Mesh: Workaround to load 3mf files not supported by zipios library

src/Base/Tools.cpp

@@ -393,3 +393,17 @@ std::vector<std::string> Base::Tools::splitSubName(const std::string& subname)
 
     return subNames;
 }
+
+// ------------------------------------------------------------------------------------------------
+
+void Base::ZipTools::rewrite(const std::string& source, const std::string& target)
+{
+    Base::PyGILStateLocker lock;
+    PyObject* module = PyImport_ImportModule("freecad.utils_zip");
+    if (!module) {
+        throw Py::Exception();
+    }
+
+    Py::Module commands(module, true);
+    commands.callMemberFunction("rewrite", Py::TupleN(Py::String(source), Py::String(target)));
+}

src/Base/Tools.h

@@ -329,6 +329,14 @@ struct BaseExport Tools
     static std::vector<std::string> splitSubName(const std::string& subname);
 };
 
+struct BaseExport ZipTools
+{
+    /**
+     * @brief rewrite Rewrite a zip file under a new name.
+     */
+    static void rewrite(const std::string& source, const std::string& target);
+};
+
 
 }  // namespace Base
 

src/Ext/freecad/CMakeLists.txt

@@ -35,6 +35,7 @@ set(EXT_FILES
     sketcher.py
     UiTools.py
     utils.py
+    utils_zip.py
 )
 
 foreach (it ${EXT_FILES})

src/Ext/freecad/utils_zip.py

@@ -0,0 +1,18 @@
+# (c) 2024 Werner Mayer LGPL
+
+__author__ = "Werner Mayer"
+__url__ = "https://www.freecad.org"
+__doc__ = "Helper module to convert zip files"
+
+
+import zipfile
+
+def rewrite(source: str, target: str):
+    source_zip = zipfile.ZipFile(source, "r")
+    target_zip = zipfile.ZipFile(target, "w")
+
+    for name in source_zip.namelist():
+        target_zip.writestr(name, source_zip.open(name).read())
+
+    source_zip.close()
+    target_zip.close()

src/Mod/Mesh/App/Core/MeshIO.cpp

@@ -108,6 +108,31 @@ struct QUAD
     int iV[4];
 };
 
+class ZipFixer
+{
+public:
+    ZipFixer(const char* filename)
+        : tmp {Base::FileInfo::getTempFileName()}
+    {
+        Base::ZipTools::rewrite(filename, tmp.filePath().c_str());
+        str.open(tmp, std::ios::in | std::ios::binary);
+    }
+
+    ~ZipFixer()
+    {
+        tmp.deleteFile();
+    }
+
+    Base::ifstream& getStream()
+    {
+        return str;
+    }
+
+private:
+    Base::FileInfo tmp;
+    Base::ifstream str;
+};
+
 }  // namespace MeshCore
 
 // --------------------------------------------------------------
@@ -227,7 +252,13 @@ bool MeshInput::LoadAny(const char* FileName)
         ok = LoadSMF(str);
     }
     else if (fi.hasExtension("3mf")) {
-        ok = Load3MF(str);
+        try {
+            ok = Load3MF(str);
+        }
+        catch (const zipios::FCollException&) {
+            ZipFixer zip(FileName);
+            ok = Load3MF(zip.getStream());
+        }
     }
     else if (fi.hasExtension("off")) {
         ok = LoadOFF(str);