fflush.c

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/home/opencoverage/opencoverage/guest-scripts/coreutils/src/gnulib/lib/fflush.c

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/* fflush.c -- allow flushing input streams

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 <https://www.gnu.org/licenses/>. */

/* Written by Eric Blake. */

#include <config.h>

/* Specification. */

#include <stdio.h>

#include <errno.h>

#include <unistd.h>

#include "freading.h"

#include "stdio-impl.h"

#include "unused-parameter.h"

#undef fflush

#if defined _IO_EOF_SEEN || __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)

fp->_flags & 0x100	Description
TRUE	never evaluated
FALSE	evaluated 8314 times by 39 tests Evaluated by: b2sum base32 base64 cksum comm cp cut date df dircolors du expand fmt fold ginstall join ln md5sum mv nl od paste pr ptx rm ...

0-8314

/* _IO_free_backup_area is a bit complicated. Simply call fseek. */

fseeko (fp, 0, SEEK_CUR);

never executed: rpl_fseeko (fp, 0, 1 );

}

executed 8314 times by 39 tests: end of block

Executed by:

b2sum
base32
base64
cksum
comm
cp
cut
date
df
dircolors
du
expand
fmt
fold
ginstall
join
ln
md5sum
mv
nl
od
paste
pr
ptx
rm
...

8314

#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__ || defined __ANDROID__

/* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */

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, MSVC, NonStop Kernel, OpenVMS */

/* Nothing to do. */

# else /* other implementations */

fseeko (fp, 0, SEEK_CUR);

# endif

}

#endif

#if ! (defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */)

# if (defined __sferror || defined __DragonFly__ || defined __ANDROID__) && defined __SNPT

/* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */

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)

{

100

# if defined __sferror || defined __DragonFly__ || defined __ANDROID__

101

/* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */

102

# if defined __CYGWIN__

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/* fp_->_offset is typed as an integer. */

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fp_->_offset = pos;

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# else

106

/* fp_->_offset is an fpos_t. */

107

/* Use a union, since on NetBSD, the compilation flags determine

108

whether fpos_t is typedef'd to off_t or a struct containing a

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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

125

output and seekable input streams are supported. */

126

int

127

rpl_fflush (FILE *stream)

128

{

129

/* When stream is NULL, POSIX and C99 only require flushing of "output

130

streams and update streams in which the most recent operation was not

131

input", and all implementations do this.

132

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When stream is "an output stream or an update stream in which the most

134

recent operation was not input", POSIX and C99 requires that fflush

135

writes out any buffered data, and all implementations do this.

136

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When stream is, however, an input stream or an update stream in

138

which the most recent operation was input, C99 specifies nothing,

139

and POSIX only specifies behavior if the stream is seekable.

140

mingw, in particular, drops the input buffer, leaving the file

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descriptor positioned at the end of the input buffer. I.e. ftell

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(stream) is lost. We don't want to call the implementation's

143

fflush in this case.

144

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We test ! freading (stream) here, rather than fwriting (stream), because

146

what we need to know is whether the stream holds a "read buffer", and on

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mingw this is indicated by _IOREAD, regardless of _IOWRT. */

148

if (stream == NULL || ! freading (stream))

stream == ((void *)0)	Description
TRUE	never evaluated
FALSE	evaluated 86978 times by 106 tests Evaluated by: [ b2sum base32 base64 basename cat chcon chgrp chmod chown chroot cksum comm cp csplit cut date dd df dir dircolors dirname du echo env ...

! (__freading (stream) != 0)	Description
TRUE	evaluated 78664 times by 106 tests Evaluated by: [ b2sum base32 base64 basename cat chcon chgrp chmod chown chroot cksum comm cp csplit cut date dd df dir dircolors dirname du echo env ...
FALSE	evaluated 8314 times by 39 tests Evaluated by: b2sum base32 base64 cksum comm cp cut date df dircolors du expand fmt fold ginstall join ln md5sum mv nl od paste pr ptx rm ...

0-86978

149

return fflush (stream);

executed 78664 times by 106 tests: return fflush (stream);

Executed by:

[
b2sum
base32
base64
basename
cat
chcon
chgrp
chmod
chown
chroot
cksum
comm
cp
csplit
cut
date
dd
df
dir
dircolors
dirname
du
echo
env
...

78664

150

151

#if defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */

152

153

clear_ungetc_buffer_preserving_position (stream);

154

155

return fflush (stream);

executed 8314 times by 39 tests: return fflush (stream);

Executed by:

b2sum
base32
base64
cksum
comm
cp
cut
date
df
dircolors
du
expand
fmt
fold
ginstall
join
ln
md5sum
mv
nl
od
paste
pr
ptx
rm
...

8314

#else

{

/* Notes about the file-position indicator:

160

1) The file position indicator is incremented by fgetc() and decremented

161

by ungetc():

162

<http://www.opengroup.org/susv3/functions/fgetc.html>

163

"... the fgetc() function shall ... advance the associated file

164

position indicator for the stream ..."

165

<http://www.opengroup.org/susv3/functions/ungetc.html>

166

"The file-position indicator is decremented by each successful

167

call to ungetc()..."

168

2) <http://www.opengroup.org/susv3/functions/ungetc.html> says:

169

"The value of the file-position indicator for the stream after

170

reading or discarding all pushed-back bytes shall be the same

171

as it was before the bytes were pushed back."

172

Here we are discarding all pushed-back bytes. But more specifically,

173

3) <http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt> says:

174

"[After fflush(),] the file offset of the underlying open file

175

description shall be set to the file position of the stream, and

176

any characters pushed back onto the stream by ungetc() ... shall

177

be discarded." */

178

179

/* POSIX does not specify fflush behavior for non-seekable input

180

streams. Some implementations purge unread data, some return

181

EBADF, some do nothing. */

182

off_t pos = ftello (stream);

if (pos == -1)

{

errno = EBADF;

return EOF;

}

/* Clear the ungetc buffer. */

190

clear_ungetc_buffer (stream);

191

192

/* To get here, we must be flushing a seekable input stream, so the

193

semantics of fpurge are now appropriate to clear the buffer. To

194

avoid losing data, the lseek is also necessary. */

195

{

196

int result = fpurge (stream);

if (result != 0)

return result;

}

# if (defined __sferror || defined __DragonFly__ || defined __ANDROID__) && defined __SNPT

202

/* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */

203

204

{

205

/* Disable seek optimization for the next fseeko call. This tells the

206

following fseeko call to seek to the desired position directly, rather

207

than to seek to a block-aligned boundary. */

208

int saved_flags = disable_seek_optimization (stream);

209

int result = fseeko (stream, pos, SEEK_SET);

210

211

restore_seek_optimization (stream, saved_flags);

return result;

}

# else

pos = lseek (fileno (stream), pos, SEEK_SET);

218

if (pos == -1)

219

return EOF;

220

/* After a successful lseek, update the file descriptor's position cache

221

in the stream. */

222

update_fpos_cache (stream, pos);

return 0;

# endif

}

#endif

}

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