Support reverse patching in merge-to-branch.sh

tools/merge-to-branch.sh

 #!/bin/bash
 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
@@ skipping 31 matching lines @@
 cat << EOF
 usage: $0 [OPTIONS]... [BRANCH] [REVISION]...
 
 Performs the necessary steps to merge revisions from bleeding_edge
 to other branches, including trunk.
 
 OPTIONS:
   -h    Show this message
   -s    Specify the step where to start work. Default: 0.
   -p    Specify a patch file to apply as part of the merge
+  -r    Reverse specified patches
 EOF
 }
 
 persist_patch_commit_hashes() {
   echo "PATCH_COMMIT_HASHES=( ${PATCH_COMMIT_HASHES[@]} )" > $COMMIT_HASHES_FILE
 }
 
 restore_patch_commit_hashes() {
   source $COMMIT_HASHES_FILE
 }
 
 restore_patch_commit_hashes_if_unset() {
   [[ "${#PATCH_COMMIT_HASHES[@]}" == 0 ]] && restore_patch_commit_hashes
   [[ "${#PATCH_COMMIT_HASHES[@]}" == 0 ]] && [[ -z "$EXTRA_PATCH" ]] && \
       die "Variable PATCH_COMMIT_HASHES could not be restored."
 }
 
 ########## Option parsing
 
-while getopts ":hs:fp:" OPTION ; do
+while getopts ":hs:fp:r" OPTION ; do
   case $OPTION in
     h)  usage
         exit 0
         ;;
     p)  EXTRA_PATCH=$OPTARG
         ;;
     f)  rm -f "$ALREADY_MERGING_SENTINEL_FILE"
         ;;
+    r)  REVERSE_PATCH="--reverse"
+        ;;
     s)  START_STEP=$OPTARG
         ;;
     ?)  echo "Illegal option: -$OPTARG"
         usage
         exit 1
         ;;
   esac
 done
 let OPTION_COUNT=$OPTIND-1
 shift $OPTION_COUNT
@@ skipping 37 matching lines @@
     [[ -n "$NEXT_HASH" ]] \
       || die "Cannot determine git hash for r$REVISION"
     PATCH_COMMIT_HASHES[$current]="$NEXT_HASH"
     [[ -n "$REVISION_LIST" ]] && REVISION_LIST="$REVISION_LIST,"
     REVISION_LIST="$REVISION_LIST r$REVISION"
     let current+=1
   done
   if [ -z "$REVISION_LIST" ] ; then
     NEW_COMMIT_MSG="Applied patch to $MERGE_TO_BRANCH branch."
   else
-    NEW_COMMIT_MSG="Merged$REVISION_LIST into $MERGE_TO_BRANCH branch."
+    if [ -n "$REVERSE_PATCH" ] ; then
+      NEW_COMMIT_MSG="Rollback of$REVISION_LIST in \
+$MERGE_TO_BRANCH branch."
+    else
+      NEW_COMMIT_MSG="Merged$REVISION_LIST into \
+$MERGE_TO_BRANCH branch."
+    fi;
   fi;
 
   echo "$NEW_COMMIT_MSG" > $COMMITMSG_FILE
   echo "" >> $COMMITMSG_FILE
   for HASH in ${PATCH_COMMIT_HASHES[@]} ; do
     PATCH_MERGE_DESCRIPTION=$(git log -1 --format=%s $HASH)
     echo "$PATCH_MERGE_DESCRIPTION" >> $COMMITMSG_FILE
     echo "" >> $COMMITMSG_FILE
   done
   for HASH in ${PATCH_COMMIT_HASHES[@]} ; do
@@ skipping 110 matching lines @@
   restore_if_unset "TO_URL"
   restore_if_unset "REVISION_LIST"
   restore_version_if_unset "NEW"
   common_cleanup
   echo "*** SUMMARY ***"
   echo "version: $NEWMAJOR.$NEWMINOR.$NEWBUILD.$NEWPATCH"
   echo "branch: $TO_URL"
   echo "svn revision: $SVN_REVISION"
   [[ -n "$REVISION_LIST" ]] && echo "patches:$REVISION_LIST"
 fi