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] [--no-commit] [-s <strategy>]... <merge-message> <head> <remote>+"
  13 }
  14
  15 all_strategies='recursive octopus resolve stupid ours'
  16 default_strategies='recursive'
  17 use_strategies=
  18
  19 dropsave() {
  20         rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
  21                  "$GIT_DIR/MERGE_SAVE" || exit 1
  22 }
  23
  24 savestate() {
  25         # Stash away any local modifications.
  26         git-diff-index -z --name-only $head |
  27         cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
  28 }
  29
  30 restorestate() {
  31         if test -f "$GIT_DIR/MERGE_SAVE"
  32         then
  33                 git reset --hard $head
  34                 cpio -iuv <"$GIT_DIR/MERGE_SAVE"
  35                 git-update-index --refresh >/dev/null
  36         fi
  37 }
  38
  39 finish () {
  40         test '' = "$2" || echo "$2"
  41         case "$merge_msg" in
  42         '')
  43                 echo "No merge message -- not updating HEAD"
  44                 ;;
  45         *)
  46                 git-update-ref HEAD "$1" "$head" || exit 1
  47                 ;;
  48         esac
  49
  50         case "$no_summary" in
  51         '')
  52                 git-diff-tree -p -M "$head" "$1" |
  53                 git-apply --stat --summary
  54                 ;;
  55         esac
  56 }
  57
  58 while case "$#" in 0) break ;; esac
  59 do
  60         case "$1" in
  61         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
  62                 --no-summa|--no-summar|--no-summary)
  63                 no_summary=t ;;
  64         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
  65                 no_commit=t ;;
  66         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
  67                 --strateg=*|--strategy=*|\
  68         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
  69                 case "$#,$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: $all_strategies" ;;
  83                 esac
  84                 ;;
  85         -*)     usage ;;
  86         *)      break ;;
  87         esac
  88         shift
  89 done
  90
  91 test "$#" -le 2 && usage ;# we need at least two heads.
  92
  93 merge_msg="$1"
  94 shift
  95 head_arg="$1"
  96 head=$(git-rev-parse --verify "$1"^0) || usage
  97 shift
  98
  99 # All the rest are remote heads
 100 for remote
 101 do
 102         git-rev-parse --verify "$remote"^0 >/dev/null ||
 103             die "$remote - not something we can merge"
 104 done
 105
 106 case "$#" in
 107 1)
 108         common=$(git-merge-base --all $head "$@")
 109         ;;
 110 *)
 111         common=$(git-show-branch --merge-base $head "$@")
 112         ;;
 113 esac
 114 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 115
 116 case "$#,$common,$no_commit" in
 117 *,'',*)
 118         # No common ancestors found. We need a real merge.
 119         ;;
 120 1,"$1",*)
 121         # If head can reach all the merge then we are up to date.
 122         # but first the most common case of merging one remote
 123         echo "Already up-to-date."
 124         dropsave
 125         exit 0
 126         ;;
 127 1,"$head",*)
 128         # Again the most common case of merging one remote.
 129         echo "Updating from $head to $1."
 130         git-update-index --refresh 2>/dev/null
 131         new_head=$(git-rev-parse --verify "$1^0") &&
 132         git-read-tree -u -m $head "$new_head" &&
 133         finish "$new_head" "Fast forward"
 134         dropsave
 135         exit 0
 136         ;;
 137 1,?*"$LF"?*,*)
 138         # We are not doing octopus and not fast forward.  Need a
 139         # real merge.
 140         ;;
 141 1,*,)
 142         # We are not doing octopus, not fast forward, and have only
 143         # one common.  See if it is really trivial.
 144         echo "Trying really trivial in-index merge..."
 145         git-update-index --refresh 2>/dev/null
 146         if git-read-tree --trivial -m -u $common $head "$1" &&
 147            result_tree=$(git-write-tree)
 148         then
 149             echo "Wonderful."
 150             result_commit=$(
 151                 echo "$merge_msg" |
 152                 git-commit-tree $result_tree -p HEAD -p "$1"
 153             ) || exit
 154             finish "$result_commit" "In-index merge"
 155             dropsave
 156             exit 0
 157         fi
 158         echo "Nope."
 159         ;;
 160 *)
 161         # An octopus.  If we can reach all the remote we are up to date.
 162         up_to_date=t
 163         for remote
 164         do
 165                 common_one=$(git-merge-base --all $head $remote)
 166                 if test "$common_one" != "$remote"
 167                 then
 168                         up_to_date=f
 169                         break
 170                 fi
 171         done
 172         if test "$up_to_date" = t
 173         then
 174                 echo "Already up-to-date. Yeeah!"
 175                 dropsave
 176                 exit 0
 177         fi
 178         ;;
 179 esac
 180
 181 case "$use_strategies" in
 182 '')
 183         case "$#" in
 184         1)
 185                 use_strategies="$default_strategies" ;;
 186         *)
 187                 use_strategies=octopus ;;
 188         esac
 189         ;;
 190 esac
 191
 192 # At this point, we need a real merge.  No matter what strategy
 193 # we use, it would operate on the index, possibly affecting the
 194 # working tree, and when resolved cleanly, have the desired tree
 195 # in the index -- this means that the index must be in sync with
 196 # the $head commit.  The strategies are responsible to ensure this.
 197
 198 case "$use_strategies" in
 199 ?*' '?*)
 200     # Stash away the local changes so that we can try more than one.
 201     savestate
 202     single_strategy=no
 203     ;;
 204 *)
 205     rm -f "$GIT_DIR/MERGE_SAVE"
 206     single_strategy=yes
 207     ;;
 208 esac
 209
 210 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 211 for strategy in $use_strategies
 212 do
 213     test "$wt_strategy" = '' || {
 214         echo "Rewinding the tree to pristine..."
 215         restorestate
 216     }
 217     case "$single_strategy" in
 218     no)
 219         echo "Trying merge strategy $strategy..."
 220         ;;
 221     esac
 222
 223     # Remember which strategy left the state in the working tree
 224     wt_strategy=$strategy
 225
 226     git-merge-$strategy $common -- "$head_arg" "$@"
 227     exit=$?
 228     if test "$no_commit" = t && test "$exit" = 0
 229     then
 230         exit=1 ;# pretend it left conflicts.
 231     fi
 232
 233     test "$exit" = 0 || {
 234
 235         # The backend exits with 1 when conflicts are left to be resolved,
 236         # with 2 when it does not handle the given merge at all.
 237
 238         if test "$exit" -eq 1
 239         then
 240             cnt=`{
 241                 git-diff-files --name-only
 242                 git-ls-files --unmerged
 243             } | wc -l`
 244             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 245             then
 246                 best_strategy=$strategy
 247                 best_cnt=$cnt
 248             fi
 249         fi
 250         continue
 251     }
 252
 253     # Automerge succeeded.
 254     result_tree=$(git-write-tree) && break
 255 done
 256
 257 # If we have a resulting tree, that means the strategy module
 258 # auto resolved the merge cleanly.
 259 if test '' != "$result_tree"
 260 then
 261     parents="-p $head"
 262     for remote
 263     do
 264         parents="$parents -p $remote"
 265     done
 266     result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
 267     finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
 268     dropsave
 269     exit 0
 270 fi
 271
 272 # Pick the result from the best strategy and have the user fix it up.
 273 case "$best_strategy" in
 274 '')
 275         restorestate
 276         die "No merge strategy handled the merge."
 277         ;;
 278 "$wt_strategy")
 279         # We already have its result in the working tree.
 280         ;;
 281 *)
 282         echo "Rewinding the tree to pristine..."
 283         restorestate
 284         echo "Using the $best_strategy to prepare resolving by hand."
 285         git-merge-$best_strategy $common -- "$head_arg" "$@"
 286         ;;
 287 esac
 288 for remote
 289 do
 290         echo $remote
 291 done >"$GIT_DIR/MERGE_HEAD"
 292 echo $merge_msg >"$GIT_DIR/MERGE_MSG"
 293
 294 die "Automatic merge failed/prevented; fix up by hand"