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