242 lines
7.4 KiB
C
242 lines
7.4 KiB
C
/* Linuxthreads - a simple clone()-based implementation of Posix */
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/* threads for Linux. */
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/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
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/* */
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/* This program is free software; you can redistribute it and/or */
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/* modify it under the terms of the GNU Library General Public License */
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/* as published by the Free Software Foundation; either version 2 */
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/* of the License, or (at your option) any later version. */
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/* */
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/* This program is distributed in the hope that it will be useful, */
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/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
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/* GNU Library General Public License for more details. */
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/* Handling of signals */
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#include <errno.h>
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#include <signal.h>
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#include "pthread.h"
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#include "internals.h"
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#include "spinlock.h"
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#include <ucontext.h>
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#include <sigcontextinfo.h>
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int pthread_sigmask(int how, const sigset_t * newmask, sigset_t * oldmask)
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{
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sigset_t mask;
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if (newmask != NULL) {
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mask = *newmask;
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/* Don't allow __pthread_sig_restart to be unmasked.
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Don't allow __pthread_sig_cancel to be masked. */
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switch(how) {
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case SIG_SETMASK:
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sigaddset(&mask, __pthread_sig_restart);
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sigdelset(&mask, __pthread_sig_cancel);
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break;
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case SIG_BLOCK:
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sigdelset(&mask, __pthread_sig_cancel);
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break;
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case SIG_UNBLOCK:
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sigdelset(&mask, __pthread_sig_restart);
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break;
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}
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newmask = &mask;
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}
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if (sigprocmask(how, newmask, oldmask) == -1)
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return errno;
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else
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return 0;
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}
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int pthread_kill(pthread_t thread, int signo)
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{
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pthread_handle handle = thread_handle(thread);
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int pid;
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__pthread_lock(&handle->h_lock, NULL);
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if (invalid_handle(handle, thread)) {
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__pthread_unlock(&handle->h_lock);
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return ESRCH;
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}
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pid = handle->h_descr->p_pid;
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__pthread_unlock(&handle->h_lock);
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if (kill(pid, signo) == -1)
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return errno;
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else
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return 0;
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}
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/* User-provided signal handlers */
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typedef void (*arch_sighandler_t) __PMT ((int, SIGCONTEXT));
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static union
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{
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arch_sighandler_t old;
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void (*rt) (int, struct siginfo *, struct ucontext *);
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} sighandler[NSIG];
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/* The wrapper around user-provided signal handlers */
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static void pthread_sighandler(int signo, SIGCONTEXT ctx)
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{
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pthread_descr self;
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char * in_sighandler;
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#ifdef __i386__
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asm volatile ("movw %w0,%%gs" : : "r" (ctx.gs));
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#endif
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self = thread_self();
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/* If we're in a sigwait operation, just record the signal received
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and return without calling the user's handler */
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if (THREAD_GETMEM(self, p_sigwaiting)) {
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THREAD_SETMEM(self, p_sigwaiting, 0);
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THREAD_SETMEM(self, p_signal, signo);
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return;
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}
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/* Record that we're in a signal handler and call the user's
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handler function */
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in_sighandler = THREAD_GETMEM(self, p_in_sighandler);
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if (in_sighandler == NULL)
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THREAD_SETMEM(self, p_in_sighandler, CURRENT_STACK_FRAME);
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sighandler[signo].old(signo, SIGCONTEXT_EXTRA_ARGS ctx);
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if (in_sighandler == NULL)
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THREAD_SETMEM(self, p_in_sighandler, NULL);
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}
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/* The same, this time for real-time signals. */
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static void pthread_sighandler_rt(int signo, struct siginfo *si,
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struct ucontext *uc)
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{
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pthread_descr self;
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char * in_sighandler;
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#ifdef __i386__
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asm volatile ("movw %w0,%%gs" : : "r" (uc->uc_mcontext.gregs[GS]));
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#endif
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self = thread_self();
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/* If we're in a sigwait operation, just record the signal received
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and return without calling the user's handler */
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if (THREAD_GETMEM(self, p_sigwaiting)) {
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THREAD_SETMEM(self, p_sigwaiting, 0);
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THREAD_SETMEM(self, p_signal, signo);
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return;
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}
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/* Record that we're in a signal handler and call the user's
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handler function */
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in_sighandler = THREAD_GETMEM(self, p_in_sighandler);
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if (in_sighandler == NULL)
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THREAD_SETMEM(self, p_in_sighandler, CURRENT_STACK_FRAME);
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sighandler[signo].rt(signo, si, uc);
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if (in_sighandler == NULL)
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THREAD_SETMEM(self, p_in_sighandler, NULL);
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}
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/* The wrapper around sigaction. Install our own signal handler
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around the signal. */
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int sigaction(int sig, const struct sigaction * act,
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struct sigaction * oact)
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{
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struct sigaction newact;
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struct sigaction *newactp;
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if (sig == __pthread_sig_restart ||
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sig == __pthread_sig_cancel ||
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(sig == __pthread_sig_debug && __pthread_sig_debug > 0))
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return EINVAL;
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if (act)
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{
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newact = *act;
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if (act->sa_handler != SIG_IGN && act->sa_handler != SIG_DFL
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&& sig > 0 && sig < NSIG)
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{
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if (act->sa_flags & SA_SIGINFO)
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newact.sa_handler = (__sighandler_t) pthread_sighandler_rt;
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else
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newact.sa_handler = (__sighandler_t) pthread_sighandler;
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}
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newactp = &newact;
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}
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else
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newactp = NULL;
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if (__sigaction(sig, newactp, oact) == -1)
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return -1;
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if (sig > 0 && sig < NSIG)
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{
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if (oact != NULL)
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oact->sa_handler = (__sighandler_t) sighandler[sig].old;
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if (act)
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/* For the assignment is does not matter whether it's a normal
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or real-time signal. */
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sighandler[sig].old = (arch_sighandler_t) act->sa_handler;
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}
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return 0;
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}
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/* A signal handler that does nothing */
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static void pthread_null_sighandler(int sig) { }
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/* sigwait -- synchronously wait for a signal */
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int sigwait(const sigset_t * set, int * sig)
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{
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volatile pthread_descr self = thread_self();
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sigset_t mask;
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int s;
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sigjmp_buf jmpbuf;
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struct sigaction sa;
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/* Get ready to block all signals except those in set
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and the cancellation signal.
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Also check that handlers are installed on all signals in set,
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and if not, install our dummy handler. This is conformant to
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POSIX: "The effect of sigwait() on the signal actions for the
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signals in set is unspecified." */
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sigfillset(&mask);
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sigdelset(&mask, __pthread_sig_cancel);
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for (s = 1; s <= NSIG; s++) {
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if (sigismember(set, s) &&
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s != __pthread_sig_restart &&
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s != __pthread_sig_cancel &&
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s != __pthread_sig_debug) {
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sigdelset(&mask, s);
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if (sighandler[s].old == NULL ||
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sighandler[s].old == (arch_sighandler_t) SIG_DFL ||
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sighandler[s].old == (arch_sighandler_t) SIG_IGN) {
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sa.sa_handler = pthread_null_sighandler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = 0;
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sigaction(s, &sa, NULL);
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}
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}
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}
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/* Test for cancellation */
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if (sigsetjmp(jmpbuf, 1) == 0) {
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THREAD_SETMEM(self, p_cancel_jmp, &jmpbuf);
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if (! (THREAD_GETMEM(self, p_canceled)
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&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE)) {
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/* Reset the signal count */
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THREAD_SETMEM(self, p_signal, 0);
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/* Say we're in sigwait */
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THREAD_SETMEM(self, p_sigwaiting, 1);
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/* Unblock the signals and wait for them */
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sigsuspend(&mask);
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}
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}
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THREAD_SETMEM(self, p_cancel_jmp, NULL);
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/* The signals are now reblocked. Check for cancellation */
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pthread_testcancel();
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/* We should have self->p_signal != 0 and equal to the signal received */
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*sig = THREAD_GETMEM(self, p_signal);
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return 0;
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}
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/* Redefine raise() to send signal to calling thread only,
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as per POSIX 1003.1c */
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int raise (int sig)
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{
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int retcode = pthread_kill(pthread_self(), sig);
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if (retcode == 0)
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return 0;
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else {
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errno = retcode;
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return -1;
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}
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}
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