logo

bootstrap-initrd

Linux initrd to bootstrap from a small binary seed git clone https://hacktivis.me/git/bootstrap-initrd.git

getty-stub.c (1666B)

    

  1. // bootstrap-initrd: Linux initrd to bootstrap from a small binary seed
  2. // SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
  3. // SPDX-License-Identifier: MPL-2.0
  5. #define _GNU_SOURCE // TIOCSCTTY, vhangup
  6. #define _POSIX_C_SOURCE 200809L
  8. #include <errno.h>
  9. #include <fcntl.h> // open, O_RDWR
  10. #include <signal.h>
  11. #include <stdio.h>  // fprintf
  12. #include <stdlib.h> // setenv
  13. #include <string.h> // strerror
  14. #include <sys/ioctl.h>
  15. #include <unistd.h> // setsid, isatty
  17. int
  18. main(int argc, char *argv[])
  19. {
  20. 	argc -= 1;
  21. 	argv += 1;
  23. 	if(argc < 2)
  24. 	{
  25. 		fprintf(stderr, "Usage: getty tty cmd [args...]\n");
  26. 		return 1;
  27. 	}
  29. 	signal(SIGHUP, SIG_IGN);
  31. 	setenv("TERM", "linux", 1);
  33. 	setsid();
  35. 	char *tty = argv[0];
  36. 	argc -= 1;
  37. 	argv += 1;
  39. 	int tty_fd = open(tty, O_RDWR);
  40. 	if(tty_fd < 0)
  41. 	{
  42. 		fprintf(stderr, "getty: Failed opening TTY '%s': %s\n", tty, strerror(errno));
  43. 		return 1;
  44. 	}
  46. 	if(ioctl(tty_fd, TIOCSCTTY, (void *)1) != 0)
  47. 	{
  48. 		fprintf(stderr, "getty: Couldn't set controlling TTY: %s\n", strerror(errno));
  49. 		return 1;
  50. 	}
  52. 	vhangup();
  53. 	close(tty_fd);
  55. 	tty_fd = open(tty, O_RDWR);
  56. 	if(tty_fd < 0)
  57. 	{
  58. 		fprintf(stderr, "getty: Failed opening TTY '%s': %s\n", tty, strerror(errno));
  59. 		return 1;
  60. 	}
  62. 	if(dup2(tty_fd, 0) < 0)
  63. 	{
  64. 		fprintf(stderr, "getty: Failed setting TTY as stdin: %s\n", strerror(errno));
  65. 		return 1;
  66. 	}
  67. 	if(dup2(tty_fd, 1) < 0)
  68. 	{
  69. 		fprintf(stderr, "getty: Failed setting TTY as stdout: %s\n", strerror(errno));
  70. 		return 1;
  71. 	}
  72. 	if(dup2(tty_fd, 2) < 0)
  73. 	{
  74. 		fprintf(stderr, "getty: Failed setting TTY as stderr: %s\n", strerror(errno));
  75. 		return 1;
  76. 	}
  78. 	signal(SIGHUP, SIG_DFL);
  80. 	return execvp(argv[0], argv);
  81. }