git-merge.sh

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