file(file);
        fclose(file);
        return 1;
}

static int grep_dir(const char *dir)
{
        int matched = 0;
        recursive_action(dir, 0
                | ACTION_RECURSE
                | ((option_mask32 & OPT_R) ? ACTION_FOLLOWLINKS : 0)
                | ACTION_FOLLOWLINKS_L0 /* grep -r ... SYMLINK follows it */
                | ACTION_DEPTHFIRST
                | 0,
                /* fileAction= */ file_action_grep,
                /* dirAction= */ NULL,
                /* userData= */ &matched
        );
        return matched;
}

int grep_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int grep_main(int argc UNUSED_PARAM, char **argv)
{
        FILE *file;
        int matched;
        llist_t *fopt = NULL;
#if ENABLE_FEATURE_GREP_CONTEXT
        int Copt, opts;
#endif
        INIT_G();

        /* For grep, exitcode of 1 is "not found". Other errors are 2: */
        xfunc_error_retval = 2;

        /* do normal option parsing */
#if ENABLE_FEATURE_GREP_CONTEXT
        /* -H unsets -h; -C unsets -A,-B */
        opts = getopt32long(argv, "^"
                OPTSTR_GREP
                        "\0"
                        "H-h:C-AB",
                "color\0" Optional_argument "\xff",
                &pattern_head, &fopt, &max_matches,
                &lines_after, &lines_before, &Copt
                , NULL
        );

        if (opts & OPT_C) {
                /* -C unsets prev -A and -B, but following -A or -B
                 * may override it */
                if (!(opts & OPT_A)) /* not overridden */
                        lines_after = Copt;
                if (!(opts & OPT_B)) /* not overridden */
                        lines_before = Copt;
        }
        /* sanity checks */
        if (opts & (OPT_c|OPT_q|OPT_l|OPT_L)) {
                option_mask32 &= ~OPT_n;
                lines_before = 0;
                lines_after = 0;
        } else if (lines_before > 0) {
                if (lines_before > INT_MAX / sizeof(long long))
                        lines_before = INT_MAX / sizeof(long long);
                /* overflow in (lines_before * sizeof(x)) is prevented (above) */
                before_buf = xzalloc(lines_before * sizeof(before_buf[0]));
                IF_EXTRA_COMPAT(before_buf_size = xzalloc(lines_before * sizeof(before_buf_size[0]));)
        }
#else
        /* with auto sanity checks */
        getopt32(argv, "^" OPTSTR_GREP "\0" "H-h:c-n:q-n:l-n:", // why trailing ":"?
                &pattern_head, &fopt, &max_matches);
#endif
        invert_search = ((option_mask32 & OPT_v) != 0); /* 0 | 1 */

        {       /* convert char **argv to pattern_list */
                llist_t *cur, *new = NULL;
                for (cur = pattern_head; cur; cur = cur->link)
                        load_pattern_list(&new, cur->data);
                llist_free(pattern_head, NULL);
                pattern_head = new;
        }
        if (option_mask32 & OPT_f) {
                load_regexes_from_file(fopt);
                if (!pattern_head) { /* -f EMPTY_FILE? */
                        /* GNU grep treats it as "nothing matches" except when -x */
                        const char *data = (option_mask32 & OPT_x) ? ".*" : "";
                        llist_add_to(&pattern_head, new_grep_list_data((char*)data, 0));
                        invert_search ^= 1;
                }
        }

        if (ENABLE_FGREP && applet_name[0] == 'f')
                option_mask32 |= OPT_F;

#if !ENABLE_EXTRA_COMPAT
        if (!(option_mask32 & (OPT_o | OPT_w | OPT_x)))
                reflags = REG_NOSUB;
#endif

        if ((ENABLE_EGREP && applet_name[0] == 'e')
         || (option_mask32 & OPT_E)
        ) {
                reflags |= REG_EXTENDED;
        }
#if ENABLE_EXTRA_COMPAT
        else {
                reflags = RE_SYNTAX_GREP;
        }
#endif

        if (option_mask32 & OPT_i) {
#if !ENABLE_EXTRA_COMPAT
                reflags |= REG_ICASE;
#else
                int i;
                case_fold = xmalloc(256);
                for (i = 0; i < 256; i++)
                        case_fold[i] = (unsigned char)i;
                for (i = 'a'; i <= 'z'; i++)
                        case_fold[i] = (unsigned char)(i - ('a' - 'A'));
#endif
        }

        argv += optind;

        /* if we didn't get a pattern from -e and no command file was specified,
         * first parameter should be the pattern. no pattern, no worky */
        if (pattern_head == NULL) {
                if (*argv == NULL)
                        bb_show_usage();
                load_pattern_list(&pattern_head, *argv++);
        }

        /* argv[0..(argc-1)] should be names of file to grep through. If
         * there is more than one file to grep, we will print the filenames. */
        if (argv[0] && argv[1])
                print_filename = 1;
        /* -H / -h of course override */
        if (option_mask32 & OPT_H)
                print_filename = 1;
        if (option_mask32 & OPT_h)
                print_filename = 0;

        /* If no files were specified, or '-' was specified, take input from
         * stdin. Otherwise, we grep through all the files specified. */
        matched = 0;
        do {
                cur_file = *argv;
                file = stdin;
                if (!cur_file || LONE_DASH(cur_file)) {
                        cur_file = "(standard input)";
                } else {
                        if (option_mask32 & (OPT_r|OPT_R)) {
                                struct stat st;
                                if (stat(cur_file, &st) == 0 && S_ISDIR(st.st_mode)) {
                                        if (!(option_mask32 & OPT_h))
                                                print_filename = 1;
                                        matched |= grep_dir(cur_file);
                                        goto grep_done;
                                }
                        }
                        /* else: fopen(dir) will succeed, but reading won't */
                        file = fopen_for_read(cur_file);
                        if (file == NULL) {
                                if (!SUPPRESS_ERR_MSGS)
                                        bb_simple_perror_msg(cur_file);
                                open_errors = 1;
                                continue;
                        }
                }
                matched |= grep_file(file);
                fclose_if_not_stdin(file);
 grep_done: ;
        } while (*argv && *++argv);

        /* destroy all the elements in the pattern list */
        if (ENABLE_FEATURE_CLEAN_UP) {
                while (pattern_head) {
                        llist_t *pattern_head_ptr = pattern_head;
                        grep_list_data_t *gl = (grep_list_data_t *)pattern_head_ptr->data;

                        pattern_head = pattern_head->link;
                        if (gl->flg_mem_allocated_compiled & ALLOCATED)
                                free(gl->pattern);
                        if (gl->flg_mem_allocated_compiled & COMPILED)
                                regfree(&gl->compiled_regex);
                        free(gl);
                        free(pattern_head_ptr);
                }
        }
        /* 0 = success, 1 = failed, 2 = error */
        if (open_errors)
                return 2;
        return !matched; /* invert return value: 0 = success, 1 = failed */
}