[patchv2] Minor O_CLOEXEC optimization, "regression" fix

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Wed, 09 Oct 2013 15:34:17 +0200, Kai Tietz wrote:
> So yes, probing for EINVAL seems to me like a valid way to probe for valid
> arguments here.

OK, therefore updated the patch.

No regressions on {x86_64,x86_64-m32,i686}-fedora21pre-linux-gnu.
It still reduces the number of syscalls.


Thanks,
Jan


gdb/
2013-10-09  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* common/filestuff.c (gdb_fopen_cloexec): Remove initialization of
	result variable.  Rename variable fopen_e_ever_failed to
	fopen_e_ever_failed_einval.  Retry fopen only for errno EINVAL.

diff --git a/gdb/common/filestuff.c b/gdb/common/filestuff.c
index d3b13e8..4032f36 100644
--- a/gdb/common/filestuff.c
+++ b/gdb/common/filestuff.c
@@ -310,16 +310,16 @@ gdb_open_cloexec (const char *filename, int flags, unsigned long mode)
 FILE *
 gdb_fopen_cloexec (const char *filename, const char *opentype)
 {
-  FILE *result = NULL;
+  FILE *result;
   /* Probe for "e" support once.  But, if we can tell the operating
      system doesn't know about close on exec mode "e" without probing,
      skip it.  E.g., the Windows runtime issues an "Invalid parameter
      passed to C runtime function" OutputDebugString warning for
      unknown modes.  Assume that if O_CLOEXEC is zero, then "e" isn't
      supported.  */
-  static int fopen_e_ever_failed = O_CLOEXEC == 0;
+  static int fopen_e_ever_failed_einval = O_CLOEXEC == 0;
 
-  if (!fopen_e_ever_failed)
+  if (!fopen_e_ever_failed_einval)
     {
       char *copy;
 
@@ -329,15 +329,16 @@ gdb_fopen_cloexec (const char *filename, const char *opentype)
 	 this path.  */
       strcat (copy, "e");
       result = fopen (filename, copy);
-    }
 
-  if (result == NULL)
-    {
-      /* Fallback.  */
-      result = fopen (filename, opentype);
-      if (result != NULL)
-	fopen_e_ever_failed = 1;
+      if (result == NULL && errno == EINVAL)
+	{
+	  result = fopen (filename, opentype);
+	  if (result != NULL)
+	    fopen_e_ever_failed_einval = 1;
+	}
     }
+  else
+    result = fopen (filename, opentype);
 
   if (result != NULL)
     maybe_mark_cloexec (fileno (result));