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 fredrik stupid octopus'
  16
  17 all_strategies='fredrik octopus resolve stupid'
  18 default_strategies='resolve octopus'
  19 use_strategies=
  20
  21 dropheads() {
  22         rm -f -- "$GIT_DIR/MERGE_HEAD" || exit 1
  23 }
  24
  25 summary() {
  26         case "$no_summary" in
  27         '')
  28                 git-diff-tree -p -M $head "$1" |
  29                 git-apply --stat --summary
  30                 ;;
  31         esac
  32 }
  33
  34 while case "$#" in 0) break ;; esac
  35 do
  36         case "$1" in
  37         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
  38                 --no-summa|--no-summar|--no-summary)
  39                 no_summary=t ;;
  40         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
  41                 --strateg=*|--strategy=*|\
  42         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
  43                 case "$#,$1" in
  44                 *,*=*)
  45                         strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
  46                 0,*)
  47                         usage ;;
  48                 *)
  49                         strategy="$2"
  50                         shift ;;
  51                 esac
  52                 case " $all_strategies " in
  53                 *" $strategy "*)
  54                         use_strategies="$use_strategies$strategy " ;;
  55                 *)
  56                         die "available strategies are: $all_strategies" ;;
  57                 esac
  58                 ;;
  59         -*)     usage ;;
  60         *)      break ;;
  61         esac
  62         shift
  63 done
  64
  65 case "$use_strategies" in
  66 '')
  67         use_strategies=$default_strategies
  68         ;;
  69 esac
  70 test "$#" -le 2 && usage ;# we need at least two heads.
  71
  72 merge_msg="$1"
  73 shift
  74 head=$(git-rev-parse --verify "$1"^0) || usage
  75 shift
  76
  77 # All the rest are remote heads
  78 for remote
  79 do
  80         git-rev-parse --verify "$remote"^0 >/dev/null ||
  81             die "$remote - not something we can merge"
  82 done
  83
  84 common=$(git-show-branch --merge-base $head "$@")
  85 echo "$head" >"$GIT_DIR/ORIG_HEAD"
  86
  87 case "$#,$common" in
  88 *,'')
  89         die "Unable to find common commit between $head and $*"
  90         ;;
  91 1,"$1")
  92         # If head can reach all the merge then we are up to date.
  93         # but first the most common case of merging one remote
  94         echo "Already up-to-date. Yeeah!"
  95         dropheads
  96         exit 0
  97         ;;
  98 1,"$head")
  99         # Again the most common case of merging one remote.
 100         echo "Updating from $head to $1."
 101         git-update-index --refresh 2>/dev/null
 102         git-read-tree -u -m $head "$1" || exit 1
 103         git-rev-parse --verify "$1^0" > "$GIT_DIR/HEAD"
 104         summary "$1"
 105         dropheads
 106         exit 0
 107         ;;
 108 1,*)
 109         # We are not doing octopus and not fast forward.  Need a
 110         # real merge.
 111         ;;
 112 *)
 113         # An octopus.  If we can reach all the remote we are up to date.
 114         up_to_date=t
 115         for remote
 116         do
 117                 common_one=$(git-merge-base $head $remote)
 118                 if test "$common_one" != "$remote"
 119                 then
 120                         up_to_date=f
 121                         break
 122                 fi
 123         done
 124         if test "$up_to_date" = t
 125         then
 126                 echo "Already up-to-date. Yeeah!"
 127                 dropheads
 128                 exit 0
 129         fi
 130         ;;
 131 esac
 132
 133 # At this point we need a real merge.  Require that the tree matches
 134 # exactly our head.
 135
 136 git-update-index --refresh &&
 137 test '' = "`git-diff-index --cached --name-only $head`" || {
 138         die "Need real merge but the working tree has local changes."
 139 }
 140
 141 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 142 for strategy in $use_strategies
 143 do
 144     test "$wt_strategy" = '' || {
 145         echo "Rewinding the tree to pristine..."
 146         git reset --hard $head
 147     }
 148     echo "Trying merge strategy $strategy..."
 149     wt_strategy=$strategy
 150     git-merge-$strategy $common -- $head "$@" || {
 151
 152         # The backend exits with 1 when conflicts are left to be resolved,
 153         # with 2 when it does not handle the given merge at all.
 154
 155         exit=$?
 156         if test "$exit" -eq 1
 157         then
 158             cnt=`{
 159                 git-diff-files --name-only
 160                 git-ls-files --unmerged
 161             } | wc -l`
 162             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 163             then
 164                 best_strategy=$strategy
 165                 best_cnt=$cnt
 166             fi
 167         fi
 168         continue
 169     }
 170
 171     # Automerge succeeded.
 172     result_tree=$(git-write-tree) && break
 173 done
 174
 175 # If we have a resulting tree, that means the strategy module
 176 # auto resolved the merge cleanly.
 177 if test '' != "$result_tree"
 178 then
 179     parents="-p $head"
 180     for remote
 181     do
 182         parents="$parents -p $remote"
 183     done
 184     result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents)
 185     echo "Committed merge $result_commit, made by $wt_strategy."
 186     echo $result_commit >"$GIT_DIR/HEAD"
 187     summary $result_commit
 188     dropheads
 189     exit 0
 190 fi
 191
 192 # Pick the result from the best strategy and have the user fix it up.
 193 case "$best_strategy" in
 194 '')
 195         git reset --hard $head
 196         die "No merge strategy handled the merge."
 197         ;;
 198 "$wt_strategy")
 199         # We already have its result in the working tree.
 200         ;;
 201 *)
 202         echo "Rewinding the tree to pristine..."
 203         git reset --hard $head
 204         echo "Using the $best_strategy to prepare resolving by hand."
 205         git-merge-$best_strategy $common -- $head "$@"
 206         ;;
 207 esac
 208 for remote
 209 do
 210         echo $remote
 211 done >"$GIT_DIR/MERGE_HEAD"
 212 die "Automatic merge failed; fix up by hand"