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