Andrew's git / gitweb.git / git-merge.sh
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git-merge.shon commit Merge branch 'js/apply-build-ancestor' (52d5bc9)
   1#!/bin/sh
   2#
   3# Copyright (c) 2005 Junio C Hamano
   4#
   5
   6USAGE='[-n] [--summary] [--no-commit] [--squash] [-s <strategy>] [-m=<merge-message>] <commit>+'
   7
   8SUBDIRECTORY_OK=Yes
   9. git-sh-setup
  10require_work_tree
  11cd_to_toplevel
  12
  13test -z "$(git ls-files -u)" ||
  14        die "You are in the middle of a conflicted merge."
  15
  16LF='
  17'
  18
  19all_strategies='recur recursive octopus resolve stupid ours subtree'
  20default_twohead_strategies='recursive'
  21default_octopus_strategies='octopus'
  22no_fast_forward_strategies='subtree ours'
  23no_trivial_strategies='recursive recur subtree ours'
  24use_strategies=
  25
  26allow_fast_forward=t
  27allow_trivial_merge=t
  28
  29dropsave() {
  30        rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
  31                 "$GIT_DIR/MERGE_SAVE" || exit 1
  32}
  33
  34savestate() {
  35        # Stash away any local modifications.
  36        git diff-index -z --name-only $head |
  37        cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
  38}
  39
  40restorestate() {
  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
  49finish_up_to_date () {
  50        case "$squash" in
  51        t)
  52                echo "$1 (nothing to squash)" ;;
  53        '')
  54                echo "$1" ;;
  55        esac
  56        dropsave
  57}
  58
  59squash_message () {
  60        echo Squashed commit of the following:
  61        echo
  62        git log --no-merges ^"$head" $remote
  63}
  64
  65finish () {
  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
 102merge_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 '$remote'"
 119        fi
 120}
 121
 122case "$#" in 0) usage ;; esac
 123
 124have_message=
 125while test $# != 0
 126do
 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="$1"
 166                have_message=t
 167                ;;
 168        -*)     usage ;;
 169        *)      break ;;
 170        esac
 171        shift
 172done
 173
 174if test -z "$show_diffstat"; then
 175    test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
 176    test -z "$show_diffstat" && show_diffstat=t
 177fi
 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
 185if 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"
 189then
 190        merge_msg="$1"
 191        shift
 192        head_arg="$1"
 193        shift
 194elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 195then
 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
 212else
 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}$merge_name"
 227fi
 228head=$(git rev-parse --verify "$head_arg"^0) || usage
 229
 230# All the rest are remote heads
 231test "$#" = 0 && usage ;# we need at least one remote head.
 232set_reflog_action "merge $*"
 233
 234remoteheads=
 235for remote
 236do
 237        remotehead=$(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
 242done
 243set x $remoteheads ; shift
 244
 245case "$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        ;;
 266esac
 267
 268for s in $use_strategies
 269do
 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                *" $ss "*)
 283                        allow_trivial_merge=f
 284                        break
 285                        ;;
 286                esac
 287        done
 288done
 289
 290case "$#" in
 2911)
 292        common=$(git merge-base --all $head "$@")
 293        ;;
 294*)
 295        common=$(git show-branch --merge-base $head "$@")
 296        ;;
 297esac
 298echo "$head" >"$GIT_DIR/ORIG_HEAD"
 299
 300case "$allow_fast_forward,$#,$common,$no_commit" in
 301?,*,'',*)
 302        # No common ancestors found. We need a real merge.
 303        ;;
 304?,1,"$1",*)
 305        # If head can reach all the merge then we are up to date.
 306        # but first the most common case of merging one remote.
 307        finish_up_to_date "Already up-to-date."
 308        exit 0
 309        ;;
 310t,1,"$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        ;;
 371esac
 372
 373# We are going to make a new commit.
 374git 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 $head commit.  The strategies are responsible to ensure this.
 381
 382case "$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    ;;
 392esac
 393
 394result_tree= best_cnt=-1 best_strategy= wt_strategy=
 395merge_was_ok=
 396for strategy in $use_strategies
 397do
 398    test "$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
 441done
 442
 443# If we have a resulting tree, that means the strategy module
 444# auto resolved the merge cleanly.
 445if test '' != "$result_tree"
 446then
 447    parents=$(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 $wt_strategy."
 450    dropsave
 451    exit 0
 452fi
 453
 454# Pick the result from the best strategy and have the user fix it up.
 455case "$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" "$@"
 476        ;;
 477esac
 478
 479if test "$squash" = t
 480then
 481        finish
 482else
 483        for remote
 484        do
 485                echo $remote
 486        done >"$GIT_DIR/MERGE_HEAD"
 487        printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
 488fi
 489
 490if test "$merge_was_ok" = t
 491then
 492        echo >&2 \
 493        "Automatic merge went well; stopped before committing as requested"
 494        exit 0
 495else
 496        {
 497            echo '
 498Conflicts:
 499'
 500                git ls-files --unmerged |
 501                sed -e 's/^[^   ]*      /       /' |
 502                uniq
 503        } >>"$GIT_DIR/MERGE_MSG"
 504        git rerere
 505        die "Automatic merge failed; fix conflicts and then commit the result."
 506fi