Andrew's git / gitweb.git / git-merge.sh
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git-merge.shon commit git-gc --auto: add documentation. (e9831e8)
   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                        git gc --auto
  86                        ;;
  87                esac
  88                ;;
  89        esac
  90        case "$1" in
  91        '')
  92                ;;
  93        ?*)
  94                if test "$show_diffstat" = t
  95                then
  96                        # We want color (if set), but no pager
  97                        GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
  98                fi
  99                ;;
 100        esac
 101}
 102
 103merge_name () {
 104        remote="$1"
 105        rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
 106        bh=$(git show-ref -s --verify "refs/heads/$remote" 2>/dev/null)
 107        if test "$rh" = "$bh"
 108        then
 109                echo "$rh               branch '$remote' of ."
 110        elif truname=$(expr "$remote" : '\(.*\)~[1-9][0-9]*$') &&
 111                git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
 112        then
 113                echo "$rh               branch '$truname' (early part) of ."
 114        elif test "$remote" = "FETCH_HEAD" -a -r "$GIT_DIR/FETCH_HEAD"
 115        then
 116                sed -e 's/      not-for-merge   /               /' -e 1q \
 117                        "$GIT_DIR/FETCH_HEAD"
 118        else
 119                echo "$rh               commit '$remote'"
 120        fi
 121}
 122
 123case "$#" in 0) usage ;; esac
 124
 125have_message=
 126while case "$#" in 0) break ;; esac
 127do
 128        case "$1" in
 129        -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
 130                --no-summa|--no-summar|--no-summary)
 131                show_diffstat=false ;;
 132        --summary)
 133                show_diffstat=t ;;
 134        --sq|--squ|--squa|--squas|--squash)
 135                squash=t no_commit=t ;;
 136        --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
 137                no_commit=t ;;
 138        -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 139                --strateg=*|--strategy=*|\
 140        -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
 141                case "$#,$1" in
 142                *,*=*)
 143                        strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
 144                1,*)
 145                        usage ;;
 146                *)
 147                        strategy="$2"
 148                        shift ;;
 149                esac
 150                case " $all_strategies " in
 151                *" $strategy "*)
 152                        use_strategies="$use_strategies$strategy " ;;
 153                *)
 154                        die "available strategies are: $all_strategies" ;;
 155                esac
 156                ;;
 157        -m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
 158                merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
 159                have_message=t
 160                ;;
 161        -m|--m|--me|--mes|--mess|--messa|--messag|--message)
 162                shift
 163                case "$#" in
 164                1)      usage ;;
 165                esac
 166                merge_msg="$1"
 167                have_message=t
 168                ;;
 169        -*)     usage ;;
 170        *)      break ;;
 171        esac
 172        shift
 173done
 174
 175if test -z "$show_diffstat"; then
 176    test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
 177    test -z "$show_diffstat" && show_diffstat=t
 178fi
 179
 180# This could be traditional "merge <msg> HEAD <commit>..."  and the
 181# way we can tell it is to see if the second token is HEAD, but some
 182# people might have misused the interface and used a committish that
 183# is the same as HEAD there instead.  Traditional format never would
 184# have "-m" so it is an additional safety measure to check for it.
 185
 186if test -z "$have_message" &&
 187        second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
 188        head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
 189        test "$second_token" = "$head_commit"
 190then
 191        merge_msg="$1"
 192        shift
 193        head_arg="$1"
 194        shift
 195elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 196then
 197        # If the merged head is a valid one there is no reason to
 198        # forbid "git merge" into a branch yet to be born.  We do
 199        # the same for "git pull".
 200        if test 1 -ne $#
 201        then
 202                echo >&2 "Can merge only exactly one commit into empty head"
 203                exit 1
 204        fi
 205
 206        rh=$(git rev-parse --verify "$1^0") ||
 207                die "$1 - not something we can merge"
 208
 209        git update-ref -m "initial pull" HEAD "$rh" "" &&
 210        git read-tree --reset -u HEAD
 211        exit
 212
 213else
 214        # We are invoked directly as the first-class UI.
 215        head_arg=HEAD
 216
 217        # All the rest are the commits being merged; prepare
 218        # the standard merge summary message to be appended to
 219        # the given message.  If remote is invalid we will die
 220        # later in the common codepath so we discard the error
 221        # in this loop.
 222        merge_name=$(for remote
 223                do
 224                        merge_name "$remote"
 225                done | git fmt-merge-msg
 226        )
 227        merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
 228fi
 229head=$(git rev-parse --verify "$head_arg"^0) || usage
 230
 231# All the rest are remote heads
 232test "$#" = 0 && usage ;# we need at least one remote head.
 233set_reflog_action "merge $*"
 234
 235remoteheads=
 236for remote
 237do
 238        remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
 239            die "$remote - not something we can merge"
 240        remoteheads="${remoteheads}$remotehead "
 241        eval GITHEAD_$remotehead='"$remote"'
 242        export GITHEAD_$remotehead
 243done
 244set x $remoteheads ; shift
 245
 246case "$use_strategies" in
 247'')
 248        case "$#" in
 249        1)
 250                var="`git config --get pull.twohead`"
 251                if test -n "$var"
 252                then
 253                        use_strategies="$var"
 254                else
 255                        use_strategies="$default_twohead_strategies"
 256                fi ;;
 257        *)
 258                var="`git config --get pull.octopus`"
 259                if test -n "$var"
 260                then
 261                        use_strategies="$var"
 262                else
 263                        use_strategies="$default_octopus_strategies"
 264                fi ;;
 265        esac
 266        ;;
 267esac
 268
 269for s in $use_strategies
 270do
 271        for ss in $no_fast_forward_strategies
 272        do
 273                case " $s " in
 274                *" $ss "*)
 275                        allow_fast_forward=f
 276                        break
 277                        ;;
 278                esac
 279        done
 280        for ss in $no_trivial_strategies
 281        do
 282                case " $s " in
 283                *" $ss "*)
 284                        allow_trivial_merge=f
 285                        break
 286                        ;;
 287                esac
 288        done
 289done
 290
 291case "$#" in
 2921)
 293        common=$(git merge-base --all $head "$@")
 294        ;;
 295*)
 296        common=$(git show-branch --merge-base $head "$@")
 297        ;;
 298esac
 299echo "$head" >"$GIT_DIR/ORIG_HEAD"
 300
 301case "$allow_fast_forward,$#,$common,$no_commit" in
 302?,*,'',*)
 303        # No common ancestors found. We need a real merge.
 304        ;;
 305?,1,"$1",*)
 306        # If head can reach all the merge then we are up to date.
 307        # but first the most common case of merging one remote.
 308        finish_up_to_date "Already up-to-date."
 309        exit 0
 310        ;;
 311t,1,"$head",*)
 312        # Again the most common case of merging one remote.
 313        echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 314        git update-index --refresh 2>/dev/null
 315        msg="Fast forward"
 316        if test -n "$have_message"
 317        then
 318                msg="$msg (no commit created; -m option ignored)"
 319        fi
 320        new_head=$(git rev-parse --verify "$1^0") &&
 321        git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
 322        finish "$new_head" "$msg" || exit
 323        dropsave
 324        exit 0
 325        ;;
 326?,1,?*"$LF"?*,*)
 327        # We are not doing octopus and not fast forward.  Need a
 328        # real merge.
 329        ;;
 330?,1,*,)
 331        # We are not doing octopus, not fast forward, and have only
 332        # one common.
 333        git update-index --refresh 2>/dev/null
 334        case "$allow_trivial_merge" in
 335        t)
 336                # See if it is really trivial.
 337                git var GIT_COMMITTER_IDENT >/dev/null || exit
 338                echo "Trying really trivial in-index merge..."
 339                if git read-tree --trivial -m -u -v $common $head "$1" &&
 340                   result_tree=$(git write-tree)
 341                then
 342                        echo "Wonderful."
 343                        result_commit=$(
 344                                printf '%s\n' "$merge_msg" |
 345                                git commit-tree $result_tree -p HEAD -p "$1"
 346                        ) || exit
 347                        finish "$result_commit" "In-index merge"
 348                        dropsave
 349                        exit 0
 350                fi
 351                echo "Nope."
 352        esac
 353        ;;
 354*)
 355        # An octopus.  If we can reach all the remote we are up to date.
 356        up_to_date=t
 357        for remote
 358        do
 359                common_one=$(git merge-base --all $head $remote)
 360                if test "$common_one" != "$remote"
 361                then
 362                        up_to_date=f
 363                        break
 364                fi
 365        done
 366        if test "$up_to_date" = t
 367        then
 368                finish_up_to_date "Already up-to-date. Yeeah!"
 369                exit 0
 370        fi
 371        ;;
 372esac
 373
 374# We are going to make a new commit.
 375git var GIT_COMMITTER_IDENT >/dev/null || exit
 376
 377# At this point, we need a real merge.  No matter what strategy
 378# we use, it would operate on the index, possibly affecting the
 379# working tree, and when resolved cleanly, have the desired tree
 380# in the index -- this means that the index must be in sync with
 381# the $head commit.  The strategies are responsible to ensure this.
 382
 383case "$use_strategies" in
 384?*' '?*)
 385    # Stash away the local changes so that we can try more than one.
 386    savestate
 387    single_strategy=no
 388    ;;
 389*)
 390    rm -f "$GIT_DIR/MERGE_SAVE"
 391    single_strategy=yes
 392    ;;
 393esac
 394
 395result_tree= best_cnt=-1 best_strategy= wt_strategy=
 396merge_was_ok=
 397for strategy in $use_strategies
 398do
 399    test "$wt_strategy" = '' || {
 400        echo "Rewinding the tree to pristine..."
 401        restorestate
 402    }
 403    case "$single_strategy" in
 404    no)
 405        echo "Trying merge strategy $strategy..."
 406        ;;
 407    esac
 408
 409    # Remember which strategy left the state in the working tree
 410    wt_strategy=$strategy
 411
 412    git-merge-$strategy $common -- "$head_arg" "$@"
 413    exit=$?
 414    if test "$no_commit" = t && test "$exit" = 0
 415    then
 416        merge_was_ok=t
 417        exit=1 ;# pretend it left conflicts.
 418    fi
 419
 420    test "$exit" = 0 || {
 421
 422        # The backend exits with 1 when conflicts are left to be resolved,
 423        # with 2 when it does not handle the given merge at all.
 424
 425        if test "$exit" -eq 1
 426        then
 427            cnt=`{
 428                git diff-files --name-only
 429                git ls-files --unmerged
 430            } | wc -l`
 431            if test $best_cnt -le 0 -o $cnt -le $best_cnt
 432            then
 433                best_strategy=$strategy
 434                best_cnt=$cnt
 435            fi
 436        fi
 437        continue
 438    }
 439
 440    # Automerge succeeded.
 441    result_tree=$(git write-tree) && break
 442done
 443
 444# If we have a resulting tree, that means the strategy module
 445# auto resolved the merge cleanly.
 446if test '' != "$result_tree"
 447then
 448    parents=$(git show-branch --independent "$head" "$@" | sed -e 's/^/-p /')
 449    result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
 450    finish "$result_commit" "Merge made by $wt_strategy."
 451    dropsave
 452    exit 0
 453fi
 454
 455# Pick the result from the best strategy and have the user fix it up.
 456case "$best_strategy" in
 457'')
 458        restorestate
 459        case "$use_strategies" in
 460        ?*' '?*)
 461                echo >&2 "No merge strategy handled the merge."
 462                ;;
 463        *)
 464                echo >&2 "Merge with strategy $use_strategies failed."
 465                ;;
 466        esac
 467        exit 2
 468        ;;
 469"$wt_strategy")
 470        # We already have its result in the working tree.
 471        ;;
 472*)
 473        echo "Rewinding the tree to pristine..."
 474        restorestate
 475        echo "Using the $best_strategy to prepare resolving by hand."
 476        git-merge-$best_strategy $common -- "$head_arg" "$@"
 477        ;;
 478esac
 479
 480if test "$squash" = t
 481then
 482        finish
 483else
 484        for remote
 485        do
 486                echo $remote
 487        done >"$GIT_DIR/MERGE_HEAD"
 488        printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
 489fi
 490
 491if test "$merge_was_ok" = t
 492then
 493        echo >&2 \
 494        "Automatic merge went well; stopped before committing as requested"
 495        exit 0
 496else
 497        {
 498            echo '
 499Conflicts:
 500'
 501                git ls-files --unmerged |
 502                sed -e 's/^[^   ]*      /       /' |
 503                uniq
 504        } >>"$GIT_DIR/MERGE_MSG"
 505        git rerere
 506        die "Automatic merge failed; fix conflicts and then commit the result."
 507fi