git-merge.sh

   1 #!/bin/sh
   2 #
   3 # Copyright (c) 2005 Junio C Hamano
   4 #
   5
   6 . git-sh-setup
   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 "$1"^0) || usage
  97 shift
  98
  99 # All the rest are remote heads
 100 remoteheads=
 101 for remote
 102 do
 103         remotehead=$(git-rev-parse --verify "$remote"^0) ||
 104             die "$remote - not something we can merge"
 105         remoteheads="${remoteheads}$remotehead "
 106 done
 107 set x $remoteheads ; shift
 108
 109 case "$#" in
 110 1)
 111         common=$(git-merge-base --all $head "$@")
 112         ;;
 113 *)
 114         common=$(git-show-branch --merge-base $head "$@")
 115         ;;
 116 esac
 117 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 118
 119 case "$#,$common,$no_commit" in
 120 *,'',*)
 121         # No common ancestors found. We need a real merge.
 122         ;;
 123 1,"$1",*)
 124         # If head can reach all the merge then we are up to date.
 125         # but first the most common case of merging one remote
 126         echo "Already up-to-date."
 127         dropsave
 128         exit 0
 129         ;;
 130 1,"$head",*)
 131         # Again the most common case of merging one remote.
 132         echo "Updating from $head to $1."
 133         git-update-index --refresh 2>/dev/null
 134         new_head=$(git-rev-parse --verify "$1^0") &&
 135         git-read-tree -u -m $head "$new_head" &&
 136         finish "$new_head" "Fast forward"
 137         dropsave
 138         exit 0
 139         ;;
 140 1,?*"$LF"?*,*)
 141         # We are not doing octopus and not fast forward.  Need a
 142         # real merge.
 143         ;;
 144 1,*,)
 145         # We are not doing octopus, not fast forward, and have only
 146         # one common.  See if it is really trivial.
 147         echo "Trying really trivial in-index merge..."
 148         git-update-index --refresh 2>/dev/null
 149         if git-read-tree --trivial -m -u $common $head "$1" &&
 150            result_tree=$(git-write-tree)
 151         then
 152             echo "Wonderful."
 153             result_commit=$(
 154                 echo "$merge_msg" |
 155                 git-commit-tree $result_tree -p HEAD -p "$1"
 156             ) || exit
 157             finish "$result_commit" "In-index merge"
 158             dropsave
 159             exit 0
 160         fi
 161         echo "Nope."
 162         ;;
 163 *)
 164         # An octopus.  If we can reach all the remote we are up to date.
 165         up_to_date=t
 166         for remote
 167         do
 168                 common_one=$(git-merge-base --all $head $remote)
 169                 if test "$common_one" != "$remote"
 170                 then
 171                         up_to_date=f
 172                         break
 173                 fi
 174         done
 175         if test "$up_to_date" = t
 176         then
 177                 echo "Already up-to-date. Yeeah!"
 178                 dropsave
 179                 exit 0
 180         fi
 181         ;;
 182 esac
 183
 184 case "$use_strategies" in
 185 '')
 186         case "$#" in
 187         1)
 188                 use_strategies="$default_strategies" ;;
 189         *)
 190                 use_strategies=octopus ;;
 191         esac
 192         ;;
 193 esac
 194
 195 # At this point, we need a real merge.  No matter what strategy
 196 # we use, it would operate on the index, possibly affecting the
 197 # working tree, and when resolved cleanly, have the desired tree
 198 # in the index -- this means that the index must be in sync with
 199 # the $head commit.  The strategies are responsible to ensure this.
 200
 201 case "$use_strategies" in
 202 ?*' '?*)
 203     # Stash away the local changes so that we can try more than one.
 204     savestate
 205     single_strategy=no
 206     ;;
 207 *)
 208     rm -f "$GIT_DIR/MERGE_SAVE"
 209     single_strategy=yes
 210     ;;
 211 esac
 212
 213 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 214 for strategy in $use_strategies
 215 do
 216     test "$wt_strategy" = '' || {
 217         echo "Rewinding the tree to pristine..."
 218         restorestate
 219     }
 220     case "$single_strategy" in
 221     no)
 222         echo "Trying merge strategy $strategy..."
 223         ;;
 224     esac
 225
 226     # Remember which strategy left the state in the working tree
 227     wt_strategy=$strategy
 228
 229     git-merge-$strategy $common -- "$head_arg" "$@"
 230     exit=$?
 231     if test "$no_commit" = t && test "$exit" = 0
 232     then
 233         exit=1 ;# pretend it left conflicts.
 234     fi
 235
 236     test "$exit" = 0 || {
 237
 238         # The backend exits with 1 when conflicts are left to be resolved,
 239         # with 2 when it does not handle the given merge at all.
 240
 241         if test "$exit" -eq 1
 242         then
 243             cnt=`{
 244                 git-diff-files --name-only
 245                 git-ls-files --unmerged
 246             } | wc -l`
 247             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 248             then
 249                 best_strategy=$strategy
 250                 best_cnt=$cnt
 251             fi
 252         fi
 253         continue
 254     }
 255
 256     # Automerge succeeded.
 257     result_tree=$(git-write-tree) && break
 258 done
 259
 260 # If we have a resulting tree, that means the strategy module
 261 # auto resolved the merge cleanly.
 262 if test '' != "$result_tree"
 263 then
 264     parents="-p $head"
 265     for remote
 266     do
 267         parents="$parents -p $remote"
 268     done
 269     result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
 270     finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
 271     dropsave
 272     exit 0
 273 fi
 274
 275 # Pick the result from the best strategy and have the user fix it up.
 276 case "$best_strategy" in
 277 '')
 278         restorestate
 279         echo >&2 "No merge strategy handled the merge."
 280         exit 2
 281         ;;
 282 "$wt_strategy")
 283         # We already have its result in the working tree.
 284         ;;
 285 *)
 286         echo "Rewinding the tree to pristine..."
 287         restorestate
 288         echo "Using the $best_strategy to prepare resolving by hand."
 289         git-merge-$best_strategy $common -- "$head_arg" "$@"
 290         ;;
 291 esac
 292 for remote
 293 do
 294         echo $remote
 295 done >"$GIT_DIR/MERGE_HEAD"
 296 echo $merge_msg >"$GIT_DIR/MERGE_MSG"
 297
 298 die "Automatic merge failed/prevented; fix up by hand"