Sun Apr 2 13:13:52 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu>

	* sysdeps/mach/hurd/i386/trampoline.c: Add a link to
 	SS->active_resources, so that _hurdsig_longjmp_from_handler will
 	be called when a longjmp unwinds the signal frame.
	* sysdeps/mach/hurd/i386/sigreturn.c: Remove the link on the
 	SS->active_resources chain added by _hurd_setup_sighandler.
	* hurd/sigunwind.c: New file.
	* hurd/Makefile (sig): Add sigunwind.

	* Makerules (lib%.so: lib%_pic.a): Remove dir name from $*.

	* MakeTAGS (tags-sources): Include $(all-dist).
	[subdir] (all-dist): Define to $(distribute).

1 files changed, 135 insertions, 0 deletions

diff --git a/hurd/sigunwind.c b/hurd/sigunwind.c
new file mode 100644
index 0000000000..7420f43ae4
--- /dev/null
+++ b/hurd/sigunwind.c
@@ -0,0 +1,135 @@
+/* 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;
+}