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