webdav: fix mixed property statuses in multi-status responses

This PR fixes a bug in the WebDAV backend where directories or files could
randomly "disappear" from listings due to strict and fragile multi-status code
parsing.

Co-authored-by: bright <nako_ruru@sina.com>

backend/webdav/api/types.go

@@ -98,21 +98,19 @@ func (p *Prop) Code() int {
 	return code
 }
 
-// StatusOK examines the Status and returns an OK flag
+// Parse a status of the form "HTTP/1.1 2xx"
+var parseStatus2XX = regexp.MustCompile(`^HTTP/[\d.]+\s+2\d{2}`)
+
+// StatusOK returns true if there is at least one 2XX response.
 func (p *Prop) StatusOK() bool {
-	// Fetch status code as int
-	c := p.Code()
-
 	// Assume OK if no statuses received
-	if c == -1 {
+	if len(p.Status) == 0 {
 		return true
 	}
-	if c == 0 {
-		return false
-	}
-	if c >= 200 && c < 300 {
-		return true
-
+	for _, statusStr := range p.Status {
+		if parseStatus2XX.MatchString(statusStr) {
+			return true
+		}
 	}
 	return false
 }

backend/webdav/api/types_test.go

@@ -0,0 +1,29 @@
+package api
+
+import (
+	"testing"
+)
+
+func TestPropStatusOK(t *testing.T) {
+	tests := []struct {
+		name   string
+		status []string
+		want   bool
+	}{
+		{"Empty status", []string{}, true},
+		{"Single 200 OK", []string{"HTTP/1.1 200 OK"}, true},
+		{"Single 404 Not Found", []string{"HTTP/1.1 404 Not Found"}, false},
+		{"Mixed status with 404 first", []string{"HTTP/1.1 404 Not Found", "HTTP/1.1 200 OK"}, true},
+		{"Mixed status with 200 first", []string{"HTTP/1.1 200 OK", "HTTP/1.1 404 Not Found"}, true},
+		{"Multiple non-2xx statuses", []string{"HTTP/1.1 404 Not Found", "HTTP/1.1 403 Forbidden"}, false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			p := &Prop{Status: tt.status}
+			if got := p.StatusOK(); got != tt.want {
+				t.Errorf("Prop.StatusOK() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}