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utils-std

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

cat.c (2703B)

    

  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/fs.h"
  8. #include <assert.h>
  9. #include <errno.h>
  10. #include <fcntl.h>  // open, O_RDONLY
  11. #include <limits.h> // SSIZE_MAX
  12. #include <stdio.h>  // fprintf, BUFSIZ
  13. #include <stdlib.h> // abort
  14. #include <string.h> // strerror, strncmp
  15. #include <unistd.h> // read, write, close, getopt
  17. const char *argv0 = "cat";
  19. static void
  20. usage(void)
  21. {
  22. 	fprintf(stderr, "Usage: cat [-u] [files ...]\n");
  23. }
  25. int
  26. main(int argc, char *argv[])
  27. {
  28. 	int c = -1;
  29. 	while((c = getopt(argc, argv, ":u")) != -1)
  30. 	{
  31. 		switch(c)
  32. 		{
  33. 		case 'u':
  34. 			// POSIX: Ignored, buffered streams aren't used
  35. 			break;
  36. 		case ':':
  37. 			fprintf(stderr, "%s: error: Missing operand for option: '-%c'\n", argv0, optopt);
  38. 			usage();
  39. 			return 1;
  40. 		case '?':
  41. 			fprintf(stderr, "%s: error: Unrecognised option: '-%c'\n", argv0, optopt);
  42. 			usage();
  43. 			return 1;
  44. 		default:
  45. 			abort();
  46. 		}
  47. 	}
  49. 	argc -= optind;
  50. 	argv += optind;
  52. 	if(argc < 1)
  53. 	{
  54. 		if(auto_fd_copy(STDIN_FILENO, STDOUT_FILENO, SSIZE_MAX) < 0)
  55. 		{
  56. 			fprintf(stderr, "%s: error: Failed copying data from <stdin>: %s\n", argv0, strerror(errno));
  57. 			return 1;
  58. 		}
  59. 	}
  60. 	else
  61. 	{
  62. 		for(int argi = 0; argi < argc; argi++)
  63. 		{
  64. 			if(strncmp(argv[argi], "-", 2) == 0)
  65. 			{
  66. 				if(auto_fd_copy(STDIN_FILENO, STDOUT_FILENO, SSIZE_MAX) < 0)
  67. 				{
  68. 					fprintf(
  69. 					    stderr, "%s: error: Failed copying data from <stdin>: %s\n", argv0, strerror(errno));
  70. 					return 1;
  71. 				}
  72. 			}
  73. 			else
  74. 			{
  75. 				assert(errno == 0);
  76. 				int fd = open(argv[argi], O_RDONLY);
  77. 				if(fd < 0)
  78. 				{
  79. 					fprintf(stderr,
  80. 					        "%s: error: Failed opening file '%s': %s\n",
  81. 					        argv0,
  82. 					        argv[argi],
  83. 					        strerror(errno));
  84. 					errno = 0;
  85. 					return 1;
  86. 				}
  88. 				if(auto_fd_copy(fd, STDOUT_FILENO, SSIZE_MAX) < 0)
  89. 				{
  90. 					fprintf(stderr,
  91. 					        "%s: error: Failed copying data from file '%s': %s\n",
  92. 					        argv0,
  93. 					        argv[argi],
  94. 					        strerror(errno));
  95. 					return 1;
  96. 				}
  98. 				assert(errno == 0);
  99. 				if(close(fd) < 0)
  100. 				{
  101. 					fprintf(stderr,
  102. 					        "%s: error: Failed closing file '%s': %s\n",
  103. 					        argv0,
  104. 					        argv[argi],
  105. 					        strerror(errno));
  106. 					errno = 0;
  107. 					return 1;
  108. 				}
  109. 			}
  110. 		}
  111. 	}
  113. 	if(close(STDIN_FILENO) != 0)
  114. 	{
  115. 		fprintf(stderr, "%s: error: Failed closing file <stdin>: %s\n", argv0, strerror(errno));
  116. 		return 1;
  117. 	}
  119. 	if(close(STDOUT_FILENO) != 0)
  120. 	{
  121. 		fprintf(stderr, "%s: error: Failed closing file <stdout>: %s\n", argv0, strerror(errno));
  122. 		return 1;
  123. 	}
  125. 	return 0;
  126. }