The man page for gitattributes suggests that one use of the diff attribute is to force text-based diffs, even when the file contains embedded NULs. Yet actually trying this falls flat, since git generates invalid diffs when encountering embedded NUL. Here is a pared-down example showing the bug. I based it off of what I was trying to do in the git repository for GNU m4, where I was working on adding testcases to make m4 seamlessly handle embedded NUL. $ git --version git version 1.5.4.rc0.67.gf9c5 $ mkdir sample $ cd sample $ git init Initialized empty Git repository in .git/ $ printf 'context with\0embedded nul\nbefore\nmore context\n' > file $ git add file $ git commit -m initial Created initial commit 25108f6: initial 1 files changed, 0 insertions(+), 0 deletions(-) create mode 100644 file $ git tag t1 $ sed -i 's/before/after/' file $ git add file $ git commit -m later Created commit a5ee10c: later 1 files changed, 0 insertions(+), 0 deletions(-) $ git tag t2 $ git reset --hard t1 HEAD is now at 25108f6... initial $ sed -i 's/more/some &/' file $ echo 'file diff' > .gitattributes $ git add .gitattributes file $ git commit -m 'switch file to text mode' Created commit 0f2a9b2: switch file to text mode 2 files changed, 2 insertions(+), 1 deletions(-) create mode 100644 .gitattributes $ git tag t3 $ git reset --hard t2 HEAD is now at a5ee10c... later $ git rebase --onto t3 t1 First, rewinding head to replay your work on top of it... HEAD is now at 0f2a9b2... switch file to text mode Applying later error: patch failed: file:1 error: file: patch does not apply Using index info to reconstruct a base tree... error: patch failed: file:1 error: file: patch does not apply Did you hand edit your patch? It does not apply to blobs recorded in its index. Cannot fall back to three-way merge. Patch failed at 0001. When you have resolved this problem run "git rebase --continue". If you would prefer to skip this patch, instead run "git rebase --skip". To restore the original branch and stop rebasing run "git rebase --abort". Looking closer at .dotest/0001, the diff is indeed invalid, containing the single line context with-before instead of the desired two lines context with^@embedded nul -before I'm also wondering if using GIT_EXTERNAL_DIFF would provide a way to work around this bug in git diff, since GNU diffutils doesn't seem to have any problems when doing text-mode diffs with embedded NUL: $ diff -u -a <(git show t1:file) <(git show t2:file) | cat -v --- /dev/fd/63 2006-11-30 17:00:00.000000000 -0700 +++ /dev/fd/62 2006-11-30 17:00:00.000000000 -0700 @@ -1,3 +1,3 @@ context with^@embedded nul -before +after more context -- Don't work too hard, make some time for fun as well! Eric Blake ebb9@xxxxxxx - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
