# HG changeset patch
# User Eric Blake <eblake@redhat.com>
# Date 1304370050 21600
# Node ID 68c96ae4be1ac9121bff164e8ede82a347188e65
# Parent  fa93679417c10a100b238fcd3c8033385f62aae0
fflush: also replace fclose when fixing fflush

This fixes the fclose failures detected in the previous patch,
but only when the GPL fflush module is also in use.  That is
because the need for behavior of resetting seekable input streams
is much less common, and the fix more complex.  The LGPLv2+ test
for fclose() in isolation is relaxed to pass if fflush is not
being replaced to cater to input streams.

* modules/fflush (Depends-on): Add fclose.
* m4/fflush.m4 (gl_FUNC_FFLUSH): Also replace fclose.
* lib/fclose.c (rpl_fclose): Don't cause spurious failures on
memstreams with no backing fd.
* doc/posix-functions/fclose.texi (fclose): Document the use of
fflush module to fix the bug.
* tests/test-fclose.c (main): Relax test when fclose is used in
isolation.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
 2011-05-02  Eric Blake  <eblake@redhat.com>
 
+	fflush: also replace fclose when fixing fflush
+	* modules/fflush (Depends-on): Add fclose.
+	* m4/fflush.m4 (gl_FUNC_FFLUSH): Also replace fclose.
+	* lib/fclose.c (rpl_fclose): Don't cause spurious failures on
+	memstreams with no backing fd.
+	* doc/posix-functions/fclose.texi (fclose): Document the use of
+	fflush module to fix the bug.
+	* tests/test-fclose.c (main): Relax test when fclose is used in
+	isolation.
+
 	fclose: add some tests
 	* modules/fclose-tests: New test module.
 	* tests/test-fclose.c: New file.
diff --git a/doc/posix-functions/fclose.texi b/doc/posix-functions/fclose.texi
--- a/doc/posix-functions/fclose.texi
+++ b/doc/posix-functions/fclose.texi
@@ -4,9 +4,17 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/fclose.html}
 
-Gnulib module: fclose
+Gnulib module: fclose, fflush
 
-Portability problems fixed by Gnulib:
+Portability problems fixed by Gnulib module @code{fflush}:
+@itemize
+@item
+On some platforms, this function fails to set the file position of a
+seekable input stream to the byte after the last one actually read:
+glibc 2.13, FreeBSD.
+@end itemize
+
+Portability problems fixed by Gnulib module @code{fclose}:
 @itemize
 @item
 On Windows platforms (excluding Cygwin), @code{socket} and @code{accept}
@@ -17,10 +25,6 @@
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-On some platforms, this function fails to set the file position of a
-seekable input stream to the byte after the last one actually read:
-glibc 2.13, FreeBSD.
-@item
 On Windows platforms (excluding Cygwin), this function does not set @code{errno}
 upon failure.
 @end itemize
diff --git a/lib/fclose.c b/lib/fclose.c
--- a/lib/fclose.c
+++ b/lib/fclose.c
@@ -24,13 +24,19 @@
 
 #include "freading.h"
 
-/* Override fclose() to call the overridden close().  */
+/* Override fclose() to call the overridden fflush() or close().  */
 
 int
 rpl_fclose (FILE *fp)
 #undef fclose
 {
   int saved_errno = 0;
+  int fd;
+
+  /* Don't change behavior on memstreams.  */
+  fd = fileno (fp);
+  if (fd < 0)
+    return fclose (fp);
 
   /* We only need to flush the file if it is not reading or if it is
      seekable.  This only guarantees the file position of input files
@@ -39,7 +45,7 @@
       && fflush (fp))
     saved_errno = errno;
 
-  if (close (fileno (fp)) < 0 && saved_errno == 0)
+  if (close (fd) < 0 && saved_errno == 0)
     saved_errno = errno;
 
   fclose (fp); /* will fail with errno = EBADF */
diff --git a/m4/fflush.m4 b/m4/fflush.m4
--- a/m4/fflush.m4
+++ b/m4/fflush.m4
@@ -1,4 +1,4 @@
-# fflush.m4 serial 8
+# fflush.m4 serial 9
 
 # Copyright (C) 2007-2011 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -61,6 +61,7 @@
     ])
   if test $gl_cv_func_fflush_stdin = no; then
     gl_REPLACE_FFLUSH
+    gl_REPLACE_FCLOSE
   fi
 ])
 
diff --git a/modules/fflush b/modules/fflush
--- a/modules/fflush
+++ b/modules/fflush
@@ -7,6 +7,7 @@
 m4/fflush.m4
 
 Depends-on:
+fclose
 fpurge
 ftello
 freading
@@ -20,6 +21,7 @@
 
 configure.ac:
 gl_FUNC_FFLUSH
+gl_MODULE_INDICATOR([fflush])
 gl_STDIO_MODULE_INDICATOR([fflush])
 
 Makefile.am:
diff --git a/tests/test-fclose.c b/tests/test-fclose.c
--- a/tests/test-fclose.c
+++ b/tests/test-fclose.c
@@ -62,7 +62,9 @@
   ASSERT (errno == EBADF);
   ASSERT (lseek (fd, 0, SEEK_CUR) == 2);
 
-  /* Likewise for an input stream.  */
+#if GNULIB_FFLUSH
+  /* Likewise for an input stream, but only when we know fflush works
+     on input streams.  */
   fd2 = dup (fd);
   ASSERT (0 <= fd2);
   f = fdopen (fd2, "r");
@@ -73,6 +75,7 @@
   ASSERT (lseek (fd2, 0, SEEK_CUR) == -1);
   ASSERT (errno == EBADF);
   ASSERT (lseek (fd, 0, SEEK_CUR) == 3);
+#endif
 
   /* Test that fclose() sets errno if someone else closes the stream
      fd behind the back of stdio.  */