logo

utils-std

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

truncate.c (2735B)

    

  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
  7. #include "../lib/bitmasks.h"   // FIELD_CLR
  8. #include "../lib/truncation.h" // parse_size
  10. #include <errno.h>
  11. #include <fcntl.h> // open
  12. #include <stdbool.h>
  13. #include <stdio.h>  // fprintf
  14. #include <stdlib.h> // abort
  15. #include <string.h> // strerror
  16. #include <sys/stat.h>
  17. #include <unistd.h> // getopt
  19. const char *argv0 = "truncate";
  21. static void
  22. usage(void)
  23. {
  24. 	fprintf(stderr, "Usage: truncate [-co] [-r ref_file] [-s size] file...\n");
  25. }
  27. int
  28. main(int argc, char *argv[])
  29. {
  30. 	int open_flags = O_WRONLY | O_CREAT | O_NONBLOCK;
  31. 	bool size_set = false;
  33. 	struct truncation tr = {
  34. 	    .op = OP_SET,
  35. 	    .size = 0,
  36. 	};
  37. 	char *ref_file = NULL;
  39. 	int c = -1;
  40. 	while((c = getopt(argc, argv, ":cr:s:")) != -1)
  41. 	{
  42. 		switch(c)
  43. 		{
  44. 		case 'c':
  45. 			FIELD_CLR(open_flags, O_CREAT);
  46. 			break;
  47. 		case 'r':
  48. 			if(size_set)
  49. 			{
  50. 				fprintf(stderr, "truncate: error: Truncation size can only be set once\n");
  51. 				usage();
  52. 				return 1;
  53. 			}
  54. 			ref_file = optarg;
  55. 			size_set = true;
  56. 			break;
  57. 		case 's':
  58. 			if(size_set)
  59. 			{
  60. 				fprintf(stderr, "truncate: error: Truncation size can only be set once\n");
  61. 				usage();
  62. 				return 1;
  63. 			}
  64. 			if(parse_size(optarg, &tr) < 0)
  65. 			{
  66. 				usage();
  67. 				return 1;
  68. 			}
  69. 			size_set = true;
  70. 			break;
  71. 		case ':':
  72. 			fprintf(stderr, "truncate: error: Missing operand for option: '-%c'\n", optopt);
  73. 			usage();
  74. 			return 1;
  75. 		case '?':
  76. 			fprintf(stderr, "truncate: error: Unrecognised option: '-%c'\n", optopt);
  77. 			usage();
  78. 			return 1;
  79. 		default:
  80. 			abort();
  81. 		}
  82. 	}
  84. 	argc -= optind;
  85. 	argv += optind;
  87. 	if(argc < 1) usage();
  89. 	if(!size_set)
  90. 	{
  91. 		fprintf(stderr,
  92. 		        "truncate: error: target size wasn't set, you need to pass one of -d / -r / -s\n");
  93. 		return 1;
  94. 	}
  96. 	if(ref_file != NULL)
  97. 	{
  98. 		struct stat ref_stats;
  99. 		if(stat(optarg, &ref_stats) < 0)
  100. 		{
  101. 			fprintf(stderr,
  102. 			        "truncate: error: Couldn't get status for file '%s': %s\n",
  103. 			        optarg,
  104. 			        strerror(errno));
  105. 			return 1;
  106. 		}
  107. 		tr.op = OP_SET;
  109. 		tr.size = ref_stats.st_size;
  110. 	}
  112. 	for(int argi = 0; argi < argc; argi++)
  113. 	{
  114. 		char *arg = argv[argi];
  116. 		// same flags to open as touch(1)
  117. 		int fd = open(arg, open_flags, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
  118. 		if(fd < 0)
  119. 		{
  120. 			fprintf(stderr, "truncate: error: Failed to open '%s': %s\n", arg, strerror(errno));
  121. 			return 1;
  122. 		}
  124. 		if(apply_truncation(fd, tr, arg) < 0) return 1;
  126. 		if(close(fd) < 0)
  127. 		{
  128. 			fprintf(stderr, "truncate: error: Failed closing fd for '%s': %s\n", arg, strerror(errno));
  129. 			return 1;
  130. 		}
  131. 	}
  133. 	return 0;
  134. }