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utils-std

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

iso_parse.c (3613B)

    

  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 _DEFAULT_SOURCE         // tm_gmtoff/tm_zone
  6. #define _XOPEN_SOURCE 700       // strptime (NetBSD)
  7. #define _POSIX_C_SOURCE 200809L // st_atim/st_mtim
  9. #include "./iso_parse.h"
  11. #include <assert.h>
  12. #include <ctype.h>    /* isdigit */
  13. #include <errno.h>    /* errno */
  14. #include <inttypes.h> /* PRId16 */
  15. #include <limits.h>   /* TZNAME_MAX */
  16. #include <stdio.h>    /* perror, sscanf */
  17. #include <stdlib.h>   /* strtol */
  18. #include <string.h>   /* memset */
  19. #include <time.h>     /* strptime, tm */
  21. // Sets errstr on failure
  22. // YYYY-MM-DD[T ]hh:mm:SS([,\.]frac)?(Z|[+\-]hh:?mm)?
  23. char *
  24. iso_parse(char *arg, struct tm *time, long *nsec, const char **errstr)
  25. {
  26. 	// For Alpine's abuild compatibility
  27. 	if(arg[0] == '@')
  28. 	{
  29. 		arg++;
  31. 		char *endptr = NULL;
  32. 		time_t now = strtol(arg, &endptr, 10);
  33. 		if(errno != 0)
  34. 		{
  35. 			*errstr = strerror(errno);
  36. 			errno = 0;
  37. 			return NULL;
  38. 		}
  40. 		nsec = 0;
  41. 		gmtime_r(&now, time);
  43. 		return endptr;
  44. 	}
  46. 	// No %F in POSIX
  47. 	char *s = strptime(arg, "%Y-%m-%d", time);
  49. 	if(s == NULL)
  50. 	{
  51. 		*errstr = "strptime(…, \"%Y-%m-%d\", …) returned NULL";
  52. 		errno = 0;
  53. 		return NULL;
  54. 	}
  55. 	if(s[0] != 'T' && s[0] != ' ')
  56. 	{
  57. 		*errstr = "Couldn't find time-separator (T or space) after date (Y-m-d)";
  58. 		errno = 0;
  59. 		return NULL;
  60. 	}
  61. 	s++;
  63. 	s = strptime(s, "%H:%M:%S", time);
  64. 	if(s == NULL)
  65. 	{
  66. 		*errstr = "strptime(…, \"%H:%M:%S\", …) returned NULL";
  67. 		errno = 0;
  68. 		return NULL;
  69. 	}
  71. 	if(s[0] == ',' || s[0] == '.')
  72. 	{
  73. 		double fraction = 0.0;
  74. 		int parsed = 0;
  76. 		if(s[0] == ',') s[0] = '.';
  78. 		if(sscanf(s, "%10lf%n", &fraction, &parsed) < 1)
  79. 		{
  80. 			if(errno == 0)
  81. 			{
  82. 				*errstr = "Failed to parse fractional seconds";
  83. 			}
  84. 			else
  85. 			{
  86. 				*errstr = strerror(errno);
  87. 				errno = 0;
  88. 			}
  89. 			return NULL;
  90. 		}
  92. 		*nsec = (long)(fraction * 1000000000);
  93. 		s += parsed;
  95. 		// too many digits
  96. 		if(isdigit(s[0]))
  97. 		{
  98. 			*errstr = "Too many digits (> 10) for fractional seconds";
  99. 			return NULL;
  100. 		}
  101. 	}
  103. 	if(s != NULL && s[0] != '\0')
  104. 	{
  105. 		if(s[0] == 'Z' && s[1] == '\0')
  106. 		{
  107. 			time->tm_gmtoff = 0;
  108. 			time->tm_zone = "UTC";
  109. 		}
  110. 		else
  111. 		{
  112. 			int neg;
  113. 			if(*s == '+')
  114. 				neg = 0;
  115. 			else if(*s == '-')
  116. 				neg = 1;
  117. 			else
  118. 			{
  119. 				*errstr = "Invalid timezone offset, must start with + or -";
  120. 				return NULL;
  121. 			}
  123. 			char *o = s + 1;
  125. 			if(isdigit(o[0]) && isdigit(o[1]))
  126. 			{
  127. 				time->tm_gmtoff = (o[0] - '0') * 36000 + (o[1] - '0') * 3600;
  128. 				o += 2;
  129. 			}
  130. 			else
  131. 			{
  132. 				*errstr = "Invalid timezone offset, no digits after [+|-]";
  133. 				return NULL;
  134. 			}
  136. 			if(o[0] == ':') o++;
  138. 			if(isdigit(o[0]) && isdigit(o[1]))
  139. 			{
  140. 				time->tm_gmtoff += (o[0] - '0') * 600 + (o[1] - '0') * 60;
  141. 				o += 2;
  142. 			}
  143. 			else
  144. 			{
  145. 				*errstr = "Invalid timezone offset, no digits after [+|-]";
  146. 				return NULL;
  147. 			}
  149. 			if(neg) time->tm_gmtoff = -time->tm_gmtoff;
  151. #ifndef TZNAME_MAX
  152. #define TZNAME_MAX _POSIX_TZNAME_MAX
  153. #endif
  154. 			static char offname[TZNAME_MAX + 1] = "";
  155. 			assert(o - s < TZNAME_MAX);
  156. 			memcpy(offname, s, o - s);
  157. 			time->tm_zone = offname;
  158. 		}
  159. 	}
  161. 	return s;
  162. }
  164. // Because mktime() messes with tm_gmtoff yet doesn't applies it, even in POSIX.1-2024
  165. // Returns (time_t)-1 on failure
  166. time_t
  167. mktime_tz(struct tm *tm)
  168. {
  169. 	long gmtoff = tm->tm_gmtoff;
  170. 	const char *zone = tm->tm_zone;
  172. 	time_t res = mktime(tm);
  173. 	tm->tm_gmtoff = gmtoff;
  174. 	tm->tm_zone = zone;
  176. 	if(res == (time_t)-1) return res;
  178. 	// 12:00+02:00 corresponds to 10:00Z so needs to be reversed
  179. 	res += -gmtoff;
  181. 	return res;
  182. }