git-merge.sh

   1 #!/bin/sh
   2 #
   3 # Copyright (c) 2005 Junio C Hamano
   4 #
   5
   6 USAGE='[-n] [--summary] [--no-commit] [--squash] [-s <strategy>] [-m=<merge-message>] <commit>+'
   7
   8 SUBDIRECTORY_OK=Yes
   9 . git-sh-setup
  10 require_work_tree
  11 cd_to_toplevel
  12
  13 test -z "$(git ls-files -u)" ||
  14         die "You are in the middle of a conflicted merge."
  15
  16 LF='
  17 '
  18
  19 all_strategies='recur recursive octopus resolve stupid ours subtree'
  20 default_twohead_strategies='recursive'
  21 default_octopus_strategies='octopus'
  22 no_fast_forward_strategies='subtree ours'
  23 no_trivial_strategies='recursive recur subtree ours'
  24 use_strategies=
  25
  26 allow_fast_forward=t
  27 allow_trivial_merge=t
  28
  29 dropsave() {
  30         rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
  31                  "$GIT_DIR/MERGE_SAVE" || exit 1
  32 }
  33
  34 savestate() {
  35         # Stash away any local modifications.
  36         git diff-index -z --name-only $head |
  37         cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
  38 }
  39
  40 restorestate() {
  41         if test -f "$GIT_DIR/MERGE_SAVE"
  42         then
  43                 git reset --hard $head >/dev/null
  44                 cpio -iuv <"$GIT_DIR/MERGE_SAVE"
  45                 git update-index --refresh >/dev/null
  46         fi
  47 }
  48
  49 finish_up_to_date () {
  50         case "$squash" in
  51         t)
  52                 echo "$1 (nothing to squash)" ;;
  53         '')
  54                 echo "$1" ;;
  55         esac
  56         dropsave
  57 }
  58
  59 squash_message () {
  60         echo Squashed commit of the following:
  61         echo
  62         git log --no-merges ^"$head" $remote
  63 }
  64
  65 finish () {
  66         if test '' = "$2"
  67         then
  68                 rlogm="$GIT_REFLOG_ACTION"
  69         else
  70                 echo "$2"
  71                 rlogm="$GIT_REFLOG_ACTION: $2"
  72         fi
  73         case "$squash" in
  74         t)
  75                 echo "Squash commit -- not updating HEAD"
  76                 squash_message >"$GIT_DIR/SQUASH_MSG"
  77                 ;;
  78         '')
  79                 case "$merge_msg" in
  80                 '')
  81                         echo "No merge message -- not updating HEAD"
  82                         ;;
  83                 *)
  84                         git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
  85                         ;;
  86                 esac
  87                 ;;
  88         esac
  89         case "$1" in
  90         '')
  91                 ;;
  92         ?*)
  93                 if test "$show_diffstat" = t
  94                 then
  95                         # We want color (if set), but no pager
  96                         GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
  97                 fi
  98                 ;;
  99         esac
 100 }
 101
 102 merge_name () {
 103         remote="$1"
 104         rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
 105         bh=$(git show-ref -s --verify "refs/heads/$remote" 2>/dev/null)
 106         if test "$rh" = "$bh"
 107         then
 108                 echo "$rh               branch '$remote' of ."
 109         elif truname=$(expr "$remote" : '\(.*\)~[1-9][0-9]*$') &&
 110                 git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
 111         then
 112                 echo "$rh               branch '$truname' (early part) of ."
 113         elif test "$remote" = "FETCH_HEAD" -a -r "$GIT_DIR/FETCH_HEAD"
 114         then
 115                 sed -e 's/      not-for-merge   /               /' -e 1q \
 116                         "$GIT_DIR/FETCH_HEAD"
 117         else
 118                 echo "$rh               commit '$remote'"
 119         fi
 120 }
 121
 122 case "$#" in 0) usage ;; esac
 123
 124 have_message=
 125 while test $# != 0
 126 do
 127         case "$1" in
 128         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
 129                 --no-summa|--no-summar|--no-summary)
 130                 show_diffstat=false ;;
 131         --summary)
 132                 show_diffstat=t ;;
 133         --sq|--squ|--squa|--squas|--squash)
 134                 squash=t no_commit=t ;;
 135         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
 136                 no_commit=t ;;
 137         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 138                 --strateg=*|--strategy=*|\
 139         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
 140                 case "$#,$1" in
 141                 *,*=*)
 142                         strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
 143                 1,*)
 144                         usage ;;
 145                 *)
 146                         strategy="$2"
 147                         shift ;;
 148                 esac
 149                 case " $all_strategies " in
 150                 *" $strategy "*)
 151                         use_strategies="$use_strategies$strategy " ;;
 152                 *)
 153                         die "available strategies are: $all_strategies" ;;
 154                 esac
 155                 ;;
 156         -m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
 157                 merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
 158                 have_message=t
 159                 ;;
 160         -m|--m|--me|--mes|--mess|--messa|--messag|--message)
 161                 shift
 162                 case "$#" in
 163                 1)      usage ;;
 164                 esac
 165                 merge_msg="$1"
 166                 have_message=t
 167                 ;;
 168         -*)     usage ;;
 169         *)      break ;;
 170         esac
 171         shift
 172 done
 173
 174 if test -z "$show_diffstat"; then
 175     test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
 176     test -z "$show_diffstat" && show_diffstat=t
 177 fi
 178
 179 # This could be traditional "merge <msg> HEAD <commit>..."  and the
 180 # way we can tell it is to see if the second token is HEAD, but some
 181 # people might have misused the interface and used a committish that
 182 # is the same as HEAD there instead.  Traditional format never would
 183 # have "-m" so it is an additional safety measure to check for it.
 184
 185 if test -z "$have_message" &&
 186         second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
 187         head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
 188         test "$second_token" = "$head_commit"
 189 then
 190         merge_msg="$1"
 191         shift
 192         head_arg="$1"
 193         shift
 194 elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 195 then
 196         # If the merged head is a valid one there is no reason to
 197         # forbid "git merge" into a branch yet to be born.  We do
 198         # the same for "git pull".
 199         if test 1 -ne $#
 200         then
 201                 echo >&2 "Can merge only exactly one commit into empty head"
 202                 exit 1
 203         fi
 204
 205         rh=$(git rev-parse --verify "$1^0") ||
 206                 die "$1 - not something we can merge"
 207
 208         git update-ref -m "initial pull" HEAD "$rh" "" &&
 209         git read-tree --reset -u HEAD
 210         exit
 211
 212 else
 213         # We are invoked directly as the first-class UI.
 214         head_arg=HEAD
 215
 216         # All the rest are the commits being merged; prepare
 217         # the standard merge summary message to be appended to
 218         # the given message.  If remote is invalid we will die
 219         # later in the common codepath so we discard the error
 220         # in this loop.
 221         merge_name=$(for remote
 222                 do
 223                         merge_name "$remote"
 224                 done | git fmt-merge-msg
 225         )
 226         merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
 227 fi
 228 head=$(git rev-parse --verify "$head_arg"^0) || usage
 229
 230 # All the rest are remote heads
 231 test "$#" = 0 && usage ;# we need at least one remote head.
 232 set_reflog_action "merge $*"
 233
 234 remoteheads=
 235 for remote
 236 do
 237         remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
 238             die "$remote - not something we can merge"
 239         remoteheads="${remoteheads}$remotehead "
 240         eval GITHEAD_$remotehead='"$remote"'
 241         export GITHEAD_$remotehead
 242 done
 243 set x $remoteheads ; shift
 244
 245 case "$use_strategies" in
 246 '')
 247         case "$#" in
 248         1)
 249                 var="`git config --get pull.twohead`"
 250                 if test -n "$var"
 251                 then
 252                         use_strategies="$var"
 253                 else
 254                         use_strategies="$default_twohead_strategies"
 255                 fi ;;
 256         *)
 257                 var="`git config --get pull.octopus`"
 258                 if test -n "$var"
 259                 then
 260                         use_strategies="$var"
 261                 else
 262                         use_strategies="$default_octopus_strategies"
 263                 fi ;;
 264         esac
 265         ;;
 266 esac
 267
 268 for s in $use_strategies
 269 do
 270         for ss in $no_fast_forward_strategies
 271         do
 272                 case " $s " in
 273                 *" $ss "*)
 274                         allow_fast_forward=f
 275                         break
 276                         ;;
 277                 esac
 278         done
 279         for ss in $no_trivial_strategies
 280         do
 281                 case " $s " in
 282                 *" $ss "*)
 283                         allow_trivial_merge=f
 284                         break
 285                         ;;
 286                 esac
 287         done
 288 done
 289
 290 case "$#" in
 291 1)
 292         common=$(git merge-base --all $head "$@")
 293         ;;
 294 *)
 295         common=$(git show-branch --merge-base $head "$@")
 296         ;;
 297 esac
 298 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 299
 300 case "$allow_fast_forward,$#,$common,$no_commit" in
 301 ?,*,'',*)
 302         # No common ancestors found. We need a real merge.
 303         ;;
 304 ?,1,"$1",*)
 305         # If head can reach all the merge then we are up to date.
 306         # but first the most common case of merging one remote.
 307         finish_up_to_date "Already up-to-date."
 308         exit 0
 309         ;;
 310 t,1,"$head",*)
 311         # Again the most common case of merging one remote.
 312         echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 313         git update-index --refresh 2>/dev/null
 314         msg="Fast forward"
 315         if test -n "$have_message"
 316         then
 317                 msg="$msg (no commit created; -m option ignored)"
 318         fi
 319         new_head=$(git rev-parse --verify "$1^0") &&
 320         git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
 321         finish "$new_head" "$msg" || exit
 322         dropsave
 323         exit 0
 324         ;;
 325 ?,1,?*"$LF"?*,*)
 326         # We are not doing octopus and not fast forward.  Need a
 327         # real merge.
 328         ;;
 329 ?,1,*,)
 330         # We are not doing octopus, not fast forward, and have only
 331         # one common.
 332         git update-index --refresh 2>/dev/null
 333         case "$allow_trivial_merge" in
 334         t)
 335                 # See if it is really trivial.
 336                 git var GIT_COMMITTER_IDENT >/dev/null || exit
 337                 echo "Trying really trivial in-index merge..."
 338                 if git read-tree --trivial -m -u -v $common $head "$1" &&
 339                    result_tree=$(git write-tree)
 340                 then
 341                         echo "Wonderful."
 342                         result_commit=$(
 343                                 printf '%s\n' "$merge_msg" |
 344                                 git commit-tree $result_tree -p HEAD -p "$1"
 345                         ) || exit
 346                         finish "$result_commit" "In-index merge"
 347                         dropsave
 348                         exit 0
 349                 fi
 350                 echo "Nope."
 351         esac
 352         ;;
 353 *)
 354         # An octopus.  If we can reach all the remote we are up to date.
 355         up_to_date=t
 356         for remote
 357         do
 358                 common_one=$(git merge-base --all $head $remote)
 359                 if test "$common_one" != "$remote"
 360                 then
 361                         up_to_date=f
 362                         break
 363                 fi
 364         done
 365         if test "$up_to_date" = t
 366         then
 367                 finish_up_to_date "Already up-to-date. Yeeah!"
 368                 exit 0
 369         fi
 370         ;;
 371 esac
 372
 373 # We are going to make a new commit.
 374 git var GIT_COMMITTER_IDENT >/dev/null || exit
 375
 376 # At this point, we need a real merge.  No matter what strategy
 377 # we use, it would operate on the index, possibly affecting the
 378 # working tree, and when resolved cleanly, have the desired tree
 379 # in the index -- this means that the index must be in sync with
 380 # the $head commit.  The strategies are responsible to ensure this.
 381
 382 case "$use_strategies" in
 383 ?*' '?*)
 384     # Stash away the local changes so that we can try more than one.
 385     savestate
 386     single_strategy=no
 387     ;;
 388 *)
 389     rm -f "$GIT_DIR/MERGE_SAVE"
 390     single_strategy=yes
 391     ;;
 392 esac
 393
 394 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 395 merge_was_ok=
 396 for strategy in $use_strategies
 397 do
 398     test "$wt_strategy" = '' || {
 399         echo "Rewinding the tree to pristine..."
 400         restorestate
 401     }
 402     case "$single_strategy" in
 403     no)
 404         echo "Trying merge strategy $strategy..."
 405         ;;
 406     esac
 407
 408     # Remember which strategy left the state in the working tree
 409     wt_strategy=$strategy
 410
 411     git-merge-$strategy $common -- "$head_arg" "$@"
 412     exit=$?
 413     if test "$no_commit" = t && test "$exit" = 0
 414     then
 415         merge_was_ok=t
 416         exit=1 ;# pretend it left conflicts.
 417     fi
 418
 419     test "$exit" = 0 || {
 420
 421         # The backend exits with 1 when conflicts are left to be resolved,
 422         # with 2 when it does not handle the given merge at all.
 423
 424         if test "$exit" -eq 1
 425         then
 426             cnt=`{
 427                 git diff-files --name-only
 428                 git ls-files --unmerged
 429             } | wc -l`
 430             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 431             then
 432                 best_strategy=$strategy
 433                 best_cnt=$cnt
 434             fi
 435         fi
 436         continue
 437     }
 438
 439     # Automerge succeeded.
 440     result_tree=$(git write-tree) && break
 441 done
 442
 443 # If we have a resulting tree, that means the strategy module
 444 # auto resolved the merge cleanly.
 445 if test '' != "$result_tree"
 446 then
 447     parents=$(git show-branch --independent "$head" "$@" | sed -e 's/^/-p /')
 448     result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
 449     finish "$result_commit" "Merge made by $wt_strategy."
 450     dropsave
 451     exit 0
 452 fi
 453
 454 # Pick the result from the best strategy and have the user fix it up.
 455 case "$best_strategy" in
 456 '')
 457         restorestate
 458         case "$use_strategies" in
 459         ?*' '?*)
 460                 echo >&2 "No merge strategy handled the merge."
 461                 ;;
 462         *)
 463                 echo >&2 "Merge with strategy $use_strategies failed."
 464                 ;;
 465         esac
 466         exit 2
 467         ;;
 468 "$wt_strategy")
 469         # We already have its result in the working tree.
 470         ;;
 471 *)
 472         echo "Rewinding the tree to pristine..."
 473         restorestate
 474         echo "Using the $best_strategy to prepare resolving by hand."
 475         git-merge-$best_strategy $common -- "$head_arg" "$@"
 476         ;;
 477 esac
 478
 479 if test "$squash" = t
 480 then
 481         finish
 482 else
 483         for remote
 484         do
 485                 echo $remote
 486         done >"$GIT_DIR/MERGE_HEAD"
 487         printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
 488 fi
 489
 490 if test "$merge_was_ok" = t
 491 then
 492         echo >&2 \
 493         "Automatic merge went well; stopped before committing as requested"
 494         exit 0
 495 else
 496         {
 497             echo '
 498 Conflicts:
 499 '
 500                 git ls-files --unmerged |
 501                 sed -e 's/^[^   ]*      /       /' |
 502                 uniq
 503         } >>"$GIT_DIR/MERGE_MSG"
 504         git rerere
 505         die "Automatic merge failed; fix conflicts and then commit the result."
 506 fi