git-merge.sh

   1 #!/bin/sh
   2 #
   3 # Copyright (c) 2005 Junio C Hamano
   4 #
   5
   6 . git-sh-setup || die "Not a git archive"
   7
   8 LF='
   9 '
  10
  11 usage () {
  12     die "git-merge [-n] [-s <strategy>]... <merge-message> <head> <remote>+"
  13 }
  14
  15 # all_strategies='resolve recursive stupid octopus'
  16
  17 all_strategies='recursive octopus resolve stupid'
  18 default_strategies='resolve octopus'
  19 use_strategies=
  20
  21 dropsave() {
  22         rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
  23                  "$GIT_DIR/MERGE_SAVE" || exit 1
  24 }
  25
  26 savestate() {
  27         # Stash away any local modifications.
  28         git-diff-index -z --name-only $head |
  29         cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
  30 }
  31
  32 restorestate() {
  33         if test -f "$GIT_DIR/MERGE_SAVE"
  34         then
  35                 git reset --hard $head
  36                 cpio -iuv <"$GIT_DIR/MERGE_SAVE"
  37                 git-update-index --refresh >/dev/null
  38         fi
  39 }
  40
  41 finish () {
  42         test '' = "$2" || echo "$2"
  43         case "$merge_msg" in
  44         '')
  45                 echo "No merge message -- not updating HEAD"
  46                 ;;
  47         *)
  48                 git-update-ref HEAD "$1" "$head" || exit 1
  49                 ;;
  50         esac
  51
  52         case "$no_summary" in
  53         '')
  54                 git-diff-tree -p -M "$head" "$1" |
  55                 git-apply --stat --summary
  56                 ;;
  57         esac
  58 }
  59
  60 while case "$#" in 0) break ;; esac
  61 do
  62         case "$1" in
  63         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
  64                 --no-summa|--no-summar|--no-summary)
  65                 no_summary=t ;;
  66         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
  67                 --strateg=*|--strategy=*|\
  68         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
  69                 case "$#,$1" in
  70                 *,*=*)
  71                         strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
  72                 1,*)
  73                         usage ;;
  74                 *)
  75                         strategy="$2"
  76                         shift ;;
  77                 esac
  78                 case " $all_strategies " in
  79                 *" $strategy "*)
  80                         use_strategies="$use_strategies$strategy " ;;
  81                 *)
  82                         die "available strategies are: $all_strategies" ;;
  83                 esac
  84                 ;;
  85         -*)     usage ;;
  86         *)      break ;;
  87         esac
  88         shift
  89 done
  90
  91 case "$use_strategies" in
  92 '')
  93         use_strategies=$default_strategies
  94         ;;
  95 esac
  96 test "$#" -le 2 && usage ;# we need at least two heads.
  97
  98 merge_msg="$1"
  99 shift
 100 head_arg="$1"
 101 head=$(git-rev-parse --verify "$1"^0) || usage
 102 shift
 103
 104 # All the rest are remote heads
 105 for remote
 106 do
 107         git-rev-parse --verify "$remote"^0 >/dev/null ||
 108             die "$remote - not something we can merge"
 109 done
 110
 111 common=$(git-show-branch --merge-base $head "$@")
 112 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 113
 114 case "$#,$common" in
 115 *,'')
 116         # No common ancestors found. We need a real merge.
 117         ;;
 118 1,"$1")
 119         # If head can reach all the merge then we are up to date.
 120         # but first the most common case of merging one remote
 121         echo "Already up-to-date."
 122         dropsave
 123         exit 0
 124         ;;
 125 1,"$head")
 126         # Again the most common case of merging one remote.
 127         echo "Updating from $head to $1."
 128         git-update-index --refresh 2>/dev/null
 129         new_head=$(git-rev-parse --verify "$1^0") &&
 130         git-read-tree -u -m $head "$new_head" &&
 131         finish "$new_head" "Fast forward"
 132         dropsave
 133         exit 0
 134         ;;
 135 1,?*"$LF"?*)
 136         # We are not doing octopus and not fast forward.  Need a
 137         # real merge.
 138         ;;
 139 1,*)
 140         # We are not doing octopus, not fast forward, and have only
 141         # one common.  See if it is really trivial.
 142         echo "Trying really trivial in-index merge..."
 143         git-update-index --refresh 2>/dev/null
 144         if git-read-tree --trivial -m -u $common $head "$1" &&
 145            result_tree=$(git-write-tree)
 146         then
 147             echo "Wonderful."
 148             result_commit=$(
 149                 echo "$merge_msg" |
 150                 git-commit-tree $result_tree -p HEAD -p "$1"
 151             ) || exit
 152             finish "$result_commit" "In-index merge"
 153             dropsave
 154             exit 0
 155         fi
 156         echo "Nope."
 157         ;;
 158 *)
 159         # An octopus.  If we can reach all the remote we are up to date.
 160         up_to_date=t
 161         for remote
 162         do
 163                 common_one=$(git-merge-base $head $remote)
 164                 if test "$common_one" != "$remote"
 165                 then
 166                         up_to_date=f
 167                         break
 168                 fi
 169         done
 170         if test "$up_to_date" = t
 171         then
 172                 echo "Already up-to-date. Yeeah!"
 173                 dropsave
 174                 exit 0
 175         fi
 176         ;;
 177 esac
 178
 179 # At this point, we need a real merge.  No matter what strategy
 180 # we use, it would operate on the index, possibly affecting the
 181 # working tree, and when resolved cleanly, have the desired tree
 182 # in the index -- this means that the index must be in sync with
 183 # the $head commit.  The strategies are responsible to ensure this.
 184
 185 case "$use_strategies" in
 186 ?*' '?*)
 187     # Stash away the local changes so that we can try more than one.
 188     savestate
 189     single_strategy=no
 190     ;;
 191 *)
 192     rm -f "$GIT_DIR/MERGE_SAVE"
 193     single_strategy=yes
 194     ;;
 195 esac
 196
 197 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 198 for strategy in $use_strategies
 199 do
 200     test "$wt_strategy" = '' || {
 201         echo "Rewinding the tree to pristine..."
 202         restorestate
 203     }
 204     case "$single_strategy" in
 205     no)
 206         echo "Trying merge strategy $strategy..."
 207         ;;
 208     esac
 209
 210     # Remember which strategy left the state in the working tree
 211     wt_strategy=$strategy
 212
 213     git-merge-$strategy $common -- "$head_arg" "$@" || {
 214
 215         # The backend exits with 1 when conflicts are left to be resolved,
 216         # with 2 when it does not handle the given merge at all.
 217
 218         exit=$?
 219         if test "$exit" -eq 1
 220         then
 221             cnt=`{
 222                 git-diff-files --name-only
 223                 git-ls-files --unmerged
 224             } | wc -l`
 225             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 226             then
 227                 best_strategy=$strategy
 228                 best_cnt=$cnt
 229             fi
 230         fi
 231         continue
 232     }
 233
 234     # Automerge succeeded.
 235     result_tree=$(git-write-tree) && break
 236 done
 237
 238 # If we have a resulting tree, that means the strategy module
 239 # auto resolved the merge cleanly.
 240 if test '' != "$result_tree"
 241 then
 242     parents="-p $head"
 243     for remote
 244     do
 245         parents="$parents -p $remote"
 246     done
 247     result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
 248     finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
 249     dropsave
 250     exit 0
 251 fi
 252
 253 # Pick the result from the best strategy and have the user fix it up.
 254 case "$best_strategy" in
 255 '')
 256         restorestate
 257         die "No merge strategy handled the merge."
 258         ;;
 259 "$wt_strategy")
 260         # We already have its result in the working tree.
 261         ;;
 262 *)
 263         echo "Rewinding the tree to pristine..."
 264         restorestate
 265         echo "Using the $best_strategy to prepare resolving by hand."
 266         git-merge-$best_strategy $common -- "$head_arg" "$@"
 267         ;;
 268 esac
 269 for remote
 270 do
 271         echo $remote
 272 done >"$GIT_DIR/MERGE_HEAD"
 273 echo $merge_msg >"$GIT_DIR/MERGE_MSG"
 274
 275 die "Automatic merge failed; fix up by hand"