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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /hurd/hurdsig.c
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initial import
Diffstat (limited to 'hurd/hurdsig.c')
-rw-r--r--hurd/hurdsig.c1080
1 files changed, 1080 insertions, 0 deletions
diff --git a/hurd/hurdsig.c b/hurd/hurdsig.c
new file mode 100644
index 0000000000..2c6f6a17d2
--- /dev/null
+++ b/hurd/hurdsig.c
@@ -0,0 +1,1080 @@
+/* Copyright (C) 1991, 1992, 1993, 1994, 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 <stdlib.h>
+#include <stdio.h>
+#include <hurd.h>
+#include <hurd/signal.h>
+#include <cthreads.h> /* For `struct mutex'. */
+#include <string.h>
+#include "hurdfault.h"
+#include "hurdmalloc.h" /* XXX */
+
+const char *_hurdsig_getenv (const char *);
+
+struct mutex _hurd_siglock;
+int _hurd_stopped;
+
+/* Port that receives signals and other miscellaneous messages. */
+mach_port_t _hurd_msgport;
+
+/* Thread listening on it. */
+thread_t _hurd_msgport_thread;
+
+/* Thread which receives task-global signals. */
+thread_t _hurd_sigthread;
+
+/* Linked-list of per-thread signal state. */
+struct hurd_sigstate *_hurd_sigstates;
+
+static void
+default_sigaction (struct sigaction actions[NSIG])
+{
+ int signo;
+
+ __sigemptyset (&actions[0].sa_mask);
+ actions[0].sa_flags = SA_RESTART;
+ actions[0].sa_handler = SIG_DFL;
+
+ for (signo = 1; signo < NSIG; ++signo)
+ actions[signo] = actions[0];
+}
+
+struct hurd_sigstate *
+_hurd_thread_sigstate (thread_t thread)
+{
+ struct hurd_sigstate *ss;
+ __mutex_lock (&_hurd_siglock);
+ for (ss = _hurd_sigstates; ss != NULL; ss = ss->next)
+ if (ss->thread == thread)
+ break;
+ if (ss == NULL)
+ {
+ ss = malloc (sizeof (*ss));
+ if (ss == NULL)
+ __libc_fatal ("hurd: Can't allocate thread sigstate\n");
+ ss->thread = thread;
+ __spin_lock_init (&ss->lock);
+
+ /* Initialze default state. */
+ __sigemptyset (&ss->blocked);
+ __sigemptyset (&ss->pending);
+ memset (&ss->sigaltstack, 0, sizeof (ss->sigaltstack));
+ ss->suspended = 0;
+#ifdef noteven
+ __condition_init (&ss->arrived);
+#endif
+ ss->intr_port = MACH_PORT_NULL;
+ ss->context = NULL;
+
+ /* Initialize the sigaction vector from the default signal receiving
+ thread's state, and its from the system defaults. */
+ if (thread == _hurd_sigthread)
+ default_sigaction (ss->actions);
+ else
+ {
+ struct hurd_sigstate *s;
+ for (s = _hurd_sigstates; s != NULL; s = s->next)
+ if (s->thread == _hurd_sigthread)
+ break;
+ if (s)
+ {
+ __spin_lock (&s->lock);
+ memcpy (ss->actions, s->actions, sizeof (s->actions));
+ __spin_unlock (&s->lock);
+ }
+ else
+ default_sigaction (ss->actions);
+ }
+
+ ss->next = _hurd_sigstates;
+ _hurd_sigstates = ss;
+ }
+ __mutex_unlock (&_hurd_siglock);
+ return ss;
+}
+
+/* Signal delivery itself is on this page. */
+
+#include <hurd/fd.h>
+#include <hurd/core.h>
+#include <hurd/paths.h>
+#include <setjmp.h>
+#include <fcntl.h>
+#include <sys/wait.h>
+#include "thread_state.h"
+#include <hurd/msg_server.h>
+#include <hurd/msg_reply.h> /* For __msg_sig_post_reply. */
+#include <assert.h>
+#include <hurd/interrupt.h>
+
+int _hurd_core_limit; /* XXX */
+
+/* Call the core server to mummify us before we die.
+ Returns nonzero if a core file was written. */
+static int
+write_corefile (int signo, long int sigcode, int sigerror)
+{
+ error_t err;
+ mach_port_t coreserver;
+ file_t file, coredir;
+ const char *name;
+
+ /* XXX RLIMIT_CORE:
+ When we have a protocol to make the server return an error
+ for RLIMIT_FSIZE, then tell the corefile fs server the RLIMIT_CORE
+ value in place of the RLIMIT_FSIZE value. */
+
+ /* First get a port to the core dumping server. */
+ coreserver = MACH_PORT_NULL;
+ name = _hurdsig_getenv ("CORESERVER");
+ if (name != NULL)
+ coreserver = __file_name_lookup (name, 0, 0);
+ if (coreserver == MACH_PORT_NULL)
+ coreserver = __file_name_lookup (_SERVERS_CORE, 0, 0);
+ if (coreserver == MACH_PORT_NULL)
+ return 0;
+
+ /* Get a port to the directory where the new core file will reside. */
+ name = _hurdsig_getenv ("COREFILE");
+ if (name == NULL)
+ name = "core";
+ coredir = __file_name_split (name, (char **) &name);
+ if (coredir == MACH_PORT_NULL)
+ return 0;
+ /* Create the new file, but don't link it into the directory yet. */
+ if (err = __dir_mkfile (coredir, O_WRONLY|O_CREAT,
+ 0600 & ~_hurd_umask, /* XXX ? */
+ &file))
+ return 0;
+
+ /* Call the core dumping server to write the core file. */
+ err = __core_dump_task (coreserver,
+ __mach_task_self (),
+ file, _hurdsig_getenv ("GNUTARGET"),
+ signo, sigcode, sigerror);
+ __mach_port_deallocate (__mach_task_self (), coreserver);
+ if (! err)
+ /* The core dump into FILE succeeded, so now link it into the
+ directory. */
+ err = __dir_link (file, coredir, name);
+ __mach_port_deallocate (__mach_task_self (), file);
+ __mach_port_deallocate (__mach_task_self (), coredir);
+ return !err;
+}
+
+
+/* Send a sig_post reply message if it hasn't already been sent. */
+static inline void
+post_reply (mach_port_t *reply_port, mach_msg_type_name_t reply_port_type,
+ int untraced,
+ error_t result)
+{
+ if (reply_port == NULL || *reply_port == MACH_PORT_NULL)
+ return;
+ (untraced ? __msg_sig_post_untraced_reply : __msg_sig_post_reply)
+ (*reply_port, reply_port_type, result);
+ *reply_port = MACH_PORT_NULL;
+}
+
+
+/* The lowest-numbered thread state flavor value is 1,
+ so we use bit 0 in machine_thread_all_state.set to
+ record whether we have done thread_abort. */
+#define THREAD_ABORTED 1
+
+/* SS->thread is suspended. Abort the thread and get its basic state. If
+ REPLY_PORT is not NULL, send a reply on *REPLY_PORT after aborting the
+ thread. */
+static void
+abort_thread (struct hurd_sigstate *ss, struct machine_thread_all_state *state,
+ mach_port_t *reply_port, mach_msg_type_name_t reply_port_type,
+ int untraced)
+{
+ if (!(state->set & THREAD_ABORTED))
+ {
+ __thread_abort (ss->thread);
+ /* Clear all thread state flavor set bits, because thread_abort may
+ have changed the state. */
+ state->set = THREAD_ABORTED;
+ }
+
+ if (reply_port)
+ post_reply (reply_port, reply_port_type, untraced, 0);
+
+ machine_get_basic_state (ss->thread, state);
+}
+
+/* Find the location of the MiG reply port cell in use by the thread whose
+ state is described by THREAD_STATE. Make sure that this location can be
+ set without faulting, or else return NULL. */
+
+static mach_port_t *
+interrupted_reply_port_location (struct machine_thread_all_state *thread_state)
+{
+ mach_port_t *portloc = (mach_port_t *) __hurd_threadvar_location_from_sp
+ (_HURD_THREADVAR_MIG_REPLY, (void *) thread_state->basic.SP);
+
+ if (_hurdsig_catch_fault (SIGSEGV))
+ {
+ assert (_hurdsig_fault_sigcode == (long int) portloc);
+ /* Faulted trying to read the stack. */
+ return NULL;
+ }
+
+ /* Fault now if this pointer is bogus. */
+ *(volatile mach_port_t *) portloc = *portloc;
+
+ _hurdsig_end_catch_fault ();
+
+ return portloc;
+}
+
+
+/* SS->thread is suspended.
+
+ Abort any interruptible RPC operation the thread is doing.
+
+ This uses only the constant member SS->thread and the unlocked, atomically
+ set member SS->intr_port, so no locking is needed.
+
+ If successfully sent an interrupt_operation and therefore the thread should
+ wait for its pending RPC to return (possibly EINTR) before taking the
+ incoming signal, returns the reply port to be received on. Otherwise
+ returns MACH_PORT_NULL.
+
+ *STATE_CHANGE is set nonzero if STATE->basic was modified and should
+ be applied back to the thread if it might ever run again, else zero. */
+
+static mach_port_t
+abort_rpcs (struct hurd_sigstate *ss, int signo,
+ struct machine_thread_all_state *state, int *state_change,
+ mach_port_t *reply_port, mach_msg_type_name_t reply_port_type,
+ int untraced)
+{
+ mach_port_t msging_port;
+ mach_port_t intr_port;
+
+ *state_change = 0;
+
+ intr_port = ss->intr_port;
+ if (intr_port == MACH_PORT_NULL)
+ /* No interruption needs done. */
+ return MACH_PORT_NULL;
+
+ /* Abort the thread's kernel context, so any pending message send or
+ receive completes immediately or aborts. */
+ abort_thread (ss, state, reply_port, reply_port_type, untraced);
+
+ if (_hurdsig_rcv_interrupted_p (state, &msging_port))
+ {
+ error_t err;
+
+ /* The RPC request message was sent and the thread was waiting for
+ the reply message; now the message receive has been aborted, so
+ the mach_msg_call will return MACH_RCV_INTERRUPTED. We must tell
+ the server to interrupt the pending operation. The thread must
+ wait for the reply message before running the signal handler (to
+ guarantee that the operation has finished being interrupted), so
+ our nonzero return tells the trampoline code to finish the message
+ receive operation before running the handler. */
+
+ err = __interrupt_operation (intr_port);
+
+ if (err)
+ {
+ mach_port_t *reply;
+
+ /* The interrupt didn't work.
+ Destroy the receive right the thread is blocked on. */
+ __mach_port_destroy (__mach_task_self (), msging_port);
+
+ /* The system call return value register now contains
+ MACH_RCV_INTERRUPTED; when mach_msg resumes, it will retry the
+ call. Since we have just destroyed the receive right, the
+ retry will fail with MACH_RCV_INVALID_NAME. Instead, just
+ change the return value here to EINTR so mach_msg will not
+ retry and the EINTR error code will propagate up. */
+ state->basic.SYSRETURN = EINTR;
+ *state_change = 1;
+
+ /* If that was the thread's MiG reply port (which I think should
+ always be the case), clear the reply port cell so it won't be
+ reused. */
+ reply = interrupted_reply_port_location (state);
+ if (reply != NULL && *reply == msging_port)
+ *reply = MACH_PORT_NULL;
+ }
+
+ /* All threads whose RPCs were interrupted by the interrupt_operation
+ call above will retry their RPCs unless we clear SS->intr_port.
+ So we clear it for the thread taking a signal when SA_RESTART is
+ clear, so that its call returns EINTR. */
+ if (!(ss->actions[signo].sa_flags & SA_RESTART))
+ ss->intr_port = MACH_PORT_NULL;
+
+ return err ? MACH_PORT_NULL : msging_port;
+ }
+
+ /* One of the following is true:
+
+ 1. The RPC has not yet been sent. The thread will start its operation
+ after the signal has been handled.
+
+ 2. The RPC has finished, but not yet cleared SS->intr_port.
+ The thread will clear SS->intr_port after running the handler.
+
+ 3. The RPC request message was being sent was aborted. The mach_msg
+ system call will return MACH_SEND_INTERRUPTED, and HURD_EINTR_RPC will
+ notice the interruption (either retrying the RPC or returning EINTR). */
+
+ return MACH_PORT_NULL;
+}
+
+/* Abort the RPCs being run by all threads but this one;
+ all other threads should be suspended. If LIVE is nonzero, those
+ threads may run again, so they should be adjusted as necessary to be
+ happy when resumed. STATE is clobbered as a scratch area; its initial
+ contents are ignored, and its contents on return are not useful. */
+
+static void
+abort_all_rpcs (int signo, struct machine_thread_all_state *state, int live)
+{
+ /* We can just loop over the sigstates. Any thread doing something
+ interruptible must have one. We needn't bother locking because all
+ other threads are stopped. */
+
+ struct hurd_sigstate *ss;
+ size_t nthreads;
+ mach_port_t *reply_ports;
+
+ /* First loop over the sigstates to count them.
+ We need to know how big a vector we will need for REPLY_PORTS. */
+ nthreads = 0;
+ for (ss = _hurd_sigstates; ss != NULL; ss = ss->next)
+ ++nthreads;
+
+ reply_ports = alloca (nthreads * sizeof *reply_ports);
+
+ nthreads = 0;
+ for (ss = _hurd_sigstates; ss != NULL; ss = ss->next)
+ if (ss->thread == _hurd_msgport_thread)
+ reply_ports[nthreads++] = MACH_PORT_NULL;
+ else
+ {
+ int state_changed;
+ state->set = 0; /* Reset scratch area. */
+
+ /* Abort any operation in progress with interrupt_operation.
+ Record the reply port the thread is waiting on.
+ We will wait for all the replies below. */
+ reply_ports[nthreads++] = abort_rpcs (ss, signo, state, &state_changed,
+ NULL, 0, 0);
+ if (state_changed && live)
+ /* Aborting the RPC needed to change this thread's state,
+ and it might ever run again. So write back its state. */
+ __thread_set_state (ss->thread, MACHINE_THREAD_STATE_FLAVOR,
+ (natural_t *) &state->basic,
+ MACHINE_THREAD_STATE_COUNT);
+ }
+
+ /* Wait for replies from all the successfully interrupted RPCs. */
+ while (nthreads-- > 0)
+ if (reply_ports[nthreads] != MACH_PORT_NULL)
+ {
+ error_t err;
+ mach_msg_header_t head;
+ err = __mach_msg (&head, MACH_RCV_MSG, 0, sizeof head,
+ reply_ports[nthreads],
+ MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
+ if (err != MACH_RCV_TOO_LARGE)
+ assert_perror (err);
+ }
+}
+
+
+struct hurd_signal_preempt *_hurd_signal_preempt[NSIG];
+struct mutex _hurd_signal_preempt_lock;
+
+/* Mask of stop signals. */
+#define STOPSIGS (sigmask (SIGTTIN) | sigmask (SIGTTOU) | \
+ sigmask (SIGSTOP) | sigmask (SIGTSTP))
+
+/* Deliver a signal. SS is not locked. */
+void
+_hurd_internal_post_signal (struct hurd_sigstate *ss,
+ int signo, long int sigcode, int sigerror,
+ mach_port_t reply_port,
+ mach_msg_type_name_t reply_port_type,
+ int untraced)
+{
+ struct machine_thread_all_state thread_state;
+ enum { stop, ignore, core, term, handle } act;
+ sighandler_t handler;
+ struct hurd_signal_preempt *pe;
+ sighandler_t (*preempt) (thread_t, int, long int, int) = NULL;
+ sigset_t pending;
+ int ss_suspended;
+
+ /* Reply to this sig_post message. */
+ inline void reply (void)
+ {
+ post_reply (&reply_port, reply_port_type, untraced, 0);
+ }
+
+ /* Mark the signal as pending. */
+ void mark_pending (void)
+ {
+ __sigaddset (&ss->pending, signo);
+ /* Save the code to be given to the handler when SIGNO is
+ unblocked. */
+ ss->pending_data[signo].code = sigcode;
+ ss->pending_data[signo].error = sigerror;
+ }
+
+ /* Suspend the process with SIGNO. */
+ void suspend (void)
+ {
+ /* Stop all other threads and mark ourselves stopped. */
+ __USEPORT (PROC,
+ ({
+ /* Hold the siglock while stopping other threads to be
+ sure it is not held by another thread afterwards. */
+ __mutex_lock (&_hurd_siglock);
+ __proc_dostop (port, _hurd_msgport_thread);
+ __mutex_unlock (&_hurd_siglock);
+ abort_all_rpcs (signo, &thread_state, 1);
+ __proc_mark_stop (port, signo);
+ }));
+ _hurd_stopped = 1;
+ }
+
+ post_signal:
+
+ thread_state.set = 0; /* We know nothing. */
+
+ /* Check for a preempted signal. Preempted signals
+ can arrive during critical sections. */
+ __mutex_lock (&_hurd_signal_preempt_lock);
+ for (pe = _hurd_signal_preempt[signo]; pe != NULL; pe = pe->next)
+ if (sigcode >= pe->first && sigcode <= pe->last)
+ {
+ preempt = pe->handler;
+ break;
+ }
+ __mutex_unlock (&_hurd_signal_preempt_lock);
+
+ handler = SIG_DFL;
+ if (preempt)
+ /* Let the preempting handler examine the thread.
+ If it returns SIG_DFL, we run the normal handler;
+ otherwise we use the handler it returns. */
+ handler = (*preempt) (ss->thread, signo, sigcode, sigerror);
+
+ ss_suspended = 0;
+
+ if (handler != SIG_DFL)
+ /* Run the preemption-provided handler. */
+ act = handle;
+ else
+ {
+ /* No preemption. Do normal handling. */
+
+ __spin_lock (&ss->lock);
+
+ handler = ss->actions[signo].sa_handler;
+
+ if (!untraced && (_hurd_exec_flags & EXEC_TRACED))
+ {
+ /* We are being traced. Stop to tell the debugger of the signal. */
+ if (_hurd_stopped)
+ /* Already stopped. Mark the signal as pending;
+ when resumed, we will notice it and stop again. */
+ mark_pending ();
+ else
+ suspend ();
+ __spin_unlock (&ss->lock);
+ reply ();
+ return;
+ }
+
+ if (handler == SIG_DFL)
+ /* Figure out the default action for this signal. */
+ switch (signo)
+ {
+ case 0:
+ /* A sig_post msg with SIGNO==0 is sent to
+ tell us to check for pending signals. */
+ act = ignore;
+ break;
+
+ case SIGTTIN:
+ case SIGTTOU:
+ case SIGSTOP:
+ case SIGTSTP:
+ act = stop;
+ break;
+
+ case SIGCONT:
+ case SIGIO:
+ case SIGURG:
+ case SIGCHLD:
+ case SIGWINCH:
+ act = ignore;
+ break;
+
+ case SIGQUIT:
+ case SIGILL:
+ case SIGTRAP:
+ case SIGIOT:
+ case SIGEMT:
+ case SIGFPE:
+ case SIGBUS:
+ case SIGSEGV:
+ case SIGSYS:
+ act = core;
+ break;
+
+ case SIGINFO:
+ if (_hurd_pgrp == _hurd_pid)
+ {
+ /* We are the process group leader. Since there is no
+ user-specified handler for SIGINFO, we use a default one
+ which prints something interesting. We use the normal
+ handler mechanism instead of just doing it here to avoid
+ the signal thread faulting or blocking in this
+ potentially hairy operation. */
+ act = handle;
+ handler = _hurd_siginfo_handler;
+ }
+ else
+ act = ignore;
+ break;
+
+ default:
+ act = term;
+ break;
+ }
+ else if (handler == SIG_IGN)
+ act = ignore;
+ else
+ act = handle;
+
+ if (__sigmask (signo) & STOPSIGS)
+ /* Stop signals clear a pending SIGCONT even if they
+ are handled or ignored (but not if preempted). */
+ ss->pending &= ~sigmask (SIGCONT);
+ else
+ {
+ if (signo == SIGCONT)
+ /* Even if handled or ignored (but not preempted), SIGCONT clears
+ stop signals and resumes the process. */
+ ss->pending &= ~STOPSIGS;
+
+ if (_hurd_stopped && act != stop && (untraced || signo == SIGCONT))
+ {
+ /* Resume the process from being stopped. */
+ thread_t *threads;
+ mach_msg_type_number_t nthreads, i;
+ error_t err;
+ /* Tell the proc server we are continuing. */
+ __USEPORT (PROC, __proc_mark_cont (port));
+ /* Fetch ports to all our threads and resume them. */
+ err = __task_threads (__mach_task_self (), &threads, &nthreads);
+ assert_perror (err);
+ for (i = 0; i < nthreads; ++i)
+ {
+ if (threads[i] != _hurd_msgport_thread &&
+ (act != handle || threads[i] != ss->thread))
+ __thread_resume (threads[i]);
+ __mach_port_deallocate (__mach_task_self (), threads[i]);
+ }
+ __vm_deallocate (__mach_task_self (),
+ (vm_address_t) threads,
+ nthreads * sizeof *threads);
+ _hurd_stopped = 0;
+ /* The thread that will run the handler is already suspended. */
+ ss_suspended = 1;
+ }
+ }
+ }
+
+ if (_hurd_orphaned && act == stop &&
+ (__sigmask (signo) & (__sigmask (SIGTTIN) | __sigmask (SIGTTOU) |
+ __sigmask (SIGTSTP))))
+ {
+ /* If we would ordinarily stop for a job control signal, but we are
+ orphaned so noone would ever notice and continue us again, we just
+ quietly die, alone and in the dark. */
+ sigcode = signo;
+ signo = SIGKILL;
+ act = term;
+ }
+
+ /* Handle receipt of a blocked signal, or any signal while stopped.
+ It matters that we test ACT first here, because we must never pass
+ SIGNO==0 to __sigismember. */
+ if ((act != ignore && __sigismember (&ss->blocked, signo)) ||
+ (signo != SIGKILL && _hurd_stopped))
+ {
+ mark_pending ();
+ act = ignore;
+ }
+
+ /* Perform the chosen action for the signal. */
+ switch (act)
+ {
+ case stop:
+ if (_hurd_stopped)
+ /* We are already stopped, but receiving an untraced stop
+ signal. Instead of resuming and suspending again, just
+ notify the proc server of the new stop signal. */
+ __USEPORT (PROC, __proc_mark_stop (port, signo));
+ else
+ /* Suspend the process. */
+ suspend ();
+ break;
+
+ case ignore:
+ /* Nobody cares about this signal. */
+ break;
+
+ case term: /* Time to die. */
+ case core: /* And leave a rotting corpse. */
+ nirvana:
+ /* Have the proc server stop all other threads in our task. */
+ __USEPORT (PROC, __proc_dostop (port, _hurd_msgport_thread));
+ /* No more user instructions will be executed.
+ The signal can now be considered delivered. */
+ reply ();
+ /* Abort all server operations now in progress. */
+ abort_all_rpcs (signo, &thread_state, 0);
+
+ {
+ int status = W_EXITCODE (0, signo);
+ /* Do a core dump if desired. Only set the wait status bit saying we
+ in fact dumped core if the operation was actually successful. */
+ if (act == core && write_corefile (signo, sigcode, sigerror))
+ status |= WCOREFLAG;
+ /* Tell proc how we died and then stick the saber in the gut. */
+ _hurd_exit (status);
+ /* NOTREACHED */
+ }
+
+ case handle:
+ /* Call a handler for this signal. */
+ {
+ struct sigcontext *scp;
+ int wait_for_reply, state_changed;
+
+ /* Stop the thread and abort its pending RPC operations. */
+ if (! ss_suspended)
+ __thread_suspend (ss->thread);
+
+ /* Abort the thread's kernel context, so any pending message send
+ or receive completes immediately or aborts. If an interruptible
+ RPC is in progress, abort_rpcs will do this. But we must always
+ do it before fetching the thread's state, because
+ thread_get_state is never kosher before thread_abort. */
+ abort_thread (ss, &thread_state, NULL, 0, 0);
+
+ wait_for_reply = (abort_rpcs (ss, signo, &thread_state, &state_changed,
+ &reply_port, reply_port_type, untraced)
+ != MACH_PORT_NULL);
+
+ if (ss->critical_section)
+ {
+ /* The thread is in a critical section. Mark the signal as
+ pending. When it finishes the critical section, it will
+ check for pending signals. */
+ mark_pending ();
+ assert (! state_changed);
+ __thread_resume (ss->thread);
+ break;
+ }
+
+ /* Call the machine-dependent function to set the thread up
+ to run the signal handler, and preserve its old context. */
+ scp = _hurd_setup_sighandler (ss, handler,
+ signo, sigcode,
+ wait_for_reply, &thread_state);
+ if (scp == NULL)
+ {
+ /* We got a fault setting up the stack frame for the handler.
+ Nothing to do but die; BSD gets SIGILL in this case. */
+ sigcode = signo; /* XXX ? */
+ signo = SIGILL;
+ act = core;
+ goto nirvana;
+ }
+
+ /* Set the machine-independent parts of the signal context. */
+
+ scp->sc_error = sigerror;
+ {
+ /* Fetch the thread variable for the MiG reply port,
+ and set it to MACH_PORT_NULL. */
+ mach_port_t *loc = interrupted_reply_port_location (&thread_state);
+ if (loc)
+ {
+ scp->sc_reply_port = *loc;
+ *loc = MACH_PORT_NULL;
+ }
+ else
+ scp->sc_reply_port = MACH_PORT_NULL;
+ }
+
+ /* Block SIGNO and requested signals while running the handler. */
+ scp->sc_mask = ss->blocked;
+ ss->blocked |= __sigmask (signo) | ss->actions[signo].sa_mask;
+
+ /* Save the intr_port in use by the interrupted code,
+ and clear the cell before running the trampoline. */
+ scp->sc_intr_port = ss->intr_port;
+ ss->intr_port = MACH_PORT_NULL;
+
+ /* Start the thread running the handler (or possibly waiting for an
+ RPC reply before running the handler). */
+ __thread_set_state (ss->thread, MACHINE_THREAD_STATE_FLAVOR,
+ (natural_t *) &thread_state.basic,
+ MACHINE_THREAD_STATE_COUNT);
+ __thread_resume (ss->thread);
+ thread_state.set = 0; /* Everything we know is now wrong. */
+ break;
+ }
+ }
+
+ /* The signal has either been ignored or is now being handled. We can
+ consider it delivered and reply to the killer. The exception is
+ signal 0, which can be sent by a user thread to make us check for
+ pending signals. In that case we want to deliver the pending signals
+ before replying. */
+ if (signo != 0)
+ reply ();
+
+ /* We get here unless the signal was fatal. We still hold SS->lock.
+ Check for pending signals, and loop to post them. */
+#define PENDING (!_hurd_stopped && (pending = ss->pending & ~ss->blocked))
+ if (PENDING)
+ {
+ pending:
+ for (signo = 1; signo < NSIG; ++signo)
+ if (__sigismember (&pending, signo))
+ {
+ __sigdelset (&ss->pending, signo);
+ sigcode = ss->pending_data[signo].code;
+ sigerror = ss->pending_data[signo].error;
+ __spin_unlock (&ss->lock);
+ goto post_signal;
+ }
+ }
+
+ /* No pending signals left undelivered for this thread.
+ If we were sent signal 0, we need to check for pending
+ signals for all threads. */
+ if (signo == 0)
+ {
+ __spin_unlock (&ss->lock);
+ __mutex_lock (&_hurd_siglock);
+ for (ss = _hurd_sigstates; ss != NULL; ss = ss->next)
+ {
+ __spin_lock (&ss->lock);
+ if (PENDING)
+ goto pending;
+ __spin_unlock (&ss->lock);
+ }
+ __mutex_unlock (&_hurd_siglock);
+ }
+ else
+ {
+ /* No more signals pending; SS->lock is still locked.
+ Wake up any sigsuspend call that is blocking SS->thread. */
+ if (ss->suspended != MACH_PORT_NULL)
+ {
+ /* There is a sigsuspend waiting. Tell it to wake up. */
+ error_t err;
+ mach_msg_header_t msg;
+ err = __mach_port_insert_right (__mach_task_self (),
+ ss->suspended, ss->suspended,
+ MACH_MSG_TYPE_MAKE_SEND);
+ assert_perror (err);
+ msg.msgh_bits = MACH_MSGH_BITS (MACH_MSG_TYPE_MOVE_SEND, 0);
+ msg.msgh_remote_port = ss->suspended;
+ msg.msgh_local_port = MACH_PORT_NULL;
+ /* These values do not matter. */
+ msg.msgh_id = 8675309; /* Jenny, Jenny. */
+ msg.msgh_seqno = 17; /* Random. */
+ ss->suspended = MACH_PORT_NULL;
+ err = __mach_msg (&msg, MACH_SEND_MSG, sizeof msg, 0,
+ MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE,
+ MACH_PORT_NULL);
+ assert_perror (err);
+ }
+ __spin_unlock (&ss->lock);
+ }
+
+ /* All pending signals delivered to all threads.
+ Now we can send the reply message even for signal 0. */
+ reply ();
+}
+
+/* Decide whether REFPORT enables the sender to send us a SIGNO signal.
+ Returns zero if so, otherwise the error code to return to the sender. */
+
+static error_t
+signal_allowed (int signo, mach_port_t refport)
+{
+ if (signo < 0 || signo >= NSIG)
+ return EINVAL;
+
+ if (refport == __mach_task_self ())
+ /* Can send any signal. */
+ goto win;
+
+ /* Avoid needing to check for this below. */
+ if (refport == MACH_PORT_NULL)
+ return EPERM;
+
+ switch (signo)
+ {
+ case SIGINT:
+ case SIGQUIT:
+ case SIGTSTP:
+ case SIGHUP:
+ case SIGINFO:
+ case SIGTTIN:
+ case SIGTTOU:
+ /* Job control signals can be sent by the controlling terminal. */
+ if (__USEPORT (CTTYID, port == refport))
+ goto win;
+ break;
+
+ case SIGCONT:
+ {
+ /* A continue signal can be sent by anyone in the session. */
+ mach_port_t sessport;
+ if (! __USEPORT (PROC, __proc_getsidport (port, &sessport)))
+ {
+ __mach_port_deallocate (__mach_task_self (), sessport);
+ if (refport == sessport)
+ goto win;
+ }
+ }
+ break;
+
+ case SIGIO:
+ case SIGURG:
+ {
+ /* Any io object a file descriptor refers to might send us
+ one of these signals using its async ID port for REFPORT.
+
+ This is pretty wide open; it is not unlikely that some random
+ process can at least open for reading something we have open,
+ get its async ID port, and send us a spurious SIGIO or SIGURG
+ signal. But BSD is actually wider open than that!--you can set
+ the owner of an io object to any process or process group
+ whatsoever and send them gratuitous signals.
+
+ Someday we could implement some reasonable scheme for
+ authorizing SIGIO and SIGURG signals properly. */
+
+ int d;
+ __mutex_lock (&_hurd_dtable_lock);
+ for (d = 0; (unsigned int) d < (unsigned int) _hurd_dtablesize; ++d)
+ {
+ struct hurd_userlink ulink;
+ io_t port;
+ mach_port_t asyncid;
+ if (_hurd_dtable[d] == NULL)
+ continue;
+ port = _hurd_port_get (&_hurd_dtable[d]->port, &ulink);
+ if (! __io_get_icky_async_id (port, &asyncid))
+ {
+ if (refport == asyncid)
+ /* Break out of the loop on the next iteration. */
+ d = -1;
+ __mach_port_deallocate (__mach_task_self (), asyncid);
+ }
+ _hurd_port_free (&_hurd_dtable[d]->port, &ulink, port);
+ }
+ /* If we found a lucky winner, we've set D to -1 in the loop. */
+ if (d < 0)
+ goto win;
+ }
+ }
+
+ /* If this signal is legit, we have done `goto win' by now.
+ When we return the error, mig deallocates REFPORT. */
+ return EPERM;
+
+ win:
+ /* Deallocate the REFPORT send right; we are done with it. */
+ __mach_port_deallocate (__mach_task_self (), refport);
+
+ return 0;
+}
+
+/* Implement the sig_post RPC from <hurd/msg.defs>;
+ sent when someone wants us to get a signal. */
+kern_return_t
+_S_msg_sig_post (mach_port_t me,
+ mach_port_t reply_port, mach_msg_type_name_t reply_port_type,
+ int signo,
+ mach_port_t refport)
+{
+ error_t err;
+
+ if (err = signal_allowed (signo, refport))
+ return err;
+
+ /* Post the signal to the designated signal-receiving thread. This will
+ reply when the signal can be considered delivered. */
+ _hurd_internal_post_signal (_hurd_thread_sigstate (_hurd_sigthread),
+ signo, 0, 0, reply_port, reply_port_type,
+ 0); /* Stop if traced. */
+
+ return MIG_NO_REPLY; /* Already replied. */
+}
+
+/* Implement the sig_post_untraced RPC from <hurd/msg.defs>;
+ sent when the debugger wants us to really get a signal
+ even if we are traced. */
+kern_return_t
+_S_msg_sig_post_untraced (mach_port_t me,
+ mach_port_t reply_port,
+ mach_msg_type_name_t reply_port_type,
+ int signo,
+ mach_port_t refport)
+{
+ error_t err;
+
+ if (err = signal_allowed (signo, refport))
+ return err;
+
+ /* Post the signal to the designated signal-receiving thread. This will
+ reply when the signal can be considered delivered. */
+ _hurd_internal_post_signal (_hurd_thread_sigstate (_hurd_sigthread),
+ signo, 0, 0, reply_port, reply_port_type,
+ 1); /* Untraced flag. */
+
+ return MIG_NO_REPLY; /* Already replied. */
+}
+
+extern void __mig_init (void *);
+
+#include <mach/task_special_ports.h>
+
+/* Initialize the message port and _hurd_sigthread and start the signal
+ thread. */
+
+void
+_hurdsig_init (void)
+{
+ error_t err;
+ vm_size_t stacksize;
+
+ __mutex_init (&_hurd_siglock);
+
+ if (err = __mach_port_allocate (__mach_task_self (),
+ MACH_PORT_RIGHT_RECEIVE,
+ &_hurd_msgport))
+ __libc_fatal ("hurd: Can't create message port receive right\n");
+
+ /* Make a send right to the signal port. */
+ if (err = __mach_port_insert_right (__mach_task_self (),
+ _hurd_msgport,
+ _hurd_msgport,
+ MACH_MSG_TYPE_MAKE_SEND))
+ __libc_fatal ("hurd: Can't create send right to message port\n");
+
+ /* Set the default thread to receive task-global signals
+ to this one, the main (first) user thread. */
+ _hurd_sigthread = __mach_thread_self ();
+
+ /* Start the signal thread listening on the message port. */
+
+ if (err = __thread_create (__mach_task_self (), &_hurd_msgport_thread))
+ __libc_fatal ("hurd: Can't create signal thread\n");
+
+ stacksize = __vm_page_size * 4; /* Small stack for signal thread. */
+ if (err = __mach_setup_thread (__mach_task_self (), _hurd_msgport_thread,
+ _hurd_msgport_receive,
+ (vm_address_t *) &__hurd_sigthread_stack_base,
+ &stacksize))
+ __libc_fatal ("hurd: Can't setup signal thread\n");
+
+ __hurd_sigthread_stack_end = __hurd_sigthread_stack_base + stacksize;
+ __hurd_sigthread_variables =
+ malloc (__hurd_threadvar_max * sizeof (unsigned long int));
+ if (__hurd_sigthread_variables == NULL)
+ __libc_fatal ("hurd: Can't allocate thread variables for signal thread\n");
+
+ /* Reinitialize the MiG support routines so they will use a per-thread
+ variable for the cached reply port. */
+ __mig_init ((void *) __hurd_sigthread_stack_base);
+
+ if (err = __thread_resume (_hurd_msgport_thread))
+ __libc_fatal ("hurd: Can't resume signal thread\n");
+
+#if 0 /* Don't confuse poor gdb. */
+ /* Receive exceptions on the signal port. */
+ __task_set_special_port (__mach_task_self (),
+ TASK_EXCEPTION_PORT, _hurd_msgport);
+#endif
+}
+ /* XXXX */
+/* Reauthenticate with the proc server. */
+
+static void
+reauth_proc (mach_port_t new)
+{
+ mach_port_t ref, ignore;
+
+ ref = __mach_reply_port ();
+ if (! HURD_PORT_USE (&_hurd_ports[INIT_PORT_PROC],
+ __proc_reauthenticate (port, ref,
+ MACH_MSG_TYPE_MAKE_SEND) ||
+ __auth_user_authenticate (new, port, ref,
+ MACH_MSG_TYPE_MAKE_SEND,
+ &ignore))
+ && ignore != MACH_PORT_NULL)
+ __mach_port_deallocate (__mach_task_self (), ignore);
+ __mach_port_destroy (__mach_task_self (), ref);
+
+ (void) &reauth_proc; /* Silence compiler warning. */
+}
+text_set_element (_hurd_reauth_hook, reauth_proc);
+
+/* Like `getenv', but safe for the signal thread to run.
+ If the environment is trashed, this will just return NULL. */
+
+const char *
+_hurdsig_getenv (const char *variable)
+{
+ if (_hurdsig_catch_fault (SIGSEGV))
+ /* We bombed in getenv. */
+ return NULL;
+ else
+ {
+ const char *value = getenv (variable);
+ /* Fault now if VALUE is a bogus string. */
+ (void) strlen (value);
+ _hurdsig_end_catch_fault ();
+ return value;
+ }
+}