[PATCH 7/6][BZ #11216] Return fmemopen stream when len==0.

[OndÅej BÃlka <neleai at seznam dot cz>]

As previous patches changed fmemopen behavior a lot it may be rigth 
time to fix that when len==0 fmemopen returns NULL. See:
http://sourceware.org/bugzilla/show_bug.cgi?id=11216

I could get this behavior by setting binmode flag.

Comments?

	* libio/fmemopen.c (fmemopen): Return stream when len==0.

>From a74de5327710f46a9921f28d13a678d2ad53d251 Mon Sep 17 00:00:00 2001
From: Ondrej Bilka <neleai@seznam.cz>
Date: Sat, 1 Jun 2013 18:10:35 +0200
Subject: [PATCH] fmemopen

---
 libio/fmemopen.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/libio/fmemopen.c b/libio/fmemopen.c
index 42632c2..9dfabc6 100644
--- a/libio/fmemopen.c
+++ b/libio/fmemopen.c
@@ -203,19 +203,13 @@ fmemopen (void *buf, size_t len, const char *mode)
   cookie_io_functions_t iof;
   fmemopen_cookie_t *c;
 
-  if (__glibc_unlikely (len == 0))
-    {
-      __set_errno (EINVAL);
-      return NULL;
-    }
-
   c = (fmemopen_cookie_t *) malloc (sizeof (fmemopen_cookie_t));
   if (c == NULL)
     return NULL;
 
   if (buf == NULL)
     {
-      buf = (char *) malloc (len);
+      buf = (char *) malloc (len + 1);
       if (buf == NULL)
         {
           free (c);
@@ -238,7 +232,7 @@ fmemopen (void *buf, size_t len, const char *mode)
   c->pos = 0;
   c->size = len;
   c->append = (mode[0] == 'a');
-  if (c->mybuffer || mode[0] == 'w')
+  if ((c->mybuffer || mode[0] == 'w') && len != 0)
     c->buffer[0] = '\0';
   c->maxpos = strnlen (c->buffer, len);
 
@@ -253,6 +247,10 @@ fmemopen (void *buf, size_t len, const char *mode)
         c->pos = 0;
     }
 
+  /* We need to set binary mode to cause fmemopen_write always fail.  */
+  if (__glibc_unlikely (len == 0))
+    c->binmode = 1;
+
   iof.read = fmemopen_read;
   iof.write = fmemopen_write;
   iof.seek = fmemopen_seek;
-- 
1.7.10.4