fadvise: new module providing a simpler interface to posix_fadvise

* bootstrap.conf: Include the new module
* gl/lib/fadvise.c: Provide a simpler interface to posix_fadvise.
(fadvise): Provide hint to the whole file associated with a stream.
(fdadvise): Provide hint to the specific portion of a file
associated with a file descriptor.
* gl/lib/fadvise.h: Redefine POSIX_FADV_* to FADVISE_* enums.
* gl/modules/fadvise: New file.
* m4/jm-macros.m4: Remove the no longer needed posix_fadvise check.
* .x-sc_program_name: Exclude test-fadvise.c from this check.
* gl/tests/test-fadvise (main): New test program.
* gl/modules/fadvise-testss: A new index to reference the tests.
* src/sort.c (stream_open): Use the new interface.
* src/dd.c (iwrite): Likewise.

1 files changed, 43 insertions, 0 deletions

diff --git a/gl/tests/test-fadvise.c b/gl/tests/test-fadvise.c
new file mode 100644
index 000000000..10b448f37
--- /dev/null
+++ b/gl/tests/test-fadvise.c
@@ -0,0 +1,43 @@
+/* Test that fadvise works as advertised.
+   Copyright (C) 2010 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Pádraig Brady.  */
+
+#include <config.h>
+#include <stdio.h>
+
+#include "fadvise.h"
+
+int
+main (void)
+{
+  /* Valid.  */
+  fadvise (stdin, FADVISE_SEQUENTIAL);
+  fdadvise (fileno (stdin), 0, 0, FADVISE_RANDOM);
+
+  /* Ignored.  */
+  fadvise (NULL, FADVISE_RANDOM);
+
+  /* Invalid.  */
+  fdadvise (42, 0, 0, FADVISE_RANDOM);
+  /* Unfortunately C enums are not types.
+     One could hack type safety by wrapping in a struct,
+     but it's probably not worth the complexity in this case.  */
+  fadvise (stdin, FADVISE_SEQUENTIAL + FADVISE_RANDOM);
+  fadvise (stdin, 4242);
+
+  return 0;
+}