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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
#if !defined(CONFIG_LINUX)
/*
* Generates a Linux device number (a.k.a. dev_t) for given device major
* and minor numbers.
*
* To be more precise: it generates a device number in glibc's format
* (MMMM_Mmmm_mmmM_MMmm, 64 bits) actually, which is compatible with
* Linux's format (mmmM_MMmm, 32 bits), as described in <bits/sysmacros.h>.
*/
static inline uint64_t makedev_dotl(uint32_t dev_major, uint32_t dev_minor)
{
uint64_t dev;
// from glibc sysmacros.h:
dev = (((uint64_t) (dev_major & 0x00000fffu)) << 8);
dev |= (((uint64_t) (dev_major & 0xfffff000u)) << 32);
dev |= (((uint64_t) (dev_minor & 0x000000ffu)) << 0);
dev |= (((uint64_t) (dev_minor & 0xffffff00u)) << 12);
return dev;
}
#endif
/*
* Converts given device number from host's device number format to Linux
* device number format. As both the size of type dev_t and encoding of
* dev_t is system dependant, we have to convert them for Linux guests if
* host is not running Linux.
*/
static inline uint64_t host_dev_to_dotl_dev(dev_t dev)
{
#ifdef CONFIG_LINUX
return dev;
#else
return makedev_dotl(major(dev), minor(dev));
#endif
}
#ifdef CONFIG_DARWIN
#define qemu_fgetxattr(...) fgetxattr(__VA_ARGS__, 0, 0)
#define qemu_lgetxattr(...) getxattr(__VA_ARGS__, 0, XATTR_NOFOLLOW)
#define qemu_llistxattr(...) listxattr(__VA_ARGS__, XATTR_NOFOLLOW)
#define qemu_lremovexattr(...) removexattr(__VA_ARGS__, XATTR_NOFOLLOW)
static inline int qemu_lsetxattr(const char *path, const char *name,
const void *value, size_t size, int flags) {
return setxattr(path, name, value, size, 0, flags | XATTR_NOFOLLOW);
}
#else
#define qemu_fgetxattr fgetxattr
#define qemu_lgetxattr lgetxattr
#define qemu_llistxattr llistxattr
#define qemu_lremovexattr lremovexattr
#define qemu_lsetxattr lsetxattr
#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;
#ifndef CONFIG_DARWIN
again:
#endif
fd = openat(dirfd, name, flags | O_NOFOLLOW | O_NOCTTY | O_NONBLOCK,
mode);
if (fd == -1) {
#ifndef CONFIG_DARWIN
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;
}
#endif
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);
/*
* Darwin has d_seekoff, which appears to function similarly to d_off.
* However, it does not appear to be supported on all file systems,
* so ensure it is manually injected earlier and call here when
* needed.
*/
static inline off_t qemu_dirent_off(struct dirent *dent)
{
#ifdef CONFIG_DARWIN
return dent->d_seekoff;
#else
return dent->d_off;
#endif
}
/**
* qemu_dirent_dup() - Duplicate directory entry @dent.
*
* @dent: original directory entry to be duplicated
* Return: duplicated directory entry which should be freed with g_free()
*
* It is highly recommended to use this function instead of open coding
* duplication of dirent objects, because the actual struct dirent
* size may be bigger or shorter than sizeof(struct dirent) and correct
* handling is platform specific (see gitlab issue #841).
*/
static inline struct dirent *qemu_dirent_dup(struct dirent *dent)
{
size_t sz = 0;
#if defined _DIRENT_HAVE_D_RECLEN
/* Avoid use of strlen() if platform supports d_reclen. */
sz = dent->d_reclen;
#endif
/*
* Test sz for zero even if d_reclen is available
* because some drivers may set d_reclen to zero.
*/
if (sz == 0) {
/* Fallback to the most portable way. */
sz = offsetof(struct dirent, d_name) +
strlen(dent->d_name) + 1;
}
return g_memdup(dent, sz);
}
/*
* As long as mknodat is not available on macOS, this workaround
* using pthread_fchdir_np is needed. qemu_mknodat is defined in
* os-posix.c. pthread_fchdir_np is weakly linked here as a guard
* in case it disappears in future macOS versions, because it is
* is a private API.
*/
#if defined CONFIG_DARWIN && defined CONFIG_PTHREAD_FCHDIR_NP
int pthread_fchdir_np(int fd) __attribute__((weak_import));
#endif
int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev);
#endif
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