Add support for SVG files with large header

news/147.bugfix

@@ -0,0 +1,6 @@
+Fixed the issue where SVG images containing extensive metadata were not being displayed
+correctly (resulting in a width/height of 1px). This problem could occur when the
+<svg> tag exceeded the MAX_INFO_BYTES limit.
+
+Fixes `issue 147 <https://github.com/plone/plone.namedfile/issues/147>`_.
+[mliebischer]

plone/namedfile/file.py

@@ -405,7 +405,8 @@ def _setData(self, data):
         super()._setData(data)
         firstbytes = self.getFirstBytes()
         res = getImageInfo(firstbytes)
-        if res == ("image/jpeg", -1, -1) or res == ("image/tiff", -1, -1):
+        if res == ("image/jpeg", -1, -1) or res == ("image/tiff", -1, -1) or \
+                res == ("image/svg+xml", -1, -1):
             # header was longer than firstbytes
             start = len(firstbytes)
             length = max(0, MAX_INFO_BYTES - start)

plone/namedfile/tests/__init__.py

@@ -1,8 +1,8 @@
 import os
 
 
-def getFile(filename):
+def getFile(filename, length=None):
     """return contents of the file with the given name"""
     filename = os.path.join(os.path.dirname(__file__), filename)
     with open(filename, "rb") as data_file:
-        return data_file.read()
+        return data_file.read(length)

plone/namedfile/tests/test_blobfile.py

@@ -27,6 +27,7 @@
 from zope.component import provideUtility
 from zope.interface.verify import verifyClass
 
+import os
 import struct
 import transaction
 import unittest
@@ -79,7 +80,7 @@ def testInterface(self):
         self.assertTrue(INamedBlobImage.implementedBy(NamedBlobImage))
         self.assertTrue(verifyClass(INamedBlobFile, NamedBlobImage))
 
-    def testDataMutatorWithLargeHeader(self):
+    def testDataMutatorWithLargeJPGHeader(self):
         from plone.namedfile.file import IMAGE_INFO_BYTES
 
         bogus_header_length = struct.pack(">H", IMAGE_INFO_BYTES * 2)
@@ -93,6 +94,23 @@ def testDataMutatorWithLargeHeader(self):
         image._setData(data)
         self.assertEqual(image.getImageSize(), (1024, 680))
 
+    def testDataMutatorWithLargeSVGHeader(self):
+        from plone.namedfile.file import IMAGE_INFO_BYTES
+
+        to_big_header_data = b'd' * (IMAGE_INFO_BYTES * 2)
+
+        data = (
+            b'<svg xmlns="http://www.w3.org/2000/svg" '
+            b'width="1024px" '
+            b'height="680px" '
+            b'foobar="' + to_big_header_data + b'">'
+            b'</svg>"'
+        )
+        image = self._makeImage()
+        image._setData(data)
+        self.assertEqual(image.getImageSize(), (1024, 680))
+        self.assertGreater(len(to_big_header_data), IMAGE_INFO_BYTES)
+
 
 class TestImageFunctional(unittest.TestCase):
 

plone/namedfile/tests/test_svg.py

@@ -1,11 +1,11 @@
+import unittest
+
 from plone.namedfile.file import NamedImage
 from plone.namedfile.tests import getFile
 from plone.namedfile.utils import get_contenttype
 from plone.namedfile.utils.svg_utils import dimension_int
 from plone.namedfile.utils.svg_utils import process_svg
 
-import unittest
-
 
 class TestSvg(unittest.TestCase):
     def test_get_contenttype(self):
@@ -23,6 +23,25 @@ def test_process_svg(self):
         self.assertEqual(width, 158)
         self.assertEqual(height, 40)
 
+    def test_process_svg__indicate_header_truncation(self):
+        """ Check that we can detect SVG files where the file header was
+         larger than the requested first bytes. process_svg() should
+         return -1 as dimensions to indicate the truncation."""
+
+        truncated_data = getFile("image_large_header.svg", length=1024)
+        content_type, width, height = process_svg(truncated_data)
+        self.assertEqual(content_type, "image/svg+xml")
+        self.assertEqual(width, -1)
+        self.assertEqual(height, -1)
+
+    def test_process_svg__can_handle_large_header(self):
+
+        data = getFile("image_large_header.svg")
+        content_type, width, height = process_svg(data)
+        self.assertEqual(content_type, "image/svg+xml")
+        self.assertEqual(width, 1041)
+        self.assertEqual(height, 751)
+
     def test_dimension_int(self):
 
         self.assertEqual(dimension_int("auto"), 0)

plone/namedfile/utils/svg_utils.py

@@ -21,15 +21,16 @@ def process_svg(data):
             w = dimension_int(el.attrib.get("width"))
             h = dimension_int(el.attrib.get("height"))
             break
-    except et.ParseError:
+        w = w if w > 1 else 1
+        h = h if h > 1 else 1
+    except et.ParseError as e:
+        log.debug(f"Failed to parse SVG dimensions: {e}")
         pass
 
     if tag == "{http://www.w3.org/2000/svg}svg" or (
         size == 1024 and b"http://www.w3.org/2000/svg" in data
     ):
         content_type = "image/svg+xml"
-        w = w if w > 1 else 1
-        h = h if h > 1 else 1
 
     return content_type, w, h