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Very nice patch from Rich Felker to portably set the stream error indicator and

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thus remove a lot of nasty old code that didn't.
This commit is contained in:
Rob Landley 2006-03-23 15:30:26 +00:00
parent dce5809ebc
commit fb3a631310
1 changed files with 27 additions and 104 deletions
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131
libbb/printf.c
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@ -4,20 +4,7 @@
*
* Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
*
* 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 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* Mar 12, 2003 Manuel Novoa III
@ -33,102 +20,23 @@
* failure. That would allow us to defer error checking until applet
* exit. Unfortunately, there is no standard way of setting a streams
* error indicator... even though we can clear it with clearerr().
*/
/* Mar 22, 2006 Rich Felker III
*
* Therefore, we have to resort to implementation dependent code. Feel
* free to send patches for stdio implementations where the following
* fails.
*
* NOTE: None of this is thread safe. As busybox is a non-threaded app,
* that isn't currently an issue.
* Actually there is a portable way to set the error indicator. See below.
* It is not thread-safe as written due to a race condition with file
* descriptors but since BB is not threaded that does not matter. It can be
* made thread-safe at the expense of slightly more code, if this is ever
* needed in the future.
*/
#include <stdio.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include "libbb.h"
#if defined(__UCLIBC__)
# if defined(__FLAG_ERROR)
/* Using my newer stdio implementation. Unlocked macros are:
* #define __CLEARERR(stream) \
((stream)->modeflags &= ~(__FLAG_EOF|__FLAG_ERROR), (void)0)
* #define __FEOF(stream) ((stream)->modeflags & __FLAG_EOF)
* #define __FERROR(stream) ((stream)->modeflags & __FLAG_ERROR)
*/
# if defined(__MASK_READING)
# define SET_FERROR_UNLOCKED(S) ((S)->__modeflags |= __FLAG_ERROR)
# else
# define SET_FERROR_UNLOCKED(S) ((S)->modeflags |= __FLAG_ERROR)
# endif
# elif defined(__MODE_ERR)
/* Using either the original stdio implementation (from dev86) or
* my original stdio rewrite. Macros were:
* #define ferror(fp) (((fp)->mode&__MODE_ERR) != 0)
* #define feof(fp) (((fp)->mode&__MODE_EOF) != 0)
* #define clearerr(fp) ((fp)->mode &= ~(__MODE_EOF|__MODE_ERR),0)
*/
#define SET_FERROR_UNLOCKED(S) ((S)->mode |= __MODE_ERR)
# else
# error unknown uClibc stdio implemenation!
# endif
#elif defined(__NEWLIB_H__)
/* I honestly don't know if there are different versions of stdio in
* newlibs history. Anyway, here's what's current.
* #define __sfeof(p) (((p)->_flags & __SEOF) != 0)
* #define __sferror(p) (((p)->_flags & __SERR) != 0)
* #define __sclearerr(p) ((void)((p)->_flags &= ~(__SERR|__SEOF)))
*/
# define SET_FERROR_UNLOCKED(S) ((S)->_flags |= __SERR)
#elif defined(__GLIBC__)
# if defined(_STDIO_USES_IOSTREAM)
/* Apparently using the newer libio implementation, with associated defines:
* #define _IO_feof_unlocked(__fp) (((__fp)->_flags & _IO_EOF_SEEN) != 0)
* #define _IO_ferror_unlocked(__fp) (((__fp)->_flags & _IO_ERR_SEEN) != 0)
*/
# define SET_FERROR_UNLOCKED(S) ((S)->_flags |= _IO_ERR_SEEN)
# else
/* Assume the older version of glibc which used a bitfield entry
* as a stream error flag. The associated defines were:
* #define __clearerr(stream) ((stream)->__error = (stream)->__eof = 0)
* #define feof_unlocked(stream) ((stream)->__eof != 0)
* #define ferror_unlocked(stream) ((stream)->__error != 0)
*/
# define SET_FERROR_UNLOCKED(S) ((S)->__error = 1)
# endif
#elif defined(__dietlibc__)
/*
* WARNING!!! dietlibc is quite buggy. WARNING!!!
*
* Some example bugs as of March 12, 2003...
* 1) fputc() doesn't set the error indicator on failure.
* 2) freopen() doesn't maintain the same stream object, contrary to
* standards. This makes it useless in its primary role of
* reassociating stdin/stdout/stderr.
* 3) printf() often fails to correctly format output when conversions
* involve padding. It is also practically useless for floating
* point output.
*
* But, if you're determined to use it anyway, (as of the current version)
* you can extract the information you need from dietstdio.h. See the
* other library implementations for examples.
*/
# error dietlibc is currently not supported. Please see the commented source.
#else /* some other lib */
/* Please see the comments for the above supported libraries for examples
* of what is required to support your stdio implementation.
*/
# error Your stdio library is currently not supported. Please see the commented source.
#endif
#ifdef L_bb_vfprintf
extern int bb_vfprintf(FILE * __restrict stream,
const char * __restrict format,
@ -137,7 +45,22 @@ extern int bb_vfprintf(FILE * __restrict stream,
int rv;
if ((rv = vfprintf(stream, format, arg)) < 0) {
SET_FERROR_UNLOCKED(stream);
/* The following sequence portably sets the error flag for
* stream on any remotely POSIX-compliant implementation. */
int errno_save = errno;
int fd = fileno(stream);
int tmp = dup(fd);
fflush(stream);
close(fd);
/* Force an attempted write to nonexistant fd => EBADF */
fputc(0, stream);
fflush(stream);
/* Restore the stream's original fd */
dup2(tmp, fd);
close(tmp);
errno = errno_save;
}
return rv;