Merge tag 'pull-aspeed-20220630' of https://github.com/legoater/qemu into staging
[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 #if !defined(CONFIG_LINUX)
23
24 /*
25 * Generates a Linux device number (a.k.a. dev_t) for given device major
26 * and minor numbers.
27 *
28 * To be more precise: it generates a device number in glibc's format
29 * (MMMM_Mmmm_mmmM_MMmm, 64 bits) actually, which is compatible with
30 * Linux's format (mmmM_MMmm, 32 bits), as described in <bits/sysmacros.h>.
31 */
32 static inline uint64_t makedev_dotl(uint32_t dev_major, uint32_t dev_minor)
33 {
34 uint64_t dev;
35
36 // from glibc sysmacros.h:
37 dev = (((uint64_t) (dev_major & 0x00000fffu)) << 8);
38 dev |= (((uint64_t) (dev_major & 0xfffff000u)) << 32);
39 dev |= (((uint64_t) (dev_minor & 0x000000ffu)) << 0);
40 dev |= (((uint64_t) (dev_minor & 0xffffff00u)) << 12);
41 return dev;
42 }
43
44 #endif
45
46 /*
47 * Converts given device number from host's device number format to Linux
48 * device number format. As both the size of type dev_t and encoding of
49 * dev_t is system dependant, we have to convert them for Linux guests if
50 * host is not running Linux.
51 */
52 static inline uint64_t host_dev_to_dotl_dev(dev_t dev)
53 {
54 #ifdef CONFIG_LINUX
55 return dev;
56 #else
57 return makedev_dotl(major(dev), minor(dev));
58 #endif
59 }
60
61 /* Translates errno from host -> Linux if needed */
62 static inline int errno_to_dotl(int err) {
63 #if defined(CONFIG_LINUX)
64 /* nothing to translate (Linux -> Linux) */
65 #elif defined(CONFIG_DARWIN)
66 /*
67 * translation mandatory for macOS hosts
68 *
69 * FIXME: Only most important errnos translated here yet, this should be
70 * extended to as many errnos being translated as possible in future.
71 */
72 if (err == ENAMETOOLONG) {
73 err = 36; /* ==ENAMETOOLONG on Linux */
74 } else if (err == ENOTEMPTY) {
75 err = 39; /* ==ENOTEMPTY on Linux */
76 } else if (err == ELOOP) {
77 err = 40; /* ==ELOOP on Linux */
78 } else if (err == ENOATTR) {
79 err = 61; /* ==ENODATA on Linux */
80 } else if (err == ENOTSUP) {
81 err = 95; /* ==EOPNOTSUPP on Linux */
82 } else if (err == EOPNOTSUPP) {
83 err = 95; /* ==EOPNOTSUPP on Linux */
84 }
85 #else
86 #error Missing errno translation to Linux for this host system
87 #endif
88 return err;
89 }
90
91 #ifdef CONFIG_DARWIN
92 #define qemu_fgetxattr(...) fgetxattr(__VA_ARGS__, 0, 0)
93 #define qemu_lgetxattr(...) getxattr(__VA_ARGS__, 0, XATTR_NOFOLLOW)
94 #define qemu_llistxattr(...) listxattr(__VA_ARGS__, XATTR_NOFOLLOW)
95 #define qemu_lremovexattr(...) removexattr(__VA_ARGS__, XATTR_NOFOLLOW)
96 static inline int qemu_lsetxattr(const char *path, const char *name,
97 const void *value, size_t size, int flags) {
98 return setxattr(path, name, value, size, 0, flags | XATTR_NOFOLLOW);
99 }
100 #else
101 #define qemu_fgetxattr fgetxattr
102 #define qemu_lgetxattr lgetxattr
103 #define qemu_llistxattr llistxattr
104 #define qemu_lremovexattr lremovexattr
105 #define qemu_lsetxattr lsetxattr
106 #endif
107
108 static inline void close_preserve_errno(int fd)
109 {
110 int serrno = errno;
111 close(fd);
112 errno = serrno;
113 }
114
115 static inline int openat_dir(int dirfd, const char *name)
116 {
117 return openat(dirfd, name,
118 O_DIRECTORY | O_RDONLY | O_NOFOLLOW | O_PATH_9P_UTIL);
119 }
120
121 static inline int openat_file(int dirfd, const char *name, int flags,
122 mode_t mode)
123 {
124 int fd, serrno, ret;
125
126 #ifndef CONFIG_DARWIN
127 again:
128 #endif
129 fd = openat(dirfd, name, flags | O_NOFOLLOW | O_NOCTTY | O_NONBLOCK,
130 mode);
131 if (fd == -1) {
132 #ifndef CONFIG_DARWIN
133 if (errno == EPERM && (flags & O_NOATIME)) {
134 /*
135 * The client passed O_NOATIME but we lack permissions to honor it.
136 * Rather than failing the open, fall back without O_NOATIME. This
137 * doesn't break the semantics on the client side, as the Linux
138 * open(2) man page notes that O_NOATIME "may not be effective on
139 * all filesystems". In particular, NFS and other network
140 * filesystems ignore it entirely.
141 */
142 flags &= ~O_NOATIME;
143 goto again;
144 }
145 #endif
146 return -1;
147 }
148
149 serrno = errno;
150 /* O_NONBLOCK was only needed to open the file. Let's drop it. We don't
151 * do that with O_PATH since fcntl(F_SETFL) isn't supported, and openat()
152 * ignored it anyway.
153 */
154 if (!(flags & O_PATH_9P_UTIL)) {
155 ret = fcntl(fd, F_SETFL, flags);
156 assert(!ret);
157 }
158 errno = serrno;
159 return fd;
160 }
161
162 ssize_t fgetxattrat_nofollow(int dirfd, const char *path, const char *name,
163 void *value, size_t size);
164 int fsetxattrat_nofollow(int dirfd, const char *path, const char *name,
165 void *value, size_t size, int flags);
166 ssize_t flistxattrat_nofollow(int dirfd, const char *filename,
167 char *list, size_t size);
168 ssize_t fremovexattrat_nofollow(int dirfd, const char *filename,
169 const char *name);
170
171 /*
172 * Darwin has d_seekoff, which appears to function similarly to d_off.
173 * However, it does not appear to be supported on all file systems,
174 * so ensure it is manually injected earlier and call here when
175 * needed.
176 */
177 static inline off_t qemu_dirent_off(struct dirent *dent)
178 {
179 #ifdef CONFIG_DARWIN
180 return dent->d_seekoff;
181 #else
182 return dent->d_off;
183 #endif
184 }
185
186 /**
187 * qemu_dirent_dup() - Duplicate directory entry @dent.
188 *
189 * @dent: original directory entry to be duplicated
190 * Return: duplicated directory entry which should be freed with g_free()
191 *
192 * It is highly recommended to use this function instead of open coding
193 * duplication of dirent objects, because the actual struct dirent
194 * size may be bigger or shorter than sizeof(struct dirent) and correct
195 * handling is platform specific (see gitlab issue #841).
196 */
197 static inline struct dirent *qemu_dirent_dup(struct dirent *dent)
198 {
199 size_t sz = 0;
200 #if defined _DIRENT_HAVE_D_RECLEN
201 /* Avoid use of strlen() if platform supports d_reclen. */
202 sz = dent->d_reclen;
203 #endif
204 /*
205 * Test sz for zero even if d_reclen is available
206 * because some drivers may set d_reclen to zero.
207 */
208 if (sz == 0) {
209 /* Fallback to the most portable way. */
210 sz = offsetof(struct dirent, d_name) +
211 strlen(dent->d_name) + 1;
212 }
213 return g_memdup(dent, sz);
214 }
215
216 /*
217 * As long as mknodat is not available on macOS, this workaround
218 * using pthread_fchdir_np is needed. qemu_mknodat is defined in
219 * os-posix.c. pthread_fchdir_np is weakly linked here as a guard
220 * in case it disappears in future macOS versions, because it is
221 * is a private API.
222 */
223 #if defined CONFIG_DARWIN && defined CONFIG_PTHREAD_FCHDIR_NP
224 int pthread_fchdir_np(int fd) __attribute__((weak_import));
225 #endif
226 int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev);
227
228 #endif