| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Mini cmp implementation for busybox
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| 4 | *
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| 5 | * Copyright (C) 2000,2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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| 8 | */
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| 9 |
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| 10 | /* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
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| 11 | /* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
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| 12 |
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| 13 | /* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
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| 14 | *
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| 15 | * Original version majorly reworked for SUSv3 compliance, bug fixes, and
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| 16 | * size optimizations. Changes include:
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| 17 | * 1) Now correctly distinguishes between errors and actual file differences.
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| 18 | * 2) Proper handling of '-' args.
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| 19 | * 3) Actual error checking of i/o.
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| 20 | * 4) Accept SUSv3 -l option. Note that we use the slightly nicer gnu format
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| 21 | * in the '-l' case.
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| 22 | */
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| 23 |
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| 24 | #include "libbb.h"
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| 25 |
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| 26 | static FILE *cmp_xfopen_input(const char *filename)
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| 27 | {
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| 28 | FILE *fp;
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| 29 |
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| 30 | fp = fopen_or_warn_stdin(filename);
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| 31 | if (fp)
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| 32 | return fp;
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| 33 | xfunc_die(); /* We already output an error message. */
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| 34 | }
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| 35 |
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| 36 | static const char fmt_eof[] ALIGN1 = "cmp: EOF on %s\n";
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| 37 | static const char fmt_differ[] ALIGN1 = "%s %s differ: char %"OFF_FMT"d, line %d\n";
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| 38 | // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%"OFF_FMT"d %o %o\n"
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| 39 | static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"d %3o %3o\n";
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| 40 |
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| 41 | static const char opt_chars[] ALIGN1 = "sl";
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| 42 | #define CMP_OPT_s (1<<0)
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| 43 | #define CMP_OPT_l (1<<1)
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| 44 |
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| 45 | int cmp_main(int argc, char **argv);
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| 46 | int cmp_main(int argc, char **argv)
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| 47 | {
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| 48 | FILE *fp1, *fp2, *outfile = stdout;
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| 49 | const char *filename1, *filename2 = "-";
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| 50 | USE_DESKTOP(off_t skip1 = 0, skip2 = 0;)
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| 51 | off_t char_pos = 0;
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| 52 | int line_pos = 1; /* Hopefully won't overflow... */
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| 53 | const char *fmt;
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| 54 | int c1, c2;
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| 55 | unsigned opt;
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| 56 | int retval = 0;
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| 57 |
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| 58 | xfunc_error_retval = 2; /* 1 is returned if files are different. */
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| 59 |
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| 60 | opt_complementary = "-1"
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| 61 | USE_DESKTOP(":?4")
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| 62 | SKIP_DESKTOP(":?2")
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| 63 | ":l--s:s--l";
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| 64 | opt = getopt32(argv, opt_chars);
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| 65 | argv += optind;
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| 66 |
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| 67 | filename1 = *argv;
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| 68 | fp1 = cmp_xfopen_input(filename1);
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| 69 |
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| 70 | if (*++argv) {
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| 71 | filename2 = *argv;
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| 72 | #if ENABLE_DESKTOP
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| 73 | if (*++argv) {
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| 74 | skip1 = XATOOFF(*argv);
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| 75 | if (*++argv) {
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| 76 | skip2 = XATOOFF(*argv);
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| 77 | }
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| 78 | }
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| 79 | #endif
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| 80 | }
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| 81 |
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| 82 | fp2 = cmp_xfopen_input(filename2);
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| 83 | if (fp1 == fp2) { /* Paranoia check... stdin == stdin? */
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| 84 | /* Note that we don't bother reading stdin. Neither does gnu wc.
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| 85 | * But perhaps we should, so that other apps down the chain don't
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| 86 | * get the input. Consider 'echo hello | (cmp - - && cat -)'.
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| 87 | */
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| 88 | return 0;
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| 89 | }
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| 90 |
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| 91 | if (opt & CMP_OPT_l)
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| 92 | fmt = fmt_l_opt;
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| 93 | else
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| 94 | fmt = fmt_differ;
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| 95 |
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| 96 | #if ENABLE_DESKTOP
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| 97 | while (skip1) { getc(fp1); skip1--; }
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| 98 | while (skip2) { getc(fp2); skip2--; }
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| 99 | #endif
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| 100 | do {
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| 101 | c1 = getc(fp1);
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| 102 | c2 = getc(fp2);
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| 103 | ++char_pos;
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| 104 | if (c1 != c2) { /* Remember: a read error may have occurred. */
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| 105 | retval = 1; /* But assume the files are different for now. */
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| 106 | if (c2 == EOF) {
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| 107 | /* We know that fp1 isn't at EOF or in an error state. But to
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| 108 | * save space below, things are setup to expect an EOF in fp1
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| 109 | * if an EOF occurred. So, swap things around.
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| 110 | */
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| 111 | fp1 = fp2;
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| 112 | filename1 = filename2;
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| 113 | c1 = c2;
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| 114 | }
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| 115 | if (c1 == EOF) {
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| 116 | die_if_ferror(fp1, filename1);
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| 117 | fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
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| 118 | outfile = stderr;
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| 119 | /* There may have been output to stdout (option -l), so
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| 120 | * make sure we fflush before writing to stderr. */
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| 121 | xfflush_stdout();
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| 122 | }
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| 123 | if (!(opt & CMP_OPT_s)) {
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| 124 | if (opt & CMP_OPT_l) {
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| 125 | line_pos = c1; /* line_pos is unused in the -l case. */
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| 126 | }
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| 127 | fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
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| 128 | if (opt) { /* This must be -l since not -s. */
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| 129 | /* If we encountered an EOF,
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| 130 | * the while check will catch it. */
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| 131 | continue;
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| 132 | }
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| 133 | }
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| 134 | break;
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| 135 | }
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| 136 | if (c1 == '\n') {
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| 137 | ++line_pos;
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| 138 | }
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| 139 | } while (c1 != EOF);
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| 140 |
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| 141 | die_if_ferror(fp1, filename1);
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| 142 | die_if_ferror(fp2, filename2);
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| 143 |
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| 144 | fflush_stdout_and_exit(retval);
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| 145 | }
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