Exception in diff view

[Dirk Stöcker]

As I now grep the log for ValueError for #13792 following came up:

2024-10-12 05:15:10,605 Trac[api] WARNING: HTML preview using PatchRenderer with <RenderingContext <Resource 'ticket:15802, attachment:circular_building_tool_3.patch'>> failed: 
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/trac/mimeview/api.py", line 810, in render
    result = renderer.render(context, full_mimetype,
  File "/usr/local/lib/python3.10/dist-packages/trac/mimeview/patch.py", line 51, in render
    changes = self._diff_to_hdf(content.splitlines(),
  File "/usr/local/lib/python3.10/dist-packages/trac/mimeview/patch.py", line 113, in _diff_to_hdf
    oldpath, newpath = diffcmd_line.split()[-2:]
ValueError: not enough values to unpack (expected 2, got 1)

Happens when calling: ​https://josm.openstreetmap.de/attachment/ticket/15802/circular_building_tool.patch

Seems the code assumes something about the diff which isn't true. Didn't investigate further.

[Jun Omae]

It seems to be caused by the process for GIT binary patch in the diff file.

trac/mimeview/patch.py

@@ -107 +107 @@
                 if not line.startswith('--- '):
                     if not line.startswith('Index: ') and line != '=' * 67:
                         comments.append(line)
-                    if line == "GIT binary patch":
-                        binary = True
-                        diffcmd_line = comments[0] # diff --git a/... b/,,,
-                        oldpath, newpath = diffcmd_line.split()[-2:]
-                        if any(c.startswith('new file') for c in comments):
-                            oldpath = '/dev/null'
-                        if any(c.startswith('deleted file') for c in comments):
-                            newpath = '/dev/null'
-                        oldinfo = ['', oldpath]
-                        newinfo = ['', newpath]
-                        index = [c for c in comments if c.startswith('index ')]
-                        if index: # index 8f****78..1e****5c
-                            oldrev, newrev = index[0].split()[-1].split('..')
-                            oldinfo.append(oldrev)
-                            newinfo.append(newrev)
+                    if line != "GIT binary patch":
                         line = next(lines)
-                        while line:
-                            comments.append(line)
-                            line = next(lines)
+                        continue
+                    binary = True
+                    for pos, c in enumerate(comments):
+                        if c.startswith('diff --git '):
+                            break
                     else:
-                        line = next(lines)
                         continue
+                    diffcmd_line = comments[pos]  # diff --git a/... b/,,,
+                    oldpath, newpath = diffcmd_line.split()[-2:]
+                    if any(c.startswith('new file') for c in comments[pos:]):
+                        oldpath = '/dev/null'
+                    if any(c.startswith('deleted file') for c
+                                                        in comments[pos:]):
+                        newpath = '/dev/null'
+                    oldinfo = ['', oldpath]
+                    newinfo = ['', newpath]
+                    for c in comments[pos:]:
+                        if c.startswith('index '):  # index 8f****78..1e****5c
+                            oldrev, newrev = c.split()[-1].split('..')
+                            oldinfo.append(oldrev)
+                            newinfo.append(newrev)
+                            break
+                    line = next(lines)
+                    while line:
+                        comments.append(line)
+                        line = next(lines)
 
                 if not oldinfo and not newinfo:
                     # Base filename/version from '--- <file> [rev]'

[Jun Omae]

#9140 is a variant of the same issue while processing GIT binary diffs.