util/scripts/gerrit-rebase

   1 #!/usr/bin/env bash
   2
   3 # Copyright 2016 Google Inc.
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; version 2 of the License.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13
  14 # $0 from-branch to-branch
  15 #
  16 # applies all commits that from-branch has over to-branch,
  17 # based on a common ancestor and gerrit meta-data
  18 from=$1
  19 to=$2
  20
  21 # match string: this is the git commit line that is used to
  22 # identify commits that were already copied over.
  23 #
  24 # Must not contain spaces except for leading and trailing.
  25 #
  26 # The first pick was Change-Id, but it was lost too often,
  27 # so go for Reviewed-on instead. It's also unique because it
  28 # contains the gerrit instance's host name and the change's number
  29 # on that system.
  30 match_string='[-A-Za-z]*[Rr]eviewed-on:'
  31
  32 # Custom root: allow a certain CL (identified by matching either side's
  33 # match_string) to be the new root, instead of using git's common history only.
  34 # This allows cutting down on commits that are re-evaluated on every run.
  35 #
  36 # Use:
  37 # To the commit message of a commit on the "to" side, add
  38 # $custom_root: match_string (the part coming after $match_string)
  39 #
  40 # For a $match_string of ~ "Reviewed-on: " this might
  41 # be "$custom_root: https://example.com/12345"
  42 #
  43 # On traversal, the commit with "$match_string: https://example.com/12345"
  44 # is then considered a base commit.
  45 custom_root='^Gerrit-Rebase-Ignore-CLs-Before:'
  46
  47 # fetch common ancestor
  48 common_base=$(git merge-base ${from} ${to} 2>/dev/null)
  49
  50 if [ -z "${common_base}" ]; then
  51         echo \"${from}\" or \"${to}\" is not a valid branch name.
  52         exit 1
  53 fi
  54
  55 from_base=$common_base
  56
  57 # fetch custom root ID
  58 croot_marker=$(git log --pretty=%b -1 --grep "${custom_root}" \
  59         ${common_base}..${to} | \
  60         grep "${custom_root}" | cut -d: -f2-)
  61 if [ -n "${croot_marker}" ]; then
  62         from_base=$( ( \
  63                 git log --pretty=%H -1 \
  64                 --grep "^${match_string}${croot_marker}" \
  65                 ${from_base}..${from}; echo ${from_base} )| head -1)
  66 fi
  67
  68 # collect matches that are present on the target side
  69 to_matches="$(git log ${common_base}..${to} | \
  70         grep "^    ${match_string}" | \
  71         cut -d: -f2-)"
  72
  73 # start rebase process, but fail immediately by enforcing an invalid todo
  74 GIT_SEQUENCE_EDITOR="echo foo >" \
  75         git rebase -i --onto ${to} ${from} ${to} 2>/dev/null
  76
  77 # write new rebase todo
  78 # the appended "commit" line triggers handling of the last log entry
  79 commit=""
  80 (git log --reverse ${from_base}..${from} | \
  81         grep -E "(^commit [0-9a-f]{40}\$|^    ${match_string})"; \
  82         echo "commit") | \
  83 while read key value; do
  84         if [ "${key}" = "commit" ]; then
  85                 if [ -n "${commit}" ]; then
  86                         git log -n 1 --pretty="pick %h %s" ${commit}
  87                 fi
  88                 commit="${value}"
  89         else
  90                 # if value was already found on the "to" side, skip this
  91                 # commit
  92                 if [[ ${to_matches} == *"${value}"* ]]; then
  93                         commit=""
  94                 fi
  95         fi
  96 done | GIT_SEQUENCE_EDITOR="cat >" git rebase --edit-todo
  97
  98 # allow user to edit todo
  99 git rebase --edit-todo
 100
 101 # start processing todo to mimick git rebase -i behavior
 102 git rebase --continue