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utils-std

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

truncate.c (3266B)

    

  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 "../config.h"
  8. #include "../lib/bitmasks.h" // FIELD_CLR
  9. #include "../libutils/getopt_nolong.h"
  10. #include "../libutils/truncation.h" // parse_size
  12. #include <errno.h>
  13. #include <fcntl.h> // open
  14. #include <stdbool.h>
  15. #include <stdio.h>  // fprintf
  16. #include <stdlib.h> // abort
  17. #include <string.h> // strerror
  18. #include <sys/stat.h>
  19. #include <unistd.h> // getopt
  20. #ifdef HAS_GETOPT_LONG
  21. #include <getopt.h>
  22. #endif
  24. const char *argv0 = "truncate";
  26. static void
  27. usage(void)
  28. {
  29. 	fprintf(stderr, "Usage: truncate [-co] [-r ref_file] [-s size] file...\n");
  30. }
  32. int
  33. main(int argc, char *argv[])
  34. {
  35. 	int open_flags = O_WRONLY | O_CREAT | O_NONBLOCK;
  36. 	bool size_set = false;
  38. 	struct truncation tr = {
  39. 	    .op = OP_SET,
  40. 	    .size = 0,
  41. 	};
  42. 	char *ref_file = NULL;
  44. #ifdef HAS_GETOPT_LONG
  45. 	// Strictly for GNUisms compatibility so no long-only options
  46. 	// clang-format off
  47. 	static struct option opts[] = {
  48. 		{"no-create", no_argument, NULL, 'c'},
  49. 		{"reference", required_argument, NULL, 'r'},
  50. 		{"size", required_argument, NULL, 's'},
  51. 		{0, 0, 0, 0},
  52. 	};
  53. 	// clang-format on
  55. 	// Need + as first character to get POSIX-style option parsing
  56. 	for(int c = -1; (c = getopt_long(argc, argv, "+:cr:s:", opts, NULL)) != -1;)
  57. #else
  58. 	for(int c = -1; (c = getopt_nolong(argc, argv, ":cr:s:")) != -1;)
  59. #endif
  60. 	{
  61. 		switch(c)
  62. 		{
  63. 		case 'c':
  64. 			FIELD_CLR(open_flags, O_CREAT);
  65. 			break;
  66. 		case 'r':
  67. 			if(size_set)
  68. 			{
  69. 				fprintf(stderr, "truncate: error: Truncation size can only be set once\n");
  70. 				usage();
  71. 				return 1;
  72. 			}
  73. 			ref_file = optarg;
  74. 			size_set = true;
  75. 			break;
  76. 		case 's':
  77. 			if(size_set)
  78. 			{
  79. 				fprintf(stderr, "truncate: error: Truncation size can only be set once\n");
  80. 				usage();
  81. 				return 1;
  82. 			}
  83. 			if(parse_size(optarg, &tr) < 0)
  84. 			{
  85. 				usage();
  86. 				return 1;
  87. 			}
  88. 			size_set = true;
  89. 			break;
  90. 		case ':':
  91. 			fprintf(stderr, "truncate: error: Missing operand for option: '-%c'\n", optopt);
  92. 			usage();
  93. 			return 1;
  94. 		case '?':
  95. 			GETOPT_UNKNOWN_OPT
  96. 			usage();
  97. 			return 1;
  98. 		default:
  99. 			abort();
  100. 		}
  101. 	}
  103. 	argc -= optind;
  104. 	argv += optind;
  106. 	if(argc < 1) usage();
  108. 	if(!size_set)
  109. 	{
  110. 		fprintf(stderr,
  111. 		        "truncate: error: target size wasn't set, you need to pass one of -d / -r / -s\n");
  112. 		return 1;
  113. 	}
  115. 	if(ref_file != NULL)
  116. 	{
  117. 		struct stat ref_stats;
  118. 		if(stat(optarg, &ref_stats) < 0)
  119. 		{
  120. 			fprintf(stderr,
  121. 			        "truncate: error: Couldn't get status for file '%s': %s\n",
  122. 			        optarg,
  123. 			        strerror(errno));
  124. 			return 1;
  125. 		}
  126. 		tr.op = OP_SET;
  128. 		tr.size = ref_stats.st_size;
  129. 	}
  131. 	for(int argi = 0; argi < argc; argi++)
  132. 	{
  133. 		char *arg = argv[argi];
  135. 		// same flags to open as touch(1)
  136. 		int fd = open(arg, open_flags, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
  137. 		if(fd < 0)
  138. 		{
  139. 			fprintf(stderr, "truncate: error: Failed to open '%s': %s\n", arg, strerror(errno));
  140. 			return 1;
  141. 		}
  143. 		if(apply_truncation(fd, tr, arg) < 0) return 1;
  145. 		if(close(fd) < 0)
  146. 		{
  147. 			fprintf(stderr, "truncate: error: Failed closing fd for '%s': %s\n", arg, strerror(errno));
  148. 			return 1;
  149. 		}
  150. 	}
  152. 	return 0;
  153. }