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utils-std

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

mktemp.c (3556B)

    

  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
  8. #include <errno.h>
  9. #include <limits.h> // PATH_MAX
  10. #include <stdbool.h>
  11. #include <stdio.h>  // fprintf
  12. #include <stdlib.h> // getenv
  13. #include <string.h> // strerror
  14. #include <unistd.h> // getopt, getentropy
  16. const char *argv0 = "mktemp";
  18. static int
  19. unsafe_mktemp(char *template)
  20. {
  21. 	size_t l = strlen(template);
  23. 	size_t len = 0;
  24. 	size_t off = l - 1;
  25. 	while(off > 0 && template[off] == 'X')
  26. 		off--, len++;
  28. 	if(len < 6)
  29. 	{
  30. 		fprintf(stderr,
  31. 		        "%s: error: Template '%s' is invalid (need >= 6 final X, got %zd)\n",
  32. 		        argv0,
  33. 		        template,
  34. 		        len);
  35. 		return 1;
  36. 	}
  38. 	for(int retries = 100; 0 < retries; retries--)
  39. 	{
  40. 		unsigned long r = 0;
  41. 		if(getentropy(&r, sizeof(r)) != 0)
  42. 		{
  43. 			fprintf(stderr,
  44. 			        "%s: error: Failed to get entropy for random filename: %s\n",
  45. 			        argv0,
  46. 			        strerror(errno));
  47. 			return 1;
  48. 		}
  50. 		for(int i = len; i > 0; i--, r >>= 5)
  51. 			template[off + i] = 'A' + (r & 15) + (r & 16) * 2;
  53. 		if(access(template, F_OK) != 0 && errno == ENOENT)
  54. 		{
  55. 			puts(template);
  56. 			return 0;
  57. 		}
  58. 	}
  60. 	fprintf(stderr, "%s: error: Exhausted all 100 attempts at generating a filename\n", argv0);
  61. 	return 1;
  62. }
  64. int
  65. main(int argc, char *argv[])
  66. {
  67. 	bool o_create_dir = false, o_quiet = false, o_unsafe = false;
  68. 	char template[PATH_MAX] = "tmp.XXXXXXXXXX";
  69. 	const char *tmpdir = NULL;
  71. 	int c = -1;
  72. 	while((c = getopt(argc, argv, ":dqp:tu")) != -1)
  73. 	{
  74. 		switch(c)
  75. 		{
  76. 		case 'd':
  77. 			o_create_dir = true;
  78. 			break;
  79. 		case 'q':
  80. 			o_quiet = true;
  81. 			break;
  82. 		case 'p':
  83. 			tmpdir = optarg;
  84. 			break;
  85. 		case 't':
  86. 			if(tmpdir == NULL) tmpdir = getenv("TMPDIR");
  87. 			if(tmpdir == NULL) tmpdir = "/tmp";
  88. 			break;
  89. 		case 'u':
  90. 			o_unsafe = true;
  91. 			break;
  92. 		case '?':
  93. 			fprintf(stderr, "%s: error: Unrecognised option: '-%c'\n", argv0, optopt);
  94. 			return 1;
  95. 		default:
  96. 			fprintf(stderr, "%s: error: Unhandled getopt case '%c'\n", argv0, c);
  97. 			abort();
  98. 		}
  99. 	}
  101. 	argc -= optind;
  102. 	argv += optind;
  104. 	if(argc == 1)
  105. 	{
  106. 		strncpy(template, *argv, PATH_MAX);
  107. 	}
  108. 	else if(argc > 1)
  109. 	{
  110. 		fprintf(stderr, "%s: error: Only one template argument is supported, got %d\n", argv0, argc);
  111. 		return 1;
  112. 	}
  114. 	if(tmpdir)
  115. 	{
  116. 		if(chdir(tmpdir) < 0)
  117. 		{
  118. 			fprintf(stderr,
  119. 			        "%s: error: Failed changing directory into tmpdir '%s': %s\n",
  120. 			        argv0,
  121. 			        tmpdir,
  122. 			        strerror(errno));
  123. 			return 1;
  124. 		}
  126. 		printf("%s/", tmpdir);
  127. 	}
  129. 	char template_copy[PATH_MAX] = "";
  130. 	memcpy(template_copy, template, PATH_MAX);
  132. 	if(o_unsafe) return unsafe_mktemp(template);
  134. 	if(o_create_dir)
  135. 	{
  136. 		char *dir = mkdtemp(template);
  137. 		if(dir == NULL)
  138. 		{
  139. 			if(!o_quiet)
  140. 				fprintf(stderr,
  141. 				        "%s: error: Failed creating random directory with template '%s': %s\n",
  142. 				        argv0,
  143. 				        template_copy,
  144. 				        strerror(errno));
  146. 			return 1;
  147. 		}
  149. 		puts(dir);
  151. 		return 0;
  152. 	}
  154. 	int fd = mkstemp(template);
  155. 	if(fd < 0)
  156. 	{
  157. 		if(!o_quiet)
  158. 			fprintf(stderr,
  159. 			        "%s: error: Failed creating random file with template '%s': %s\n",
  160. 			        argv0,
  161. 			        template_copy,
  162. 			        strerror(errno));
  164. 		return 1;
  165. 	}
  167. 	puts(template);
  169. 	if(close(fd) < 0)
  170. 	{
  171. 		if(!o_quiet) fprintf(stderr, "%s: error: Failed closing file: %s\n", argv0, strerror(errno));
  173. 		return 1;
  174. 	}
  176. 	return 0;
  177. }