--- /dev/null
+/* longjmp cleanup function for unwinding past signal handlers.
+Copyright (C) 1995 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 Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <hurd.h>
+#include "thread_state.h"
+#include <setjmp.h>
+#include <assert.h>
+
+extern void _hurd_longjmp_thread_state (struct machine_thread_state *,
+ jmp_buf env, int value);
+
+
+/* _hurd_setup_sighandler puts a link on the `active resources' chain so that
+ _longjmp_unwind will call this function with the `struct sigcontext *'
+ describing the context interrupted by the signal, when `longjmp' is jumping
+ to an environment that unwinds past the interrupted frame. */
+
+void
+_hurdsig_longjmp_from_handler (void *data, jmp_buf env, int val)
+{
+ struct sigcontext *scp = data;
+ struct hurd_sigstate *ss = _hurd_self_sigstate ();
+ int onstack;
+ inline void cleanup (void)
+ {
+ /* Destroy the MiG reply port used by the signal handler, and restore
+ the reply port in use by the thread when interrupted. */
+ mach_port_t *reply_port =
+ (mach_port_t *) __hurd_threadvar_location (_HURD_THREADVAR_MIG_REPLY);
+ if (*reply_port)
+ __mach_port_destroy (__mach_task_self (), *reply_port);
+ *reply_port = scp->sc_reply_port;
+ }
+
+ __spin_lock (&ss->lock);
+ /* We should only ever be called from _longjmp_unwind (in jmp-unwind.c),
+ which calls us inside a critical section. */
+ assert (ss->critical_section);
+ /* Are we on the alternate signal stack now? */
+ onstack = (ss->sigaltstack.ss_flags & SA_ONSTACK);
+ __spin_unlock (&ss->lock);
+
+ if (onstack && ! scp->sc_onstack)
+ {
+ /* We are unwinding off the signal stack. We must use sigreturn to
+ do it robustly. Mutate the sigcontext so that when sigreturn
+ resumes from that context, it will be as if `__longjmp (ENV, VAL)'
+ were done. */
+
+ struct hurd_userlink *link;
+
+ /* Continue _longjmp_unwind's job of running the unwind
+ forms for frames being unwound, since we will not
+ return to its loop like this one, which called us. */
+ for (link = ss->active_resources;
+ link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link);
+ link = link->thread.next)
+ if (_hurd_userlink_unlink (link))
+ {
+ if (link->cleanup == &_hurdsig_longjmp_from_handler)
+ {
+ /* We are unwinding past another signal handler invocation.
+ Just finish the cleanup for this (inner) one, and then
+ swap SCP to restore to the outer context. */
+ cleanup ();
+ scp = link->cleanup_data;
+ }
+ else
+ (*link->cleanup) (link->cleanup_data, env, val);
+ }
+
+#define sc_machine_thread_state paste(sc_,machine_thread_state)
+#define paste(a,b) paste1(a,b)
+#define paste1(a,b) a##b
+
+ /* There are no more unwind forms to be run!
+ Now we can just have the sigreturn do the longjmp for us. */
+ _hurd_longjmp_thread_state
+ ((struct machine_thread_state *) &scp->sc_machine_thread_state,
+ env, val);
+
+ /* Restore to the same current signal mask. If sigsetjmp saved the
+ mask, longjmp has already restored it as desired; if not, we
+ should leave it as it is. */
+ scp->sc_mask = ss->blocked;
+
+ /* sigreturn expects the link added by _hurd_setup_sighandler
+ to still be there, but _longjmp_unwind removed it just before
+ calling us. Put it back now so sigreturn can find it. */
+ link = (void *) &scp[1];
+ assert (! link->resource.next && ! link->resource.prevp);
+ assert (link->thread.next == ss->active_resources);
+ assert (link->thread.prevp = &ss->active_resources);
+ if (link->thread.next)
+ link->thread.next->thread.prevp = &link->thread.next;
+ ss->active_resources = link;
+
+ /* We must momentarily exit the critical section so that sigreturn
+ does not get upset with us. But we don't want signal handlers
+ running right now, because we are presently in the bogus state of
+ having run all the unwind forms back to ENV's frame, but our SP is
+ still inside those unwound frames. */
+ __spin_lock (&ss->lock);
+ ss->critical_section = 0;
+ ss->blocked = ~(sigset_t) 0 & ~_SIG_CANT_MASK;
+ __spin_unlock (&ss->lock);
+
+ /* Restore to the modified signal context that now
+ performs `longjmp (ENV, VAL)'. */
+ __sigreturn (scp);
+ assert (! "sigreturn returned!");
+ }
+
+ /* We are not unwinding off the alternate signal stack. So nothing
+ really funny is going on here. We can just clean up this handler
+ frame and let _longjmp_unwind continue unwinding. */
+ cleanup ();
+ ss->intr_port = scp->sc_intr_port;
+}
Cambridge, MA 02139, USA. */
#include <hurd/signal.h>
+#include <hurd/userlink.h>
#include "thread_state.h"
#include <assert.h>
#include <errno.h>
void *sigreturn_returns_here;
struct sigcontext *return_scp; /* Same; arg to sigreturn. */
struct sigcontext ctx;
+ struct hurd_userlink link;
} *stackframe;
if (ss->context)
{
int ok;
+ extern void _hurdsig_longjmp_from_handler (void *, jmp_buf, int);
+
+ /* Add a link to the thread's active-resources list. We mark this as
+ the only user of the "resource", so the cleanup function will be
+ called by any longjmp which is unwinding past the signal frame.
+ The cleanup function (in sigunwind.c) will make sure that all the
+ appropriate cleanups done by sigreturn are taken care of. */
+ stackframe->link.cleanup = &_hurdsig_longjmp_from_handler;
+ stackframe->link.cleanup_data = &stackframe->ctx;
+ stackframe->link.resource.next = NULL;
+ stackframe->link.resource.prevp = NULL;
+ stackframe->link.thread.next = ss->active_resources;
+ stackframe->link.thread.prevp = &ss->active_resources;
+ if (stackframe->link.thread.next)
+ stackframe->link.thread.next->thread.prevp
+ = &stackframe->link.thread.next;
+ ss->active_resources = &stackframe->link;
+
/* Set up the arguments for the signal handler. */
stackframe->signo = signo;
stackframe->sigcode = sigcode;
projects / thirdparty / glibc.git / commitdiff
