# HG changeset patch
# User Eric Blake <ebb9@byu.net>
# Date 1176781088 0
# Node ID f82b54db5bb81a876d72bbfe3bd12c172ddc245d
# Parent  996bed2dc377d41425601cd617ea9ccd43281a96
Make fflush rely on fpurge.
* lib/fflush.c (rpl_fflush): Rely on fpurge module, rather than
open coding all variants.
* modules/fflush (Depends-on): Add fpurge and unistd.
* modules/fflush-tests (Depends-on): Unistd is no longer extra.
* m4/fflush.m4 (gl_REPLACE_FFLUSH): Simplify.

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2007-04-16  Eric Blake  <ebb9@byu.net>
 
+	Make fflush rely on fpurge.
+	* lib/fflush.c (rpl_fflush): Rely on fpurge module, rather than
+	open coding all variants.
+	* modules/fflush (Depends-on): Add fpurge and unistd.
+	* modules/fflush-tests (Depends-on): Unistd is no longer extra.
+	* m4/fflush.m4 (gl_REPLACE_FFLUSH): Simplify.
+
 	Fix --with-tests compilation on cygwin.
 	* modules/argmatch-tests (Makefile.am): List gnulib library first
 	in LDADD.
diff --git a/lib/fflush.c b/lib/fflush.c
--- a/lib/fflush.c
+++ b/lib/fflush.c
@@ -21,13 +21,7 @@
 #include <errno.h>
 #include <stdio.h>
 
-#if HAVE_STDIO_EXT_H
-# include <stdio_ext.h>
-#endif
-
-#if HAVE_FPURGE && ! HAVE_DECL_FPURGE
-int fpurge (FILE *);
-#endif
+#include "fpurge.h"
 
 #undef fflush
 
@@ -36,53 +30,31 @@
 int
 rpl_fflush (FILE *stream)
 {
-  int e; /* Capture errno of first fflush if nothing else succeeds.  */
   int result;
+  off_t pos;
 
   /* Try flushing the stream.  C89 guarantees behavior of output
      streams, so we only need to worry if failure might have been on
      an input stream.  When stream is NULL, POSIX only requires
      flushing of output streams.  */
   result = fflush (stream);
-  if (! stream || result == 0 || (e = errno) != EBADF)
+  if (! stream || result == 0 || errno != EBADF)
     return result;
 
-  /* POSIX does not specify behavior for non-seekable streams.  */
-  if (fseeko (stream, 0, SEEK_CUR) != 0)
+  /* POSIX does not specify fflush behavior for non-seekable input
+     streams.  */
+  pos = ftello (stream);
+  if (pos == -1)
     {
-      errno = e;
+      errno = EBADF;
       return EOF;
     }
 
   /* To get here, we must be flushing a seekable input stream, so the
-     semantics of fpurge are now appropriate.  */
-#if HAVE_FPURGE
+     semantics of fpurge are now appropriate to clear the buffer.  To
+     avoid losing data, the lseek is also necessary.  */
   result = fpurge (stream);
-#elif HAVE___FPURGE
-  /* __fpurge has no return value, and on Solaris, we can't even trust
-     errno.  So assume it succeeds.  */
-  __fpurge (stream);
-  result = 0;
-#else /* ! HAVE___FPURGE */
-
-  /* No single replacement; do it manually.  */
-  {
-    off_t position = ftello (stream);
-    if (position == -1)
-      {
-	result = EOF; /* Should not happen; we know stream is seekable.  */
-      }
-    /* Set position of stream; hopefully the stdio routines don't
-       overoptimize by not setting the underlying file position.  */
-    else if (fseeko (stream, position, SEEK_SET) != 0)
-      {
-	result = EOF;
-	errno = e;
-      }
-    else
-      result = 0;
-  }
-#endif /* ! HAVE___FPURGE */
-
+  if (result == 0 && lseek (fileno (stream), pos, SEEK_SET) == -1)
+    return EOF;
   return result;
 }
diff --git a/m4/fflush.m4 b/m4/fflush.m4
--- a/m4/fflush.m4
+++ b/m4/fflush.m4
@@ -1,4 +1,4 @@
-#serial 1
+#serial 2
 
 # Copyright (C) 2007 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
diff --git a/modules/fflush b/modules/fflush
--- a/modules/fflush
+++ b/modules/fflush
@@ -6,7 +6,9 @@
 m4/fflush.m4
 
 Depends-on:
+fpurge
 stdio
+unistd
 
 configure.ac:
 gl_FUNC_FFLUSH
diff --git a/modules/fflush-tests b/modules/fflush-tests
--- a/modules/fflush-tests
+++ b/modules/fflush-tests
@@ -2,7 +2,6 @@
 tests/test-fflush.c
 
 Depends-on:
-unistd
 
 configure.ac: