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utils-std

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

nice.c (1973B)

    

  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 // nice() is in XSI
  8. #include <assert.h>
  9. #include <errno.h>
  10. #include <stdio.h>  // fprintf
  11. #include <stdlib.h> // abort
  12. #include <string.h> // strerror
  13. #include <unistd.h> // getopt, nice
  15. const char *argv0 = "nice";
  17. static void
  18. usage(void)
  19. {
  20. 	fprintf(stderr, "Usage: nice [-n increment] command [argument ...]\n");
  21. }
  23. int
  24. main(int argc, char *argv[])
  25. {
  26. 	long incr = 0;
  28. 	int c = -1;
  29. 	while((c = getopt(argc, argv, ":n:")) != -1)
  30. 	{
  31. 		switch(c)
  32. 		{
  33. 		case 'n':
  34. 			assert(errno == 0);
  35. 			char *endptr = NULL;
  37. 			incr = strtol(optarg, &endptr, 10);
  39. 			if(endptr && *endptr != 0) errno = EINVAL;
  40. 			if(errno != 0)
  41. 			{
  42. 				fprintf(stderr,
  43. 				        "%s: error: Failed parsing '%s' as a number: %s\n",
  44. 				        argv0,
  45. 				        optarg,
  46. 				        strerror(errno));
  47. 				usage();
  48. 				return 125;
  49. 			}
  50. 			break;
  51. 		case ':':
  52. 			fprintf(stderr, "%s: error: Missing operand for option: '-%c'\n", argv0, optopt);
  53. 			usage();
  54. 			return 125;
  55. 		case '?':
  56. 			fprintf(stderr, "%s: error: Unrecognised option: '-%c'\n", argv0, optopt);
  57. 			usage();
  58. 			return 125;
  59. 		default:
  60. 			abort();
  61. 		}
  62. 	}
  64. 	argc -= optind;
  65. 	argv += optind;
  67. 	if(argc == 0) return 0;
  69. 	errno = 0;
  71. 	if(nice((int)incr) == -1)
  72. 	{
  73. 		switch(errno)
  74. 		{
  75. 		case 0:
  76. 			break;
  77. 		case EPERM:
  78. 			fprintf(
  79. 			    stderr, "%s: warning: Failed setting nice to %ld: %s\n", argv0, incr, strerror(errno));
  80. 			errno = 0;
  81. 			break;
  82. 		default:
  83. 			fprintf(stderr, "%s: error: Failed setting nice to %ld: %s\n", argv0, incr, strerror(errno));
  84. 			return 125;
  85. 		}
  86. 	}
  88. 	assert(argv[0]);
  89. 	assert(errno == 0);
  90. 	if(execvp(argv[0], argv) < 0)
  91. 	{
  92. 		fprintf(stderr, "%s: error: Failed executing '%s': %s\n", argv0, argv[0], strerror(errno));
  94. 		return (errno == ENOENT) ? 127 : 126;
  95. 	}
  97. 	abort();
  98. }