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utils-std

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

pwd.c (2157B)

    

  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 <limits.h> // PATH_MAX
  7. #include <stdbool.h>
  8. #include <stdio.h>  // puts, perror, printf
  9. #include <stdlib.h> // getenv
  10. #include <sys/stat.h>
  11. #include <unistd.h> // getcwd
  13. const char *argv0 = "pwd";
  15. enum pwd
  16. {
  17. 	PWD_L = 0,
  18. 	PWD_P = 1,
  19. };
  21. static void
  22. usage(void)
  23. {
  24. 	fputs("Usage: pwd [-L|-P]\n", stderr);
  25. }
  27. static bool
  28. is_absolute(char *path)
  29. {
  30. 	if(!path) return false;
  31. 	if(path[0] != '/') return false;
  33. 	size_t dotlen = 0;
  34. 	for(size_t i = 1; path[i] != '\0'; i++)
  35. 	{
  36. 		switch(path[i])
  37. 		{
  38. 		case '.':
  39. 			dotlen++;
  40. 			break;
  41. 		case '/':
  42. 			if(dotlen == 1 || dotlen == 2) return false;
  44. 			dotlen = 0;
  45. 			break;
  46. 		default:
  47. 			dotlen = 0;
  48. 			break;
  49. 		}
  50. 	}
  52. 	return true;
  53. }
  55. static bool
  56. is_pwd(char *path)
  57. {
  58. 	if(!is_absolute(path)) return false;
  60. 	struct stat path_status;
  61. 	if(stat(path, &path_status) < 0) return false;
  63. 	struct stat dot_status;
  64. 	if(stat(".", &dot_status) < 0) return false;
  66. 	if(path_status.st_dev != dot_status.st_dev) return false;
  67. 	if(path_status.st_ino != dot_status.st_ino) return false;
  69. 	return true;
  70. }
  72. int
  73. main(int argc, char *argv[])
  74. {
  75. 	enum pwd mode = PWD_L;
  77. 	for(int c = -1; (c = getopt(argc, argv, ":LP")) != -1;)
  78. 	{
  79. 		switch(c)
  80. 		{
  81. 		case 'L':
  82. 			mode = PWD_L;
  83. 			break;
  84. 		case 'P':
  85. 			mode = PWD_P;
  86. 			break;
  87. 		case ':':
  88. 			fprintf(stderr, "%s: error: Missing operand for option '-%c'\n", argv0, optopt);
  89. 			usage();
  90. 			return 1;
  91. 		case '?':
  92. 			fprintf(stderr, "%s: error: Unrecognised option '-%c'\n", argv0, optopt);
  93. 			usage();
  94. 			return 1;
  95. 		}
  96. 	}
  98. 	argc -= optind;
  99. 	argv += optind;
  101. 	if(argc != 0)
  102. 	{
  103. 		usage();
  104. 		return 1;
  105. 	}
  107. 	if(mode == PWD_L)
  108. 	{
  109. 		char *pwd = getenv("PWD");
  110. 		if(is_pwd(pwd))
  111. 		{
  112. 			if(puts(pwd) < 0)
  113. 			{
  114. 				perror("pwd: error: puts");
  115. 				return 1;
  116. 			}
  118. 			return 0;
  119. 		}
  120. 	}
  122. 	char pwd[PATH_MAX] = "";
  123. 	if(getcwd(pwd, sizeof(pwd)) == NULL)
  124. 	{
  125. 		perror("pwd: error: getcwd");
  126. 		return 1;
  127. 	}
  129. 	if(puts(pwd) < 0)
  130. 	{
  131. 		perror("pwd: error: puts");
  132. 		return 1;
  133. 	}
  135. 	return 0;
  136. }