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559644ddd2
When saving config files we just overwrite old content of the file. In case something fails during that process (e.g. disk gets full) we lose both old and new content. This patch makes the process more robust by writing the new content into a separate file and only if that succeeds the original file is atomically replaced with the new one.
78 lines
2.6 KiB
C
78 lines
2.6 KiB
C
/*
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* virfile.h: safer file handling
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*
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* Copyright (C) 2010-2011 Red Hat, Inc.
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* Copyright (C) 2010 IBM Corporation
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* Copyright (C) 2010 Stefan Berger
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* Copyright (C) 2010 Eric Blake
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#ifndef __VIR_FILES_H_
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# define __VIR_FILES_H_
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# include <stdio.h>
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# include "internal.h"
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# include "ignore-value.h"
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/* Don't call these directly - use the macros below */
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int virFileClose(int *fdptr, bool preserve_errno) ATTRIBUTE_RETURN_CHECK;
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int virFileFclose(FILE **file, bool preserve_errno) ATTRIBUTE_RETURN_CHECK;
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FILE *virFileFdopen(int *fdptr, const char *mode) ATTRIBUTE_RETURN_CHECK;
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/* For use on normal paths; caller must check return value,
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and failure sets errno per close. */
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# define VIR_CLOSE(FD) virFileClose(&(FD), false)
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# define VIR_FCLOSE(FILE) virFileFclose(&(FILE), false)
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/* Wrapper around fdopen that consumes fd on success. */
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# define VIR_FDOPEN(FD, MODE) virFileFdopen(&(FD), MODE)
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/* For use on cleanup paths; errno is unaffected by close,
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and no return value to worry about. */
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# define VIR_FORCE_CLOSE(FD) ignore_value(virFileClose(&(FD), true))
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# define VIR_FORCE_FCLOSE(FILE) ignore_value(virFileFclose(&(FILE), true))
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/* Opaque type for managing a wrapper around an O_DIRECT fd. */
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struct _virFileDirectFd;
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typedef struct _virFileDirectFd virFileDirectFd;
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typedef virFileDirectFd *virFileDirectFdPtr;
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int virFileDirectFdFlag(void);
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virFileDirectFdPtr virFileDirectFdNew(int *fd, const char *name)
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ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
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int virFileDirectFdClose(virFileDirectFdPtr dfd);
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void virFileDirectFdFree(virFileDirectFdPtr dfd);
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int virFileLock(int fd, bool shared, off_t start, off_t len);
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int virFileUnlock(int fd, off_t start, off_t len);
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typedef int (*virFileRewriteFunc)(int fd, void *opaque);
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int virFileRewrite(const char *path,
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mode_t mode,
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virFileRewriteFunc rewrite,
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void *opaque);
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#endif /* __VIR_FILES_H */
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