logo

utils-std

Collection of commonly available Unix tools

readlink.c (1327B)

    

  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
  7. #include <errno.h>
  8. #include <limits.h> // PATH_MAX
  9. #include <stdbool.h>
  10. #include <stdio.h>  // fprintf
  11. #include <string.h> // strerror
  12. #include <unistd.h> // getopt
  14. static void
  15. usage()
  16. {
  17. 	fprintf(stderr, "Usage: readlink [-n] file\n");
  18. }
  20. int
  21. main(int argc, char *argv[])
  22. {
  23. 	bool newline = true;
  25. 	int c = -1;
  26. 	while((c = getopt(argc, argv, ":n")) != -1)
  27. 	{
  28. 		switch(c)
  29. 		{
  30. 		case 'n':
  31. 			newline = false;
  32. 			break;
  33. 		case ':':
  34. 			fprintf(stderr, "readlink: Error: Missing operand for option: '-%c'\n", optopt);
  35. 			usage();
  36. 			return 1;
  37. 		case '?':
  38. 			fprintf(stderr, "readlink: Error: Unrecognised option: '-%c'\n", optopt);
  39. 			usage();
  40. 			return 1;
  41. 		}
  42. 	}
  44. 	argv += optind;
  45. 	argc -= optind;
  47. 	if(argc != 1)
  48. 	{
  49. 		fprintf(stderr, "readlink: Expected one file as argument, got %d\n", argc);
  50. 		usage();
  51. 		return 1;
  52. 	}
  54. 	char buf[PATH_MAX] = "";
  55. 	if(readlink(argv[0], buf, sizeof(buf) - 1) < 0)
  56. 	{
  57. 		fprintf(stderr,
  58. 		        "readlink: Error: Failed reading symbolic link of '%s': %s\n",
  59. 		        argv[0],
  60. 		        strerror(errno));
  61. 		return 1;
  62. 	}
  64. 	printf("%s", buf);
  65. 	if(newline) printf("\n");
  67. 	return 0;
  68. }