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