LXR busybox/editors/cmp.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini cmp implementation for busybox
   4 *
   5 * Copyright (C) 2000,2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9
  10/* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
  11/* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
  12
  13//usage:#define cmp_trivial_usage
  14//usage:       "[-l] [-s] FILE1 [FILE2" IF_DESKTOP(" [SKIP1 [SKIP2]]") "]"
  15//usage:#define cmp_full_usage "\n\n"
  16//usage:       "Compare FILE1 with FILE2 (or stdin)\n"
  17//usage:     "\n        -l      Write the byte numbers (decimal) and values (octal)"
  18//usage:     "\n                for all differing bytes"
  19//usage:     "\n        -s      Quiet"
  20
  21#include "libbb.h"
  22
  23static const char fmt_eof[] ALIGN1 = "cmp: EOF on %s\n";
  24static const char fmt_differ[] ALIGN1 = "%s %s differ: char %"OFF_FMT"u, line %u\n";
  25// This fmt_l_opt uses gnu-isms.  SUSv3 would be "%.0s%.0s%"OFF_FMT"u %o %o\n"
  26static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"u %3o %3o\n";
  27
  28static const char opt_chars[] ALIGN1 = "sl";
  29#define CMP_OPT_s (1<<0)
  30#define CMP_OPT_l (1<<1)
  31
  32int cmp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  33int cmp_main(int argc UNUSED_PARAM, char **argv)
  34{
  35        FILE *fp1, *fp2, *outfile = stdout;
  36        const char *filename1, *filename2 = "-";
  37        off_t skip1 = 0, skip2 = 0, char_pos = 0;
  38        int line_pos = 1; /* Hopefully won't overflow... */
  39        const char *fmt;
  40        int c1, c2;
  41        unsigned opt;
  42        int retval = 0;
  43
  44        opt_complementary = "-1"
  45                        IF_DESKTOP(":?4")
  46                        IF_NOT_DESKTOP(":?2")
  47                        ":l--s:s--l";
  48        opt = getopt32(argv, opt_chars);
  49        argv += optind;
  50
  51        filename1 = *argv;
  52        if (*++argv) {
  53                filename2 = *argv;
  54                if (ENABLE_DESKTOP && *++argv) {
  55                        skip1 = XATOOFF(*argv);
  56                        if (*++argv) {
  57                                skip2 = XATOOFF(*argv);
  58                        }
  59                }
  60        }
  61
  62        xfunc_error_retval = 2;  /* missing file results in exitcode 2 */
  63        if (opt & CMP_OPT_s)
  64                logmode = 0;  /* -s suppresses open error messages */
  65        fp1 = xfopen_stdin(filename1);
  66        fp2 = xfopen_stdin(filename2);
  67        if (fp1 == fp2) {               /* Paranoia check... stdin == stdin? */
  68                /* Note that we don't bother reading stdin.  Neither does gnu wc.
  69                 * But perhaps we should, so that other apps down the chain don't
  70                 * get the input.  Consider 'echo hello | (cmp - - && cat -)'.
  71                 */
  72                return 0;
  73        }
  74        logmode = LOGMODE_STDIO;
  75
  76        if (opt & CMP_OPT_l)
  77                fmt = fmt_l_opt;
  78        else
  79                fmt = fmt_differ;
  80
  81        if (ENABLE_DESKTOP) {
  82                while (skip1) { getc(fp1); skip1--; }
  83                while (skip2) { getc(fp2); skip2--; }
  84        }
  85        do {
  86                c1 = getc(fp1);
  87                c2 = getc(fp2);
  88                ++char_pos;
  89                if (c1 != c2) {                 /* Remember: a read error may have occurred. */
  90                        retval = 1;             /* But assume the files are different for now. */
  91                        if (c2 == EOF) {
  92                                /* We know that fp1 isn't at EOF or in an error state.  But to
  93                                 * save space below, things are setup to expect an EOF in fp1
  94                                 * if an EOF occurred.  So, swap things around.
  95                                 */
  96                                fp1 = fp2;
  97                                filename1 = filename2;
  98                                c1 = c2;
  99                        }
 100                        if (c1 == EOF) {
 101                                die_if_ferror(fp1, filename1);
 102                                fmt = fmt_eof;  /* Well, no error, so it must really be EOF. */
 103                                outfile = stderr;
 104                                /* There may have been output to stdout (option -l), so
 105                                 * make sure we fflush before writing to stderr. */
 106                                fflush_all();
 107                        }
 108                        if (!(opt & CMP_OPT_s)) {
 109                                if (opt & CMP_OPT_l) {
 110                                        line_pos = c1;  /* line_pos is unused in the -l case. */
 111                                }
 112                                fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
 113                                if (opt) {      /* This must be -l since not -s. */
 114                                        /* If we encountered an EOF,
 115                                         * the while check will catch it. */
 116                                        continue;
 117                                }
 118                        }
 119                        break;
 120                }
 121                if (c1 == '\n') {
 122                        ++line_pos;
 123                }
 124        } while (c1 != EOF);
 125
 126        die_if_ferror(fp1, filename1);
 127        die_if_ferror(fp2, filename2);
 128
 129        fflush_stdout_and_exit(retval);
 130}
 131