sigaction.c 4.7 KB

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  1. /* POSIX.1 `sigaction' call for Linux/x86-64.
  2. Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, write to the Free
  14. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  15. 02111-1307 USA. */
  16. #include <errno.h>
  17. #include <stddef.h>
  18. #include <signal.h>
  19. #include <string.h>
  20. #include <sys/syscall.h>
  21. /* The difference here is that the sigaction structure used in the
  22. kernel is not the same as we use in the libc. Therefore we must
  23. translate it here. */
  24. #include <bits/kernel_sigaction.h>
  25. /* We do not globally define the SA_RESTORER flag so do it here. */
  26. #define SA_RESTORER 0x04000000
  27. extern __typeof(sigaction) __libc_sigaction;
  28. #ifdef __NR_rt_sigaction
  29. /* Using the hidden attribute here does not change the code but it
  30. helps to avoid warnings. */
  31. extern void restore_rt (void) __asm__ ("__restore_rt") attribute_hidden;
  32. extern void restore (void) __asm__ ("__restore") attribute_hidden;
  33. /* Experimentally off - libc_hidden_proto(memcpy) */
  34. /* If ACT is not NULL, change the action for SIG to *ACT.
  35. If OACT is not NULL, put the old action for SIG in *OACT. */
  36. int
  37. __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
  38. {
  39. int result;
  40. struct kernel_sigaction kact, koact;
  41. enum {
  42. SIGSET_MIN_SIZE = sizeof(kact.sa_mask) < sizeof(act->sa_mask)
  43. ? sizeof(kact.sa_mask) : sizeof(act->sa_mask)
  44. };
  45. if (act) {
  46. kact.k_sa_handler = act->sa_handler;
  47. memcpy (&kact.sa_mask, &act->sa_mask, SIGSET_MIN_SIZE);
  48. kact.sa_flags = act->sa_flags | SA_RESTORER;
  49. kact.sa_restorer = &restore_rt;
  50. }
  51. /* NB: kernel (as of 2.6.25) will return EINVAL
  52. * if sizeof(kact.sa_mask) does not match kernel's sizeof(sigset_t) */
  53. result = INLINE_SYSCALL (rt_sigaction, 4, sig,
  54. act ? __ptrvalue (&kact) : NULL,
  55. oact ? __ptrvalue (&koact) : NULL,
  56. sizeof(kact.sa_mask));
  57. if (oact && result >= 0) {
  58. oact->sa_handler = koact.k_sa_handler;
  59. memcpy (&oact->sa_mask, &koact.sa_mask, SIGSET_MIN_SIZE);
  60. oact->sa_flags = koact.sa_flags;
  61. oact->sa_restorer = koact.sa_restorer;
  62. }
  63. return result;
  64. }
  65. #else
  66. extern void restore (void) __asm__ ("__restore") attribute_hidden;
  67. /* If ACT is not NULL, change the action for SIG to *ACT.
  68. If OACT is not NULL, put the old action for SIG in *OACT. */
  69. int
  70. __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
  71. {
  72. int result;
  73. struct old_kernel_sigaction kact, koact;
  74. #ifdef SIGCANCEL
  75. if (sig == SIGCANCEL) {
  76. __set_errno (EINVAL);
  77. return -1;
  78. }
  79. #endif
  80. if (act) {
  81. kact.k_sa_handler = act->sa_handler;
  82. kact.sa_mask = act->sa_mask.__val[0];
  83. kact.sa_flags = act->sa_flags | SA_RESTORER;
  84. kact.sa_restorer = &restore;
  85. }
  86. __asm__ __volatile__ ("syscall\n"
  87. : "=a" (result)
  88. : "0" (__NR_sigaction), "mr" (sig),
  89. "c" (act ? __ptrvalue (&kact) : 0),
  90. "d" (oact ? __ptrvalue (&koact) : 0));
  91. if (result < 0) {
  92. __set_errno(-result);
  93. return -1;
  94. }
  95. if (oact) {
  96. oact->sa_handler = koact.k_sa_handler;
  97. oact->sa_mask.__val[0] = koact.sa_mask;
  98. oact->sa_flags = koact.sa_flags;
  99. oact->sa_restorer = koact.sa_restorer;
  100. }
  101. return result;
  102. }
  103. #endif
  104. #ifndef LIBC_SIGACTION
  105. /* libc_hidden_proto(sigaction) */
  106. weak_alias(__libc_sigaction,sigaction)
  107. libc_hidden_weak(sigaction)
  108. #endif
  109. /* NOTE: Please think twice before making any changes to the bits of
  110. code below. GDB needs some intimate knowledge about it to
  111. recognize them as signal trampolines, and make backtraces through
  112. signal handlers work right. Important are both the names
  113. (__restore_rt) and the exact instruction sequence.
  114. If you ever feel the need to make any changes, please notify the
  115. appropriate GDB maintainer. */
  116. #define RESTORE(name, syscall) RESTORE2 (name, syscall)
  117. # define RESTORE2(name, syscall) \
  118. __asm__ ( \
  119. ".text\n" \
  120. "__" #name ":\n" \
  121. " movq $" #syscall ", %rax\n" \
  122. " syscall\n" \
  123. );
  124. #ifdef __NR_rt_sigaction
  125. /* The return code for realtime-signals. */
  126. RESTORE (restore_rt, __NR_rt_sigreturn)
  127. #endif
  128. #ifdef __NR_sigreturn
  129. RESTORE (restore, __NR_sigreturn)
  130. #endif