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utils-std

Collection of commonly available Unix tools git clone https://anongit.hacktivis.me/git/utils-std.git/

which.c (2727B)

    

  1. // utils-std: Collection of commonly available Unix tools
  2. // SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
  3. // SPDX-License-Identifier: MPL-2.0
  5. #define _POSIX_C_SOURCE 200809L
  6. #include "../config.h"
  7. #include "../libutils/getopt_nolong.h"
  8. #include "../libutils/strchrnul.h"
  10. #include <errno.h>
  11. #include <limits.h> // PATH_MAX
  12. #include <stdbool.h>
  13. #include <stdio.h>  // fprintf
  14. #include <stdlib.h> // getenv
  15. #include <string.h> // strcpy, memcpy
  16. #include <unistd.h> // access, getopt
  17. #ifdef HAS_GETOPT_LONG
  18. #include <getopt.h>
  19. #endif
  21. const char *argv0 = "which";
  23. int
  24. main(int argc, char *argv[])
  25. {
  26. 	bool opt_a = false, opt_s = false;
  27. 	int missing = 0;
  29. 	char *path = getenv("PATH");
  30. 	if(path == NULL)
  31. 	{
  32. 		fputs("which: error: $PATH environment unset", stderr);
  33. 		return 1;
  34. 	}
  36. #ifdef HAS_GETOPT_LONG
  37. 	// Strictly for GNUisms compatibility so no long-only options
  38. 	// clang-format off
  39. 	static struct option opts[] = {
  40. 		{"all", no_argument, NULL, 'a'},
  41. 		{0, 0, 0, 0},
  42. 	};
  43. 	// clang-format on
  45. 	// Need + as first character to get POSIX-style option parsing
  46. 	for(int c = -1; (c = getopt_long(argc, argv, "+as", opts, NULL)) != -1;)
  47. #else
  48. 	for(int c = -1; (c = getopt_nolong(argc, argv, "as")) != -1;)
  49. #endif
  50. 	{
  51. 		switch(c)
  52. 		{
  53. 		case 'a':
  54. 			opt_a = true;
  55. 			break;
  56. 		case 's':
  57. 			opt_s = true;
  58. 			break;
  59. 		case '?':
  60. 			GETOPT_UNKNOWN_OPT
  61. 			return 1;
  62. 		default:
  63. 			abort();
  64. 		}
  65. 	}
  67. 	argc -= optind;
  68. 	argv += optind;
  70. 	if(argc <= 0) return 1;
  72. 	for(int i = 0; i < argc; i++)
  73. 	{
  74. 		char *cmd = argv[i];
  75. 		size_t cmdlen = strlen(cmd);
  76. 		bool found = false;
  77. 		char *start = path;
  79. 		if(strchr(cmd, '/'))
  80. 		{
  81. 			puts(cmd);
  82. 			continue;
  83. 		}
  85. 		const char *prev = start;
  86. 		while(true)
  87. 		{
  88. 			static char buf[PATH_MAX] = "";
  89. 			const char *stop = utils_strchrnul(prev, ':');
  91. 			size_t buflen = stop - prev;
  92. 			memcpy(buf, prev, buflen);
  94. 			if((PATH_MAX - buflen - 1) < cmdlen)
  95. 			{
  96. 				buf[buflen] = '\0';
  97. 				fprintf(stderr,
  98. 				        "which: warning: Concatenation of PATH element '%s' and command '%s' would be "
  99. 				        "greater than PATH_MAX\n",
  100. 				        buf,
  101. 				        cmd);
  102. 				goto which_cont;
  103. 			}
  105. 			buf[buflen++] = '/';
  107. 			memcpy(buf + buflen, cmd, cmdlen);
  108. 			buflen += cmdlen;
  109. 			buf[buflen] = '\0';
  111. 			errno = 0;
  112. 			if(access(buf, X_OK) == 0)
  113. 			{
  114. 				if(!opt_s) puts(buf);
  116. 				found = true;
  118. 				if(!opt_a) break;
  119. 			}
  121. 			switch(errno)
  122. 			{
  123. 			case ENOENT:
  124. 			case 0:
  125. 				break;
  126. 			default:
  127. 				fprintf(stderr,
  128. 				        "which: warning: Failed checking access on file '%s': %s\n",
  129. 				        buf,
  130. 				        strerror(errno));
  131. 				break;
  132. 			}
  134. 		which_cont:
  135. 			if(*stop == '\0') break;
  136. 			prev = stop + 1;
  137. 		}
  139. 		if(!found) missing++;
  140. 	}
  142. 	return missing;
  143. }