Make the combination of fflush and fseek/fseeko POSIX compliant.

6 files changed, 113 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 244370a2ae..6218a8e72f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,18 @@
 2007-04-25  Bruno Haible  <bruno@clisp.org>
 
+	Make fflush+fseek POSIX-compliant on FreeBSD and MacOS X.
+	* lib/fseeko.c: New file.
+	* lib/stdio_.h: Include <sys/types.h> when off_t is needed.
+	(fseeko, fseek): Define to replacements if REPLACE_FFLUSH.
+	* m4/fseeko.m4 (gl_CHECK_FSEEKO): New macro, extracted from
+	gl_FUNC_FSEEKO.
+	(gl_FUNC_FSEEKO): Invoke it.
+	* m4/fflush.m4 (gl_REPLACE_FFLUSH): Arrange to compile fseeko.c. Invoke
+	gl_CHECK_FSEEKO. Define HAVE_FSEEKO.
+	* modules/fflush (Files): Add lib/fseeko.c, m4/fseeko.m4.
+
+2007-04-25  Bruno Haible  <bruno@clisp.org>
+
 	* modules/fflush (Depends-on): Add ftello.
 
 2007-04-25  Bruno Haible  <bruno@clisp.org>
diff --git a/lib/fseeko.c b/lib/fseeko.c
new file mode 100644
index 0000000000..de44802b6f
--- /dev/null
+++ b/lib/fseeko.c
@@ -0,0 +1,72 @@
+/* An fseek() function that, together with fflush(), is POSIX compliant.
+   Copyright (C) 2007 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>
+
+/* Specification.  */
+#include <stdio.h>
+
+/* Get off_t and lseek.  */
+#include <unistd.h>
+
+#undef fseeko
+#if !HAVE_FSEEKO
+# define fseeko fseek
+#endif
+
+int
+rpl_fseeko (FILE *fp, off_t offset, int whence)
+{
+  /* These tests are based on fpurge.c.  */
+#if defined _IO_ferror_unlocked     /* GNU libc, BeOS */
+  if (fp->_IO_read_end == fp->_IO_read_ptr
+      && fp->_IO_write_ptr == fp->_IO_write_base
+      && fp->_IO_save_base == NULL)
+#elif defined __sferror             /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
+# if defined __NetBSD__ || defined __OpenBSD__ /* NetBSD, OpenBSD */
+   /* See <http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup>
+      and <http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup> */
+#  define fp_ub ((struct { struct __sbuf _ub; } *) fp->_ext._base)->_ub
+# else                                         /* FreeBSD, MacOS X, Cygwin */
+#  define fp_ub fp->_ub
+# endif
+  if (fp->_p == fp->_bf._base
+      && fp->_r == 0
+      && fp->_w == ((fp->_flags & (__SLBF | __SNBF)) == 0 /* fully buffered? */
+		    ? fp->_bf._size
+		    : 0)
+      && fp_ub._base == NULL)
+#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
+# if defined __sun && defined __sparc && defined _LP64 /* Solaris/SPARC 64-bit */
+#  define fp_ ((struct { unsigned char *_ptr; \
+                         unsigned char *_base; \
+                         unsigned char *_end; \
+                         long _cnt; \
+                       } *) fp)
+  if (fp_->_ptr == fp_->_base
+      && (fp_->_ptr == NULL || fp_->_cnt == 0))
+# else
+  if (fp->_ptr == fp->_base
+      && (fp->_ptr == NULL || fp->_cnt == 0))
+# endif
+#else
+  #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
+#endif
+    return (lseek (fileno (fp), offset, whence) == (off_t)(-1) ? -1 : 0);
+  else
+    return fseeko (fp, offset, whence);
+}
diff --git a/lib/stdio_.h b/lib/stdio_.h
index 46ec407c9c..8b78d7bcc7 100644
--- a/lib/stdio_.h
+++ b/lib/stdio_.h
@@ -38,6 +38,11 @@
 #include <stdarg.h>
 #include <stddef.h>
 
+#if @GNULIB_FFLUSH@ && @REPLACE_FFLUSH@
+/* Get off_t.  */
+# include <sys/types.h>
+#endif
+
 #ifndef __attribute__
 /* This feature is available in gcc versions 2.5 and later.  */
 # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5) || __STRICT_ANSI__
@@ -207,7 +212,12 @@ extern int vsprintf (char *str, const char *format, va_list args)
 # endif
 #endif
 
-#if @GNULIB_FSEEKO@
+#if @GNULIB_FFLUSH@ && @REPLACE_FFLUSH@
+/* Provide fseek, fseeko functions that are aware of a preceding fflush().  */
+# define fseeko rpl_fseeko
+extern int fseeko (FILE *fp, off_t offset, int whence);
+# define fseek(fp, offset, whence) fseeko (fp, (off_t)(offset), whence)
+#elif @GNULIB_FSEEKO@
 # if !@HAVE_FSEEKO@
 /* Assume 'off_t' is the same type as 'long'.  */
 #  define fseeko fseek
diff --git a/m4/fflush.m4 b/m4/fflush.m4
index d4ebeccb6c..fca7769be1 100755
--- a/m4/fflush.m4
+++ b/m4/fflush.m4
@@ -1,4 +1,4 @@
-#serial 2
+#serial 3
 
 # Copyright (C) 2007 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -45,6 +45,12 @@ AC_DEFUN([gl_FUNC_FFLUSH],
 AC_DEFUN([gl_REPLACE_FFLUSH],
 [
   AC_LIBOBJ([fflush])
+  AC_LIBOBJ([fseeko])
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   REPLACE_FFLUSH=1
+  gl_CHECK_FSEEKO
+  if test $gl_cv_func_fseeko = yes; then
+    AC_DEFINE([HAVE_FSEEKO], 1,
+      [Define to 1 if you have the fseeko() function or macro.])
+  fi
 ])
diff --git a/m4/fseeko.m4 b/m4/fseeko.m4
index 86d42f40cc..fd3f019f7f 100644
--- a/m4/fseeko.m4
+++ b/m4/fseeko.m4
@@ -7,13 +7,18 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_FSEEKO],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  gl_CHECK_FSEEKO
+  if test $gl_cv_func_fseeko = no; then
+    HAVE_FSEEKO=0
+  fi
+])
+
+AC_DEFUN([gl_CHECK_FSEEKO],
+[
   AC_REQUIRE([AC_PROG_CC])
   AC_CACHE_CHECK([for fseeko], [gl_cv_func_fseeko],
     [
       AC_TRY_LINK([#include <stdio.h>], [fseeko (stdin, 0, 0);],
         [gl_cv_func_fseeko=yes], [gl_cv_func_fseeko=no])
     ])
-  if test $gl_cv_func_fseeko = no; then
-    HAVE_FSEEKO=0
-  fi
 ])
diff --git a/modules/fflush b/modules/fflush
index b23b44a85f..62a2d59700 100755
--- a/modules/fflush
+++ b/modules/fflush
@@ -3,7 +3,9 @@ Discard pending data on both input and output streams.
 
 Files:
 lib/fflush.c
+lib/fseeko.c
 m4/fflush.m4
+m4/fseeko.m4
 
 Depends-on:
 fpurge