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authorJunio C Hamano <junkio@cox.net>2005-11-14 08:41:53 (GMT)
committerJunio C Hamano <junkio@cox.net>2005-11-18 23:53:15 (GMT)
commit7f59dbbb8f8d479c1d31453eac06ec765436a780 (patch)
tree69af49ca677953f768baf8ad6e015b1aeb8bd113 /git-rebase.sh
parentf9039f30d56e3815eaab870d8b19c7b94aded8aa (diff)
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Rewrite rebase to use git-format-patch piped to git-am.
The current rebase implementation finds commits in our tree but not in the upstream tree using git-cherry, and tries to apply them using git-cherry-pick (i.e. always use 3-way) one by one. Which is fine, but when some of the changes do not apply cleanly, it punts, and punts badly. Suppose you have commits A-B-C-D-E since you forked from the upstream and submitted the changes for inclusion. You fetch from upstream head U and find that B has been picked up. You run git-rebase to update your branch, which tries to apply changes contained in A-C-D-E, in this order, but replaying of C fails, because the upstream got changes that touch the same area from elsewhere. Now what? It notes that fact, and goes ahead to apply D and E, and at the very end tells you to deal with C by hand. Even if you somehow managed to replay C on top of the result, you would now end up with ...-B-...-U-A-D-E-C. Breaking the order between B and others was the conscious decision made by the upstream, so we would not worry about it, and even if it were worrisome, it is too late for us to fix now. What D and E do may well depend on having C applied before them, which is a problem for us. This rewrites rebase to use git-format-patch piped to git-am, and when the patch does not apply, have git-am fall back on 3-way merge. The updated diff/patch pair knows how to apply trivial binary patches as long as the pre- and post-images are locally available, so this should work on a repository with binary files as well. The primary benefit of this change is that it makes rebase easier to use when some of the changes do not replay cleanly. In the "unapplicable patch in the middle" case, this "rebase" works like this: - A series of patches in e-mail form is created that records what A-C-D-E do, and is fed to git-am. This is stored in .dotest/ directory, just like the case you tried to apply them from your mailbox. Your branch is rewound to the tip of upstream U, and the original head is kept in .git/ORIG_HEAD, so you could "git reset --hard ORIG_HEAD" in case the end result is really messy. - Patch A applies cleanly. This could either be a clean patch application on top of rewound head (i.e. same as upstream head), or git-am might have internally fell back on 3-way (i.e. it would have done the same thing as git-cherry-pick). In either case, a rebased commit A is made on top of U. - Patch C does not apply. git-am stops here, with conflicts to be resolved in the working tree. Yet-to-be-applied D and E are still kept in .dotest/ directory at this point. What the user does is exactly the same as fixing up unapplicable patch when running git-am: - Resolve conflict just like any merge conflicts. - "git am --resolved --3way" to continue applying the patches. - This applies the fixed-up patch so by definition it had better apply. "git am" knows the patch after the fixed-up one is D and then E; it applies them, and you will get the changes from A-C-D-E commits on top of U, in this order. I've been using this without noticing any problem, and as people may know I do a lot of rebases. Signed-off-by: Junio C Hamano <junkio@cox.net>
Diffstat (limited to 'git-rebase.sh')
-rwxr-xr-xgit-rebase.sh72
1 files changed, 16 insertions, 56 deletions
diff --git a/git-rebase.sh b/git-rebase.sh
index fa95009..5289762 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -5,65 +5,25 @@
. git-sh-setup || die "Not a git archive."
-usage="usage: $0 "'<upstream> [<head>]
-
-Uses output from git-cherry to rebase local commits to the new head of
-upstream tree.'
-
-case "$#,$1" in
-1,*..*)
- upstream=$(expr "$1" : '\(.*\)\.\.') ours=$(expr "$1" : '.*\.\.\(.*\)$')
- set x "$upstream" "$ours"
- shift ;;
-esac
+# The other head is given
+other=$(git-rev-parse --verify "$1^0") || exit
+# The tree must be really really clean.
git-update-index --refresh || exit
+diff=$(git-diff-index --cached --name-status -r HEAD)
+case "$different" in
+?*) echo "$diff"
+ exit 1
+ ;;
+esac
+# If the branch to rebase is given, first switch to it.
case "$#" in
-1) ours_symbolic=HEAD ;;
-2) ours_symbolic="$2" ;;
-*) die "$usage" ;;
+2)
+ git-checkout "$2" || exit
esac
-upstream=`git-rev-parse --verify "$1"` &&
-ours=`git-rev-parse --verify "$ours_symbolic"` || exit
-different1=$(git-diff-index --name-only --cached "$ours") &&
-different2=$(git-diff-index --name-only "$ours") &&
-test "$different1$different2" = "" ||
-die "Your working tree does not match $ours_symbolic."
-
-git-read-tree -m -u $ours $upstream &&
-new_head=$(git-rev-parse --verify "$upstream^0") &&
-git-update-ref HEAD "$new_head" || exit
-
-tmp=.rebase-tmp$$
-fail=$tmp-fail
-trap "rm -rf $tmp-*" 1 2 3 15
-
->$fail
-
-git-cherry -v $upstream $ours |
-while read sign commit msg
-do
- case "$sign" in
- -)
- echo >&2 "* Already applied: $msg"
- continue ;;
- esac
- echo >&2 "* Applying: $msg"
- S=$(git-rev-parse --verify HEAD) &&
- git-cherry-pick --replay $commit || {
- echo >&2 "* Not applying the patch and continuing."
- echo $commit >>$fail
- git-reset --hard $S
- }
-done
-if test -s $fail
-then
- echo >&2 Some commits could not be rebased, check by hand:
- cat >&2 $fail
- echo >&2 "(the same list of commits are found in $tmp)"
- exit 1
-else
- rm -f $fail
-fi
+# Rewind the head to "$other"
+git-reset --hard "$other"
+git-format-patch -k --stdout --full-index "$other" ORIG_HEAD |
+git am --binary -3 -k