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utils-std

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

nice.c (1926B)

    

  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. 	for(int c = -1; (c = getopt(argc, argv, ":n:")) != -1;)
  29. 	{
  30. 		char *endptr = NULL;
  32. 		switch(c)
  33. 		{
  34. 		case 'n':
  35. 			incr = strtol(optarg, &endptr, 10);
  37. 			if(endptr && *endptr != 0) errno = EINVAL;
  38. 			if(errno != 0)
  39. 			{
  40. 				fprintf(stderr,
  41. 				        "%s: error: Failed parsing '%s' as a number: %s\n",
  42. 				        argv0,
  43. 				        optarg,
  44. 				        strerror(errno));
  45. 				usage();
  46. 				return 125;
  47. 			}
  48. 			break;
  49. 		case ':':
  50. 			fprintf(stderr, "%s: error: Missing operand for option: '-%c'\n", argv0, optopt);
  51. 			usage();
  52. 			return 125;
  53. 		case '?':
  54. 			fprintf(stderr, "%s: error: Unrecognised option: '-%c'\n", argv0, optopt);
  55. 			usage();
  56. 			return 125;
  57. 		default:
  58. 			abort();
  59. 		}
  60. 	}
  62. 	argc -= optind;
  63. 	argv += optind;
  65. 	if(argc == 0) return 0;
  67. 	errno = 0;
  69. 	if(nice((int)incr) == -1)
  70. 	{
  71. 		switch(errno)
  72. 		{
  73. 		case 0:
  74. 			break;
  75. 		case EPERM:
  76. 			fprintf(
  77. 			    stderr, "%s: warning: Failed setting nice to %ld: %s\n", argv0, incr, strerror(errno));
  78. 			errno = 0;
  79. 			break;
  80. 		default:
  81. 			fprintf(stderr, "%s: error: Failed setting nice to %ld: %s\n", argv0, incr, strerror(errno));
  82. 			return 125;
  83. 		}
  84. 	}
  86. 	assert(argv[0]);
  87. 	if(execvp(argv[0], argv) < 0)
  88. 	{
  89. 		fprintf(stderr, "%s: error: Failed executing '%s': %s\n", argv0, argv[0], strerror(errno));
  91. 		return (errno == ENOENT) ? 127 : 126;
  92. 	}
  94. 	abort();
  95. }