* lin-lwp.c (detach_callback): Don't call stop_wait_callback.

(stop_wait_callback): Handle !lp->signalled also.
	(lin_lwp_has_pending, flush_callback): New functions.
	(lin_lwp_wait): Call flush_callback.
	* linux-proc.c (linux_proc_add_line_to_sigset): New function.
	(linux_proc_pending_signals): New function.
	* linux-nat.h (linux_proc_pending_signals): Add prototype.

gdb/ChangeLog

@@ -1,3 +1,13 @@
+2003-09-07  Daniel Jacobowitz  <drow@mvista.com>
+
+	* lin-lwp.c (detach_callback): Don't call stop_wait_callback.
+	(stop_wait_callback): Handle !lp->signalled also.
+	(lin_lwp_has_pending, flush_callback): New functions.
+	(lin_lwp_wait): Call flush_callback.
+	* linux-proc.c (linux_proc_add_line_to_sigset): New function.
+	(linux_proc_pending_signals): New function.
+	* linux-nat.h (linux_proc_pending_signals): Add prototype.
+
 2003-09-07  Daniel Jacobowitz  <drow@mvista.com>
 
 	From Nick Kelsey <nickk@ubicom.com>:

gdb/lin-lwp.c

@@ -417,7 +417,12 @@ detach_callback (struct lwp_info *lp, void *data)
       lp->stopped = 0;
       lp->signalled = 0;
       lp->status = 0;
-      stop_wait_callback (lp, NULL);
+      /* FIXME drow/2003-08-26: There was a call to stop_wait_callback
+	 here.  But since lp->signalled was cleared above,
+	 stop_wait_callback didn't do anything; the process was left
+	 running.  Shouldn't we be waiting for it to stop?
+	 I've removed the call, since stop_wait_callback now does do
+	 something when called with lp->signalled == 0.  */
 
       gdb_assert (lp->status == 0 || WIFSTOPPED (lp->status));
     }
@@ -696,7 +701,7 @@ stop_wait_callback (struct lwp_info *lp, void *data)
 {
   sigset_t *flush_mask = data;
 
-  if (!lp->stopped && lp->signalled)
+  if (!lp->stopped)
     {
       int status;
 
@@ -707,6 +712,12 @@ stop_wait_callback (struct lwp_info *lp, void *data)
       /* Ignore any signals in FLUSH_MASK.  */
       if (flush_mask && sigismember (flush_mask, WSTOPSIG (status)))
 	{
+	  if (!lp->signalled)
+	    {
+	      lp->stopped = 1;
+	      return 0;
+	    }
+
 	  errno = 0;
 	  ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0);
 	  if (debug_lin_lwp)
@@ -822,6 +833,88 @@ stop_wait_callback (struct lwp_info *lp, void *data)
   return 0;
 }
 
+/* Check whether PID has any pending signals in FLUSH_MASK.  If so set
+   the appropriate bits in PENDING, and return 1 - otherwise return 0.  */
+
+static int
+lin_lwp_has_pending (int pid, sigset_t *pending, sigset_t *flush_mask)
+{
+  sigset_t blocked, ignored;
+  int i;
+
+  linux_proc_pending_signals (pid, pending, &blocked, &ignored);
+
+  if (!flush_mask)
+    return 0;
+
+  for (i = 1; i < NSIG; i++)
+    if (sigismember (pending, i))
+      if (!sigismember (flush_mask, i)
+	  || sigismember (&blocked, i)
+	  || sigismember (&ignored, i))
+	sigdelset (pending, i);
+
+  if (sigisemptyset (pending))
+    return 0;
+
+  return 1;
+}
+
+/* DATA is interpreted as a mask of signals to flush.  If LP has
+   signals pending, and they are all in the flush mask, then arrange
+   to flush them.  LP should be stopped, as should all other threads
+   it might share a signal queue with.  */
+
+static int
+flush_callback (struct lwp_info *lp, void *data)
+{
+  sigset_t *flush_mask = data;
+  sigset_t pending, intersection, blocked, ignored;
+  int pid, status;
+
+  /* Normally, when an LWP exits, it is removed from the LWP list.  The
+     last LWP isn't removed till later, however.  So if there is only
+     one LWP on the list, make sure it's alive.  */
+  if (lwp_list == lp && lp->next == NULL)
+    if (!lin_lwp_thread_alive (lp->ptid))
+      return 0;
+
+  /* Just because the LWP is stopped doesn't mean that new signals
+     can't arrive from outside, so this function must be careful of
+     race conditions.  However, because all threads are stopped, we
+     can assume that the pending mask will not shrink unless we resume
+     the LWP, and that it will then get another signal.  We can't
+     control which one, however.  */
+
+  if (lp->status)
+    {
+      if (debug_lin_lwp)
+	printf_unfiltered ("FC: LP has pending status %06x\n", lp->status);
+      if (WIFSTOPPED (lp->status) && sigismember (flush_mask, WSTOPSIG (lp->status)))
+	lp->status = 0;
+    }
+
+  while (lin_lwp_has_pending (GET_LWP (lp->ptid), &pending, flush_mask))
+    {
+      int ret;
+      
+      errno = 0;
+      ret = ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0);
+      if (debug_lin_lwp)
+	fprintf_unfiltered (gdb_stderr,
+			    "FC: Sent PTRACE_CONT, ret %d %d\n", ret, errno);
+
+      lp->stopped = 0;
+      stop_wait_callback (lp, flush_mask);
+      if (debug_lin_lwp)
+	fprintf_unfiltered (gdb_stderr,
+			    "FC: Wait finished; saved status is %d\n",
+			    lp->status);
+    }
+
+  return 0;
+}
+
 /* Return non-zero if LP has a wait status pending.  */
 
 static int
@@ -1465,6 +1558,7 @@ retry:
   /* ... and wait until all of them have reported back that they're no
      longer running.  */
   iterate_over_lwps (stop_wait_callback, &flush_mask);
+  iterate_over_lwps (flush_callback, &flush_mask);
 
   /* If we're not waiting for a specific LWP, choose an event LWP from
      among those that have had events.  Giving equal priority to all

gdb/linux-nat.h

@@ -65,6 +65,9 @@ extern int linux_proc_xfer_memory (CORE_ADDR addr, char *myaddr, int len,
 				   int write, struct mem_attrib *attrib,
 				   struct target_ops *target);
 
+/* Find process PID's pending signal set from /proc/pid/status.  */
+void linux_proc_pending_signals (int pid, sigset_t *pending, sigset_t *blocked, sigset_t *ignored);
+
 /* linux-nat functions for handling fork events.  */
 extern void linux_record_stopped_pid (int pid);
 extern void linux_enable_event_reporting (ptid_t ptid);

gdb/linux-proc.c

@@ -35,6 +35,8 @@
 #include "cli/cli-decode.h"	/* for add_info */
 #include "gdb_string.h"
 
+#include <signal.h>
+
 #include "linux-nat.h"
 
 #ifndef O_LARGEFILE
@@ -622,3 +624,84 @@ linux_proc_xfer_memory (CORE_ADDR addr, char *myaddr, int len, int write,
   close (fd);
   return ret;
 }
+
+/* Parse LINE as a signal set and add its set bits to SIGS.  */
+
+static void
+linux_proc_add_line_to_sigset (const char *line, sigset_t *sigs)
+{
+  int len = strlen (line) - 1;
+  const char *p;
+  int signum;
+
+  if (line[len] != '\n')
+    error ("Could not parse signal set: %s", line);
+
+  p = line;
+  signum = len * 4;
+  while (len-- > 0)
+    {
+      int digit;
+
+      if (*p >= '0' && *p <= '9')
+	digit = *p - '0';
+      else if (*p >= 'a' && *p <= 'f')
+	digit = *p - 'a' + 10;
+      else
+	error ("Could not parse signal set: %s", line);
+
+      signum -= 4;
+
+      if (digit & 1)
+	sigaddset (sigs, signum + 1);
+      if (digit & 2)
+	sigaddset (sigs, signum + 2);
+      if (digit & 4)
+	sigaddset (sigs, signum + 3);
+      if (digit & 8)
+	sigaddset (sigs, signum + 4);
+
+      p++;
+    }
+}
+
+/* Find process PID's pending signals from /proc/pid/status and set SIGS
+   to match.  */
+
+void
+linux_proc_pending_signals (int pid, sigset_t *pending, sigset_t *blocked, sigset_t *ignored)
+{
+  FILE *procfile;
+  char buffer[MAXPATHLEN], fname[MAXPATHLEN];
+  int signum;
+
+  sigemptyset (pending);
+  sigemptyset (blocked);
+  sigemptyset (ignored);
+  sprintf (fname, "/proc/%d/status", pid);
+  procfile = fopen (fname, "r");
+  if (procfile == NULL)
+    error ("Could not open %s", fname);
+
+  while (fgets (buffer, MAXPATHLEN, procfile) != NULL)
+    {
+      /* Normal queued signals are on the SigPnd line in the status
+	 file.  However, 2.6 kernels also have a "shared" pending queue
+	 for delivering signals to a thread group, so check for a ShdPnd
+	 line also.
+
+	 Unfortunately some Red Hat kernels include the shared pending queue
+	 but not the ShdPnd status field.  */
+
+      if (strncmp (buffer, "SigPnd:\t", 8) == 0)
+	linux_proc_add_line_to_sigset (buffer + 8, pending);
+      else if (strncmp (buffer, "ShdPnd:\t", 8) == 0)
+	linux_proc_add_line_to_sigset (buffer + 8, pending);
+      else if (strncmp (buffer, "SigBlk:\t", 8) == 0)
+	linux_proc_add_line_to_sigset (buffer + 8, blocked);
+      else if (strncmp (buffer, "SigIgn:\t", 8) == 0)
+	linux_proc_add_line_to_sigset (buffer + 8, ignored);
+    }
+
+  fclose (procfile);
+}