X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Ffflush.c;h=dc9fbcd4ec69732611b3ac3f6e3d102c465e1ab4;hb=1276a2c5f24c0c932426aca9c899fa524d2443f2;hp=cae5a5c165da7a262baf0422e67b28888ec3f94c;hpb=27de795dd766ae4dd5627b8d5a612807879b735a;p=gnulib.git
diff --git a/lib/fflush.c b/lib/fflush.c
index cae5a5c16..dc9fbcd4e 100644
--- a/lib/fflush.c
+++ b/lib/fflush.c
@@ -1,10 +1,10 @@
/* fflush.c -- allow flushing input streams
- Copyright (C) 2007 Free Software Foundation, Inc.
+ Copyright (C) 2007-2014 Free Software Foundation, Inc.
- This program is free software; you can redistribute it and/or modify
+ 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.
+ 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
@@ -12,8 +12,7 @@
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. */
+ along with this program. If not, see . */
/* Written by Eric Blake. */
@@ -26,18 +25,104 @@
#include
#include "freading.h"
-#include "fpurge.h"
+
+#include "stdio-impl.h"
+
+#include "unused-parameter.h"
#undef fflush
+
+#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+
+/* Clear the stream's ungetc buffer, preserving the value of ftello (fp). */
+static void
+clear_ungetc_buffer_preserving_position (FILE *fp)
+{
+ if (fp->_flags & _IO_IN_BACKUP)
+ /* _IO_free_backup_area is a bit complicated. Simply call fseek. */
+ fseeko (fp, 0, SEEK_CUR);
+}
+
+#else
+
+/* Clear the stream's ungetc buffer. May modify the value of ftello (fp). */
+static void
+clear_ungetc_buffer (FILE *fp)
+{
+# if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
+ if (HASUB (fp))
+ {
+ fp_->_p += fp_->_r;
+ fp_->_r = 0;
+ }
+# elif defined __EMX__ /* emx+gcc */
+ if (fp->_ungetc_count > 0)
+ {
+ fp->_ungetc_count = 0;
+ fp->_rcount = - fp->_rcount;
+ }
+# elif defined _IOERR /* Minix, AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, NonStop Kernel */
+ /* Nothing to do. */
+# else /* other implementations */
+ fseeko (fp, 0, SEEK_CUR);
+# endif
+}
+
+#endif
+
+#if ! (defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */)
+
+# if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
+
+static int
+disable_seek_optimization (FILE *fp)
+{
+ int saved_flags = fp_->_flags & (__SOPT | __SNPT);
+ fp_->_flags = (fp_->_flags & ~__SOPT) | __SNPT;
+ return saved_flags;
+}
+
+static void
+restore_seek_optimization (FILE *fp, int saved_flags)
+{
+ fp_->_flags = (fp_->_flags & ~(__SOPT | __SNPT)) | saved_flags;
+}
+
+# else
+
+static void
+update_fpos_cache (FILE *fp _GL_UNUSED_PARAMETER,
+ off_t pos _GL_UNUSED_PARAMETER)
+{
+# if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
+# if defined __CYGWIN__
+ /* fp_->_offset is typed as an integer. */
+ fp_->_offset = pos;
+# else
+ /* fp_->_offset is an fpos_t. */
+ /* Use a union, since on NetBSD, the compilation flags determine
+ whether fpos_t is typedef'd to off_t or a struct containing a
+ single off_t member. */
+ union
+ {
+ fpos_t f;
+ off_t o;
+ } u;
+ u.o = pos;
+ fp_->_offset = u.f;
+# endif
+ fp_->_flags |= __SOFF;
+# endif
+}
+# endif
+#endif
+
/* Flush all pending data on STREAM according to POSIX rules. Both
output and seekable input streams are supported. */
int
rpl_fflush (FILE *stream)
{
- int result;
- off_t pos;
-
/* When stream is NULL, POSIX and C99 only require flushing of "output
streams and update streams in which the most recent operation was not
input", and all implementations do this.
@@ -60,51 +145,81 @@ rpl_fflush (FILE *stream)
if (stream == NULL || ! freading (stream))
return fflush (stream);
- /* POSIX does not specify fflush behavior for non-seekable input
- streams. Some implementations purge unread data, some return
- EBADF, some do nothing. */
- pos = ftello (stream);
- if (pos == -1)
- {
- errno = EBADF;
- return EOF;
- }
+#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
- /* To get here, we must be flushing a seekable input stream, so the
- semantics of fpurge are now appropriate to clear the buffer. To
- avoid losing data, the lseek is also necessary. */
- result = fpurge (stream);
- if (result != 0)
- return result;
+ clear_ungetc_buffer_preserving_position (stream);
-#if defined __sferror && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
+ return fflush (stream);
+#else
{
- /* Disable seek optimization for the next fseeko call. This tells the
- following fseeko call to seek to the desired position directly, rather
- than to seek to a block-aligned boundary. */
- int saved_flags = stream->_flags & (__SOPT | __SNPT);
- stream->_flags = (stream->_flags & ~__SOPT) | __SNPT;
+ /* Notes about the file-position indicator:
+ 1) The file position indicator is incremented by fgetc() and decremented
+ by ungetc():
+
+ "... the fgetc() function shall ... advance the associated file
+ position indicator for the stream ..."
+
+ "The file-position indicator is decremented by each successful
+ call to ungetc()..."
+ 2) says:
+ "The value of the file-position indicator for the stream after
+ reading or discarding all pushed-back bytes shall be the same
+ as it was before the bytes were pushed back."
+ Here we are discarding all pushed-back bytes. But more specifically,
+ 3) says:
+ "[After fflush(),] the file offset of the underlying open file
+ description shall be set to the file position of the stream, and
+ any characters pushed back onto the stream by ungetc() ... shall
+ be discarded." */
+
+ /* POSIX does not specify fflush behavior for non-seekable input
+ streams. Some implementations purge unread data, some return
+ EBADF, some do nothing. */
+ off_t pos = ftello (stream);
+ if (pos == -1)
+ {
+ errno = EBADF;
+ return EOF;
+ }
+
+ /* Clear the ungetc buffer. */
+ clear_ungetc_buffer (stream);
+
+ /* To get here, we must be flushing a seekable input stream, so the
+ semantics of fpurge are now appropriate to clear the buffer. To
+ avoid losing data, the lseek is also necessary. */
+ {
+ int result = fpurge (stream);
+ if (result != 0)
+ return result;
+ }
- result = fseeko (stream, pos, SEEK_SET);
+# if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
- stream->_flags = (stream->_flags & ~(__SOPT | __SNPT)) | saved_flags;
- }
- return result;
+ {
+ /* Disable seek optimization for the next fseeko call. This tells the
+ following fseeko call to seek to the desired position directly, rather
+ than to seek to a block-aligned boundary. */
+ int saved_flags = disable_seek_optimization (stream);
+ int result = fseeko (stream, pos, SEEK_SET);
+
+ restore_seek_optimization (stream, saved_flags);
+ return result;
+ }
-#else
+# else
- pos = lseek (fileno (stream), pos, SEEK_SET);
- if (pos == -1)
- return EOF;
- /* After a successful lseek, update the file descriptor's position cache
- in the stream. */
-# if defined __sferror /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
- stream->_offset = pos;
- stream->_flags |= __SOFF;
-# endif
+ pos = lseek (fileno (stream), pos, SEEK_SET);
+ if (pos == -1)
+ return EOF;
+ /* After a successful lseek, update the file descriptor's position cache
+ in the stream. */
+ update_fpos_cache (stream, pos);
- return 0;
+ return 0;
+# endif
+ }
#endif
}