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