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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