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