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