Andrew's git / gitweb.git / contrib/examples/git-merge.sh
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contrib / examples / git-merge.shon commit t5400: avoid concurrent writes into a trace file (71406ed)
   1#!/bin/sh
   2#
   3# Copyright (c) 2005 Junio C Hamano
   4#
   5
   6OPTIONS_KEEPDASHDASH=
   7OPTIONS_SPEC="\
   8git merge [options] <remote>...
   9git merge [options] <msg> HEAD <remote>
  10--
  11stat                 show a diffstat at the end of the merge
  12n                    don't show a diffstat at the end of the merge
  13summary              (synonym to --stat)
  14log                  add list of one-line log to merge commit message
  15squash               create a single commit instead of doing a merge
  16commit               perform a commit if the merge succeeds (default)
  17ff                   allow fast-forward (default)
  18ff-only              abort if fast-forward is not possible
  19rerere-autoupdate    update index with any reused conflict resolution
  20s,strategy=          merge strategy to use
  21X=                   option for selected merge strategy
  22m,message=           message to be used for the merge commit (if any)
  23"
  24
  25SUBDIRECTORY_OK=Yes
  26. git-sh-setup
  27require_work_tree
  28cd_to_toplevel
  29
  30test -z "$(git ls-files -u)" ||
  31        die "Merge is not possible because you have unmerged files."
  32
  33! test -e "$GIT_DIR/MERGE_HEAD" ||
  34        die 'You have not concluded your merge (MERGE_HEAD exists).'
  35
  36LF='
  37'
  38
  39all_strategies='recur recursive octopus resolve stupid ours subtree'
  40all_strategies="$all_strategies recursive-ours recursive-theirs"
  41not_strategies='base file index tree'
  42default_twohead_strategies='recursive'
  43default_octopus_strategies='octopus'
  44no_fast_forward_strategies='subtree ours'
  45no_trivial_strategies='recursive recur subtree ours recursive-ours recursive-theirs'
  46use_strategies=
  47xopt=
  48
  49allow_fast_forward=t
  50fast_forward_only=
  51allow_trivial_merge=t
  52squash= no_commit= log_arg= rr_arg=
  53
  54dropsave() {
  55        rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
  56                 "$GIT_DIR/MERGE_STASH" "$GIT_DIR/MERGE_MODE" || exit 1
  57}
  58
  59savestate() {
  60        # Stash away any local modifications.
  61        git stash create >"$GIT_DIR/MERGE_STASH"
  62}
  63
  64restorestate() {
  65        if test -f "$GIT_DIR/MERGE_STASH"
  66        then
  67                git reset --hard $head >/dev/null
  68                git stash apply $(cat "$GIT_DIR/MERGE_STASH")
  69                git update-index --refresh >/dev/null
  70        fi
  71}
  72
  73finish_up_to_date () {
  74        case "$squash" in
  75        t)
  76                echo "$1 (nothing to squash)" ;;
  77        '')
  78                echo "$1" ;;
  79        esac
  80        dropsave
  81}
  82
  83squash_message () {
  84        echo Squashed commit of the following:
  85        echo
  86        git log --no-merges --pretty=medium ^"$head" $remoteheads
  87}
  88
  89finish () {
  90        if test '' = "$2"
  91        then
  92                rlogm="$GIT_REFLOG_ACTION"
  93        else
  94                echo "$2"
  95                rlogm="$GIT_REFLOG_ACTION: $2"
  96        fi
  97        case "$squash" in
  98        t)
  99                echo "Squash commit -- not updating HEAD"
 100                squash_message >"$GIT_DIR/SQUASH_MSG"
 101                ;;
 102        '')
 103                case "$merge_msg" in
 104                '')
 105                        echo "No merge message -- not updating HEAD"
 106                        ;;
 107                *)
 108                        git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
 109                        git gc --auto
 110                        ;;
 111                esac
 112                ;;
 113        esac
 114        case "$1" in
 115        '')
 116                ;;
 117        ?*)
 118                if test "$show_diffstat" = t
 119                then
 120                        # We want color (if set), but no pager
 121                        GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
 122                fi
 123                ;;
 124        esac
 125
 126        # Run a post-merge hook
 127        if test -x "$GIT_DIR"/hooks/post-merge
 128        then
 129            case "$squash" in
 130            t)
 131                "$GIT_DIR"/hooks/post-merge 1
 132                ;;
 133            '')
 134                "$GIT_DIR"/hooks/post-merge 0
 135                ;;
 136            esac
 137        fi
 138}
 139
 140merge_name () {
 141        remote="$1"
 142        rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
 143        if truname=$(expr "$remote" : '\(.*\)~[0-9]*$') &&
 144                git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
 145        then
 146                echo "$rh               branch '$truname' (early part) of ."
 147                return
 148        fi
 149        if found_ref=$(git rev-parse --symbolic-full-name --verify \
 150                                                        "$remote" 2>/dev/null)
 151        then
 152                expanded=$(git check-ref-format --branch "$remote") ||
 153                        exit
 154                if test "${found_ref#refs/heads/}" != "$found_ref"
 155                then
 156                        echo "$rh               branch '$expanded' of ."
 157                        return
 158                elif test "${found_ref#refs/remotes/}" != "$found_ref"
 159                then
 160                        echo "$rh               remote branch '$expanded' of ."
 161                        return
 162                fi
 163        fi
 164        if test "$remote" = "FETCH_HEAD" && test -r "$GIT_DIR/FETCH_HEAD"
 165        then
 166                sed -e 's/      not-for-merge   /               /' -e 1q \
 167                        "$GIT_DIR/FETCH_HEAD"
 168                return
 169        fi
 170        echo "$rh               commit '$remote'"
 171}
 172
 173parse_config () {
 174        while test $# != 0; do
 175                case "$1" in
 176                -n|--no-stat|--no-summary)
 177                        show_diffstat=false ;;
 178                --stat|--summary)
 179                        show_diffstat=t ;;
 180                --log|--no-log)
 181                        log_arg=$1 ;;
 182                --squash)
 183                        test "$allow_fast_forward" = t ||
 184                                die "You cannot combine --squash with --no-ff."
 185                        squash=t no_commit=t ;;
 186                --no-squash)
 187                        squash= no_commit= ;;
 188                --commit)
 189                        no_commit= ;;
 190                --no-commit)
 191                        no_commit=t ;;
 192                --ff)
 193                        allow_fast_forward=t ;;
 194                --no-ff)
 195                        test "$squash" != t ||
 196                                die "You cannot combine --squash with --no-ff."
 197                        test "$fast_forward_only" != t ||
 198                                die "You cannot combine --ff-only with --no-ff."
 199                        allow_fast_forward=f ;;
 200                --ff-only)
 201                        test "$allow_fast_forward" != f ||
 202                                die "You cannot combine --ff-only with --no-ff."
 203                        fast_forward_only=t ;;
 204                --rerere-autoupdate|--no-rerere-autoupdate)
 205                        rr_arg=$1 ;;
 206                -s|--strategy)
 207                        shift
 208                        case " $all_strategies " in
 209                        *" $1 "*)
 210                                use_strategies="$use_strategies$1 "
 211                                ;;
 212                        *)
 213                                case " $not_strategies " in
 214                                *" $1 "*)
 215                                        false
 216                                esac &&
 217                                type "git-merge-$1" >/dev/null 2>&1 ||
 218                                        die "available strategies are: $all_strategies"
 219                                use_strategies="$use_strategies$1 "
 220                                ;;
 221                        esac
 222                        ;;
 223                -X)
 224                        shift
 225                        xopt="${xopt:+$xopt }$(git rev-parse --sq-quote "--$1")"
 226                        ;;
 227                -m|--message)
 228                        shift
 229                        merge_msg="$1"
 230                        have_message=t
 231                        ;;
 232                --)
 233                        shift
 234                        break ;;
 235                *)      usage ;;
 236                esac
 237                shift
 238        done
 239        args_left=$#
 240}
 241
 242test $# != 0 || usage
 243
 244have_message=
 245
 246if branch=$(git-symbolic-ref -q HEAD)
 247then
 248        mergeopts=$(git config "branch.${branch#refs/heads/}.mergeoptions")
 249        if test -n "$mergeopts"
 250        then
 251                parse_config $mergeopts --
 252        fi
 253fi
 254
 255parse_config "$@"
 256while test $args_left -lt $#; do shift; done
 257
 258if test -z "$show_diffstat"; then
 259    test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
 260    test "$(git config --bool merge.stat)" = false && show_diffstat=false
 261    test -z "$show_diffstat" && show_diffstat=t
 262fi
 263
 264# This could be traditional "merge <msg> HEAD <commit>..."  and the
 265# way we can tell it is to see if the second token is HEAD, but some
 266# people might have misused the interface and used a commit-ish that
 267# is the same as HEAD there instead.  Traditional format never would
 268# have "-m" so it is an additional safety measure to check for it.
 269
 270if test -z "$have_message" &&
 271        second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
 272        head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
 273        test "$second_token" = "$head_commit"
 274then
 275        merge_msg="$1"
 276        shift
 277        head_arg="$1"
 278        shift
 279elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 280then
 281        # If the merged head is a valid one there is no reason to
 282        # forbid "git merge" into a branch yet to be born.  We do
 283        # the same for "git pull".
 284        if test 1 -ne $#
 285        then
 286                echo >&2 "Can merge only exactly one commit into empty head"
 287                exit 1
 288        fi
 289
 290        test "$squash" != t ||
 291                die "Squash commit into empty head not supported yet"
 292        test "$allow_fast_forward" = t ||
 293                die "Non-fast-forward into an empty head does not make sense"
 294        rh=$(git rev-parse --verify "$1^0") ||
 295                die "$1 - not something we can merge"
 296
 297        git update-ref -m "initial pull" HEAD "$rh" "" &&
 298        git read-tree --reset -u HEAD
 299        exit
 300
 301else
 302        # We are invoked directly as the first-class UI.
 303        head_arg=HEAD
 304
 305        # All the rest are the commits being merged; prepare
 306        # the standard merge summary message to be appended to
 307        # the given message.  If remote is invalid we will die
 308        # later in the common codepath so we discard the error
 309        # in this loop.
 310        merge_msg="$(
 311                for remote
 312                do
 313                        merge_name "$remote"
 314                done |
 315                if test "$have_message" = t
 316                then
 317                        git fmt-merge-msg -m "$merge_msg" $log_arg
 318                else
 319                        git fmt-merge-msg $log_arg
 320                fi
 321        )"
 322fi
 323head=$(git rev-parse --verify "$head_arg"^0) || usage
 324
 325# All the rest are remote heads
 326test "$#" = 0 && usage ;# we need at least one remote head.
 327set_reflog_action "merge $*"
 328
 329remoteheads=
 330for remote
 331do
 332        remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
 333            die "$remote - not something we can merge"
 334        remoteheads="${remoteheads}$remotehead "
 335        eval GITHEAD_$remotehead='"$remote"'
 336        export GITHEAD_$remotehead
 337done
 338set x $remoteheads ; shift
 339
 340case "$use_strategies" in
 341'')
 342        case "$#" in
 343        1)
 344                var="$(git config --get pull.twohead)"
 345                if test -n "$var"
 346                then
 347                        use_strategies="$var"
 348                else
 349                        use_strategies="$default_twohead_strategies"
 350                fi ;;
 351        *)
 352                var="$(git config --get pull.octopus)"
 353                if test -n "$var"
 354                then
 355                        use_strategies="$var"
 356                else
 357                        use_strategies="$default_octopus_strategies"
 358                fi ;;
 359        esac
 360        ;;
 361esac
 362
 363for s in $use_strategies
 364do
 365        for ss in $no_fast_forward_strategies
 366        do
 367                case " $s " in
 368                *" $ss "*)
 369                        allow_fast_forward=f
 370                        break
 371                        ;;
 372                esac
 373        done
 374        for ss in $no_trivial_strategies
 375        do
 376                case " $s " in
 377                *" $ss "*)
 378                        allow_trivial_merge=f
 379                        break
 380                        ;;
 381                esac
 382        done
 383done
 384
 385case "$#" in
 3861)
 387        common=$(git merge-base --all $head "$@")
 388        ;;
 389*)
 390        common=$(git merge-base --all --octopus $head "$@")
 391        ;;
 392esac
 393echo "$head" >"$GIT_DIR/ORIG_HEAD"
 394
 395case "$allow_fast_forward,$#,$common,$no_commit" in
 396?,*,'',*)
 397        # No common ancestors found. We need a real merge.
 398        ;;
 399?,1,"$1",*)
 400        # If head can reach all the merge then we are up to date.
 401        # but first the most common case of merging one remote.
 402        finish_up_to_date "Already up-to-date."
 403        exit 0
 404        ;;
 405t,1,"$head",*)
 406        # Again the most common case of merging one remote.
 407        echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 408        git update-index --refresh 2>/dev/null
 409        msg="Fast-forward"
 410        if test -n "$have_message"
 411        then
 412                msg="$msg (no commit created; -m option ignored)"
 413        fi
 414        new_head=$(git rev-parse --verify "$1^0") &&
 415        git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
 416        finish "$new_head" "$msg" || exit
 417        dropsave
 418        exit 0
 419        ;;
 420?,1,?*"$LF"?*,*)
 421        # We are not doing octopus and not fast-forward.  Need a
 422        # real merge.
 423        ;;
 424?,1,*,)
 425        # We are not doing octopus, not fast-forward, and have only
 426        # one common.
 427        git update-index --refresh 2>/dev/null
 428        case "$allow_trivial_merge,$fast_forward_only" in
 429        t,)
 430                # See if it is really trivial.
 431                git var GIT_COMMITTER_IDENT >/dev/null || exit
 432                echo "Trying really trivial in-index merge..."
 433                if git read-tree --trivial -m -u -v $common $head "$1" &&
 434                   result_tree=$(git write-tree)
 435                then
 436                        echo "Wonderful."
 437                        result_commit=$(
 438                                printf '%s\n' "$merge_msg" |
 439                                git commit-tree $result_tree -p HEAD -p "$1"
 440                        ) || exit
 441                        finish "$result_commit" "In-index merge"
 442                        dropsave
 443                        exit 0
 444                fi
 445                echo "Nope."
 446        esac
 447        ;;
 448*)
 449        # An octopus.  If we can reach all the remote we are up to date.
 450        up_to_date=t
 451        for remote
 452        do
 453                common_one=$(git merge-base --all $head $remote)
 454                if test "$common_one" != "$remote"
 455                then
 456                        up_to_date=f
 457                        break
 458                fi
 459        done
 460        if test "$up_to_date" = t
 461        then
 462                finish_up_to_date "Already up-to-date. Yeeah!"
 463                exit 0
 464        fi
 465        ;;
 466esac
 467
 468if test "$fast_forward_only" = t
 469then
 470        die "Not possible to fast-forward, aborting."
 471fi
 472
 473# We are going to make a new commit.
 474git var GIT_COMMITTER_IDENT >/dev/null || exit
 475
 476# At this point, we need a real merge.  No matter what strategy
 477# we use, it would operate on the index, possibly affecting the
 478# working tree, and when resolved cleanly, have the desired tree
 479# in the index -- this means that the index must be in sync with
 480# the $head commit.  The strategies are responsible to ensure this.
 481
 482case "$use_strategies" in
 483?*' '?*)
 484    # Stash away the local changes so that we can try more than one.
 485    savestate
 486    single_strategy=no
 487    ;;
 488*)
 489    rm -f "$GIT_DIR/MERGE_STASH"
 490    single_strategy=yes
 491    ;;
 492esac
 493
 494result_tree= best_cnt=-1 best_strategy= wt_strategy=
 495merge_was_ok=
 496for strategy in $use_strategies
 497do
 498    test "$wt_strategy" = '' || {
 499        echo "Rewinding the tree to pristine..."
 500        restorestate
 501    }
 502    case "$single_strategy" in
 503    no)
 504        echo "Trying merge strategy $strategy..."
 505        ;;
 506    esac
 507
 508    # Remember which strategy left the state in the working tree
 509    wt_strategy=$strategy
 510
 511    eval 'git-merge-$strategy '"$xopt"' $common -- "$head_arg" "$@"'
 512    exit=$?
 513    if test "$no_commit" = t && test "$exit" = 0
 514    then
 515        merge_was_ok=t
 516        exit=1 ;# pretend it left conflicts.
 517    fi
 518
 519    test "$exit" = 0 || {
 520
 521        # The backend exits with 1 when conflicts are left to be resolved,
 522        # with 2 when it does not handle the given merge at all.
 523
 524        if test "$exit" -eq 1
 525        then
 526            cnt=$({
 527                git diff-files --name-only
 528                git ls-files --unmerged
 529            } | wc -l)
 530            if test $best_cnt -le 0 || test $cnt -le $best_cnt
 531            then
 532                best_strategy=$strategy
 533                best_cnt=$cnt
 534            fi
 535        fi
 536        continue
 537    }
 538
 539    # Automerge succeeded.
 540    result_tree=$(git write-tree) && break
 541done
 542
 543# If we have a resulting tree, that means the strategy module
 544# auto resolved the merge cleanly.
 545if test '' != "$result_tree"
 546then
 547    if test "$allow_fast_forward" = "t"
 548    then
 549        parents=$(git merge-base --independent "$head" "$@")
 550    else
 551        parents=$(git rev-parse "$head" "$@")
 552    fi
 553    parents=$(echo "$parents" | sed -e 's/^/-p /')
 554    result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
 555    finish "$result_commit" "Merge made by $wt_strategy."
 556    dropsave
 557    exit 0
 558fi
 559
 560# Pick the result from the best strategy and have the user fix it up.
 561case "$best_strategy" in
 562'')
 563        restorestate
 564        case "$use_strategies" in
 565        ?*' '?*)
 566                echo >&2 "No merge strategy handled the merge."
 567                ;;
 568        *)
 569                echo >&2 "Merge with strategy $use_strategies failed."
 570                ;;
 571        esac
 572        exit 2
 573        ;;
 574"$wt_strategy")
 575        # We already have its result in the working tree.
 576        ;;
 577*)
 578        echo "Rewinding the tree to pristine..."
 579        restorestate
 580        echo "Using the $best_strategy to prepare resolving by hand."
 581        git-merge-$best_strategy $common -- "$head_arg" "$@"
 582        ;;
 583esac
 584
 585if test "$squash" = t
 586then
 587        finish
 588else
 589        for remote
 590        do
 591                echo $remote
 592        done >"$GIT_DIR/MERGE_HEAD"
 593        printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG" ||
 594                die "Could not write to $GIT_DIR/MERGE_MSG"
 595        if test "$allow_fast_forward" != t
 596        then
 597                printf "%s" no-ff
 598        else
 599                :
 600        fi >"$GIT_DIR/MERGE_MODE" ||
 601                die "Could not write to $GIT_DIR/MERGE_MODE"
 602fi
 603
 604if test "$merge_was_ok" = t
 605then
 606        echo >&2 \
 607        "Automatic merge went well; stopped before committing as requested"
 608        exit 0
 609else
 610        {
 611            echo '
 612Conflicts:
 613'
 614                git ls-files --unmerged |
 615                sed -e 's/^[^   ]*      /       /' |
 616                uniq
 617        } >>"$GIT_DIR/MERGE_MSG"
 618        git rerere $rr_arg
 619        die "Automatic merge failed; fix conflicts and then commit the result."
 620fi