[821] | 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 | * This program is free software; you can redistribute it and/or modify
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| 8 | * it under the terms of the GNU General Public License as published by
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| 9 | * the Free Software Foundation; either version 2 of the License, or
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| 10 | * (at your option) any later version.
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| 11 | *
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| 12 | * This program is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 15 | * General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with this program; if not, write to the Free Software
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| 19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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| 20 | *
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| 21 | */
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| 22 |
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| 23 | /* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
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| 24 | /* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
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| 25 |
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| 26 | /* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
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| 27 | *
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| 28 | * Original version majorly reworked for SUSv3 compliance, bug fixes, and
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| 29 | * size optimizations. Changes include:
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| 30 | * 1) Now correctly distinguishes between errors and actual file differences.
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| 31 | * 2) Proper handling of '-' args.
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| 32 | * 3) Actual error checking of i/o.
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| 33 | * 4) Accept SUSv3 -l option. Note that we use the slightly nicer gnu format
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| 34 | * in the '-l' case.
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| 35 | */
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| 36 |
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| 37 | #include <stdio.h>
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| 38 | #include <stdlib.h>
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| 39 | #include <unistd.h>
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| 40 | #include "busybox.h"
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| 41 |
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| 42 | static FILE *cmp_xfopen_input(const char *filename)
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| 43 | {
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| 44 | FILE *fp;
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| 45 |
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| 46 | if ((fp = bb_wfopen_input(filename)) != NULL) {
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| 47 | return fp;
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| 48 | }
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| 49 |
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| 50 | exit(bb_default_error_retval); /* We already output an error message. */
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| 51 | }
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| 52 |
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| 53 | static const char fmt_eof[] = "cmp: EOF on %s\n";
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| 54 | static const char fmt_differ[] = "%s %s differ: char %d, line %d\n";
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| 55 | // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%d %o %o\n"
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| 56 | static const char fmt_l_opt[] = "%.0s%.0s%d %3o %3o\n";
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| 57 |
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| 58 | static const char opt_chars[] = "sl";
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| 59 |
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| 60 | enum {
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| 61 | OPT_s = 1,
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| 62 | OPT_l = 2
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| 63 | };
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| 64 |
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| 65 | int cmp_main(int argc, char **argv)
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| 66 | {
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| 67 | FILE *fp1, *fp2, *outfile = stdout;
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| 68 | const char *filename1, *filename2;
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| 69 | const char *fmt;
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| 70 | int c1, c2, char_pos, line_pos;
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| 71 | int opt_flags;
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| 72 | int exit_val = 0;
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| 73 |
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| 74 | bb_default_error_retval = 2; /* 1 is returned if files are different. */
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| 75 |
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| 76 | opt_flags = bb_getopt_ulflags(argc, argv, opt_chars);
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| 77 |
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| 78 | if ((opt_flags == 3) || (((unsigned int)(--argc - optind)) > 1)) {
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| 79 | bb_show_usage();
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| 80 | }
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| 81 |
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| 82 | fp1 = cmp_xfopen_input(filename1 = *(argv += optind));
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| 83 |
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| 84 | filename2 = "-";
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| 85 | if (*++argv) {
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| 86 | filename2 = *argv;
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| 87 | }
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| 88 | fp2 = cmp_xfopen_input(filename2);
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| 89 |
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| 90 | if (fp1 == fp2) { /* Paranioa check... stdin == stdin? */
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| 91 | /* Note that we don't bother reading stdin. Neither does gnu wc.
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| 92 | * But perhaps we should, so that other apps down the chain don't
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| 93 | * get the input. Consider 'echo hello | (cmp - - && cat -)'.
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| 94 | */
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| 95 | return 0;
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| 96 | }
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| 97 |
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| 98 | fmt = fmt_differ;
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| 99 | if (opt_flags == OPT_l) {
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| 100 | fmt = fmt_l_opt;
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| 101 | }
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| 102 |
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| 103 | char_pos = 0;
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| 104 | line_pos = 1;
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| 105 | do {
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| 106 | c1 = getc(fp1);
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| 107 | c2 = getc(fp2);
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| 108 | ++char_pos;
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| 109 | if (c1 != c2) { /* Remember -- a read error may have occurred. */
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| 110 | exit_val = 1; /* But assume the files are different for now. */
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| 111 | if (c2 == EOF) {
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| 112 | /* We know that fp1 isn't at EOF or in an error state. But to
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| 113 | * save space below, things are setup to expect an EOF in fp1
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| 114 | * if an EOF occurred. So, swap things around.
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| 115 | */
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| 116 | fp1 = fp2;
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| 117 | filename1 = filename2;
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| 118 | c1 = c2;
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| 119 | }
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| 120 | if (c1 == EOF) {
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| 121 | bb_xferror(fp1, filename1);
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| 122 | fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
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| 123 | outfile = stderr;
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| 124 | /* There may have been output to stdout (option -l), so
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| 125 | * make sure we fflush before writing to stderr. */
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| 126 | bb_xfflush_stdout();
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| 127 | }
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| 128 | if (opt_flags != OPT_s) {
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| 129 | if (opt_flags == OPT_l) {
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| 130 | line_pos = c1; /* line_pos is unused in the -l case. */
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| 131 | }
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| 132 | bb_fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
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| 133 | if (opt_flags) { /* This must be -l since not -s. */
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| 134 | /* If we encountered and EOF, the while check will catch it. */
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| 135 | continue;
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| 136 | }
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| 137 | }
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| 138 | break;
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| 139 | }
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| 140 | if (c1 == '\n') {
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| 141 | ++line_pos;
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| 142 | }
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| 143 | } while (c1 != EOF);
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| 144 |
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| 145 | bb_xferror(fp1, filename1);
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| 146 | bb_xferror(fp2, filename2);
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| 147 |
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| 148 | bb_fflush_stdout_and_exit(exit_val);
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| 149 | }
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