/* fflush.c -- allow flushing input streams
- Copyright (C) 2007-2008 Free Software Foundation, Inc.
+ Copyright (C) 2007-2014 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
#include <unistd.h>
#include "freading.h"
-#include "fpurge.h"
#include "stdio-impl.h"
+#include "unused-parameter.h"
+
#undef fflush
-static inline void
+
+#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 /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
+# if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
if (HASUB (fp))
{
- fp->_p += stream->_r;
- fp->_r = 0;
+ fp_->_p += fp_->_r;
+ fp_->_r = 0;
}
-#endif
+# 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
}
-#if defined __sferror && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
+#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 inline int
+static int
disable_seek_optimization (FILE *fp)
{
- int saved_flags = fp->_flags & (__SOPT | __SNPT);
- fp->_flags = (fp->_flags & ~__SOPT) | __SNPT;
+ int saved_flags = fp_->_flags & (__SOPT | __SNPT);
+ fp_->_flags = (fp_->_flags & ~__SOPT) | __SNPT;
return saved_flags;
}
-static inline void
+static void
restore_seek_optimization (FILE *fp, int saved_flags)
{
- fp->_flags = (fp->_flags & ~(__SOPT | __SNPT)) | saved_flags;
+ fp_->_flags = (fp_->_flags & ~(__SOPT | __SNPT)) | saved_flags;
}
-#endif
+# else
-static inline void
-update_fpos_cache (FILE *fp)
+static void
+update_fpos_cache (FILE *fp _GL_UNUSED_PARAMETER,
+ off_t pos _GL_UNUSED_PARAMETER)
{
-#if defined __sferror /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
- fp->_offset = pos;
- fp->_flags |= __SOFF;
-#endif
+# 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.
if (stream == NULL || ! freading (stream))
return fflush (stream);
- /* Clear the ungetc buffer.
-
- This is needed before fetching the file-position indicator, because
- 1) The file position indicator is incremented by fgetc() and decremented
- by ungetc():
- <http://www.opengroup.org/susv3/functions/fgetc.html>
- "... the fgetc() function shall ... advance the associated file
- position indicator for the stream ..."
- <http://www.opengroup.org/susv3/functions/ungetc.html>
- "The file-position indicator is decremented by each successful
- call to ungetc()..."
- 2) <http://www.opengroup.org/susv3/functions/ungetc.html> 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."
- 3) Here we are discarding all pushed-back bytes.
-
- Unfortunately it is impossible to implement this on platforms with
- _IOERR, because an ungetc() on this platform prepends the pushed-back
- bytes to the buffer without an indication of the limit between the
- pushed-back bytes and the read-ahead bytes. */
- clear_ungetc_buffer (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 = disable_seek_optimization (stream);
+ /* Notes about the file-position indicator:
+ 1) The file position indicator is incremented by fgetc() and decremented
+ by ungetc():
+ <http://www.opengroup.org/susv3/functions/fgetc.html>
+ "... the fgetc() function shall ... advance the associated file
+ position indicator for the stream ..."
+ <http://www.opengroup.org/susv3/functions/ungetc.html>
+ "The file-position indicator is decremented by each successful
+ call to ungetc()..."
+ 2) <http://www.opengroup.org/susv3/functions/ungetc.html> 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) <http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt> 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 */
- restore_seek_optimization (stream, 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. */
- update_fpos_cache (stream);
+ 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
}
projects / gnulib.git / blobdiff