svn commit: trunk/busybox/libbb
landley at busybox.net
landley at busybox.net
Thu Mar 23 15:30:28 UTC 2006
Author: landley
Date: 2006-03-23 07:30:26 -0800 (Thu, 23 Mar 2006)
New Revision: 14627
Log:
Very nice patch from Rich Felker to portably set the stream error indicator and
thus remove a lot of nasty old code that didn't.
Modified:
trunk/busybox/libbb/printf.c
Changeset:
Modified: trunk/busybox/libbb/printf.c
===================================================================
--- trunk/busybox/libbb/printf.c 2006-03-23 11:40:05 UTC (rev 14626)
+++ trunk/busybox/libbb/printf.c 2006-03-23 15:30:26 UTC (rev 14627)
@@ -4,20 +4,7 @@
*
* Copyright (C) 2003 Manuel Novoa III <mjn3 at 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 @@
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;
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