Address missing /Resources object

Intercept missing page resources and generate the object.

Author: JorjMcKie

src/__init__.py

@@ -8242,6 +8242,8 @@ def _show_pdf_page(self, fz_srcpage, overlay=1, matrix=None, xref=0, oc=0, clip=
         # 1. insert Xobject in Resources
         #-------------------------------------------------------------
         resources = mupdf.pdf_dict_get_inheritable(tpageref, PDF_NAME('Resources'))
+        if not resources.m_internal:
+            resources = mupdf.pdf_dict_put_dict(tpageref,PDF_NAME('Resources'), 5)
         subres = mupdf.pdf_dict_get(resources, PDF_NAME('XObject'))
         if not subres.m_internal:
             subres = mupdf.pdf_dict_put_dict(resources, PDF_NAME('XObject'), 5)
@@ -16708,6 +16710,8 @@ def JM_merge_resources( page, temp_res):
     '''
     # page objects /Resources, /Resources/ExtGState, /Resources/Font
     resources = mupdf.pdf_dict_get(page.obj(), PDF_NAME('Resources'))
+    if not resources.m_internal:
+        resources = mupdf.pdf_dict_put_dict(page.obj(), PDF_NAME('Resources'), 5)
     main_extg = mupdf.pdf_dict_get(resources, PDF_NAME('ExtGState'))
     main_fonts = mupdf.pdf_dict_get(resources, PDF_NAME('Font'))
 

tests/resources/test_4141.pdf

@@ -0,0 +1,19 @@
+import pymupdf
+
+import os.path
+
+
+def test_4141():
+    """survive missing /Resources object in a number of cases."""
+    path = os.path.abspath(f"{__file__}/../../tests/resources/test_4141.pdf")
+    doc = pymupdf.open(path)
+    page = doc[0]
+    # make sure the right test file
+    assert doc.xref_get_key(page.xref, "Resources") == ("null", "null")
+    page.insert_htmlbox((100, 100, 200, 200), "Hallo")  # will fail without the fix
+    doc.close()
+    doc = pymupdf.open(doc.name)
+    page = doc[0]
+    tw = pymupdf.TextWriter(page.rect)
+    tw.append((100, 100), "Hallo")
+    tw.write_text(page)  # will fail without the fix