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O_DIRECT has stringent requirements. Rather than make lots of changes at each site that wants to use O_DIRECT, it is easier to offload the work through a helper process that mirrors the I/O between a pipe and the actual direct fd, so that the other end of the pipe no longer has to worry about constraints. Plus, if the kernel ever gains better posix_fadvise support, then we only have to touch a single file to let all callers benefit from a more efficient way to avoid file system caching. * src/util/virfile.h (virFileDirectFdFlag, virFileDirectFdNew) (virFileDirectFdClose, virFileDirectFdFree): New prototypes. * src/util/virdirect.c: Implement new wrapper object. * src/libvirt_private.syms (virfile.h): Export new symbols. * cfg.mk (useless_free_options): Add to list. * po/POTFILES.in: Add new translations.
69 lines
2.3 KiB
C
69 lines
2.3 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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#endif /* __VIR_FILES_H */
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