/* vi: set sw=4 ts=4: */
/*
 * xxd implementation for busybox
 *
 * Copyright (c) 2017 Denys Vlasenko <vda.linux@gmail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
//config:config XXD
//config:       bool "xxd (11 kb)"
//config:       default y
//config:       help
//config:       The xxd utility is used to display binary data in a readable
//config:       way that is comparable to the output from most hex editors.

//applet:IF_XXD(APPLET_NOEXEC(xxd, xxd, BB_DIR_USR_BIN, BB_SUID_DROP, xxd))

//kbuild:lib-$(CONFIG_XXD) += hexdump_xxd.o

// $ xxd --version
// xxd V1.10 27oct98 by Juergen Weigert
// $ xxd --help
// Usage:
//       xxd [options] [infile [outfile]]
//    or
//       xxd -r [-s [-]offset] [-c cols] [-ps] [infile [outfile]]
// Options:
//    -a          toggle autoskip: A single '*' replaces nul-lines. Default off.
//    -b          binary digit dump (incompatible with -ps,-i,-r). Default hex.
//    -c cols     format <cols> octets per line. Default 16 (-i: 12, -ps: 30).
//    -E          show characters in EBCDIC. Default ASCII.
//    -e          little-endian dump (incompatible with -ps,-i,-r).
//    -g          number of octets per group in normal output. Default 2 (-e: 4).
//    -i          output in C include file style.
//    -l len      stop after <len> octets.
//    -o off      add <off> to the displayed file position.
//    -ps         output in postscript plain hexdump style.
//    -r          reverse operation: convert (or patch) hexdump into binary.
//    -r -s off   revert with <off> added to file positions found in hexdump.
//    -s [+][-]seek  start at <seek> bytes abs. (or +: rel.) infile offset.
//    -u          use upper case hex letters.

//usage:#define xxd_trivial_usage
//usage:       "[-pri] [-g N] [-c N] [-l LEN] [-s OFS] [-o OFS] [FILE]"
//usage:#define xxd_full_usage "\n\n"
//usage:       "Hex dump FILE (or stdin)\n"
//usage:     "\n        -g N            Bytes per group"
//usage:     "\n        -c N            Bytes per line"
//usage:     "\n        -p              Show only hex bytes, assumes -c30"
//usage:     "\n        -i              C include file style"
// exactly the same help text lines in hexdump and xxd:
//usage:     "\n        -l LENGTH       Show only first LENGTH bytes"
//usage:     "\n        -s OFFSET       Skip OFFSET bytes"
//usage:     "\n        -o OFFSET       Add OFFSET to displayed offset"
//usage:     "\n        -r              Reverse (with -p, assumes no offsets in input)"

#include "libbb.h"
#include "common_bufsiz.h"
#include "dump.h"

/* This is a NOEXEC applet. Be very careful! */

#define OPT_l (1 << 0)
#define OPT_s (1 << 1)
#define OPT_a (1 << 2)
#define OPT_p (1 << 3)
#define OPT_i (1 << 4)
#define OPT_r (1 << 5)
#define OPT_g (1 << 6)
#define OPT_c (1 << 7)
#define OPT_o (1 << 8)

#define fillbuf bb_common_bufsiz1

static void write_zeros(off_t count)
{
        errno = 0;
        do {
                unsigned sz = count < COMMON_BUFSIZE ? (unsigned)count : COMMON_BUFSIZE;
                if (fwrite(fillbuf, 1, sz, stdout) != sz)
                        bb_simple_perror_msg_and_die("write error");
                count -= sz;
        } while (count != 0);
}

static void reverse(unsigned opt, const char *filename, char *opt_s)
{
        FILE *fp;
        char *buf;
        off_t cur, opt_s_ofs;

        memset(fillbuf, 0, COMMON_BUFSIZE);
        opt_s_ofs = cur = 0;
        if (opt_s) {
                opt_s_ofs = BB_STRTOOFF(opt_s, NULL, 0);
                if (errno || opt_s_ofs < 0)
                        bb_error_msg_and_die("invalid number '%s'", opt_s);
        }

        fp = filename ? xfopen_for_read(filename) : stdin;

 get_new_line:
        while ((buf = xmalloc_fgetline(fp)) != NULL) {
                char *p;

                p = buf;
                if (!(opt & OPT_p)) {
                        char *end;
                        off_t ofs;
 skip_address:
                        p = skip_whitespace(p);
                        ofs = BB_STRTOOFF(p, &end, 16);
                        if ((errno && errno != EINVAL)
                         || ofs < 0
                        /* -s SEEK value should be added before seeking */
                         || (ofs += opt_s_ofs) < 0
                        ) {
                                bb_error_msg_and_die("invalid number '%s'", p);
                        }
                        if (ofs != cur) {
                                if (fseeko(stdout, ofs, SEEK_SET) != 0) {
                                        if (ofs < cur)
                                                bb_simple_perror_msg_and_die("cannot seek");
                                        write_zeros(ofs - cur);
                                }
                                cur = ofs;
                        }
                        p = end;
                        /* NB: for xxd -r, first hex portion is address even without colon */
                        /* But if colon is there, skip it: */
                        if (*p == ':')
                                p++;
                }

                /* Process hex bytes optionally separated by whitespace */
                for (;;) {
                        uint8_t val, c;
                        int badchar = 0;
 nibble1:
                        if (opt & OPT_p)
                                p = skip_whitespace(p);
                        c = *p++;
                        if (isdigit(c))
                                val = c - '0';
                        else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
                                val = (c|0x20) - ('a' - 10);
                        else {
                                /* xxd V1.10 allows one non-hexnum char:
                                 *  echo -e "31 !3 0a 0a" | xxd -r -p
                                 * is "10<a0>" (no <cr>) - "!" is ignored,
                                 * but stops for more than one:
                                 *  echo -e "31 !!343434\n30 0a" | xxd -r -p
                                 * is "10<cr>" - "!!" drops rest of the line.
                                 * Note: this also covers whitespace chars:
                                 * xxxxxxxx: 3031 3233 3435 3637 3839 3a3b 3c3d 3e3f  0123456789:;<=>?
                                 *  detects this ^ - skips this one space
                                 * xxxxxxxx: 3031 3233 3435 3637 3839 3a3b 3c3d 3e3f  0123456789:;<=>?
                                 *                                     detects this ^^ - skips the rest
                                 */
                                if (c == '\0' || badchar)
                                        break;
                                badchar++;
                                goto nibble1;
                        }
                        val <<= 4;

 nibble2:
                        if (opt & OPT_p) {
                                /* Works the same with xxd V1.10:
                                 *  echo "31 09 32 0a" | xxd -r -p
                                 *  echo "31 0 9 32 0a" | xxd -r -p
                                 * thus allow whitespace (even multiple chars)
                                 * after byte's 1st char:
                                 */
                                p = skip_whitespace(p);
                        }

                        c = *p++;
                        if (isdigit(c))
                                val |= c - '0';
                        else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
                                val |= (c|0x20) - ('a' - 10);
                        else {
                                if (c != '\0') {
                                        /* "...3<not_hex_char>...": ignore "3",
                                         * skip everything up to next hexchar or newline:
                                         */
                                        while (!isxdigit(*p)) {
                                                if (*p == '\0') {
                                                        free(buf);
                                                        goto get_new_line;
                                                }
                                                p++;
                                        }
                                        goto nibble1;
                                }
                                /* Nibbles can join even through newline:
                                 * echo -e "31 3\n2 0a" | xxd -r -p
                                 * is "12<cr>".
                                 */
                                free(buf);
                                p = buf = xmalloc_fgetline(fp);
                                if (!buf)
                                        break;
                                if (!(opt & OPT_p)) /* -p and !-p: different behavior */
                                        goto skip_address;
                                goto nibble2;
                        }
                        putchar(val);
                        cur++;
                } /* for(;;) */
                free(buf);
        }
        //fclose(fp);
        fflush_stdout_and_exit_SUCCESS();
}

static void print_C_style(const char *p, const char *hdr)
{
        printf(hdr, isdigit(p[0]) ? "__" : "");
        while (*p) {
                bb_putchar(isalnum(*p) ? *p : '_');
                p++;
        }
}

int xxd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int xxd_main(int argc UNUSED_PARAM, char **argv)
{
        char buf[80];
        dumper_t *dumper;
        char *opt_l, *opt_o;
        char *opt_s = NULL;
        unsigned bytes = 2;
        unsigned cols = 0;
        unsigned opt;
        int r;

        setup_common_bufsiz();

        dumper = alloc_dumper();

        opt = getopt32(argv, "^" "l:s:apirg:+c:+o:" "\0" "?1" /* 1 argument max */,
                        &opt_l, &opt_s, &bytes, &cols, &opt_o
        );
        argv += optind;

        dumper->dump_vflag = ALL;
//      if (opt & OPT_a)
//              dumper->dump_vflag = SKIPNUL; ..does not exist
        if (opt & OPT_l) {
                dumper->dump_length = xstrtou_range(
                                opt_l,
                                /*base:*/ 0,
                                /*lo:*/ 0, /*hi:*/ INT_MAX
                );
        }
        if (opt & OPT_s) {
                dumper->dump_skip = xstrtoull_range(
                                opt_s,
                                /*base:*/ 0,
                                /*lo:*/ 0, /*hi:*/ OFF_T_MAX
                );
                //BUGGY for /proc/version (unseekable?)
        }

        if (opt & OPT_r) {
                reverse(opt, argv[0], opt_s);
        }

        if (opt & OPT_o) {
                /* -o accepts negative numbers too */
                dumper->xxd_displayoff = xstrtoll(opt_o, /*base:*/ 0);
        }

        if (opt & OPT_p) {
                if (cols == 0)
                        cols = 30;
                bytes = cols; /* -p ignores -gN */
        } else {
                if (cols == 0)
                        cols = (opt & OPT_i) ? 12 : 16;
                if (opt & OPT_i) {
                        bytes = 1; // -i ignores -gN
                        // output is "  0xXX, 0xXX, 0xXX...", add leading space
                        bb_dump_add(dumper, "\" \"");
                } else
                        bb_dump_add(dumper, "\"%08_ax: \""); // "address: "
        }

        if (bytes < 1 || bytes >= cols) {
                sprintf(buf, "%u/1 \"%%02x\"", cols); // cols * "XX"
                bb_dump_add(dumper, buf);
        }
        else if (bytes == 1) {
                if (opt & OPT_i)
                        sprintf(buf, "%u/1 \" 0x%%02x,\"", cols); // cols * " 0xXX,"
//TODO: compat: omit the last comma after the very last byte
                else
                        sprintf(buf, "%u/1 \"%%02x \"", cols); // cols * "XX "
                bb_dump_add(dumper, buf);
        }
        else {
/* Format "print byte" with and without trailing space */
#define BS "/1 \"%02x \""
#define B  "/1 \"%02x\""
                unsigned i;
                char *bigbuf = xmalloc(cols * (sizeof(BS)-1));
                char *p = bigbuf;
                for (i = 1; i <= cols; i++) {
                        if (i == cols || i % bytes)
                                p = stpcpy(p, B);
                        else
                                p = stpcpy(p, BS);
                }
                // for -g3, this results in B B BS B B BS... B = "xxxxxx xxxxxx .....xx"
                // todo: can be more clever and use
                // one 'bytes-1/1 "%02x"' format instead of many "B B B..." formats
                //bb_error_msg("ADDED:'%s'", bigbuf);
                bb_dump_add(dumper, bigbuf);
                free(bigbuf);
        }

        if (!(opt & (OPT_p|OPT_i))) {
                sprintf(buf, "\"  \"%u/1 \"%%_p\"\"\n\"", cols); // "  ASCII\n"
                bb_dump_add(dumper, buf);
        } else {
                bb_dump_add(dumper, "\"\n\"");
                dumper->xxd_eofstring = "\n";
        }

        if ((opt & OPT_i) && argv[0]) {
                print_C_style(argv[0], "unsigned char %s");
                printf("[] = {\n");
        }
        r = bb_dump_dump(dumper, argv);
        if (r == 0 && (opt & OPT_i) && argv[0]) {
                print_C_style(argv[0], "};\nunsigned int %s");
                printf("_len = %"OFF_FMT"u;\n", dumper->address);
        }
        return r;
}