logo

utils-std

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

mktemp.c (4370B)

    

  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. // getentropy got in POSIX.1-2024 but defining _POSIX_C_SOURCE causes too much side-effects
  6. #define _DEFAULT_SOURCE // getentropy
  7. #include "../config.h"  // HAS_*
  8. #include "../lib/getopt_nolong.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> // strerror
  16. #include <unistd.h> // getopt, getentropy
  17. #ifdef HAS_GETOPT_LONG
  18. #include <getopt.h>
  19. #endif
  21. const char *argv0 = "mktemp";
  23. static int
  24. unsafe_mktemp(char *template)
  25. {
  26. 	size_t l = strlen(template);
  28. 	size_t len = 0;
  29. 	size_t off = l - 1;
  30. 	while(off > 0 && template[off] == 'X')
  31. 		off--, len++;
  33. 	if(len < 6)
  34. 	{
  35. 		fprintf(stderr,
  36. 		        "%s: error: Template '%s' is invalid (need >= 6 final X, got %zd)\n",
  37. 		        argv0,
  38. 		        template,
  39. 		        len);
  40. 		return 1;
  41. 	}
  43. 	for(size_t i = 0; i < l; i++)
  44. 	{
  45. 		if(template[i] == '\n')
  46. 		{
  47. 			fprintf(stderr, "%s: error: Invalid character (newline) in template\n", argv0);
  48. 			return 1;
  49. 		}
  50. 	}
  52. 	for(int retries = 100; 0 < retries; retries--)
  53. 	{
  54. 		unsigned long r = 0;
  55. 		if(getentropy(&r, sizeof(r)) != 0)
  56. 		{
  57. 			fprintf(stderr,
  58. 			        "%s: error: Failed to get entropy for random filename: %s\n",
  59. 			        argv0,
  60. 			        strerror(errno));
  61. 			return 1;
  62. 		}
  64. 		for(int i = len; i > 0; i--, r >>= 5)
  65. 			template[off + i] = 'A' + (r & 15) + (r & 16) * 2;
  67. 		if(access(template, F_OK) != 0 && errno == ENOENT)
  68. 		{
  69. 			puts(template);
  70. 			return 0;
  71. 		}
  72. 	}
  74. 	fprintf(stderr, "%s: error: Exhausted all 100 attempts at generating a filename\n", argv0);
  75. 	return 1;
  76. }
  78. int
  79. main(int argc, char *argv[])
  80. {
  81. 	bool o_create_dir = false, o_quiet = false, o_unsafe = false;
  82. 	static char template[PATH_MAX] = "tmp.XXXXXXXXXX";
  83. 	const char *tmpdir = NULL;
  85. #ifdef HAS_GETOPT_LONG
  86. 	// Strictly for GNUisms compatibility so no long-only options
  87. 	// clang-format off
  88. 	static struct option opts[] = {
  89. 		{"directory", no_argument, 0, 'd'},
  90. 		{"dry-run", required_argument, 0, 'u'},
  91. 		{"quiet", no_argument, 0, 'q'},
  92. 		{"tmpdir", required_argument, 0, 'p'},
  93. 		{0, 0, 0, 0},
  94. 	};
  95. 	// clang-format on
  97. 	// Need + as first character to get POSIX-style option parsing
  98. 	for(int c = -1; (c = getopt_long(argc, argv, "+:dqp:tu", opts, NULL)) != -1;)
  99. #else
  100. 	for(int c = -1; (c = getopt_nolong(argc, argv, ":dqp:tu")) != -1;)
  101. #endif
  102. 	{
  103. 		switch(c)
  104. 		{
  105. 		case 'd':
  106. 			o_create_dir = true;
  107. 			break;
  108. 		case 'q':
  109. 			o_quiet = true;
  110. 			break;
  111. 		case 'p':
  112. 			tmpdir = optarg;
  113. 			break;
  114. 		case 't':
  115. 			if(tmpdir == NULL) tmpdir = getenv("TMPDIR");
  116. 			if(tmpdir == NULL) tmpdir = "/tmp";
  117. 			break;
  118. 		case 'u':
  119. 			o_unsafe = true;
  120. 			break;
  121. 		case '?':
  122. 			if(!got_long_opt) fprintf(stderr, "%s: error: Unrecognised option: '-%c'\n", argv0, optopt);
  123. 			return 1;
  124. 		default:
  125. 			fprintf(stderr, "%s: error: Unhandled getopt case '%c'\n", argv0, c);
  126. 			abort();
  127. 		}
  128. 	}
  130. 	argc -= optind;
  131. 	argv += optind;
  133. 	if(argc == 1)
  134. 	{
  135. 		strncpy(template, *argv, PATH_MAX);
  136. 	}
  137. 	else if(argc > 1)
  138. 	{
  139. 		fprintf(stderr, "%s: error: Only one template argument is supported, got %d\n", argv0, argc);
  140. 		return 1;
  141. 	}
  143. 	if(tmpdir)
  144. 	{
  145. 		if(chdir(tmpdir) < 0)
  146. 		{
  147. 			fprintf(stderr,
  148. 			        "%s: error: Failed changing directory into tmpdir '%s': %s\n",
  149. 			        argv0,
  150. 			        tmpdir,
  151. 			        strerror(errno));
  152. 			return 1;
  153. 		}
  155. 		printf("%s/", tmpdir);
  156. 	}
  158. 	static char template_copy[PATH_MAX] = "";
  159. 	memcpy(template_copy, template, PATH_MAX);
  161. 	if(o_unsafe) return unsafe_mktemp(template);
  163. 	if(o_create_dir)
  164. 	{
  165. 		char *dir = mkdtemp(template);
  166. 		if(dir == NULL)
  167. 		{
  168. 			if(!o_quiet)
  169. 				fprintf(stderr,
  170. 				        "%s: error: Failed creating random directory with template '%s': %s\n",
  171. 				        argv0,
  172. 				        template_copy,
  173. 				        strerror(errno));
  175. 			return 1;
  176. 		}
  178. 		puts(dir);
  180. 		return 0;
  181. 	}
  183. 	int fd = mkstemp(template);
  184. 	if(fd < 0)
  185. 	{
  186. 		if(!o_quiet)
  187. 			fprintf(stderr,
  188. 			        "%s: error: Failed creating random file with template '%s': %s\n",
  189. 			        argv0,
  190. 			        template_copy,
  191. 			        strerror(errno));
  193. 		return 1;
  194. 	}
  196. 	puts(template);
  198. 	if(close(fd) < 0)
  199. 	{
  200. 		if(!o_quiet) fprintf(stderr, "%s: error: Failed closing file: %s\n", argv0, strerror(errno));
  202. 		return 1;
  203. 	}
  205. 	return 0;
  206. }