Add ->flock() operation to low and high level interfaces

This fixes problems with emulating flock() with POSIX locking.
Reported by Sebastian Pipping.

As with lock/setlk/getlk most filesystems don't need to implement
this, as the kernel takes care of file locking.  The only reason to
implement locking operations is for network filesystems which want
file locking to work between clients.

5 files changed, 117 insertions, 8 deletions

diff --git a/lib/fuse.c b/lib/fuse.c
index 50f3d0d..f7740c3 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -1933,6 +1933,27 @@ int fuse_fs_lock(struct fuse_fs *fs, const char *path,
 	}
 }
 
+int fuse_fs_flock(struct fuse_fs *fs, const char *path,
+		  struct fuse_file_info *fi, int op)
+{
+	fuse_get_context()->private_data = fs->user_data;
+	if (fs->op.flock) {
+		if (fs->debug) {
+			int xop = op & ~LOCK_NB;
+
+			fprintf(stderr, "lock[%llu] %s%s\n",
+				(unsigned long long) fi->fh,
+				xop == LOCK_SH ? "LOCK_SH" :
+				(xop == LOCK_EX ? "LOCK_EX" :
+				 (xop == LOCK_UN ? "LOCK_UN" : "???")),
+				(op & LOCK_NB) ? "|LOCK_NB" : "");
+		}
+		return fs->op.flock(path, fi, op);
+	} else {
+		return -ENOSYS;
+	}
+}
+
 int fuse_fs_chown(struct fuse_fs *fs, const char *path, uid_t uid, gid_t gid)
 {
 	fuse_get_context()->private_data = fs->user_data;
@@ -2410,6 +2431,10 @@ void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn)
 	fuse_get_context()->private_data = fs->user_data;
 	if (!fs->op.write_buf)
 		conn->want &= ~FUSE_CAP_SPLICE_READ;
+	if (!fs->op.lock)
+		conn->want &= ~FUSE_CAP_POSIX_LOCKS;
+	if (!fs->op.flock)
+		conn->want &= ~FUSE_CAP_FLOCK_LOCKS;
 	if (fs->op.init)
 		fs->user_data = fs->op.init(conn);
 }
@@ -3754,6 +3779,24 @@ static void fuse_lib_setlk(fuse_req_t req, fuse_ino_t ino,
 	reply_err(req, err);
 }
 
+static void fuse_lib_flock(fuse_req_t req, fuse_ino_t ino,
+			   struct fuse_file_info *fi, int op)
+{
+	struct fuse *f = req_fuse_prepare(req);
+	char *path;
+	int err;
+
+	err = get_path_nullok(f, ino, &path);
+	if (err == 0) {
+		struct fuse_intr_data d;
+		fuse_prepare_interrupt(f, req, &d);
+		err = fuse_fs_flock(f->fs, path, fi, op);
+		fuse_finish_interrupt(f, req, &d);
+		free_path(f, ino, path);
+	}
+	reply_err(req, err);
+}
+
 static void fuse_lib_bmap(fuse_req_t req, fuse_ino_t ino, size_t blocksize,
 			  uint64_t idx)
 {
@@ -3939,6 +3982,7 @@ static struct fuse_lowlevel_ops fuse_path_ops = {
 	.removexattr = fuse_lib_removexattr,
 	.getlk = fuse_lib_getlk,
 	.setlk = fuse_lib_setlk,
+	.flock = fuse_lib_flock,
 	.bmap = fuse_lib_bmap,
 	.ioctl = fuse_lib_ioctl,
 	.poll = fuse_lib_poll,
diff --git a/lib/fuse_i.h b/lib/fuse_i.h
index dd98737..78f1467 100644
--- a/lib/fuse_i.h
+++ b/lib/fuse_i.h
@@ -62,7 +62,8 @@ struct fuse_ll {
 	int debug;
 	int allow_root;
 	int atomic_o_trunc;
-	int no_remote_lock;
+	int no_remote_posix_lock;
+	int no_remote_flock;
 	int big_writes;
 	int splice_write;
 	int splice_move;
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 3cf747d..b101523 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -1322,6 +1322,10 @@ static void do_release(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		fi.flush = (arg->release_flags & FUSE_RELEASE_FLUSH) ? 1 : 0;
 		fi.lock_owner = arg->lock_owner;
 	}
+	if (arg->release_flags & FUSE_RELEASE_FLOCK_UNLOCK) {
+		fi.flock_release = 1;
+		fi.lock_owner = arg->lock_owner;
+	}
 
 	if (req->f->op.release)
 		req->f->op.release(req, nodeid, &fi);
@@ -1505,11 +1509,34 @@ static void do_setlk_common(fuse_req_t req, fuse_ino_t nodeid,
 	fi.fh = arg->fh;
 	fi.lock_owner = arg->owner;
 
-	convert_fuse_file_lock(&arg->lk, &flock);
-	if (req->f->op.setlk)
-		req->f->op.setlk(req, nodeid, &fi, &flock, sleep);
-	else
-		fuse_reply_err(req, ENOSYS);
+	if (arg->lk_flags & FUSE_LK_FLOCK) {
+		int op = 0;
+
+		switch (arg->lk.type) {
+		case F_RDLCK:
+			op = LOCK_SH;
+			break;
+		case F_WRLCK:
+			op = LOCK_EX;
+			break;
+		case F_UNLCK:
+			op = LOCK_UN;
+			break;
+		}
+		if (!sleep)
+			op |= LOCK_NB;
+
+		if (req->f->op.flock)
+			req->f->op.flock(req, nodeid, &fi, op);
+		else
+			fuse_reply_err(req, ENOSYS);
+	} else {
+		convert_fuse_file_lock(&arg->lk, &flock);
+		if (req->f->op.setlk)
+			req->f->op.setlk(req, nodeid, &fi, &flock, sleep);
+		else
+			fuse_reply_err(req, ENOSYS);
+	}
 }
 
 static void do_setlk(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
@@ -1726,6 +1753,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 			f->conn.capable |= FUSE_CAP_BIG_WRITES;
 		if (arg->flags & FUSE_DONT_MASK)
 			f->conn.capable |= FUSE_CAP_DONT_MASK;
+		if (arg->flags & FUSE_FLOCK_LOCKS)
+			f->conn.capable |= FUSE_CAP_FLOCK_LOCKS;
 	} else {
 		f->conn.async_read = 0;
 		f->conn.max_readahead = 0;
@@ -1748,8 +1777,10 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 
 	if (f->atomic_o_trunc)
 		f->conn.want |= FUSE_CAP_ATOMIC_O_TRUNC;
-	if (f->op.getlk && f->op.setlk && !f->no_remote_lock)
+	if (f->op.getlk && f->op.setlk && !f->no_remote_posix_lock)
 		f->conn.want |= FUSE_CAP_POSIX_LOCKS;
+	if (f->op.flock && !f->no_remote_flock)
+		f->conn.want |= FUSE_CAP_FLOCK_LOCKS;
 	if (f->big_writes)
 		f->conn.want |= FUSE_CAP_BIG_WRITES;
 
@@ -1786,6 +1817,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		outarg.flags |= FUSE_BIG_WRITES;
 	if (f->conn.want & FUSE_CAP_DONT_MASK)
 		outarg.flags |= FUSE_DONT_MASK;
+	if (f->conn.want & FUSE_CAP_FLOCK_LOCKS)
+		outarg.flags |= FUSE_FLOCK_LOCKS;
 	outarg.max_readahead = f->conn.max_readahead;
 	outarg.max_write = f->conn.max_write;
 	if (f->conn.proto_minor >= 13) {
@@ -2360,7 +2393,10 @@ static struct fuse_opt fuse_ll_opts[] = {
 	{ "async_read", offsetof(struct fuse_ll, conn.async_read), 1 },
 	{ "sync_read", offsetof(struct fuse_ll, conn.async_read), 0 },
 	{ "atomic_o_trunc", offsetof(struct fuse_ll, atomic_o_trunc), 1},
-	{ "no_remote_lock", offsetof(struct fuse_ll, no_remote_lock), 1},
+	{ "no_remote_lock", offsetof(struct fuse_ll, no_remote_posix_lock), 1},
+	{ "no_remote_lock", offsetof(struct fuse_ll, no_remote_flock), 1},
+	{ "no_remote_flock", offsetof(struct fuse_ll, no_remote_flock), 1},
+	{ "no_remote_posix_lock", offsetof(struct fuse_ll, no_remote_posix_lock), 1},
 	{ "big_writes", offsetof(struct fuse_ll, big_writes), 1},
 	{ "splice_write", offsetof(struct fuse_ll, splice_write), 1},
 	{ "no_splice_write", offsetof(struct fuse_ll, no_splice_write), 1},
@@ -2394,6 +2430,8 @@ static void fuse_ll_help(void)
 "    -o atomic_o_trunc      enable atomic open+truncate support\n"
 "    -o big_writes          enable larger than 4kB writes\n"
 "    -o no_remote_lock      disable remote file locking\n"
+"    -o no_remote_flock     disable remote file locking (BSD)\n"
+"    -o no_remote_posix_lock disable remove file locking (POSIX)\n"
 "    -o [no_]splice_write   use splice to write to the fuse device\n"
 "    -o [no_]splice_move    move data while splicing to the fuse device\n"
 "    -o [no_]splice_read    use splice to read from the fuse device\n"
diff --git a/lib/modules/iconv.c b/lib/modules/iconv.c
index b9946d9..1b78192 100644
--- a/lib/modules/iconv.c
+++ b/lib/modules/iconv.c
@@ -549,6 +549,18 @@ static int iconv_lock(const char *path, struct fuse_file_info *fi, int cmd,
 	return err;
 }
 
+static int iconv_flock(const char *path, struct fuse_file_info *fi, int op)
+{
+	struct iconv *ic = iconv_get();
+	char *newpath;
+	int err = iconv_convpath(ic, path, &newpath, 0);
+	if (!err) {
+		err = fuse_fs_flock(ic->next, newpath, fi, op);
+		free(newpath);
+	}
+	return err;
+}
+
 static int iconv_bmap(const char *path, size_t blocksize, uint64_t *idx)
 {
 	struct iconv *ic = iconv_get();
@@ -616,6 +628,7 @@ static struct fuse_operations iconv_oper = {
 	.listxattr	= iconv_listxattr,
 	.removexattr	= iconv_removexattr,
 	.lock		= iconv_lock,
+	.flock		= iconv_flock,
 	.bmap		= iconv_bmap,
 
 	.flag_nullpath_ok = 1,
diff --git a/lib/modules/subdir.c b/lib/modules/subdir.c
index 6d9ac89..24dede6 100644
--- a/lib/modules/subdir.c
+++ b/lib/modules/subdir.c
@@ -536,6 +536,18 @@ static int subdir_lock(const char *path, struct fuse_file_info *fi, int cmd,
 	return err;
 }
 
+static int subdir_flock(const char *path, struct fuse_file_info *fi, int op)
+{
+	struct subdir *d = subdir_get();
+	char *newpath;
+	int err = subdir_addpath(d, path, &newpath);
+	if (!err) {
+		err = fuse_fs_flock(d->next, newpath, fi, op);
+		free(newpath);
+	}
+	return err;
+}
+
 static int subdir_bmap(const char *path, size_t blocksize, uint64_t *idx)
 {
 	struct subdir *d = subdir_get();
@@ -599,6 +611,7 @@ static struct fuse_operations subdir_oper = {
 	.listxattr	= subdir_listxattr,
 	.removexattr	= subdir_removexattr,
 	.lock		= subdir_lock,
+	.flock		= subdir_flock,
 	.bmap		= subdir_bmap,
 
 	.flag_nullpath_ok = 1,