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utils-std

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

truncate.c (2714B)

    

  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 <assert.h>
  11. #include <errno.h>
  12. #include <fcntl.h> // open
  13. #include <stdbool.h>
  14. #include <stdio.h>  // fprintf
  15. #include <stdlib.h> // abort
  16. #include <string.h> // strerror
  17. #include <sys/stat.h>
  18. #include <unistd.h> // getopt
  20. const char *argv0 = "truncate";
  22. static void
  23. usage(void)
  24. {
  25. 	fprintf(stderr, "Usage: truncate [-co] [-r ref_file] [-s size] file...\n");
  26. }
  28. int
  29. main(int argc, char *argv[])
  30. {
  31. 	int open_flags = O_WRONLY | O_CREAT | O_NONBLOCK;
  32. 	bool size_set = false;
  34. 	struct truncation tr = {
  35. 	    .op = OP_SET,
  36. 	    .size = 0,
  37. 	};
  38. 	char *ref_file = NULL;
  40. 	int c = -1;
  41. 	while((c = getopt(argc, argv, ":cr:s:")) != -1)
  42. 	{
  43. 		switch(c)
  44. 		{
  45. 		case 'c':
  46. 			FIELD_CLR(open_flags, O_CREAT);
  47. 			break;
  48. 		case 'r':
  49. 			if(size_set)
  50. 			{
  51. 				fprintf(stderr, "truncate: Error: Truncation size can only be set once\n");
  52. 				usage();
  53. 				return 1;
  54. 			}
  55. 			ref_file = optarg;
  56. 			size_set = true;
  57. 			break;
  58. 		case 's':
  59. 			if(size_set)
  60. 			{
  61. 				fprintf(stderr, "truncate: Error: Truncation size can only be set once\n");
  62. 				usage();
  63. 				return 1;
  64. 			}
  65. 			if(parse_size(optarg, &tr) < 0)
  66. 			{
  67. 				usage();
  68. 				return 1;
  69. 			}
  70. 			size_set = true;
  71. 			break;
  72. 		case ':':
  73. 			fprintf(stderr, "truncate: Error: Missing operand for option: '-%c'\n", optopt);
  74. 			usage();
  75. 			return 1;
  76. 		case '?':
  77. 			fprintf(stderr, "truncate: Error: Unrecognised option: '-%c'\n", optopt);
  78. 			usage();
  79. 			return 1;
  80. 		default:
  81. 			abort();
  82. 		}
  83. 	}
  85. 	argc -= optind;
  86. 	argv += optind;
  88. 	if(argc < 1) usage();
  90. 	if(!size_set)
  91. 	{
  92. 		fprintf(stderr,
  93. 		        "truncate: Error: target size wasn't set, you need to pass one of -d / -r / -s\n");
  94. 		return 1;
  95. 	}
  97. 	if(ref_file != NULL)
  98. 	{
  99. 		assert(errno == 0);
  100. 		struct stat ref_stats;
  101. 		if(stat(optarg, &ref_stats) < 0)
  102. 		{
  103. 			fprintf(stderr,
  104. 			        "truncate: Error: Couldn't get status for file '%s': %s\n",
  105. 			        optarg,
  106. 			        strerror(errno));
  107. 			return 1;
  108. 		}
  109. 		tr.op = OP_SET;
  111. 		tr.size = ref_stats.st_size;
  112. 	}
  114. 	for(int argi = 0; argi < argc; argi++)
  115. 	{
  116. 		assert(errno == 0);
  117. 		char *arg = argv[argi];
  119. 		int fd = open(arg, open_flags);
  120. 		if(fd < 0)
  121. 		{
  122. 			fprintf(stderr, "truncate: Error: Failed to open '%s': %s\n", arg, strerror(errno));
  123. 			return 1;
  124. 		}
  125. 		assert(errno == 0);
  127. 		if(apply_truncation(fd, tr, arg) < 0) return 1;
  129. 		if(close(fd) < 0)
  130. 		{
  131. 			fprintf(stderr, "truncate: Error: Failed closing fd for '%s': %s\n", arg, strerror(errno));
  132. 			return 1;
  133. 		}
  134. 	}
  135. }