More robust creation of a subprocess, attempt to solve bug #13546.

 src/w32proc.c (new_child): If no vacant slots are found in
 child_procs[], make another pass looking for slots whose process
 has exited or died.

2 files changed, 31 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 358f25b40f9..e1b8a23e6b2 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,9 @@
 2013-02-13  Eli Zaretskii  <eliz@gnu.org>
 
+	* w32proc.c (new_child): If no vacant slots are found in
+	child_procs[], make another pass looking for slots whose process
+	has exited or died.  (Bug#13546)
+
 	* w32.c (sys_pipe): When failing due to file descriptors above
 	MAXDESC, set errno to EMFILE.
 	(_sys_read_ahead): Update cp->status when failing to read serial
diff --git a/src/w32proc.c b/src/w32proc.c
index 8c09a1b1beb..1e72d41e16b 100644
--- a/src/w32proc.c
+++ b/src/w32proc.c
@@ -798,6 +798,33 @@ new_child (void)
     if (!CHILD_ACTIVE (cp) && cp->procinfo.hProcess == NULL)
       goto Initialize;
   if (child_proc_count == MAX_CHILDREN)
+    {
+      DebPrint (("new_child: No vacant slots, looking for dead processes\n"));
+      for (cp = child_procs + (child_proc_count-1); cp >= child_procs; cp--)
+	if (!CHILD_ACTIVE (cp) && cp->procinfo.hProcess)
+	  {
+	    DWORD status = 0;
+
+	    if (!GetExitCodeProcess (cp->procinfo.hProcess, &status))
+	      {
+		DebPrint (("new_child.GetExitCodeProcess: error %lu for PID %lu\n",
+			   GetLastError (), cp->procinfo.dwProcessId));
+		status = STILL_ACTIVE;
+	      }
+	    if (status != STILL_ACTIVE
+		|| WaitForSingleObject (cp->procinfo.hProcess, 0) == WAIT_OBJECT_0)
+	      {
+		DebPrint (("new_child: Freeing slot of dead process %d\n",
+			   cp->procinfo.dwProcessId));
+		CloseHandle (cp->procinfo.hProcess);
+		cp->procinfo.hProcess = NULL;
+		CloseHandle (cp->procinfo.hThread);
+		cp->procinfo.hThread = NULL;
+		goto Initialize;
+	      }
+	  }
+    }
+  if (child_proc_count == MAX_CHILDREN)
     return NULL;
   cp = &child_procs[child_proc_count++];