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utils-std

Collection of commonly available Unix tools

date.c (2987B)

    

  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
  6. #define _XOPEN_SOURCE 700 // strptime is in XSI
  8. #include "../lib/iso_parse.h" /* iso_parse */
  10. #include <errno.h>  /* errno */
  11. #include <locale.h> /* setlocale */
  12. #include <locale.h> /* setlocale() */
  13. #include <stdio.h>  /* BUFSIZ, perror(), puts() */
  14. #include <stdlib.h> /* exit(), strtol() */
  15. #include <time.h>   /* time, localtime, tm, strftime, strptime */
  16. #include <unistd.h> /* getopt(), optarg, optind */
  18. static void
  19. usage()
  20. {
  21. 	fprintf(stderr, "date [-uR] [-d datetime] [+format]\n");
  22. 	fprintf(stderr, "date [-uR] -f now_format now [+format]\n");
  23. }
  25. int
  26. main(int argc, char *argv[])
  27. {
  28. 	char outstr[BUFSIZ];
  29. 	struct tm *tm;
  30. 	time_t now;
  31. 	char *format = "%c";
  32. 	char *input_format = NULL;
  33. 	int uflag = 0;
  34. 	int dflag = 0;
  35. 	int c;
  37. 	setlocale(LC_ALL, "");
  39. 	now = time(NULL);
  40. 	if(now == (time_t)-1)
  41. 	{
  42. 		perror("date: time");
  43. 		exit(EXIT_FAILURE);
  44. 	}
  46. 	while((c = getopt(argc, argv, ":d:f:uR")) != -1)
  47. 	{
  48. 		char *errstr = NULL;
  49. 		switch(c)
  50. 		{
  51. 		case 'd': /* Custom datetime */
  52. 			if(input_format != NULL)
  53. 			{
  54. 				fprintf(stderr, "date: Cannot both use '-d' and '-f'\n");
  55. 				exit(EXIT_FAILURE);
  56. 			}
  57. 			now = iso_parse(optarg, &errstr).tv_sec;
  58. 			dflag = 1;
  59. 			if(errstr != NULL)
  60. 			{
  61. 				fprintf(stderr, "date: iso_parse(\"%s\", …): %s\n", optarg, errstr);
  62. 				exit(EXIT_FAILURE);
  63. 			}
  64. 			break;
  65. 		case 'f': /* input datetime format */
  66. 			if(dflag == 1)
  67. 			{
  68. 				fprintf(stderr, "date: Cannot both use '-d' and '-f'\n");
  69. 				exit(EXIT_FAILURE);
  70. 			}
  71. 			input_format = optarg;
  72. 			break;
  73. 		case 'u': /* UTC timezone */
  74. 			uflag++;
  75. 			break;
  76. 		case 'R': /* Email (RFC 5322) format */
  77. 			format = "%a, %d %b %Y %H:%M:%S %z";
  78. 			break;
  79. 		case ':':
  80. 			fprintf(stderr, "date: Error: Missing operand for option: '-%c'\n", optopt);
  81. 			usage();
  82. 			return 1;
  83. 		case '?':
  84. 			fprintf(stderr, "date: Error: Unrecognised option: '-%c'\n", optopt);
  85. 			usage();
  86. 			return 1;
  87. 		}
  88. 	}
  90. 	if(uflag)
  91. 	{
  92. 		tm = gmtime(&now);
  94. 		if(tm == NULL)
  95. 		{
  96. 			perror("date: gmtime");
  97. 			exit(EXIT_FAILURE);
  98. 		}
  99. 	}
  100. 	else
  101. 	{
  102. 		tm = localtime(&now);
  104. 		if(tm == NULL)
  105. 		{
  106. 			perror("date: localtime");
  107. 			exit(EXIT_FAILURE);
  108. 		}
  109. 	}
  111. 	argc -= optind;
  112. 	argv += optind;
  114. 	if(argc > 0 && input_format != NULL)
  115. 	{
  116. 		char *res = strptime(argv[0], input_format, tm);
  118. 		if(res == NULL)
  119. 		{
  120. 			fprintf(stderr,
  121. 			        "date: strptime(\"%s\", \"%s\", …) as passed by '-f' option failed\n",
  122. 			        argv[0],
  123. 			        input_format);
  124. 			exit(EXIT_FAILURE);
  125. 		}
  127. 		argv++;
  128. 		argc--;
  129. 	}
  131. 	if(argc > 0 && *argv && **argv == '+')
  132. 	{
  133. 		format = *argv + 1;
  135. 		argv++;
  136. 		argc--;
  137. 	}
  139. 	errno = 0;
  140. 	if(strftime(outstr, sizeof(outstr), format, tm) == 0 && errno != 0)
  141. 	{
  142. 		perror("date: strftime");
  143. 		exit(EXIT_FAILURE);
  144. 	}
  146. 	if(puts(outstr) < 0)
  147. 	{
  148. 		perror("date: puts");
  149. 		exit(EXIT_FAILURE);
  150. 	}
  152. 	return 0;
  153. }