AttributeError: 'FileContentStream' object has no attribute 'seek'

[Ryan J Ollos]

I get the following on Trac 1.0-stable and 1.2-stable:

12:14:49 Trac[api] WARNING: HTML preview using ZipRenderer with <RenderingContext <Resource u'repository:proj1, source:ArchiveViewer-0.1-py2.7.egg@132'>> failed: 
Traceback (most recent call last):
  File "/Users/rjollos/Documents/Workspace/trac-dev/teo-rjollos.git/trac/mimeview/api.py", line 814, in render
    rendered_content, filename, url)
  File "/Users/rjollos/Documents/Workspace/trac-dev/trac-hacks/archiveviewerplugin/1.0/archiveviewer/zip.py", line 125, in render
    zipfile = ZipFile(content.input)
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/zipfile.py", line 770, in __init__
    self._RealGetContents()
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/zipfile.py", line 809, in _RealGetContents
    endrec = _EndRecData(fp)
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/zipfile.py", line 208, in _EndRecData
    fpin.seek(0, 2)
AttributeError: 'FileContentStream' object has no attribute 'seek'

$ svn --version
svn, version 1.9.5 (r1770682)
   compiled May 12 2017, 06:52:50 on x86_64-apple-darwin16.5.0
$ python --version
Python 2.7.13

Issue appears to be associated with addition of FileContentStream class in ​r11797.

[Ryan J Ollos]

Proposed fix, tested with Trac 1.0, 1.0-stable and 1.2-stable:

archiveviewer/zip.py

@@ -36 +36 @@
 from trac.web.href import Href
 from trac.web.wsgi import _FileWrapper
 from trac.wiki.api import IWikiSyntaxProvider
+try:
+    from tracopt.versioncontrol.svn.svn_fs import FileContentStream
+except ImportError:
+    FileContentStream = False
 
 
 class ZipRenderer(Component):
@@ -118 +122 @@
     def render(self, context, mimetype, content, filename=None, url=None):
         if content and content.input:
             max_size = self.env.config.getint('attachment', 'max_zip_size', default=2097152)
-            if (Stream and isinstance(content.input, Stream)) \
+            if Stream and isinstance(content.input, Stream) \
+                    or FileContentStream and isinstance(content.input, FileContentStream) \
                     or ZipExtFile and isinstance(content.input, ZipExtFile):
                 zipfile = ZipFile(StringIO(content.input.read(max_size)))
             else:

[Jun Omae]

I consider it would be simple to use hasattr(content.input, 'seek') (untested).

archiveviewerplugin/1.0/archiveviewer/zip.py

@@ -12 +12 @@
 from genshi.builder import tag
 from genshi.core import QName
 from genshi.filters.transform import Transformer, ENTER
-try:
-    Stream = False
-    from svn.core import Stream
-except ImportError:
-    pass
+
 from trac.attachment import Attachment, AttachmentModule
 from trac.core import Component, implements, TracError
 from trac.mimeview.api import IHTMLPreviewRenderer, Mimeview
@@ -33 +29 @@
 from trac.web.href import Href
 from trac.web.wsgi import _FileWrapper
 from trac.wiki.api import IWikiSyntaxProvider
-from zipfile import ZipFile, ZipExtFile
+from zipfile import ZipFile
 import os
 import re
 
@@ -117 +113 @@
 
     def render(self, context, mimetype, content, filename=None, url=None):
         if content and content.input:
-            max_size = self.env.config.getint('attachment', 'max_zip_size', default=2097152)
-            if (Stream and isinstance(content.input, Stream)) \
-                    or ZipExtFile and isinstance(content.input, ZipExtFile):
-                zipfile = ZipFile(StringIO(content.input.read(max_size)))
-            else:
-                zipfile = ZipFile(content.input)
+            f = content.input
+            if not hasattr(f, 'seek'):
+                max_size = self.config.getint('attachment', 'max_zip_size',
+                                              2097152)
+                f = StringIO(f.read(max_size))
+            zipfile = ZipFile(f)
             listitems = []
             for info in zipfile.infolist():
                 resource = context.resource.child('zip', info.filename)

Also, [attachment] max_zip_size can be -1 to disable download as zip. I think we should check it.

[Ryan J Ollos]

Thanks, that looks good. I will test and commit.

[Ryan J Ollos]

In 16649:

ArchiveViewer 0.2dev: Fix AttributeError with Trac 1.0.2+

Patch by Jun Omae.

Refs #13202.

[Ryan J Ollos]

In 16650:

TracArchiveViewer 0.2dev: Change plugin name

This is being done to follow convention and avoid name clashes
in eventual publication to PyPI.

When upgrading, you should uninstall the old plugin first:
$ pip uninstall ArchiveViewer

Refs #13202.

[Ryan J Ollos]

Replying to Jun Omae:

Also, [attachment] max_zip_size can be -1 to disable download as zip. I think we should check it.

I created #13205 to discuss. Let me know if I'm misunderstanding the issue.