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='resolve recursive stupid octopus'
  16
  17 all_strategies='recursive octopus resolve stupid ours'
  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 "$1" in
  63         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
  64                 --no-summa|--no-summar|--no-summary)
  65                 no_summary=t ;;
  66         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
  67                 no_commit=t ;;
  68         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
  69                 --strateg=*|--strategy=*|\
  70         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
  71                 case "$#,$1" in
  72                 *,*=*)
  73                         strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
  74                 1,*)
  75                         usage ;;
  76                 *)
  77                         strategy="$2"
  78                         shift ;;
  79                 esac
  80                 case " $all_strategies " in
  81                 *" $strategy "*)
  82                         use_strategies="$use_strategies$strategy " ;;
  83                 *)
  84                         die "available strategies are: $all_strategies" ;;
  85                 esac
  86                 ;;
  87         -*)     usage ;;
  88         *)      break ;;
  89         esac
  90         shift
  91 done
  92
  93 case "$use_strategies" in
  94 '')
  95         use_strategies=$default_strategies
  96         ;;
  97 esac
  98 test "$#" -le 2 && usage ;# we need at least two heads.
  99
 100 merge_msg="$1"
 101 shift
 102 head_arg="$1"
 103 head=$(git-rev-parse --verify "$1"^0) || usage
 104 shift
 105
 106 # All the rest are remote heads
 107 for remote
 108 do
 109         git-rev-parse --verify "$remote"^0 >/dev/null ||
 110             die "$remote - not something we can merge"
 111 done
 112
 113 case "$#" in
 114 1)
 115         common=$(git-merge-base --all $head "$@")
 116         ;;
 117 *)
 118         common=$(git-show-branch --merge-base $head "$@")
 119         ;;
 120 esac
 121 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 122
 123 case "$#,$common,$no_commit" in
 124 *,'',*)
 125         # No common ancestors found. We need a real merge.
 126         ;;
 127 1,"$1",*)
 128         # If head can reach all the merge then we are up to date.
 129         # but first the most common case of merging one remote
 130         echo "Already up-to-date."
 131         dropsave
 132         exit 0
 133         ;;
 134 1,"$head",*)
 135         # Again the most common case of merging one remote.
 136         echo "Updating from $head to $1."
 137         git-update-index --refresh 2>/dev/null
 138         new_head=$(git-rev-parse --verify "$1^0") &&
 139         git-read-tree -u -m $head "$new_head" &&
 140         finish "$new_head" "Fast forward"
 141         dropsave
 142         exit 0
 143         ;;
 144 1,?*"$LF"?*,*)
 145         # We are not doing octopus and not fast forward.  Need a
 146         # real merge.
 147         ;;
 148 1,*,)
 149         # We are not doing octopus, not fast forward, and have only
 150         # one common.  See if it is really trivial.
 151         echo "Trying really trivial in-index merge..."
 152         git-update-index --refresh 2>/dev/null
 153         if git-read-tree --trivial -m -u $common $head "$1" &&
 154            result_tree=$(git-write-tree)
 155         then
 156             echo "Wonderful."
 157             result_commit=$(
 158                 echo "$merge_msg" |
 159                 git-commit-tree $result_tree -p HEAD -p "$1"
 160             ) || exit
 161             finish "$result_commit" "In-index merge"
 162             dropsave
 163             exit 0
 164         fi
 165         echo "Nope."
 166         ;;
 167 *)
 168         # An octopus.  If we can reach all the remote we are up to date.
 169         up_to_date=t
 170         for remote
 171         do
 172                 common_one=$(git-merge-base --all $head $remote)
 173                 if test "$common_one" != "$remote"
 174                 then
 175                         up_to_date=f
 176                         break
 177                 fi
 178         done
 179         if test "$up_to_date" = t
 180         then
 181                 echo "Already up-to-date. Yeeah!"
 182                 dropsave
 183                 exit 0
 184         fi
 185         ;;
 186 esac
 187
 188 # At this point, we need a real merge.  No matter what strategy
 189 # we use, it would operate on the index, possibly affecting the
 190 # working tree, and when resolved cleanly, have the desired tree
 191 # in the index -- this means that the index must be in sync with
 192 # the $head commit.  The strategies are responsible to ensure this.
 193
 194 case "$use_strategies" in
 195 ?*' '?*)
 196     # Stash away the local changes so that we can try more than one.
 197     savestate
 198     single_strategy=no
 199     ;;
 200 *)
 201     rm -f "$GIT_DIR/MERGE_SAVE"
 202     single_strategy=yes
 203     ;;
 204 esac
 205
 206 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 207 for strategy in $use_strategies
 208 do
 209     test "$wt_strategy" = '' || {
 210         echo "Rewinding the tree to pristine..."
 211         restorestate
 212     }
 213     case "$single_strategy" in
 214     no)
 215         echo "Trying merge strategy $strategy..."
 216         ;;
 217     esac
 218
 219     # Remember which strategy left the state in the working tree
 220     wt_strategy=$strategy
 221
 222     git-merge-$strategy $common -- "$head_arg" "$@"
 223     exit=$?
 224     if test "$no_commit" = t && test "$exit" = 0
 225     then
 226         exit=1 ;# pretend it left conflicts.
 227     fi
 228
 229     test "$exit" = 0 || {
 230
 231         # The backend exits with 1 when conflicts are left to be resolved,
 232         # with 2 when it does not handle the given merge at all.
 233
 234         if test "$exit" -eq 1
 235         then
 236             cnt=`{
 237                 git-diff-files --name-only
 238                 git-ls-files --unmerged
 239             } | wc -l`
 240             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 241             then
 242                 best_strategy=$strategy
 243                 best_cnt=$cnt
 244             fi
 245         fi
 246         continue
 247     }
 248
 249     # Automerge succeeded.
 250     result_tree=$(git-write-tree) && break
 251 done
 252
 253 # If we have a resulting tree, that means the strategy module
 254 # auto resolved the merge cleanly.
 255 if test '' != "$result_tree"
 256 then
 257     parents="-p $head"
 258     for remote
 259     do
 260         parents="$parents -p $remote"
 261     done
 262     result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
 263     finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
 264     dropsave
 265     exit 0
 266 fi
 267
 268 # Pick the result from the best strategy and have the user fix it up.
 269 case "$best_strategy" in
 270 '')
 271         restorestate
 272         die "No merge strategy handled the merge."
 273         ;;
 274 "$wt_strategy")
 275         # We already have its result in the working tree.
 276         ;;
 277 *)
 278         echo "Rewinding the tree to pristine..."
 279         restorestate
 280         echo "Using the $best_strategy to prepare resolving by hand."
 281         git-merge-$best_strategy $common -- "$head_arg" "$@"
 282         ;;
 283 esac
 284 for remote
 285 do
 286         echo $remote
 287 done >"$GIT_DIR/MERGE_HEAD"
 288 echo $merge_msg >"$GIT_DIR/MERGE_MSG"
 289
 290 die "Automatic merge failed/prevented; fix up by hand"