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utils-std

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

env.c (3841B)

    

  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. #define _XOPEN_SOURCE 800 // wordexp
  8. #include <assert.h>  // assert
  9. #include <errno.h>   // errno
  10. #include <stdbool.h> // bool, true, false
  11. #include <stdio.h>   // puts, fprintf
  12. #include <stdlib.h>  // putenv
  13. #include <string.h>  // strchr, strerror
  14. #include <unistd.h>  // getopt, opt*
  15. #ifdef HAS_WORDEXP
  16. #include <wordexp.h>
  17. #endif
  18. #ifdef HAS_GETOPT_LONG
  19. #include <getopt.h>
  20. #endif
  22. extern char **environ;
  23. char *envclear[1];
  25. static int
  26. do_export(void)
  27. {
  28. 	int i = 0;
  30. 	for(; environ[i] != NULL; i++)
  31. 	{
  32. 		if(puts(environ[i]) < 0)
  33. 		{
  34. 			fprintf(stderr, "env: error: Failed writing environ: %s\n", strerror(errno));
  35. 			return 1;
  36. 		}
  37. 	}
  39. 	return 0;
  40. }
  42. static void
  43. usage(void)
  44. {
  45. 	fprintf(stderr, "env [-i] [-u key] [key=value ...] [command [args]]\n");
  46. }
  48. int
  49. main(int argc, char *argv[])
  50. {
  51. 	bool flag_i = false;
  52. #ifdef HAS_WORDEXP
  53. 	bool flag_S = false;
  54. 	wordexp_t opt_S;
  55. #define OPTARGS ":iu:S:"
  56. #else
  57. #define OPTARGS ":iu:"
  58. #endif
  60. 	int c = -1;
  61. #ifdef HAS_GETOPT_LONG
  62. 	// Strictly for GNUisms compatibility so no long-only options
  63. 	// clang-format off
  64. 	static struct option opts[] = {
  65. 		{"ignore-environment", no_argument, 0, 'i'},
  66. 		{"unset", required_argument, 0, 'u'},
  67. #ifdef HAS_WORDEXP
  68. 		{"split-string", required_argument, 0, 'S'},
  69. #endif
  70. 		{0, 0, 0, 0},
  71. 	};
  72. 	// clang-format on
  74. 	// Need + as first character to get POSIX-style option parsing
  75. 	while((c = getopt_long(argc, argv, "+" OPTARGS, opts, NULL)) != -1)
  76. #else
  77. 	while((c = getopt(argc, argv, OPTARGS)) != -1)
  78. #endif
  79. 	{
  80. 		switch(c)
  81. 		{
  82. 		case 'i':
  83. 			flag_i = true;
  84. 			break;
  85. 		case 'u':
  86. 			unsetenv(optarg);
  87. 			break;
  88. #ifdef HAS_WORDEXP
  89. 		case 'S':
  90. 			flag_S = true;
  91. 			int ret = wordexp(optarg, &opt_S, WRDE_NOCMD);
  92. 			switch(ret)
  93. 			{
  94. 			case 0:
  95. 				break;
  96. 			case WRDE_BADCHAR:
  97. 				fputs("env: error: wordexpr returned WRDE_BADCHAR\n", stderr);
  98. 				return 1;
  99. 			case WRDE_BADVAL:
  100. 				fputs("env: error: Undefined shell variable (WRDE_BADVAL)\n", stderr);
  101. 				return 1;
  102. 			case WRDE_CMDSUB:
  103. 				fputs("env: error: Command substitution forbidden (WRDE_CMDSUB)\n", stderr);
  104. 				return 1;
  105. 			case WRDE_NOSPACE:
  106. 				fputs("env: error: Out of memory (WRDE_NOSPACE)\n", stderr);
  107. 				return 1;
  108. 			case WRDE_SYNTAX:
  109. 				fputs("env: error: Syntax Error (WRDE_SYNTAX)\n", stderr);
  110. 				return 1;
  111. 			default:
  112. 				fprintf(stderr, "env: error: Unknown error %d from wordexp\n", ret);
  113. 				return 1;
  114. 			}
  115. 			break;
  116. #endif
  117. 		case ':':
  118. 			fprintf(stderr, "env: error: Missing operand for option: '-%c'\n", optopt);
  119. 			usage();
  120. 			return 1;
  121. 		case '?':
  122. 			fprintf(stderr, "env: error: Unrecognised option: '-%c'\n", optopt);
  123. 			usage();
  124. 			return 1;
  125. 		default:
  126. 			assert(false);
  127. 		}
  128. 	}
  130. 	argc -= optind;
  131. 	argv += optind;
  133. 	if(flag_i)
  134. 	{
  135. 		environ = envclear;
  136. 		envclear[0] = NULL;
  137. 	}
  139. 	for(; argv[0]; argv++, argc--)
  140. 	{
  141. 		char *sep = strchr(argv[0], '=');
  142. 		if(sep == NULL)
  143. 		{
  144. 			break;
  145. 		}
  147. 		*sep = 0;
  148. 		sep++;
  150. 		if(setenv(argv[0], sep, 1))
  151. 		{
  152. 			fprintf(stderr,
  153. 			        "env: error: Failed setting environment variable '%s' to '%s': %s\n",
  154. 			        argv[0],
  155. 			        sep,
  156. 			        strerror(errno));
  157. 			return 1;
  158. 		}
  159. 	}
  161. #ifdef HAS_WORDEXP
  162. 	if(flag_S)
  163. 	{
  164. 		errno = 0;
  165. 		if(execvp(opt_S.we_wordv[0], opt_S.we_wordv) < 0)
  166. 		{
  167. 			fprintf(
  168. 			    stderr, "env: error: Failed executing '%s': %s\n", opt_S.we_wordv[0], strerror(errno));
  170. 			return (errno == ENOENT) ? 127 : 126;
  171. 		}
  172. 		assert(false);
  173. 	}
  174. #endif
  176. 	if(argc < 1)
  177. 	{
  178. 		return do_export();
  179. 	}
  181. 	assert(argv[0]);
  182. 	errno = 0;
  183. 	if(execvp(argv[0], argv) < 0)
  184. 	{
  185. 		fprintf(stderr, "env: error: Failed executing '%s': %s\n", argv[0], strerror(errno));
  187. 		return (errno == ENOENT) ? 127 : 126;
  188. 	}
  190. 	assert(false);
  191. }