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 "$remote - not something we can merge"
 111 done
 112
 113 common=$(git-show-branch --merge-base $head "$@")
 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 $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 # At this point, we need a real merge.  No matter what strategy
 182 # we use, it would operate on the index, possibly affecting the
 183 # working tree, and when resolved cleanly, have the desired tree
 184 # in the index -- this means that the index must be in sync with
 185 # the $head commit.  The strategies are responsible to ensure this.
 186
 187 case "$use_strategies" in
 188 ?*' '?*)
 189     # Stash away the local changes so that we can try more than one.
 190     savestate
 191     single_strategy=no
 192     ;;
 193 *)
 194     rm -f "$GIT_DIR/MERGE_SAVE"
 195     single_strategy=yes
 196     ;;
 197 esac
 198
 199 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 200 for strategy in $use_strategies
 201 do
 202     test "$wt_strategy" = '' || {
 203         echo "Rewinding the tree to pristine..."
 204         restorestate
 205     }
 206     case "$single_strategy" in
 207     no)
 208         echo "Trying merge strategy $strategy..."
 209         ;;
 210     esac
 211
 212     # Remember which strategy left the state in the working tree
 213     wt_strategy=$strategy
 214
 215     git-merge-$strategy $common -- "$head_arg" "$@"
 216     exit=$?
 217     if test "$no_commit" = t && test "$exit" = 0
 218     then
 219         exit=1 ;# pretend it left conflicts.
 220     fi
 221
 222     test "$exit" = 0 || {
 223
 224         # The backend exits with 1 when conflicts are left to be resolved,
 225         # with 2 when it does not handle the given merge at all.
 226
 227         if test "$exit" -eq 1
 228         then
 229             cnt=`{
 230                 git-diff-files --name-only
 231                 git-ls-files --unmerged
 232             } | wc -l`
 233             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 234             then
 235                 best_strategy=$strategy
 236                 best_cnt=$cnt
 237             fi
 238         fi
 239         continue
 240     }
 241
 242     # Automerge succeeded.
 243     result_tree=$(git-write-tree) && break
 244 done
 245
 246 # If we have a resulting tree, that means the strategy module
 247 # auto resolved the merge cleanly.
 248 if test '' != "$result_tree"
 249 then
 250     parents="-p $head"
 251     for remote
 252     do
 253         parents="$parents -p $remote"
 254     done
 255     result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
 256     finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
 257     dropsave
 258     exit 0
 259 fi
 260
 261 # Pick the result from the best strategy and have the user fix it up.
 262 case "$best_strategy" in
 263 '')
 264         restorestate
 265         die "No merge strategy handled the merge."
 266         ;;
 267 "$wt_strategy")
 268         # We already have its result in the working tree.
 269         ;;
 270 *)
 271         echo "Rewinding the tree to pristine..."
 272         restorestate
 273         echo "Using the $best_strategy to prepare resolving by hand."
 274         git-merge-$best_strategy $common -- "$head_arg" "$@"
 275         ;;
 276 esac
 277 for remote
 278 do
 279         echo $remote
 280 done >"$GIT_DIR/MERGE_HEAD"
 281 echo $merge_msg >"$GIT_DIR/MERGE_MSG"
 282
 283 die "Automatic merge failed/prevented; fix up by hand"