feat: add getRelativePath

src/lib/seallib/vfs.cpp

@@ -257,6 +257,28 @@ std::string VirtualFileSystem::trimPathSeparators(const std::string& path)
     return path.substr(start, end - start + 1);
 }
 
+bool VirtualFileSystem::getRelativePath(const MountPoint& mount, const std::string& searchPath,
+                                        std::string& outRelative) const
+{
+    if (searchPath == mount.virtualPath)
+    {
+        outRelative = "/";
+        return true;
+    }
+    if (mount.virtualPath == "/")
+    {
+        outRelative = searchPath;
+        return true;
+    }
+    std::string prefix = mount.virtualPath + '/';
+    if (searchPath.compare(0, prefix.length(), prefix) == 0)
+    {
+        outRelative = searchPath.substr(prefix.length());
+        return true;
+    }
+    return false;
+}
+
 /*
     mountpoint
 */

src/lib/seallib/vfs.h

@@ -99,6 +99,9 @@ namespace seallib
 
             static bool isPathSeparator(char c);
             static std::string trimPathSeparators(const std::string& path);
+
+            bool getRelativePath(const MountPoint& mount, const std::string& searchPath,
+                                 std::string& outRelative) const;
     };
 
     inline std::string vfsResultToString(VFSResult result)