1 files changed, 76 insertions, 0 deletions
diff --git a/lib/close-stream.c b/lib/close-stream.c
new file mode 100644
index 0000000..72d0d68
--- /dev/null
+++ b/lib/close-stream.c
@@ -0,0 +1,76 @@
+/* Close a stream, with nicer error checking than fclose's.
+
+   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2006 Free
+   Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <config.h>
+
+#include "close-stream.h"
+
+#include <errno.h>
+#include <stdbool.h>
+
+#include "__fpending.h"
+
+#if USE_UNLOCKED_IO
+# include "unlocked-io.h"
+#endif
+
+/* Close STREAM.  Return 0 if successful, EOF (setting errno)
+   otherwise.  A failure might set errno to 0 if the error number
+   cannot be determined.
+
+   If a program writes *anything* to STREAM, that program should close
+   STREAM and make sure that it succeeds before exiting.  Otherwise,
+   suppose that you go to the extreme of checking the return status
+   of every function that does an explicit write to STREAM.  The last
+   printf can succeed in writing to the internal stream buffer, and yet
+   the fclose(STREAM) could still fail (due e.g., to a disk full error)
+   when it tries to write out that buffered data.  Thus, you would be
+   left with an incomplete output file and the offending program would
+   exit successfully.  Even calling fflush is not always sufficient,
+   since some file systems (NFS and CODA) buffer written/flushed data
+   until an actual close call.
+
+   Besides, it's wasteful to check the return value from every call
+   that writes to STREAM -- just let the internal stream state record
+   the failure.  That's what the ferror test is checking below.  */
+
+int
+close_stream (FILE *stream)
+{
+  bool some_pending = (__fpending (stream) != 0);
+  bool prev_fail = (ferror (stream) != 0);
+  bool fclose_fail = (fclose (stream) != 0);
+
+  /* Return an error indication if there was a previous failure or if
+     fclose failed, with one exception: ignore an fclose failure if
+     there was no previous error, no data remains to be flushed, and
+     fclose failed with EBADF.  That can happen when a program like cp
+     is invoked like this `cp a b >&-' (i.e., with standard output
+     closed) and doesn't generate any output (hence no previous error
+     and nothing to be flushed).  */
+
+  if (prev_fail || (fclose_fail && (some_pending || errno != EBADF)))
+    {
+      if (! fclose_fail)
+	errno = 0;
+      return EOF;
+    }
+
+  return 0;
+}