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|
#!/bin/bash
#
# Copyright (c) 2012-2013 Luke Shumaker <lukeshu@sbcglobal.net>
#
set -eE
USAGE='[-h|-v|--no-tag|--tag=tag|--svn] <in-branch> <out-branch> <filters>...'
LONG_USAGE='Like filter-branch, but can be used to update branches.
This creates or updates <out-branch> from <in-branch>. If <out-branch> already
exists, it only runs new commits through the filter. This way, this can be
used to pull from a remote repository with a different layout than yours.
New commits are detected by examining a "tag" in the commit messages of
<out-branch> that can be used to tie those commits to corresponding commits in
<in-branch>. By default, the tag is "git-rewrite-id: " followed by the commit
hash of the corresponding commit; similar to the "git-svn-id" appended by
`git-svn`. However, if <in-branch> already has suitable tags in the commit
messages (such as "git-svn-id"), then that can be used, and the commit message
does not need to be edited.
-h Show this text
-v Be more verbose
--tag=<tag> Use the exiting <tag> as found in <in-branch>, instead of
the commit hash.
--no-tag Disregard a previous "--tag="; set "git-rewrite-id" to
the commit hash.
--svn An alias for "--tag=git-svn-id" (use if <in-branch> was
generated by `git-svn`).
<filters> is passed directly to `git filter-branch`, and therefore has the same
format.
'
SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
. git-sh-setup
. git-sh-i18n
require_work_tree_exists
# I $hastag is false, $ibranch's commit hashes are used as IDs
hastag=false # whether ibranch already has tags
tag='git-rewrite-id'
ibranch=''
obranch=''
wbranch=''
panic() {
echo 'panic: malformed call to internal function' >&2
exit 1
}
# Usage: verbose format arg1 arg2...
# Print the printf string, but only if in verbose mode.
# Verbose mode works by redefining this function during option parsing if -v is
# encountered.
verbose() {
:
}
################################################################################
# Usage: id2commit $branch $id
# Returns the commit on $branch with $id.
id2commit() {
[[ $# == 2 ]] || panic
local branch=$1
local id=$2
if [[ $branch == $ibranch ]] && ! $hastag; then
printf '%s\n' "$id"
else
git log "$branch" --pretty=format:'%H' --grep "${tag}: ${id}"
fi
}
# Usage: commit2id $branch $commit
# Returns the id of $commit, which is on $branch.
commit2id() {
[[ $# == 2 ]] || panic
local branch=$1
local commit=$2
if [[ $branch == $ibranch ]] && ! $hastag; then
printf '%s\n' "$commit"
else
git log "$branch" -n1 --pretty=formtat:'%B' "$commit" | sed -n "s|^\s*${tag}: ||p"
fi
}
# commit2commit
# Usage: c2c $from $to $commit
# Returns the commit on branch $to that has the same id as $commit, which is
# on branch $from.
c2c() {
[[ $# == 3 ]] || panic
local from=$1
local to=$2
local commit=$3
if [[ "$from" == "$to" ]]; then
# optimization
# also, properly normalizes $ibranch when $hastag=false
git log "$commit" -n1 --pretty=format:'%H'
else
id2commit "$to" "$(commit2id "$from" "$commit")"
fi
}
################################################################################
main() {
# Parse command line arguments #########################################
while true; do
case "${1:-}" in
--svn) hastag=true; tag='git-svn-id' ; shift 1 ;;
--tag=*) hastag=true; tag="${1#*=}" ; shift 1 ;;
--tag) hastag=true; tag=$2 ; shift 2 ;;
--no-tag) hastag=false; tag='git-rewrite-id'; shift 1 ;;
-h) usage; return 0;;
-v)
verbose() {
local fmt=$1
shift
printf "${fmt}\n" "$@"
}
shift
;;
*) break;;
esac
done
if [[ $# < 3 ]]; then
usage
return 1
fi
ibranch=$1
obranch=$2
shift 2
local filters=();
if ! $hastag; then
# Add a filter to append the id to the commit message.
# This is a little confusing to read because of double quoting.
filters=(--msg-filter "sed '\$a'\"${tag}: \${GIT_COMMIT}\"")
# Here it is annotated; "@" indicates characters to be taken
# literally, and "^" indicates string interpolation.
#
# Argument to git-filter-branch:
# sed '$a'"${tag}: ${GIT_COMMIT}"
# @@@@@@@@@^^^^^^@@@@@@@@@@@@@@@@
# Argument to sed:
# $a${tag}: ${GIT_COMMIT}
# @@^^^^^^@@^^^^^^^^^^^^^
fi
filters+=("$@")
# Main #################################################################
wbranch="$obranch.tmp"
local revlist
local rebase
if git checkout "$obranch" -- 2>/dev/null; then
# obranch exists, update it
echo 'Updating existing rewritten branch...'
local icommit="$(c2c "$ibranch" "$ibranch" "$ibranch")"
local ocommit="$(c2c "$obranch" "$ibranch" "$obranch")"
if [[ "$icommit" == "$ocommit" ]]; then
echo "Nothing to do"
return 0
fi
local common="$(c2c "$obranch" "$ibranch" "$obranch")"
if c2c "$ibranch" "$ibranch" "${common}^" &>/dev/null; then
revlist="$(c2c "$obranch" "$ibranch" "$obranch")^..${wbranch}"
else
# There is only one commit from $ibranch in $obranch
revlist="$wbranch"
fi
rebase=true
else
# obranch does not exist, create it
echo 'Creating new rewritten branch...'
revlist=$wbranch
rebase=false
fi
git checkout "$ibranch"
git branch -D "$wbranch" 2>/dev/null || true
git checkout -b "$wbranch"
git filter-branch -f "${filters[@]}" "$revlist"
if $rebase; then
# rebase the changes in wbranch onto obranch
echo 'Rebasing rewrites onto existing branch...'
local wcommit="$(c2c "$wbranch" "$ibranch" "$wbranch")"
if [[ "$wcommit" == "$ocommit" ]]; then
echo "Nothing to do"
return 0
fi
local commonish="$(c2c "$obranch" "$wbranch" "$obranch")"
cmd=(git rebase --onto "$obranch" "$commonish" "$wbranch")
verbose ''
verbose ' o---o---o %s' "$obranch"
verbose ' :'
verbose ' o---o---o---o---o %s' "$ibranch"
verbose ' \ :'
verbose ' `-C---o---o %s' "$wbranch"
verbose ''
verbose ' C = %s' "$commonish"
verbose ''
verbose ' %s' "$(printf '%q ' "${cmd[@]}")"
verbose ''
"${cmd[@]}"
git checkout "$obranch"
git branch -d "$wbranch"
else
git branch -m "$wbranch" "$obranch"
fi
}
main "$@"
|
