From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46860) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2ZY0-0000BM-S7 for qemu-devel@nongnu.org; Tue, 17 May 2016 03:36:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b2ZXy-0003sl-S8 for qemu-devel@nongnu.org; Tue, 17 May 2016 03:36:07 -0400 From: Fam Zheng Date: Tue, 17 May 2016 15:35:17 +0800 Message-Id: <1463470536-8981-9-git-send-email-famz@redhat.com> In-Reply-To: <1463470536-8981-1-git-send-email-famz@redhat.com> References: <1463470536-8981-1-git-send-email-famz@redhat.com> Subject: [Qemu-devel] [PATCH v5 08/27] 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: Kevin Wolf , Max Reitz , Jeff Cody , Markus Armbruster , Eric Blake , John Snow , qemu-block@nongnu.org, berrange@redhat.com, pbonzini@redhat.com, den@openvz.org, stefanha@redhat.com They are wrappers of POSIX fcntl "file private locking". Signed-off-by: Fam Zheng --- include/qemu/osdep.h | 2 ++ util/osdep.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 1e3221c..81913a7 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -265,6 +265,8 @@ int qemu_madvise(void *addr, size_t len, int advice); int qemu_open(const char *name, int flags, ...); int qemu_close(int fd); +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); #if defined(__HAIKU__) && defined(__i386__) #define FMT_pid "%ld" diff --git a/util/osdep.c b/util/osdep.c index d56d071..9e5d7fa 100644 --- a/util/osdep.c +++ b/util/osdep.c @@ -236,6 +236,37 @@ int qemu_close(int fd) return close(fd); } +static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type) +{ +#ifdef F_OFD_SETLK + struct flock fl = (struct flock) { + .l_whence = SEEK_SET, + /* Locking byte 1 avoids interfereing with virtlockd. */ + .l_start = start, + .l_len = len, + .l_type = fl_type, + }; + if (fcntl(fd, F_OFD_SETLK, &fl) == -1) { + return -errno; + } else { + return 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); +} + /* * A variant of write(2) which handles partial write. * -- 2.8.2