cmp.c 3.9 KB

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  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. //config:config CMP
  10. //config: bool "cmp (5.4 kb)"
  11. //config: default y
  12. //config: help
  13. //config: cmp is used to compare two files and returns the result
  14. //config: to standard output.
  15. //applet:IF_CMP(APPLET(cmp, BB_DIR_USR_BIN, BB_SUID_DROP))
  16. //kbuild:lib-$(CONFIG_CMP) += cmp.o
  17. //usage:#define cmp_trivial_usage
  18. //usage: "[-l] [-s] FILE1 [FILE2" IF_DESKTOP(" [SKIP1 [SKIP2]]") "]"
  19. //usage:#define cmp_full_usage "\n\n"
  20. //usage: "Compare FILE1 with FILE2 (or stdin)\n"
  21. //usage: "\n -l Write the byte numbers (decimal) and values (octal)"
  22. //usage: "\n for all differing bytes"
  23. //usage: "\n -s Quiet"
  24. /* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
  25. /* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
  26. #include "libbb.h"
  27. static const char fmt_eof[] ALIGN1 = "cmp: EOF on %s\n";
  28. static const char fmt_differ[] ALIGN1 = "%s %s differ: char %"OFF_FMT"u, line %u\n";
  29. // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%"OFF_FMT"u %o %o\n"
  30. static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"u %3o %3o\n";
  31. #define OPT_STR "sl"
  32. #define CMP_OPT_s (1<<0)
  33. #define CMP_OPT_l (1<<1)
  34. int cmp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  35. int cmp_main(int argc UNUSED_PARAM, char **argv)
  36. {
  37. FILE *fp1, *fp2, *outfile = stdout;
  38. const char *filename1, *filename2 = "-";
  39. off_t skip1 = 0, skip2 = 0, char_pos = 0;
  40. int line_pos = 1; /* Hopefully won't overflow... */
  41. const char *fmt;
  42. int c1, c2;
  43. unsigned opt;
  44. int retval = 0;
  45. opt = getopt32(argv, "^"
  46. OPT_STR
  47. "\0" "-1"
  48. IF_DESKTOP(":?4")
  49. IF_NOT_DESKTOP(":?2")
  50. ":l--s:s--l"
  51. );
  52. argv += optind;
  53. filename1 = *argv;
  54. if (*++argv) {
  55. filename2 = *argv;
  56. if (ENABLE_DESKTOP && *++argv) {
  57. skip1 = XATOOFF(*argv);
  58. if (*++argv) {
  59. skip2 = XATOOFF(*argv);
  60. }
  61. }
  62. }
  63. xfunc_error_retval = 2; /* missing file results in exitcode 2 */
  64. if (opt & CMP_OPT_s)
  65. logmode = 0; /* -s suppresses open error messages */
  66. fp1 = xfopen_stdin(filename1);
  67. fp2 = xfopen_stdin(filename2);
  68. if (fp1 == fp2) { /* Paranoia check... stdin == stdin? */
  69. /* Note that we don't bother reading stdin. Neither does gnu wc.
  70. * But perhaps we should, so that other apps down the chain don't
  71. * get the input. Consider 'echo hello | (cmp - - && cat -)'.
  72. */
  73. return 0;
  74. }
  75. logmode = LOGMODE_STDIO;
  76. if (opt & CMP_OPT_l)
  77. fmt = fmt_l_opt;
  78. else
  79. fmt = fmt_differ;
  80. if (ENABLE_DESKTOP) {
  81. while (skip1) { getc(fp1); skip1--; }
  82. while (skip2) { getc(fp2); skip2--; }
  83. }
  84. do {
  85. c1 = getc(fp1);
  86. c2 = getc(fp2);
  87. ++char_pos;
  88. if (c1 != c2) { /* Remember: a read error may have occurred. */
  89. retval = 1; /* But assume the files are different for now. */
  90. if (c2 == EOF) {
  91. /* We know that fp1 isn't at EOF or in an error state. But to
  92. * save space below, things are setup to expect an EOF in fp1
  93. * if an EOF occurred. So, swap things around.
  94. */
  95. fp1 = fp2;
  96. filename1 = filename2;
  97. c1 = c2;
  98. }
  99. if (c1 == EOF) {
  100. die_if_ferror(fp1, filename1);
  101. fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
  102. outfile = stderr;
  103. /* There may have been output to stdout (option -l), so
  104. * make sure we fflush before writing to stderr. */
  105. fflush_all();
  106. }
  107. if (!(opt & CMP_OPT_s)) {
  108. if (opt & CMP_OPT_l) {
  109. line_pos = c1; /* line_pos is unused in the -l case. */
  110. }
  111. fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
  112. if (opt) { /* This must be -l since not -s. */
  113. /* If we encountered an EOF,
  114. * the while check will catch it. */
  115. continue;
  116. }
  117. }
  118. break;
  119. }
  120. if (c1 == '\n') {
  121. ++line_pos;
  122. }
  123. } while (c1 != EOF);
  124. die_if_ferror(fp1, filename1);
  125. die_if_ferror(fp2, filename2);
  126. fflush_stdout_and_exit(retval);
  127. }