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/*
* 9p utilities
*
* Copyright IBM, Corp. 2017
*
* Authors:
* Greg Kurz <groug@kaod.org>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_9P_UTIL_H
#define QEMU_9P_UTIL_H
#ifdef O_PATH
#define O_PATH_9P_UTIL O_PATH
#else
#define O_PATH_9P_UTIL 0
#endif
static inline void close_preserve_errno(int fd)
{
int serrno = errno;
close(fd);
errno = serrno;
}
static inline int openat_dir(int dirfd, const char *name)
{
return openat(dirfd, name,
O_DIRECTORY | O_RDONLY | O_NOFOLLOW | O_PATH_9P_UTIL);
}
static inline int openat_file(int dirfd, const char *name, int flags,
mode_t mode)
{
int fd, serrno, ret;
again:
fd = openat(dirfd, name, flags | O_NOFOLLOW | O_NOCTTY | O_NONBLOCK,
mode);
if (fd == -1) {
if (errno == EPERM && (flags & O_NOATIME)) {
/*
* The client passed O_NOATIME but we lack permissions to honor it.
* Rather than failing the open, fall back without O_NOATIME. This
* doesn't break the semantics on the client side, as the Linux
* open(2) man page notes that O_NOATIME "may not be effective on
* all filesystems". In particular, NFS and other network
* filesystems ignore it entirely.
*/
flags &= ~O_NOATIME;
goto again;
}
return -1;
}
serrno = errno;
/* O_NONBLOCK was only needed to open the file. Let's drop it. We don't
* do that with O_PATH since fcntl(F_SETFL) isn't supported, and openat()
* ignored it anyway.
*/
if (!(flags & O_PATH_9P_UTIL)) {
ret = fcntl(fd, F_SETFL, flags);
assert(!ret);
}
errno = serrno;
return fd;
}
ssize_t fgetxattrat_nofollow(int dirfd, const char *path, const char *name,
void *value, size_t size);
int fsetxattrat_nofollow(int dirfd, const char *path, const char *name,
void *value, size_t size, int flags);
ssize_t flistxattrat_nofollow(int dirfd, const char *filename,
char *list, size_t size);
ssize_t fremovexattrat_nofollow(int dirfd, const char *filename,
const char *name);
#endif
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