meson: convert qapi-specific to meson
[qemu.git] / hw / 9pfs / 9p-util.h
1 /*
2 * 9p utilities
3 *
4 * Copyright IBM, Corp. 2017
5 *
6 * Authors:
7 * Greg Kurz <groug@kaod.org>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 */
12
13 #ifndef QEMU_9P_UTIL_H
14 #define QEMU_9P_UTIL_H
15
16 #ifdef O_PATH
17 #define O_PATH_9P_UTIL O_PATH
18 #else
19 #define O_PATH_9P_UTIL 0
20 #endif
21
22 static inline void close_preserve_errno(int fd)
23 {
24 int serrno = errno;
25 close(fd);
26 errno = serrno;
27 }
28
29 static inline int openat_dir(int dirfd, const char *name)
30 {
31 return openat(dirfd, name,
32 O_DIRECTORY | O_RDONLY | O_NOFOLLOW | O_PATH_9P_UTIL);
33 }
34
35 static inline int openat_file(int dirfd, const char *name, int flags,
36 mode_t mode)
37 {
38 int fd, serrno, ret;
39
40 again:
41 fd = openat(dirfd, name, flags | O_NOFOLLOW | O_NOCTTY | O_NONBLOCK,
42 mode);
43 if (fd == -1) {
44 if (errno == EPERM && (flags & O_NOATIME)) {
45 /*
46 * The client passed O_NOATIME but we lack permissions to honor it.
47 * Rather than failing the open, fall back without O_NOATIME. This
48 * doesn't break the semantics on the client side, as the Linux
49 * open(2) man page notes that O_NOATIME "may not be effective on
50 * all filesystems". In particular, NFS and other network
51 * filesystems ignore it entirely.
52 */
53 flags &= ~O_NOATIME;
54 goto again;
55 }
56 return -1;
57 }
58
59 serrno = errno;
60 /* O_NONBLOCK was only needed to open the file. Let's drop it. We don't
61 * do that with O_PATH since fcntl(F_SETFL) isn't supported, and openat()
62 * ignored it anyway.
63 */
64 if (!(flags & O_PATH_9P_UTIL)) {
65 ret = fcntl(fd, F_SETFL, flags);
66 assert(!ret);
67 }
68 errno = serrno;
69 return fd;
70 }
71
72 ssize_t fgetxattrat_nofollow(int dirfd, const char *path, const char *name,
73 void *value, size_t size);
74 int fsetxattrat_nofollow(int dirfd, const char *path, const char *name,
75 void *value, size_t size, int flags);
76 ssize_t flistxattrat_nofollow(int dirfd, const char *filename,
77 char *list, size_t size);
78 ssize_t fremovexattrat_nofollow(int dirfd, const char *filename,
79 const char *name);
80
81 #endif