git-merge-octopus.sh

   1 #!/bin/sh
   2 #
   3 # Copyright (c) 2005 Junio C Hamano
   4 #
   5 # Resolve two or more trees.
   6 #
   7
   8 LF='
   9 '
  10
  11 die () {
  12     echo >&2 "$*"
  13     exit 1
  14 }
  15
  16 # The first parameters up to -- are merge bases; the rest are heads.
  17 bases= head= remotes= sep_seen=
  18 for arg
  19 do
  20         case ",$sep_seen,$head,$arg," in
  21         *,--,)
  22                 sep_seen=yes
  23                 ;;
  24         ,yes,,*)
  25                 head=$arg
  26                 ;;
  27         ,yes,*)
  28                 remotes="$remotes$arg "
  29                 ;;
  30         *)
  31                 bases="$bases$arg "
  32                 ;;
  33         esac
  34 done
  35
  36 # Reject if this is not an Octopus -- resolve should be used instead.
  37 case "$remotes" in
  38 ?*' '?*)
  39         ;;
  40 *)
  41         exit 2 ;;
  42 esac
  43
  44 # MRC is the current "merge reference commit"
  45 # MRT is the current "merge result tree"
  46
  47 MRC=$head MSG= PARENT="-p $head"
  48 MRT=$(git-write-tree)
  49 CNT=1 ;# counting our head
  50 NON_FF_MERGE=0
  51 for SHA1 in $remotes
  52 do
  53         common=$(git-merge-base --all $MRC $SHA1) ||
  54                 die "Unable to find common commit with $SHA1"
  55
  56         case "$LF$common$LF" in
  57         *"$LF$SHA1$LF"*)
  58                 echo "Already up-to-date with $SHA1"
  59                 continue
  60                 ;;
  61         esac
  62
  63         CNT=`expr $CNT + 1`
  64         PARENT="$PARENT -p $SHA1"
  65
  66         if test "$common,$NON_FF_MERGE" = "$MRC,0"
  67         then
  68                 # The first head being merged was a fast-forward.
  69                 # Advance MRC to the head being merged, and use that
  70                 # tree as the intermediate result of the merge.
  71                 # We still need to count this as part of the parent set.
  72
  73                 echo "Fast forwarding to: $SHA1"
  74                 git-read-tree -u -m $head $SHA1 || exit
  75                 MRC=$SHA1 MRT=$(git-write-tree)
  76                 continue
  77         fi
  78
  79         NON_FF_MERGE=1
  80
  81         echo "Trying simple merge with $SHA1"
  82         git-read-tree -u -m $common $MRT $SHA1 || exit 2
  83         next=$(git-write-tree 2>/dev/null)
  84         if test $? -ne 0
  85         then
  86                 echo "Simple merge did not work, trying automatic merge."
  87                 git-merge-index -o git-merge-one-file -a || {
  88                         echo "Not trivially merged."
  89                         echo "Should not be doing an Octopus."
  90                         exit 2
  91                 }
  92                 next=$(git-write-tree 2>/dev/null)
  93         fi
  94
  95         # We have merged the other branch successfully.  Ideally
  96         # we could implement OR'ed heads in merge-base, and keep
  97         # a list of commits we have merged so far in MRC to feed
  98         # them to merge-base, but we approximate it by keep using
  99         # the current MRC.  We used to update it to $common, which
 100         # was incorrectly doing AND'ed merge-base here, which was
 101         # unneeded.
 102
 103         MRT=$next
 104 done
 105
 106 exit 0