Package: emacs;
Reported by: Jim Meyering <jim <at> meyering.net>
Date: Thu, 22 Sep 2011 14:40:02 UTC
Severity: minor
Tags: patch
Done: Paul Eggert <eggert <at> cs.ucla.edu>
Bug is archived. No further changes may be made.
Message #37 received at 9574 <at> debbugs.gnu.org (full text, mbox):
From: Paul Eggert <eggert <at> cs.ucla.edu> To: Chong Yidong <cyd <at> gnu.org> Cc: Glenn Morris <rgm <at> gnu.org>, 9574 <at> debbugs.gnu.org, Jim Meyering <jim <at> meyering.net> Subject: Re: bug#9574: data-loss with --batch: ignored write failure Date: Thu, 01 Nov 2012 13:09:03 -0700
On 10/29/2012 02:27 AM, Chong Yidong wrote:
> Has this bug been fixed since the above was written 6 months ago?
Sorry, no. Here's a patch, relative to trunk bzr 110763.
I won't install it right now, since we're so close
to creating a branch.
=== modified file 'ChangeLog'
--- ChangeLog 2012-10-26 18:35:36 +0000
+++ ChangeLog 2012-11-01 20:07:42 +0000
@@ -1,3 +1,11 @@
+2012-11-01 Paul Eggert <eggert <at> cs.ucla.edu>
+
+ Fix data-loss with --batch (Bug#9574).
+ * lib/close-stream.c, lib/close-stream.h, lib/fpending.c
+ * lib/fpending.h, m4/close-stream.m4, m4/fpending.m4:
+ New files, from gnulib.
+ * lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
+
2012-10-26 Glenn Morris <rgm <at> gnu.org>
* Makefile.in (EMACS_NAME): New variable.
=== modified file 'admin/ChangeLog'
--- admin/ChangeLog 2012-10-19 19:25:18 +0000
+++ admin/ChangeLog 2012-11-01 20:07:42 +0000
@@ -1,3 +1,8 @@
+2012-11-01 Paul Eggert <eggert <at> cs.ucla.edu>
+
+ Fix data-loss with --batch (Bug#9574).
+ * merge-gnulib (GNULIB_MODULES): Add close-stream.
+
2012-10-12 Kenichi Handa <handa <at> gnu.org>
* charsets/Makefile (JISC6226.map): Add missing mappings.
=== modified file 'admin/merge-gnulib'
--- admin/merge-gnulib 2012-10-19 19:25:18 +0000
+++ admin/merge-gnulib 2012-11-01 20:07:42 +0000
@@ -27,7 +27,7 @@
GNULIB_MODULES='
alloca-opt c-ctype c-strcase
- careadlinkat crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512
+ careadlinkat close-stream crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512
dtoastr dtotimespec dup2 environ execinfo
filemode getloadavg getopt-gnu gettime gettimeofday
ignore-value intprops largefile lstat
=== added file 'lib/close-stream.c'
--- lib/close-stream.c 1970-01-01 00:00:00 +0000
+++ lib/close-stream.c 2012-11-01 20:07:42 +0000
@@ -0,0 +1,78 @@
+/* Close a stream, with nicer error checking than fclose's.
+
+ Copyright (C) 1998-2002, 2004, 2006-2012 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
+ 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 <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+#include "close-stream.h"
+
+#include <errno.h>
+#include <stdbool.h>
+
+#include "fpending.h"
+
+#if USE_UNLOCKED_IO
+# include "unlocked-io.h"
+#endif
+
+/* Close STREAM. Return 0 if successful, EOF (setting errno)
+ otherwise. A failure might set errno to 0 if the error number
+ cannot be determined.
+
+ A failure with errno set to EPIPE may or may not indicate an error
+ situation worth signaling to the user. See the documentation of the
+ close_stdout_set_ignore_EPIPE function for details.
+
+ If a program writes *anything* to STREAM, that program should close
+ STREAM and make sure that it succeeds before exiting. Otherwise,
+ suppose that you go to the extreme of checking the return status
+ of every function that does an explicit write to STREAM. The last
+ printf can succeed in writing to the internal stream buffer, and yet
+ the fclose(STREAM) could still fail (due e.g., to a disk full error)
+ when it tries to write out that buffered data. Thus, you would be
+ left with an incomplete output file and the offending program would
+ exit successfully. Even calling fflush is not always sufficient,
+ since some file systems (NFS and CODA) buffer written/flushed data
+ until an actual close call.
+
+ Besides, it's wasteful to check the return value from every call
+ that writes to STREAM -- just let the internal stream state record
+ the failure. That's what the ferror test is checking below. */
+
+int
+close_stream (FILE *stream)
+{
+ const bool some_pending = (__fpending (stream) != 0);
+ const bool prev_fail = (ferror (stream) != 0);
+ const bool fclose_fail = (fclose (stream) != 0);
+
+ /* Return an error indication if there was a previous failure or if
+ fclose failed, with one exception: ignore an fclose failure if
+ there was no previous error, no data remains to be flushed, and
+ fclose failed with EBADF. That can happen when a program like cp
+ is invoked like this 'cp a b >&-' (i.e., with standard output
+ closed) and doesn't generate any output (hence no previous error
+ and nothing to be flushed). */
+
+ if (prev_fail || (fclose_fail && (some_pending || errno != EBADF)))
+ {
+ if (! fclose_fail)
+ errno = 0;
+ return EOF;
+ }
+
+ return 0;
+}
=== added file 'lib/close-stream.h'
--- lib/close-stream.h 1970-01-01 00:00:00 +0000
+++ lib/close-stream.h 2012-11-01 20:07:42 +0000
@@ -0,0 +1,2 @@
+#include <stdio.h>
+int close_stream (FILE *stream);
=== added file 'lib/fpending.c'
--- lib/fpending.c 1970-01-01 00:00:00 +0000
+++ lib/fpending.c 2012-11-01 20:07:42 +0000
@@ -0,0 +1,30 @@
+/* fpending.c -- return the number of pending output bytes on a stream
+ Copyright (C) 2000, 2004, 2006-2007, 2009-2012 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
+ 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 <http://www.gnu.org/licenses/>. */
+
+/* Written by Jim Meyering. */
+
+#include <config.h>
+
+#include "fpending.h"
+
+/* Return the number of pending (aka buffered, unflushed)
+ bytes on the stream, FP, that is open for writing. */
+size_t
+__fpending (FILE *fp)
+{
+ return PENDING_OUTPUT_N_BYTES;
+}
=== added file 'lib/fpending.h'
--- lib/fpending.h 1970-01-01 00:00:00 +0000
+++ lib/fpending.h 2012-11-01 20:07:42 +0000
@@ -0,0 +1,30 @@
+/* Declare __fpending.
+
+ Copyright (C) 2000, 2003, 2005-2006, 2009-2012 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
+ 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 <http://www.gnu.org/licenses/>.
+
+ Written by Jim Meyering. */
+
+#include <stddef.h>
+#include <stdio.h>
+
+#if HAVE_DECL___FPENDING
+# if HAVE_STDIO_EXT_H
+# include <stdio_ext.h>
+# endif
+#else
+size_t __fpending (FILE *);
+#endif
=== modified file 'lib/gnulib.mk'
--- lib/gnulib.mk 2012-10-19 19:25:18 +0000
+++ lib/gnulib.mk 2012-11-01 20:07:42 +0000
@@ -21,7 +21,7 @@
# the same distribution terms as the rest of that program.
#
# Generated by gnulib-tool.
-# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=errno --avoid=fcntl --avoid=fcntl-h --avoid=fstat --avoid=msvc-inval --avoid=msvc-nothrow --avoid=raise --avoid=select --avoid=sigprocmask --avoid=sys_types --avoid=threadlib --makefile-name=gnulib.mk --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt c-ctype c-strcase careadlinkat crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr dtotimespec dup2 environ execinfo filemode getloadavg getopt-gnu gettime gettimeofday ignore-value intprops largefile lstat manywarnings mktime pselect pthread_sigmask readlink socklen stat-time stdalign stdarg stdbool stdio strftime strtoimax strtoumax symlink sys_stat sys_time time timer-time timespec-add timespec-sub utimens warnings
+# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=errno --avoid=fcntl --avoid=fcntl-h --avoid=fstat --avoid=msvc-inval --avoid=msvc-nothrow --avoid=raise --avoid=select --avoid=sigprocmask --avoid=sys_types --avoid=threadlib --makefile-name=gnulib.mk --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt c-ctype c-strcase careadlinkat close-stream crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr dtotimespec dup2 environ execinfo filemode getloadavg getopt-gnu gettime gettimeofday ignore-value intprops largefile lstat manywarnings mktime pselect pthread_sigmask readlink socklen stat-time stdalign stdarg stdbool stdio strftime strtoimax strtoumax symlink sys_stat sys_time time timer-time timespec-add timespec-sub utimens warnings
MOSTLYCLEANFILES += core *.stackdump
@@ -84,6 +84,14 @@
## end gnulib module careadlinkat
+## begin gnulib module close-stream
+
+libgnu_a_SOURCES += close-stream.c
+
+EXTRA_DIST += close-stream.h
+
+## end gnulib module close-stream
+
## begin gnulib module crypto/md5
libgnu_a_SOURCES += md5.c
@@ -183,6 +191,15 @@
## end gnulib module filemode
+## begin gnulib module fpending
+
+
+EXTRA_DIST += fpending.c fpending.h
+
+EXTRA_libgnu_a_SOURCES += fpending.c
+
+## end gnulib module fpending
+
## begin gnulib module getloadavg
=== added file 'm4/close-stream.m4'
--- m4/close-stream.m4 1970-01-01 00:00:00 +0000
+++ m4/close-stream.m4 2012-11-01 20:07:42 +0000
@@ -0,0 +1,11 @@
+#serial 4
+dnl Copyright (C) 2006-2007, 2009-2012 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Prerequisites of lib/close-stream.c.
+AC_DEFUN([gl_CLOSE_STREAM],
+[
+ :
+])
=== added file 'm4/fpending.m4'
--- m4/fpending.m4 1970-01-01 00:00:00 +0000
+++ m4/fpending.m4 2012-11-01 20:07:42 +0000
@@ -0,0 +1,90 @@
+# serial 19
+
+# Copyright (C) 2000-2001, 2004-2012 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+dnl From Jim Meyering
+dnl Using code from emacs, based on suggestions from Paul Eggert
+dnl and Ulrich Drepper.
+
+dnl Find out how to determine the number of pending output bytes on a stream.
+dnl glibc (2.1.93 and newer) and Solaris provide __fpending. On other systems,
+dnl we have to grub around in the FILE struct.
+
+AC_DEFUN([gl_FUNC_FPENDING],
+[
+ AC_CHECK_HEADERS_ONCE([stdio_ext.h])
+ AC_CHECK_FUNCS_ONCE([__fpending])
+ fp_headers='
+# include <stdio.h>
+# if HAVE_STDIO_EXT_H
+# include <stdio_ext.h>
+# endif
+'
+ AC_CHECK_DECLS([__fpending], , , $fp_headers)
+])
+
+AC_DEFUN([gl_PREREQ_FPENDING],
+[
+ AC_CACHE_CHECK(
+ [how to determine the number of pending output bytes on a stream],
+ ac_cv_sys_pending_output_n_bytes,
+ [
+ for ac_expr in \
+ \
+ '# glibc2' \
+ 'fp->_IO_write_ptr - fp->_IO_write_base' \
+ \
+ '# traditional Unix' \
+ 'fp->_ptr - fp->_base' \
+ \
+ '# BSD' \
+ 'fp->_p - fp->_bf._base' \
+ \
+ '# SCO, Unixware' \
+ '(fp->__ptr ? fp->__ptr - fp->__base : 0)' \
+ \
+ '# QNX' \
+ '(fp->_Mode & 0x2000 /*_MWRITE*/ ? fp->_Next - fp->_Buf : 0)' \
+ \
+ '# old glibc?' \
+ 'fp->__bufp - fp->__buffer' \
+ \
+ '# old glibc iostream?' \
+ 'fp->_pptr - fp->_pbase' \
+ \
+ '# emx+gcc' \
+ 'fp->_ptr - fp->_buffer' \
+ \
+ '# Minix' \
+ 'fp->_ptr - fp->_buf' \
+ \
+ '# Plan9' \
+ 'fp->wp - fp->buf' \
+ \
+ '# VMS' \
+ '(*fp)->_ptr - (*fp)->_base' \
+ \
+ '# e.g., DGUX R4.11; the info is not available' \
+ 1 \
+ ; do
+
+ # Skip each embedded comment.
+ case "$ac_expr" in '#'*) continue;; esac
+
+ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]],
+ [[FILE *fp = stdin; (void) ($ac_expr);]])],
+ [fp_done=yes]
+ )
+ test "$fp_done" = yes && break
+ done
+
+ ac_cv_sys_pending_output_n_bytes=$ac_expr
+ ]
+ )
+ AC_DEFINE_UNQUOTED([PENDING_OUTPUT_N_BYTES],
+ $ac_cv_sys_pending_output_n_bytes,
+ [the number of pending output bytes on stream 'fp'])
+])
=== modified file 'm4/gnulib-comp.m4'
--- m4/gnulib-comp.m4 2012-10-19 19:25:18 +0000
+++ m4/gnulib-comp.m4 2012-11-01 20:07:42 +0000
@@ -44,6 +44,7 @@
# Code from module c-strcase:
# Code from module careadlinkat:
# Code from module clock-time:
+ # Code from module close-stream:
# Code from module crypto/md5:
# Code from module crypto/sha1:
# Code from module crypto/sha256:
@@ -58,6 +59,7 @@
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
# Code from module extern-inline:
# Code from module filemode:
+ # Code from module fpending:
# Code from module getloadavg:
# Code from module getopt-gnu:
# Code from module getopt-posix:
@@ -141,6 +143,8 @@
gl_FUNC_ALLOCA
AC_CHECK_FUNCS_ONCE([readlinkat])
gl_CLOCK_TIME
+ gl_CLOSE_STREAM
+ gl_MODULE_INDICATOR([close-stream])
gl_MD5
gl_SHA1
gl_SHA256
@@ -157,6 +161,11 @@
gl_EXECINFO_H
AC_REQUIRE([gl_EXTERN_INLINE])
gl_FILEMODE
+ gl_FUNC_FPENDING
+ if test $ac_cv_func___fpending = no; then
+ AC_LIBOBJ([fpending])
+ gl_PREREQ_FPENDING
+ fi
gl_GETLOADAVG
if test $HAVE_GETLOADAVG = 0; then
AC_LIBOBJ([getloadavg])
@@ -534,6 +543,8 @@
lib/c-strncasecmp.c
lib/careadlinkat.c
lib/careadlinkat.h
+ lib/close-stream.c
+ lib/close-stream.h
lib/dosname.h
lib/dtoastr.c
lib/dtotimespec.c
@@ -542,6 +553,8 @@
lib/execinfo.in.h
lib/filemode.c
lib/filemode.h
+ lib/fpending.c
+ lib/fpending.h
lib/ftoastr.c
lib/ftoastr.h
lib/getloadavg.c
@@ -609,12 +622,14 @@
m4/alloca.m4
m4/c-strtod.m4
m4/clock_time.m4
+ m4/close-stream.m4
m4/dup2.m4
m4/environ.m4
m4/execinfo.m4
m4/extensions.m4
m4/extern-inline.m4
m4/filemode.m4
+ m4/fpending.m4
m4/getloadavg.m4
m4/getopt.m4
m4/gettime.m4
=== modified file 'src/ChangeLog'
--- src/ChangeLog 2012-11-01 14:21:45 +0000
+++ src/ChangeLog 2012-11-01 20:07:42 +0000
@@ -1,3 +1,13 @@
+2012-11-01 Paul Eggert <eggert <at> cs.ucla.edu>
+
+ Fix data-loss with --batch (Bug#9574).
+ * emacs.c: Include <close-stream.h>.
+ (close_output_streams): New function.
+ (main): Pass it to atexit, so that Emacs closes stdout and stderr
+ and handles errors appropriately.
+ (Fkill_emacs): Don't worry about flushing, as close_output_stream
+ does that now.
+
2012-11-01 Eli Zaretskii <eliz <at> gnu.org>
* w32proc.c (getpgrp, setpgid): New functions. (Bug#12776)
=== modified file 'src/emacs.c'
--- src/emacs.c 2012-10-31 17:27:29 +0000
+++ src/emacs.c 2012-11-01 20:07:42 +0000
@@ -27,6 +27,7 @@
#include <sys/file.h>
#include <unistd.h>
+#include <close-stream.h>
#include <ignore-value.h>
#include "lisp.h"
@@ -675,6 +676,22 @@
#endif /* DOUG_LEA_MALLOC */
+/* Close standard output and standard error, reporting any write
+ errors as best we can. This is intended for use with atexit. */
+static void
+close_output_streams (void)
+{
+ if (close_stream (stdout) != 0)
+ {
+ fprintf (stderr, "Write error to standard output: %s\n",
+ emacs_strerror (errno));
+ fflush (stderr);
+ _exit (EXIT_FAILURE);
+ }
+
+ if (close_stream (stderr) != 0)
+ _exit (EXIT_FAILURE);
+}
/* ARGSUSED */
int
@@ -890,6 +907,8 @@
if (do_initial_setlocale)
setlocale (LC_ALL, "");
+ atexit (close_output_streams);
+
inhibit_window_system = 0;
/* Handle the -t switch, which specifies filename to use as terminal. */
@@ -1867,8 +1886,6 @@
exit_code = (XINT (arg) < 0
? XINT (arg) | INT_MIN
: XINT (arg) & INT_MAX);
- else if (noninteractive && (fflush (stdout) || ferror (stdout)))
- exit_code = EXIT_FAILURE;
else
exit_code = EXIT_SUCCESS;
exit (exit_code);
GNU bug tracking system
Copyright (C) 1999 Darren O. Benham,
1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.