Fix buffer overflow for writes to memory buffer stream (bug 18549)

1 files changed, 11 insertions, 2 deletions

diff --git a/libio/test-fmemopen.c b/libio/test-fmemopen.c
index cddf0cf5e1..63ca89f300 100644
--- a/libio/test-fmemopen.c
+++ b/libio/test-fmemopen.c
@@ -21,21 +21,30 @@ static char buffer[] = "foobar";
 
 #include <stdio.h>
 #include <string.h>
+#include <errno.h>
 
 static int
 do_test (void)
 {
   int ch;
   FILE *stream;
+  int ret = 0;
 
-  stream = fmemopen (buffer, strlen (buffer), "r");
+  stream = fmemopen (buffer, strlen (buffer), "r+");
 
   while ((ch = fgetc (stream)) != EOF)
     printf ("Got %c\n", ch);
 
+  fputc ('1', stream);
+  if (fflush (stream) != EOF || errno != ENOSPC)
+    {
+      printf ("fflush didn't fail with ENOSPC\n");
+      ret = 1;
+    }
+
   fclose (stream);
 
-  return 0;
+  return ret;
 }
 
 #define TEST_FUNCTION do_test ()