Add a tool 'git-resurrect.sh <branch>' that tries to find traces of
the <branch> in the HEAD reflog and, optionally, all merge commits in
the repository. It can then resurrect the branch, pointing it at the
most recent of all candidate commits found.
Signed-off-by: Thomas Rast <trast@xxxxxxxxxxxxxxx>
---
Boyd Stephen Smith Jr. wrote:
> I think it could be quite nice; "undelete"-type commands are generally
> well-received by users and when run against reflogs alone, that's what the
> command is.
>
> It's useful enough to me that I'd love to see it mainlined.
So here's a version for contrib with more options and some other
tweaks.
I removed the ability to "batch resurrect" with several <name>
arguments since that would have conflicted with -b <newname>, but
otherwise the features are the same.
> In my particular case, it wasn't useful without the -m option, but I
> understand why it is not the default.
Aside from the obvious speed reasons, I don't really want to teach
people that commits "know" the branch they were on. It is a pure
coincidence if you can resurrect a topic branch from merge messages;
an equivalent merge could have gone through as a fast-forward, and
you'd never know.
contrib/git-resurrect.sh | 140 ++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 140 insertions(+), 0 deletions(-)
create mode 100755 contrib/git-resurrect.sh
diff --git a/contrib/git-resurrect.sh b/contrib/git-resurrect.sh
new file mode 100755
index 0000000..29bf723
--- /dev/null
+++ b/contrib/git-resurrect.sh
@@ -0,0 +1,140 @@
+#!/bin/sh
+
+USAGE="[-h] [-r] [-m] [-t] [-n] [-b <newname>] <name>"
+LONG_USAGE="git-resurrect attempts to find traces of a branch tip
+called <name>, and tries to resurrect it. Currently, the reflog is
+searched for checkout messages, and with -r also merge messages. With
+-m and -t, the history of all refs is scanned for Merge <name> into
+other/Merge <other> into <name> (respectively) commit subjects, which
+is rather slow but allows you to resurrect other people's topic
+branches."
+
+OPTIONS_SPEC="\
+git resurrect [-h] [-r] [-m] [-t] [-n] [-b <newname>] <name>
+--
+b,branch= save branch as <newname> instead of <name>
+H,try-hard same as -r -m -t
+r,reflog-merges scan for merges recorded in reflog
+m,merges scan for merges into other branches (slow)
+t,merge-targets scan for merges of other branches into <name>
+n,dry-run don't recreate the branch"
+
+. git-sh-setup
+cd_to_toplevel
+
+search_reflog () {
+ sed -n 's~^\([^ ]*\) .*\tcheckout: moving from '"$1"' .*~\1~p' \
+ < .git/logs/HEAD
+}
+
+search_reflog_merges () {
+ sed -n 's~^[^ ]* \([^ ]*\) .*\tmerge '"$1"':~\1~p' \
+ < .git/logs/HEAD
+}
+
+search_merges () {
+ git rev-list --pretty=tformat:"%h %p:%s" --all |
+ grep "Merge branch.*'$branch'.*into" |
+ while read sha rest; do
+ parents="$(echo "$rest" | cut -d: -f1)"
+ case "$parents" in
+ *' '*' '*)
+ warn "$branch took part in octopus merge $sha"
+ warn "check manually!"
+ ;;
+ *' '*)
+ echo "$parents" | cut -d' ' -f2
+ ;;
+ esac
+ done
+}
+
+search_merge_targets () {
+ git rev-list --pretty=tformat:"%h %s" --all |
+ grep "Merge branch '[^']*' into $branch$" |
+ cut -d' ' -f1
+}
+
+dry_run=
+scan_reflog_merges=
+scan_merges=
+scan_merge_targets=
+new_name=
+
+while test "$#" != 0; do
+ case "$1" in
+ -b|--branch)
+ shift
+ new_name="$1"
+ ;;
+ -n|--dry-run)
+ dry_run=t
+ ;;
+ -m|--merges)
+ scan_merges=t
+ ;;
+ -r|--reflog_merges)
+ scan_reflog_merges=t
+ ;;
+ -t|--merge-targets)
+ scan_merge_targets=t
+ ;;
+ -H|--try-hard)
+ scan_reflog_merges=t
+ scan_merges=t
+ scan_merge_targets=t
+ ;;
+ --)
+ shift
+ break
+ ;;
+ *)
+ usage
+ ;;
+ esac
+ shift
+done
+
+test "$#" = 1 || usage
+
+branch="$1"
+test -z "$new_name" && new_name="$branch"q
+
+candidates="$(search_reflog $1)"
+if test ! -z "$scan_reflog_merges"; then
+ candidates="$candidates $(search_reflog_merges $1)"
+fi
+if test ! -z "$scan_merges"; then
+ candidates="$candidates $(search_merges $1)"
+fi
+if test ! -z "$scan_merge_targets"; then
+ candidates="$candidates $(search_merge_targets $1)"
+fi
+
+candidates="$(git rev-parse $candidates | sort -u)"
+
+if test -z "$candidates"; then
+ hint=
+ test "z$scan_merges$scan_reflog_merges$scan_merge_targets" != "zttt" \
+ && hint="(maybe try again with -H)"
+ die "no candidates for $branch found" $hint
+fi
+
+echo "** Candidates for $branch **"
+for cmt in $candidates; do
+ git --no-pager log --pretty=oneline --abbrev-commit -1 $cmt
+done
+
+newest="$(git rev-list -1 $candidates)"
+if test ! -z "$dry_run"; then
+ printf "Most recent: "
+ git --no-pager log -1 --pretty=tformat:"%h %s" $newest
+elif ! git rev-parse --verify --quiet $new_name >/dev/null; then
+ printf "** Restoring $new_name to "
+ git --no-pager log -1 --pretty=tformat:"%h %s" $newest
+ git branch $new_name $newest
+else
+ printf "Most recent: "
+ git --no-pager log -1 --pretty=tformat:"%h %s" $newest
+ echo "** $new_name already exists, doing nothing"
+fi
--
1.6.1.447.gbdf1d
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