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029ed1bd9d
Darwin does not support mknodat. However, to avoid race conditions
with later setting the permissions, we must avoid using mknod on
the full path instead. We could try to fchdir, but that would cause
problems if multiple threads try to call mknodat at the same time.
However, luckily there is a solution: Darwin includes a function
that sets the cwd for the current thread only.
This should suffice to use mknod safely.
This function (pthread_fchdir_np) is protected by a check in
meson in a patch later in this series.
Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Signed-off-by: Michael Roitzsch <reactorcontrol@icloud.com>
[Will Cohen: - Adjust coding style
- Replace clang references with gcc
- Note radar filed with Apple for missing syscall
- Replace direct syscall with pthread_fchdir_np and
adjust patch notes accordingly
- Declare pthread_fchdir_np with
- __attribute__((weak_import)) to allow checking for
its presence before usage
- Move declarations above cplusplus guard
- Add CONFIG_PTHREAD_FCHDIR_NP to meson and check for
presence in 9p-util
- Rebase to apply cleanly on top of the 2022-02-10
changes to 9pfs
- Fix line over 90 characters formatting error]
Signed-off-by: Will Cohen <wwcohen@gmail.com>
Message-Id: <20220227223522.91937-10-wwcohen@gmail.com>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
/*
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* 9p utilities (Darwin Implementation)
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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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#include "qemu/osdep.h"
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#include "qemu/xattr.h"
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#include "qapi/error.h"
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#include "qemu/error-report.h"
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#include "9p-util.h"
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ssize_t fgetxattrat_nofollow(int dirfd, const char *filename, const char *name,
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void *value, size_t size)
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{
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int ret;
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int fd = openat_file(dirfd, filename,
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O_RDONLY | O_PATH_9P_UTIL | O_NOFOLLOW, 0);
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if (fd == -1) {
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return -1;
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}
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ret = fgetxattr(fd, name, value, size, 0, 0);
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close_preserve_errno(fd);
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return ret;
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}
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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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{
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int ret;
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int fd = openat_file(dirfd, filename,
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O_RDONLY | O_PATH_9P_UTIL | O_NOFOLLOW, 0);
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if (fd == -1) {
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return -1;
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}
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ret = flistxattr(fd, list, size, 0);
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close_preserve_errno(fd);
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return ret;
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}
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ssize_t fremovexattrat_nofollow(int dirfd, const char *filename,
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const char *name)
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{
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int ret;
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int fd = openat_file(dirfd, filename, O_PATH_9P_UTIL | O_NOFOLLOW, 0);
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if (fd == -1) {
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return -1;
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}
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ret = fremovexattr(fd, name, 0);
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close_preserve_errno(fd);
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return ret;
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}
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int fsetxattrat_nofollow(int dirfd, const char *filename, const char *name,
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void *value, size_t size, int flags)
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{
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int ret;
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int fd = openat_file(dirfd, filename, O_PATH_9P_UTIL | O_NOFOLLOW, 0);
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if (fd == -1) {
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return -1;
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}
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ret = fsetxattr(fd, name, value, size, 0, flags);
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close_preserve_errno(fd);
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return ret;
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}
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/*
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* As long as mknodat is not available on macOS, this workaround
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* using pthread_fchdir_np is needed.
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*
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* Radar filed with Apple for implementing mknodat:
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* rdar://FB9862426 (https://openradar.appspot.com/FB9862426)
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*/
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#if defined CONFIG_PTHREAD_FCHDIR_NP
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int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev)
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{
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int preserved_errno, err;
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if (!pthread_fchdir_np) {
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error_report_once("pthread_fchdir_np() not available on this version of macOS");
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return -ENOTSUP;
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}
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if (pthread_fchdir_np(dirfd) < 0) {
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return -1;
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}
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err = mknod(filename, mode, dev);
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preserved_errno = errno;
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/* Stop using the thread-local cwd */
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pthread_fchdir_np(-1);
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if (err < 0) {
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errno = preserved_errno;
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}
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return err;
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}
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#endif
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