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 #ifdef CONFIG_DARWIN 62 #define qemu_fgetxattr(...) fgetxattr(__VA_ARGS__, 0, 0) 63 #define qemu_lgetxattr(...) getxattr(__VA_ARGS__, 0, XATTR_NOFOLLOW) 64 #define qemu_llistxattr(...) listxattr(__VA_ARGS__, XATTR_NOFOLLOW) 65 #define qemu_lremovexattr(...) removexattr(__VA_ARGS__, XATTR_NOFOLLOW) 66 static inline int qemu_lsetxattr(const char *path, const char *name, 67 const void *value, size_t size, int flags) { 68 return setxattr(path, name, value, size, 0, flags | XATTR_NOFOLLOW); 69 } 70 #else 71 #define qemu_fgetxattr fgetxattr 72 #define qemu_lgetxattr lgetxattr 73 #define qemu_llistxattr llistxattr 74 #define qemu_lremovexattr lremovexattr 75 #define qemu_lsetxattr lsetxattr 76 #endif 77 78 static inline void close_preserve_errno(int fd) 79 { 80 int serrno = errno; 81 close(fd); 82 errno = serrno; 83 } 84 85 static inline int openat_dir(int dirfd, const char *name) 86 { 87 return openat(dirfd, name, 88 O_DIRECTORY | O_RDONLY | O_NOFOLLOW | O_PATH_9P_UTIL); 89 } 90 91 static inline int openat_file(int dirfd, const char *name, int flags, 92 mode_t mode) 93 { 94 int fd, serrno, ret; 95 96 #ifndef CONFIG_DARWIN 97 again: 98 #endif 99 fd = openat(dirfd, name, flags | O_NOFOLLOW | O_NOCTTY | O_NONBLOCK, 100 mode); 101 if (fd == -1) { 102 #ifndef CONFIG_DARWIN 103 if (errno == EPERM && (flags & O_NOATIME)) { 104 /* 105 * The client passed O_NOATIME but we lack permissions to honor it. 106 * Rather than failing the open, fall back without O_NOATIME. This 107 * doesn't break the semantics on the client side, as the Linux 108 * open(2) man page notes that O_NOATIME "may not be effective on 109 * all filesystems". In particular, NFS and other network 110 * filesystems ignore it entirely. 111 */ 112 flags &= ~O_NOATIME; 113 goto again; 114 } 115 #endif 116 return -1; 117 } 118 119 serrno = errno; 120 /* O_NONBLOCK was only needed to open the file. Let's drop it. We don't 121 * do that with O_PATH since fcntl(F_SETFL) isn't supported, and openat() 122 * ignored it anyway. 123 */ 124 if (!(flags & O_PATH_9P_UTIL)) { 125 ret = fcntl(fd, F_SETFL, flags); 126 assert(!ret); 127 } 128 errno = serrno; 129 return fd; 130 } 131 132 ssize_t fgetxattrat_nofollow(int dirfd, const char *path, const char *name, 133 void *value, size_t size); 134 int fsetxattrat_nofollow(int dirfd, const char *path, const char *name, 135 void *value, size_t size, int flags); 136 ssize_t flistxattrat_nofollow(int dirfd, const char *filename, 137 char *list, size_t size); 138 ssize_t fremovexattrat_nofollow(int dirfd, const char *filename, 139 const char *name); 140 141 /* 142 * Darwin has d_seekoff, which appears to function similarly to d_off. 143 * However, it does not appear to be supported on all file systems, 144 * so ensure it is manually injected earlier and call here when 145 * needed. 146 */ 147 static inline off_t qemu_dirent_off(struct dirent *dent) 148 { 149 #ifdef CONFIG_DARWIN 150 return dent->d_seekoff; 151 #else 152 return dent->d_off; 153 #endif 154 } 155 156 /** 157 * qemu_dirent_dup() - Duplicate directory entry @dent. 158 * 159 * @dent: original directory entry to be duplicated 160 * Return: duplicated directory entry which should be freed with g_free() 161 * 162 * It is highly recommended to use this function instead of open coding 163 * duplication of dirent objects, because the actual struct dirent 164 * size may be bigger or shorter than sizeof(struct dirent) and correct 165 * handling is platform specific (see gitlab issue #841). 166 */ 167 static inline struct dirent *qemu_dirent_dup(struct dirent *dent) 168 { 169 size_t sz = 0; 170 #if defined _DIRENT_HAVE_D_RECLEN 171 /* Avoid use of strlen() if platform supports d_reclen. */ 172 sz = dent->d_reclen; 173 #endif 174 /* 175 * Test sz for zero even if d_reclen is available 176 * because some drivers may set d_reclen to zero. 177 */ 178 if (sz == 0) { 179 /* Fallback to the most portable way. */ 180 sz = offsetof(struct dirent, d_name) + 181 strlen(dent->d_name) + 1; 182 } 183 return g_memdup(dent, sz); 184 } 185 186 /* 187 * As long as mknodat is not available on macOS, this workaround 188 * using pthread_fchdir_np is needed. qemu_mknodat is defined in 189 * os-posix.c. pthread_fchdir_np is weakly linked here as a guard 190 * in case it disappears in future macOS versions, because it is 191 * is a private API. 192 */ 193 #if defined CONFIG_DARWIN && defined CONFIG_PTHREAD_FCHDIR_NP 194 int pthread_fchdir_np(int fd) __attribute__((weak_import)); 195 #endif 196 int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev); 197 198 #endif 199