git-merge.sh

   1 #!/bin/sh
   2 #
   3 # Copyright (c) 2005 Junio C Hamano
   4 #
   5
   6 USAGE='[-n] [--summary] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-s <strategy>] [-m=<merge-message>] <commit>+'
   7
   8 SUBDIRECTORY_OK=Yes
   9 . git-sh-setup
  10 require_work_tree
  11 cd_to_toplevel
  12
  13 test -z "$(git ls-files -u)" ||
  14         die "You are in the middle of a conflicted merge."
  15
  16 LF='
  17 '
  18
  19 all_strategies='recur recursive octopus resolve stupid ours subtree'
  20 default_twohead_strategies='recursive'
  21 default_octopus_strategies='octopus'
  22 no_fast_forward_strategies='subtree ours'
  23 no_trivial_strategies='recursive recur subtree ours'
  24 use_strategies=
  25
  26 allow_fast_forward=t
  27 allow_trivial_merge=t
  28
  29 dropsave() {
  30         rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
  31                  "$GIT_DIR/MERGE_STASH" || exit 1
  32 }
  33
  34 savestate() {
  35         # Stash away any local modifications.
  36         git stash create >"$GIT_DIR/MERGE_STASH"
  37 }
  38
  39 restorestate() {
  40         if test -f "$GIT_DIR/MERGE_STASH"
  41         then
  42                 git reset --hard $head >/dev/null
  43                 git stash apply $(cat "$GIT_DIR/MERGE_STASH")
  44                 git update-index --refresh >/dev/null
  45         fi
  46 }
  47
  48 finish_up_to_date () {
  49         case "$squash" in
  50         t)
  51                 echo "$1 (nothing to squash)" ;;
  52         '')
  53                 echo "$1" ;;
  54         esac
  55         dropsave
  56 }
  57
  58 squash_message () {
  59         echo Squashed commit of the following:
  60         echo
  61         git log --no-merges ^"$head" $remoteheads
  62 }
  63
  64 finish () {
  65         if test '' = "$2"
  66         then
  67                 rlogm="$GIT_REFLOG_ACTION"
  68         else
  69                 echo "$2"
  70                 rlogm="$GIT_REFLOG_ACTION: $2"
  71         fi
  72         case "$squash" in
  73         t)
  74                 echo "Squash commit -- not updating HEAD"
  75                 squash_message >"$GIT_DIR/SQUASH_MSG"
  76                 ;;
  77         '')
  78                 case "$merge_msg" in
  79                 '')
  80                         echo "No merge message -- not updating HEAD"
  81                         ;;
  82                 *)
  83                         git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
  84                         git gc --auto
  85                         ;;
  86                 esac
  87                 ;;
  88         esac
  89         case "$1" in
  90         '')
  91                 ;;
  92         ?*)
  93                 if test "$show_diffstat" = t
  94                 then
  95                         # We want color (if set), but no pager
  96                         GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
  97                 fi
  98                 ;;
  99         esac
 100
 101         # Run a post-merge hook
 102         if test -x "$GIT_DIR"/hooks/post-merge
 103         then
 104             case "$squash" in
 105             t)
 106                 "$GIT_DIR"/hooks/post-merge 1
 107                 ;;
 108             '')
 109                 "$GIT_DIR"/hooks/post-merge 0
 110                 ;;
 111             esac
 112         fi
 113 }
 114
 115 merge_name () {
 116         remote="$1"
 117         rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
 118         bh=$(git show-ref -s --verify "refs/heads/$remote" 2>/dev/null)
 119         if test "$rh" = "$bh"
 120         then
 121                 echo "$rh               branch '$remote' of ."
 122         elif truname=$(expr "$remote" : '\(.*\)~[1-9][0-9]*$') &&
 123                 git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
 124         then
 125                 echo "$rh               branch '$truname' (early part) of ."
 126         elif test "$remote" = "FETCH_HEAD" -a -r "$GIT_DIR/FETCH_HEAD"
 127         then
 128                 sed -e 's/      not-for-merge   /               /' -e 1q \
 129                         "$GIT_DIR/FETCH_HEAD"
 130         else
 131                 echo "$rh               commit '$remote'"
 132         fi
 133 }
 134
 135 parse_option () {
 136         case "$1" in
 137         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
 138                 --no-summa|--no-summar|--no-summary)
 139                 show_diffstat=false ;;
 140         --summary)
 141                 show_diffstat=t ;;
 142         --sq|--squ|--squa|--squas|--squash)
 143                 allow_fast_forward=t squash=t no_commit=t ;;
 144         --no-sq|--no-squ|--no-squa|--no-squas|--no-squash)
 145                 allow_fast_forward=t squash= no_commit= ;;
 146         --c|--co|--com|--comm|--commi|--commit)
 147                 allow_fast_forward=t squash= no_commit= ;;
 148         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
 149                 allow_fast_forward=t squash= no_commit=t ;;
 150         --ff)
 151                 allow_fast_forward=t squash= no_commit= ;;
 152         --no-ff)
 153                 allow_fast_forward=false squash= no_commit= ;;
 154         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 155                 --strateg=*|--strategy=*|\
 156         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
 157                 case "$#,$1" in
 158                 *,*=*)
 159                         strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
 160                 1,*)
 161                         usage ;;
 162                 *)
 163                         strategy="$2"
 164                         shift ;;
 165                 esac
 166                 case " $all_strategies " in
 167                 *" $strategy "*)
 168                         use_strategies="$use_strategies$strategy " ;;
 169                 *)
 170                         die "available strategies are: $all_strategies" ;;
 171                 esac
 172                 ;;
 173         -m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
 174                 merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
 175                 have_message=t
 176                 ;;
 177         -m|--m|--me|--mes|--mess|--messa|--messag|--message)
 178                 shift
 179                 case "$#" in
 180                 1)      usage ;;
 181                 esac
 182                 merge_msg="$1"
 183                 have_message=t
 184                 ;;
 185         -*)     usage ;;
 186         *)      return 1 ;;
 187         esac
 188         shift
 189         args_left=$#
 190 }
 191
 192 parse_config () {
 193         while test $# -gt 0
 194         do
 195                 parse_option "$@" || usage
 196                 while test $args_left -lt $#
 197                 do
 198                         shift
 199                 done
 200         done
 201 }
 202
 203 test $# != 0 || usage
 204
 205 have_message=
 206
 207 if branch=$(git-symbolic-ref -q HEAD)
 208 then
 209         mergeopts=$(git config "branch.${branch#refs/heads/}.mergeoptions")
 210         if test -n "$mergeopts"
 211         then
 212                 parse_config $mergeopts
 213         fi
 214 fi
 215
 216 while parse_option "$@"
 217 do
 218         while test $args_left -lt $#
 219         do
 220                 shift
 221         done
 222 done
 223
 224 if test -z "$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