conn->want conversion: Fix fuse_apply_conn_info_opts()

fuse_apply_conn_info_opts() was applying to 'want_ext',
which would cause conflicts with 'want' if the application
applied its own flags to 'conn->want'.

Solution is:
    - to move fuse_{set,unset,get}_feature_flag and
      convert_to_conn_want_ext() to fuse_lowlevel.c and
      to define them as part of the public API, although
      convert_to_conn_want_ext() should not be used - it is
      currently needed to be a public function due as it needs
      to be defined for the tests.

Related to https://github.com/libfuse/libfuse/issues/1171 and
https://github.com/libfuse/libfuse/pull/1172.

Closes: https://github.com/libfuse/libfuse/issues/1171
Signed-off-by: Bernd Schubert <bschubert@ddn.com>

1 files changed, 72 insertions, 6 deletions

diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 9fb793b..c2f3ccb 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2435,6 +2435,77 @@ static bool want_flags_valid(uint64_t capable, uint64_t want)
 	return true;
 }
 
+/**
+ * Get the wanted capability flags, converting from old format if necessary
+ */
+int fuse_convert_to_conn_want_ext(struct fuse_conn_info *conn)
+{
+	struct fuse_session *se = container_of(conn, struct fuse_session, conn);
+
+	/*
+	 * Convert want to want_ext if necessary.
+	 * For the high level interface this function might be called
+	 * twice, once from the high level interface and once from the
+	 * low level interface. Both, with different want_ext_default and
+	 * want_default values. In order to suppress a failure for the
+	 * second call, we check if the lower 32 bits of want_ext are
+	 * already set to the value of want.
+	 */
+	if (conn->want != se->conn_want &&
+	    fuse_lower_32_bits(conn->want_ext) != conn->want) {
+		if (conn->want_ext != se->conn_want_ext) {
+			fuse_log(FUSE_LOG_ERR,
+				"%s: Both conn->want_ext and conn->want are set.\n"
+				"want=%x, want_ext=%lx, se->want=%lx se->want_ext=%lx\n",
+				__func__, conn->want, conn->want_ext,
+				se->conn_want, se->conn_want_ext);
+			return -EINVAL;
+		}
+
+		/* high bits from want_ext, low bits from want */
+		conn->want_ext = fuse_higher_32_bits(conn->want_ext) |
+				 conn->want;
+	}
+
+	/* ensure there won't be a second conversion */
+	conn->want = fuse_lower_32_bits(conn->want_ext);
+
+	return 0;
+}
+
+bool fuse_set_feature_flag(struct fuse_conn_info *conn,
+					 uint64_t flag)
+{
+	struct fuse_session *se = container_of(conn, struct fuse_session, conn);
+
+	if (conn->capable_ext & flag) {
+		conn->want_ext |= flag;
+		se->conn_want_ext |= flag;
+		conn->want  |= flag;
+		se->conn_want |= flag;
+		return true;
+	}
+	return false;
+}
+
+void fuse_unset_feature_flag(struct fuse_conn_info *conn,
+					 uint64_t flag)
+{
+	struct fuse_session *se = container_of(conn, struct fuse_session, conn);
+
+	conn->want_ext &= ~flag;
+	se->conn_want_ext &= ~flag;
+	conn->want  &= ~flag;
+	se->conn_want &= ~flag;
+}
+
+bool fuse_get_feature_flag(struct fuse_conn_info *conn,
+					     uint64_t flag)
+{
+	return conn->capable_ext & flag ? true : false;
+}
+
+
 /* Prevent bogus data races (bogus since "init" is called before
  * multi-threading becomes relevant */
 static __attribute__((no_sanitize("thread"))) void
@@ -2603,12 +2674,8 @@ _do_init(fuse_req_t req, const fuse_ino_t nodeid, const void *op_in,
 
 	se->got_init = 1;
 	if (se->op.init) {
-		uint64_t want_ext_default = se->conn.want_ext;
-		uint32_t want_default = fuse_lower_32_bits(se->conn.want_ext);
-
 		// Apply the first 32 bits of capable_ext to capable
 		se->conn.capable = fuse_lower_32_bits(se->conn.capable_ext);
-		se->conn.want = want_default;
 
 		se->op.init(se->userdata, &se->conn);
 
@@ -2617,8 +2684,7 @@ _do_init(fuse_req_t req, const fuse_ino_t nodeid, const void *op_in,
 		 * se->conn.want_ext
 		 * Userspace might still use conn.want - we need to convert it
 		 */
-		convert_to_conn_want_ext(&se->conn, want_ext_default,
-					      want_default);
+		fuse_convert_to_conn_want_ext(&se->conn);
 	}
 
 	if (!want_flags_valid(se->conn.capable_ext, se->conn.want_ext)) {