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