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427dcb4bca
This introduces the diff-core, the layer between the diff-tree family and the external diff interface engine. The calls to the interface diff-tree family uses (diff_change and diff_addremove) have not changed and will not change. The purpose of the diff-core layer is to provide an infrastructure to transform the set of differences sent from the applications, before sending them to the external diff interface. The recently introduced rename detection code has been rewritten to use the diff-core facility. When applications send in separate creates and deletes, matching ones are transformed into a single rename-and-edit diff, and sent out to the external diff interface as such. This patch also enhances the rename detection code further to be able to detect copies. Currently this happens only as long as copy sources appear as part of the modified files, but there already is enough provision for callers to report unmodified files to diff-core, so that they can be also used as copy source candidates. Extending the callers this way will be done in a separate patch. Please see and marvel at how well this works by trying out the newly added t/t4003-diff-rename-1.sh test script. Signed-off-by: Junio C Hamano <junkio@cox.net> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
151 lines
4.9 KiB
Plaintext
151 lines
4.9 KiB
Plaintext
git-diff-cache(1)
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=================
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v0.1, May 2005
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NAME
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----
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git-diff-cache - Compares content and mode of blobs between the cache and repository
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SYNOPSIS
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--------
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'git-diff-cache' [-p] [-r] [-z] [-m] [-M] [-R] [-C] [--cached] <tree-ish>
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DESCRIPTION
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-----------
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Compares the content and mode of the blobs found via a tree object
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with the content of the current cache and, optionally ignoring the
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stat state of the file on disk.
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OPTIONS
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-------
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<tree-ish>::
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The id of a tree object to diff against.
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-p::
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Generate patch (see section on generating patches)
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-r::
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This flag does not mean anything. It is there only to match
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"git-diff-tree". Unlike "git-diff-tree", "git-diff-cache"
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always looks at all the subdirectories.
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-z::
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\0 line termination on output
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-M::
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Detect renames; implies -p.
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-C::
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Detect copies as well as renames; implies -p.
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-R::
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Output diff in reverse.
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--cached::
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do not consider the on-disk file at all
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-m::
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By default, files recorded in the index but not checked
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out are reported as deleted. This flag makes
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"git-diff-cache" say that all non-checked-out files are up
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to date.
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Output format
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-------------
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include::diff-format.txt[]
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Operating Modes
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---------------
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You can choose whether you want to trust the index file entirely
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(using the '--cached' flag) or ask the diff logic to show any files
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that don't match the stat state as being "tentatively changed". Both
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of these operations are very useful indeed.
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Cached Mode
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-----------
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If '--cached' is specified, it allows you to ask:
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show me the differences between HEAD and the current index
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contents (the ones I'd write with a "git-write-tree")
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For example, let's say that you have worked on your index file, and are
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ready to commit. You want to see eactly *what* you are going to commit is
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without having to write a new tree object and compare it that way, and to
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do that, you just do
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git-diff-cache --cached $(cat .git/HEAD)
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Example: let's say I had renamed `commit.c` to `git-commit.c`, and I had
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done an "git-update-cache" to make that effective in the index file.
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"git-diff-files" wouldn't show anything at all, since the index file
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matches my working directory. But doing a "git-diff-cache" does:
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torvalds@ppc970:~/git> git-diff-cache --cached $(cat .git/HEAD)
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-100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c
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+100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c
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You can trivially see that the above is a rename.
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In fact, "git-diff-cache --cached" *should* always be entirely equivalent to
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actually doing a "git-write-tree" and comparing that. Except this one is much
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nicer for the case where you just want to check where you are.
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So doing a "git-diff-cache --cached" is basically very useful when you are
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asking yourself "what have I already marked for being committed, and
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what's the difference to a previous tree".
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Non-cached Mode
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---------------
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The "non-cached" mode takes a different approach, and is potentially
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the more useful of the two in that what it does can't be emulated with
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a "git-write-tree" + "git-diff-tree". Thus that's the default mode.
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The non-cached version asks the question:
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show me the differences between HEAD and the currently checked out
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tree - index contents _and_ files that aren't up-to-date
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which is obviously a very useful question too, since that tells you what
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you *could* commit. Again, the output matches the "git-diff-tree -r"
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output to a tee, but with a twist.
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The twist is that if some file doesn't match the cache, we don't have
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a backing store thing for it, and we use the magic "all-zero" sha1 to
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show that. So let's say that you have edited `kernel/sched.c`, but
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have not actually done a "git-update-cache" on it yet - there is no
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"object" associated with the new state, and you get:
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torvalds@ppc970:~/v2.6/linux> git-diff-cache $(cat .git/HEAD )
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*100644->100664 blob 7476bb......->000000...... kernel/sched.c
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ie it shows that the tree has changed, and that `kernel/sched.c` has is
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not up-to-date and may contain new stuff. The all-zero sha1 means that to
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get the real diff, you need to look at the object in the working directory
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directly rather than do an object-to-object diff.
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NOTE! As with other commands of this type, "git-diff-cache" does not
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actually look at the contents of the file at all. So maybe
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`kernel/sched.c` hasn't actually changed, and it's just that you
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touched it. In either case, it's a note that you need to
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"git-upate-cache" it to make the cache be in sync.
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NOTE 2! You can have a mixture of files show up as "has been updated"
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and "is still dirty in the working directory" together. You can always
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tell which file is in which state, since the "has been updated" ones
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show a valid sha1, and the "not in sync with the index" ones will
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always have the special all-zero sha1.
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Author
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------
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Written by Linus Torvalds <torvalds@osdl.org>
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Documentation
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--------------
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Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
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GIT
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---
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Part of the link:git.html[git] suite
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