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utils-std

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

pwd.c (2217B)

    

  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 "../lib/getopt_nolong.h"
  8. #include <limits.h> // PATH_MAX
  9. #include <stdbool.h>
  10. #include <stdio.h>  // puts, perror, printf
  11. #include <stdlib.h> // getenv
  12. #include <sys/stat.h>
  13. #include <unistd.h> // getcwd
  15. const char *argv0 = "pwd";
  17. enum pwd
  18. {
  19. 	PWD_L = 0,
  20. 	PWD_P = 1,
  21. };
  23. static void
  24. usage(void)
  25. {
  26. 	fputs("Usage: pwd [-L|-P]\n", stderr);
  27. }
  29. static bool
  30. is_absolute(char *path)
  31. {
  32. 	if(!path) return false;
  33. 	if(path[0] != '/') return false;
  35. 	size_t dotlen = 0;
  36. 	for(size_t i = 1; path[i] != '\0'; i++)
  37. 	{
  38. 		switch(path[i])
  39. 		{
  40. 		case '.':
  41. 			dotlen++;
  42. 			break;
  43. 		case '/':
  44. 			if(dotlen == 1 || dotlen == 2) return false;
  46. 			dotlen = 0;
  47. 			break;
  48. 		default:
  49. 			dotlen = 0;
  50. 			break;
  51. 		}
  52. 	}
  54. 	return true;
  55. }
  57. static bool
  58. is_pwd(char *path)
  59. {
  60. 	if(!is_absolute(path)) return false;
  62. 	struct stat path_status;
  63. 	if(stat(path, &path_status) < 0) return false;
  65. 	struct stat dot_status;
  66. 	if(stat(".", &dot_status) < 0) return false;
  68. 	if(path_status.st_dev != dot_status.st_dev) return false;
  69. 	if(path_status.st_ino != dot_status.st_ino) return false;
  71. 	return true;
  72. }
  74. int
  75. main(int argc, char *argv[])
  76. {
  77. 	enum pwd mode = PWD_L;
  79. 	for(int c = -1; (c = getopt_nolong(argc, argv, ":LP")) != -1;)
  80. 	{
  81. 		switch(c)
  82. 		{
  83. 		case 'L':
  84. 			mode = PWD_L;
  85. 			break;
  86. 		case 'P':
  87. 			mode = PWD_P;
  88. 			break;
  89. 		case ':':
  90. 			fprintf(stderr, "%s: error: Missing operand for option '-%c'\n", argv0, optopt);
  91. 			usage();
  92. 			return 1;
  93. 		case '?':
  94. 			if(!got_long_opt) fprintf(stderr, "%s: error: Unrecognised option '-%c'\n", argv0, optopt);
  95. 			usage();
  96. 			return 1;
  97. 		}
  98. 	}
  100. 	argc -= optind;
  101. 	argv += optind;
  103. 	if(argc != 0)
  104. 	{
  105. 		usage();
  106. 		return 1;
  107. 	}
  109. 	if(mode == PWD_L)
  110. 	{
  111. 		char *pwd = getenv("PWD");
  112. 		if(is_pwd(pwd))
  113. 		{
  114. 			if(puts(pwd) < 0)
  115. 			{
  116. 				perror("pwd: error: puts");
  117. 				return 1;
  118. 			}
  120. 			return 0;
  121. 		}
  122. 	}
  124. 	char pwd[PATH_MAX] = "";
  125. 	if(getcwd(pwd, sizeof(pwd)) == NULL)
  126. 	{
  127. 		perror("pwd: error: getcwd");
  128. 		return 1;
  129. 	}
  131. 	if(puts(pwd) < 0)
  132. 	{
  133. 		perror("pwd: error: puts");
  134. 		return 1;
  135. 	}
  137. 	return 0;
  138. }