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utils-std

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

truncation.c (2971B)

    

  1. // Collection of Unix tools, comparable to coreutils
  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 "truncation.h"
  8. #include <assert.h>
  9. #include <ctype.h> // toupper
  10. #include <errno.h>
  11. #include <stdio.h>    // fprintf
  12. #include <stdlib.h>   // strtol
  13. #include <string.h>   // strerror
  14. #include <sys/stat.h> // fstat
  15. #include <unistd.h>   // ftruncate
  17. extern char *argv0;
  19. int
  20. apply_truncation(int fd, struct truncation tr, char *arg)
  21. {
  22. 	if(tr.op != OP_SET)
  23. 	{
  24. 		struct stat stats;
  25. 		assert(errno == 0);
  26. 		if(fstat(fd, &stats) < 0)
  27. 		{
  28. 			fprintf(
  29. 			    stderr, "truncate: error: Failed to get status of file '%s': %s\n", arg, strerror(errno));
  30. 			return -1;
  31. 		}
  33. 		int q;
  34. 		switch(tr.op)
  35. 		{
  36. 		case OP_INC:
  37. 			tr.size += stats.st_size;
  38. 			break;
  39. 		case OP_DEC:
  40. 			tr.size = stats.st_size - tr.size;
  41. 			if(tr.size < 0) tr.size = 0;
  42. 			break;
  43. 		case OP_CHK_DOWN:
  44. 			q = stats.st_size / tr.size;
  46. 			tr.size = tr.size * q;
  47. 			break;
  48. 		case OP_CHK_UP:
  49. 			q = stats.st_size / tr.size;
  50. 			if(stats.st_size % tr.size) q++;
  51. 			tr.size = tr.size * q;
  52. 			break;
  53. 		default:
  54. 			abort();
  55. 		}
  56. 	}
  58. 	if(ftruncate(fd, tr.size) < 0)
  59. 	{
  60. 		fprintf(stderr,
  61. 		        "truncate: error: Failed to truncate '%s' to %ld: %s\n",
  62. 		        arg,
  63. 		        tr.size,
  64. 		        strerror(errno));
  65. 		return -1;
  66. 	}
  68. 	return 0;
  69. }
  71. int
  72. apply_size_suffix(unsigned long *size, char *endptr)
  73. {
  74. 	char units[] = "KMGTPEZ";
  76. 	if(endptr[0] == '\0') return 0;
  78. 	size_t i = 0;
  79. 	unsigned long si = 1, iec = 1;
  80. 	char pfx = toupper(endptr[0]);
  81. 	for(; i < sizeof(units); i++)
  82. 	{
  83. 		si *= 1000;
  84. 		iec *= 1024;
  85. 		if(units[i] == pfx) break;
  86. 	}
  87. 	if(i >= sizeof(units) || si == 1)
  88. 	{
  89. 		fprintf(stderr, "%s: error: Unrecognised unit '%s'\n", argv0, endptr);
  90. 		return -1;
  91. 	}
  93. 	if(endptr[1] == 0 || (endptr[1] == 'i' && endptr[2] == 'B' && endptr[3] == 0))
  94. 	{
  95. 		*size *= iec;
  96. 		return 0;
  97. 	}
  98. 	if(endptr[1] == 'B' && endptr[2] == 0)
  99. 	{
  100. 		*size *= si;
  101. 		return 0;
  102. 	}
  104. 	fprintf(stderr, "%s: error: Unrecognised suffix '%s'\n", argv0, endptr);
  105. 	return -1;
  106. }
  108. int
  109. parse_size(const char *arg, struct truncation *buf)
  110. {
  111. 	assert(arg != NULL);
  112. 	assert(buf != NULL);
  114. 	if(arg[0] == 0)
  115. 	{
  116. 		fprintf(stderr, "%s: error: Got empty size argument\n", argv0);
  117. 		buf->size = 0;
  118. 		return -1;
  119. 	}
  121. 	enum operation_e op = OP_SET;
  123. 	switch(arg[0])
  124. 	{
  125. 	case '+':
  126. 		op = OP_INC;
  127. 		arg++;
  128. 		break;
  129. 	case '-':
  130. 		op = OP_DEC;
  131. 		arg++;
  132. 		break;
  133. 	case '/':
  134. 		op = OP_CHK_DOWN;
  135. 		arg++;
  136. 		break;
  137. 	case '%':
  138. 		op = OP_CHK_UP;
  139. 		arg++;
  140. 		break;
  141. 		// no default case intended
  142. 	}
  144. 	assert(errno == 0);
  145. 	char *endptr = NULL;
  146. 	unsigned long size = strtoul(arg, &endptr, 10);
  147. 	if(errno != 0)
  148. 	{
  149. 		fprintf(
  150. 		    stderr, "%s: error: Failed parsing '%s' as a number: %s\n", argv0, arg, strerror(errno));
  151. 		return -1;
  152. 	}
  154. 	if(endptr != NULL)
  155. 	{
  156. 		if(apply_size_suffix(&size, endptr) < 0) return -1;
  157. 	}
  159. 	buf->size = size;
  160. 	buf->op = op;
  161. 	return 0;
  162. }