[PATCH][BZ #15701] Freopen with closed file descriptors.

[Ondřej Bílka]

Hi,

This bug complains about undefined behavior when user closes file
descriptor. This is again patch or close case.

We could check this by asking kernel if descriptor is valid.

Comments?


	* libio/freopen.c: Check if file descriptors are open.

diff --git a/libio/freopen.c b/libio/freopen.c
index 6ba37bf..ca157da 100644
--- a/libio/freopen.c
+++ b/libio/freopen.c
@@ -47,6 +47,12 @@ freopen (filename, mode, fp)
     return NULL;
   _IO_acquire_lock (fp);
   int fd = _IO_fileno (fp);
+  /* Check that file descriptor is open.  */
+  if (fcntl(fd, F_GETFD) == -1)
+    {
+      return NULL;
+    }
+
   const char *gfilename = (filename == NULL && fd >= 0
 			   ? fd_to_filename (fd) : filename);
   fp->_flags2 |= _IO_FLAGS2_NOCLOSE;