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author | Fam Zheng <famz@redhat.com> | 2017-05-03 00:35:54 +0800 |
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committer | Kevin Wolf <kwolf@redhat.com> | 2017-05-11 11:15:32 +0200 |
commit | 13461fdba6588540c99bf1e32275e421da22c396 (patch) | |
tree | 11f9d6afae8e70d9419c25f50f2fe562d335f364 /util/osdep.c | |
parent | fc0932fdcfc3e5cafa3641e361b681c07f639812 (diff) | |
download | qemu-13461fdba6588540c99bf1e32275e421da22c396.zip qemu-13461fdba6588540c99bf1e32275e421da22c396.tar.gz qemu-13461fdba6588540c99bf1e32275e421da22c396.tar.bz2 |
osdep: Add qemu_lock_fd and qemu_unlock_fd
They are wrappers of POSIX fcntl "file private locking", with a
convenient "try lock" wrapper implemented with F_OFD_GETLK.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'util/osdep.c')
-rw-r--r-- | util/osdep.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/util/osdep.c b/util/osdep.c index 06fb1cf..3de4a18 100644 --- a/util/osdep.c +++ b/util/osdep.c @@ -140,6 +140,54 @@ static int qemu_parse_fdset(const char *param) { return qemu_parse_fd(param); } + +static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type) +{ +#ifdef F_OFD_SETLK + int ret; + struct flock fl = { + .l_whence = SEEK_SET, + .l_start = start, + .l_len = len, + .l_type = fl_type, + }; + ret = fcntl(fd, F_OFD_SETLK, &fl); + return ret == -1 ? -errno : 0; +#else + return -ENOTSUP; +#endif +} + +int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive) +{ + return qemu_lock_fcntl(fd, start, len, exclusive ? F_WRLCK : F_RDLCK); +} + +int qemu_unlock_fd(int fd, int64_t start, int64_t len) +{ + return qemu_lock_fcntl(fd, start, len, F_UNLCK); +} + +int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive) +{ +#ifdef F_OFD_SETLK + int ret; + struct flock fl = { + .l_whence = SEEK_SET, + .l_start = start, + .l_len = len, + .l_type = exclusive ? F_WRLCK : F_RDLCK, + }; + ret = fcntl(fd, F_OFD_GETLK, &fl); + if (ret == -1) { + return -errno; + } else { + return fl.l_type == F_UNLCK ? 0 : -EAGAIN; + } +#else + return -ENOTSUP; +#endif +} #endif /* |