Mercurial > gnulib
view lib/close-stream.c @ 37246:5cfb3a67238d
regex: avoid glibc deadlock during configure
glibc has a known bug where certain corruptions of the heap can
cause malloc to default to printing a debug message that includes
a backtrace, but the act of getting the backtrace uses dlopen
which in turn calls into malloc, causing a recursive lock ending
in deadlock. Thus, when configure is probing for a known glibc
heap corruption bug, the overall configure would hang.
The solution suggested by glibc developers is to force malloc
to quit printing debug messages, which avoids recursive malloc.
* m4/regex.m4 (gl_REGEX): Avoid recursive malloc deadlock when
glibc bug 15078 in turn triggers bug 16159.
Reported by Michal Privoznik.
Signed-off-by: Eric Blake <eblake@redhat.com>
author | Eric Blake <eblake@redhat.com> |
---|---|
date | Tue, 03 Dec 2013 10:34:13 -0700 |
parents | c741bc27922a |
children | 344018b6e5d7 |
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/* Close a stream, with nicer error checking than fclose's. Copyright (C) 1998-2002, 2004, 2006-2013 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; }