fb3a63131
Rob Landley
2006-03-23
Subject
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.
SOURCE BUG
This commit was genuinely broken at the time (not related to our build system): scripts/config/mkconfigs.c (2005-08-01 - 2006-10-05 arasi) uretilen bbconfigopts.h icine .config satirlarini kacissiz, ham newline'larla gömüyordu - gecerli C degildi, busybox'un kendi bb_mkdep araci bile parse edemiyordu (7d219aab7 ile duzeltildi, mkconfigs shell scripte cevrildi)
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Commit Diff GitHub →
libbb/printf.c+27 -104
| @@ -4,20 +4,7 @@ | |
| * | |
| * Copyright (C) 2003 Manuel Novoa III <[email protected]> | |
| * | |
| - | * 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; | |