> From: Alcolo Alcolo <alcol...@gmail.com>
> My git history is complex and it's a nightmare to rebase from old commits.
I'm not sure what you're attempting to do, but this might help. It's
a rebasing script I wrote. It appears that it was based on something
Junio wrote. The concept is that it rebases the current branch, but
unlike the standard git-rebase, it replicates the merging structure
between the merge-base commit and the head of the branch. (IIRC, the
standard git-rebase creates a linear branch based on some ordering of
the commits in the old branch.)
Dale
----------------------------------------------------------------------
#!/bin/bash
#
# Copyright (c) 2010 Junio C Hamano.
# Modified by Dale R. Worley.
# Usage: git-rebase--merge-safe <onto>
#
# Rebase the current branch to commit/branch <onto>, replicating the commit
# graph between HEAD and the merge base.
. git-sh-setup
prec=4
set -ex
# Ensure the work tree is clean.
require_clean_work_tree "rebase" "Please commit or stash them."
onto_name=$1
onto=$(git rev-parse --verify "${onto_name}^0") ||
die "Does not point to a valid commit: $1"
head_name=$( git symbolic-ref HEAD )
orig_head=$(git rev-parse --verify $head_name) ||
exit 1
echo onto=$onto
echo head_name=$head_name
echo orig_head=$orig_head
# Get the merge base, which is the root of the branch that we are rebasing.
# (For now, ignore the question of whether there is more than one merge base.)
mb=$(git merge-base "$onto" "$orig_head")
echo mb=$mb
# Get the list of commits to rebase, which is everything between $mb and
# $orig_head.
# Note that $mb is not included.
revisions=`git rev-list --reverse --ancestry-path $mb..$orig_head`
echo revisions=$revisions
# Set up the list mapping the commits on the original branch to the commits
# on the branch we are creating.
# Its format is ",old-hash1/new-hash1,old-hash2/new-hash2,...,".
# The initial value maps $mb to $onto.
map=",$mb/$onto,"
# Export these so git commit can see them.
export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE
# Process each commit in forward topological order.
for cmt in $revisions
do
# Examine the commit to extract information we will need to reconstruct it.
# First parent of the commit that has a mapping, i.e., is part of the
# branch (and has thus been rebuilt already.
first_mapped_parent=
# The new commit that was made of $first_mapped_parent.
first_mapped_parent_mapped=
# List of -p options naming the parent commits, or their new commits if they
# are in the branch.
parents=
# Dissect the old commit's data.
# Output the commit data into FD 3.
exec 3< <( git cat-file commit $cmt )
while read keyword rest <&3
do
case $keyword in
tree)
# Ignored
;;
parent)
# See if the parent is mapped, i.e., is in the
# original branch.
if [[ "$map" == *,$rest/* ]]
then
# This parent has been mapped. Get the new commit.
parent_mapped=${map#*,$rest/}
parent_mapped=${parent_mapped%%,*}
if test -z "$first_mapped_parent"
then
first_mapped_parent=$rest
first_mapped_parent_mapped=$parent_mapped
fi
else
# This parent has not been mapped.
parent_mapped=$rest
fi
# $parent_mapped is a parent of the new commit.
parents="$parents -p $parent_mapped"
;;
author)
# Extract the information about the author.
GIT_AUTHOR_NAME="${rest%% <*}"
GIT_AUTHOR_EMAIL="${rest##* <}"
GIT_AUTHOR_EMAIL="${GIT_AUTHOR_EMAIL%%> *}"
GIT_AUTHOR_DATE="${rest##*> }"
;;
committer)
# Ignored: The new commit will have this user's name
# as committer.
;;
'')
# End of fixed fields, remainder is the commit comment.
# Leave contents of FD 3 queued to be read later by
# git commit-tree.
break
;;
*)
# Ignore all other keywords.
;;
esac
done
echo GIT_AUTHOR_NAME="$GIT_AUTHOR_NAME"
echo GIT_AUTHOR_EMAIL="$GIT_AUTHOR_EMAIL"
echo GIT_AUTHOR_DATE="$GIT_AUTHOR_DATE"
echo parents="$parents"
echo first_mapped_parent=$first_mapped_parent
echo first_mapped_parent_mapped=$first_mapped_parent_mapped
test -n "$first_mapped_parent" || exit 1
# Do the three-way merge.
# Empty the index so git read-tree will merge into it.
git read-tree --empty
git read-tree -m --aggressive \
$first_mapped_parent $cmt $first_mapped_parent_mapped
git merge-index git-merge-one-file -a
# Construct the file tree for the new commit.
tree=$( git write-tree )
# Create the new commit
# Note that FD 3 contains the remainder of the commit description
# from the git cat-file above.
new_commit=$( git commit-tree $tree $parents <&3 )
echo new_commit=$new_commit
# Add the new commit to the map.
map="$map$cmt/$new_commit,"
done
echo Final commit is $new_commit
# Update the branch pointers.
git update-ref ORIG_HEAD $orig_head
git update-ref $head_name $new_commit
# Go to the new head of the branch.
git checkout ${head_name#refs/heads/}
----------------------------------------------------------------------
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