1999-09-18 Roland McGrath <roland@baalperazim.frob.com>

	* sysdeps/mach/hurd/wait4.c (__wait4): When proc_wait returns EAGAIN,
	return zero to indicate no children died yet (assuming WNOHANG).

diff --git a/sysdeps/mach/hurd/wait4.c b/sysdeps/mach/hurd/wait4.c
index 0b505ba..db6b8c0 100644 (file)
--- a/sysdeps/mach/hurd/wait4.c
+++ b/sysdeps/mach/hurd/wait4.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1993, 94, 95, 96, 97, 98 Free Software Foundation, Inc.
+/* Copyright (C) 1993,94,95,96,97,98,99 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
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or


@@ -35,8 +35,21 @@ __wait4 (pid_t pid, __WAIT_STATUS_DEFN stat_loc, int options,
   err = __USEPORT (PROC, __proc_wait (port, pid, options,
                                      stat_loc ?: &dummy, &sigcode,
                                      usage ?: &ignored, &dead));
   err = __USEPORT (PROC, __proc_wait (port, pid, options,
                                      stat_loc ?: &dummy, &sigcode,
                                      usage ?: &ignored, &dead));

-
-  return err ? (pid_t) __hurd_fail (err) : dead;
+  switch (err)
+    {
+    case 0:                    /* Got a child.  */
+      return dead;
+    case EAGAIN:
+      /* The RPC returns this error when the WNOHANG flag is set and no
+        selected children are dead (but some are living).  In that
+        situation, our return value is zero.  (The RPC can't return zero
+        for DEAD without also returning some garbage for the other out
+        parameters, so an error return is much more natural here.  Hence
+        the difference between the RPC and the POSIX.1 interface.  */
+      return (pid_t) 0;
+    default:
+      return (pid_t) __hurd_fail (err);
+    }

 }
 
 weak_alias (__wait4, wait4)
 }
 
 weak_alias (__wait4, wait4)