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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