/* POSIX.1 `sigaction' call for Linux/x86-64. Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include <errno.h> #include <stddef.h> #include <signal.h> #include <string.h> #include <sys/syscall.h> #include <bits/kernel_sigaction.h> /* We do not globally define the SA_RESTORER flag so do it here. */ #define SA_RESTORER 0x04000000 extern __typeof(sigaction) __libc_sigaction; #ifdef __NR_rt_sigaction /* Using the hidden attribute here does not change the code but it helps to avoid warnings. */ extern void restore_rt(void) __asm__ ("__restore_rt") attribute_hidden; extern void restore(void) __asm__ ("__restore") attribute_hidden; /* If ACT is not NULL, change the action for SIG to *ACT. If OACT is not NULL, put the old action for SIG in *OACT. */ int __libc_sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { struct sigaction kact; if (act) { memcpy(&kact, act, sizeof(kact)); kact.sa_flags |= SA_RESTORER; kact.sa_restorer = &restore_rt; act = &kact; } /* NB: kernel (as of 2.6.25) will return EINVAL * if sizeof(act->sa_mask) does not match kernel's sizeof(sigset_t) */ return INLINE_SYSCALL(rt_sigaction, 4, sig, act, oact, sizeof(act->sa_mask)); } #else extern void restore(void) __asm__ ("__restore") attribute_hidden; /* If ACT is not NULL, change the action for SIG to *ACT. If OACT is not NULL, put the old action for SIG in *OACT. */ int __libc_sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { int result; struct old_kernel_sigaction kact, koact; if (act) { kact.k_sa_handler = act->sa_handler; kact.sa_mask = act->sa_mask.__val[0]; kact.sa_flags = act->sa_flags | SA_RESTORER; kact.sa_restorer = &restore; } __asm__ __volatile__ ( "syscall\n" : "=a" (result) : "0" (__NR_sigaction), "mr" (sig), "c" (act ? &kact : NULL), "d" (oact ? &koact : NULL)); if (result < 0) { __set_errno(-result); return -1; } if (oact) { oact->sa_handler = koact.k_sa_handler; oact->sa_mask.__val[0] = koact.sa_mask; oact->sa_flags = koact.sa_flags; oact->sa_restorer = koact.sa_restorer; } return result; } #endif #ifndef LIBC_SIGACTION weak_alias(__libc_sigaction,sigaction) libc_hidden_weak(sigaction) #endif /* NOTE: Please think twice before making any changes to the bits of code below. GDB needs some intimate knowledge about it to recognize them as signal trampolines, and make backtraces through signal handlers work right. Important are both the names (__restore_rt) and the exact instruction sequence. If you ever feel the need to make any changes, please notify the appropriate GDB maintainer. */ #define RESTORE(name, syscall) RESTORE2(name, syscall) #define RESTORE2(name, syscall) \ __asm__ ( \ ".text\n" \ "__" #name ":\n" \ " movq $" #syscall ", %rax\n" \ " syscall\n" \ ); #ifdef __NR_rt_sigaction /* The return code for realtime-signals. */ RESTORE(restore_rt, __NR_rt_sigreturn) #endif #ifdef __NR_sigreturn RESTORE(restore, __NR_sigreturn) #endif