From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41168) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cVdmz-00040G-J3 for qemu-devel@nongnu.org; Mon, 23 Jan 2017 07:32:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cVdmy-0005u9-Lu for qemu-devel@nongnu.org; Mon, 23 Jan 2017 07:32:01 -0500 From: Fam Zheng Date: Mon, 23 Jan 2017 20:30:41 +0800 Message-Id: <20170123123056.30383-2-famz@redhat.com> In-Reply-To: <20170123123056.30383-1-famz@redhat.com> References: <20170123123056.30383-1-famz@redhat.com> Subject: [Qemu-devel] [PATCH v12 01/16] osdep: Add qemu_lock_fd and qemu_unlock_fd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Daniel P. Berrange" , qemu-block@nongnu.org, eblake@redhat.com, Kevin Wolf , rjones@redhat.com, Max Reitz 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 --- include/qemu/osdep.h | 3 +++ util/osdep.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 689f253..e864fe8 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -297,6 +297,9 @@ int qemu_close(int fd); #ifndef _WIN32 int qemu_dup(int fd); #endif +int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive); +int qemu_unlock_fd(int fd, int64_t start, int64_t len); +int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive); #if defined(__HAIKU__) && defined(__i386__) #define FMT_pid "%ld" 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 /* -- 2.9.3