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_SAVE" || exit 1
  32 }
  33
  34 savestate() {
  35         # Stash away any local modifications.
  36         git diff-index -z --name-only $head |
  37         cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
  38 }
  39
  40 restorestate() {
  41         if test -f "$GIT_DIR/MERGE_SAVE"
  42         then
  43                 git reset --hard $head >/dev/null
  44                 cpio -iuv <"$GIT_DIR/MERGE_SAVE"
  45                 git update-index --refresh >/dev/null
  46         fi
  47 }
  48
  49 finish_up_to_date () {
  50         case "$squash" in
  51         t)
  52                 echo "$1 (nothing to squash)" ;;
  53         '')
  54                 echo "$1" ;;
  55         esac
  56         dropsave
  57 }
  58
  59 squash_message () {
  60         echo Squashed commit of the following:
  61         echo
  62         git log --no-merges ^"$head" $remoteheads
  63 }
  64
  65 finish () {
  66         if test '' = "$2"
  67         then
  68                 rlogm="$GIT_REFLOG_ACTION"
  69         else
  70                 echo "$2"
  71                 rlogm="$GIT_REFLOG_ACTION: $2"
  72         fi
  73         case "$squash" in
  74         t)
  75                 echo "Squash commit -- not updating HEAD"
  76                 squash_message >"$GIT_DIR/SQUASH_MSG"
  77                 ;;
  78         '')
  79                 case "$merge_msg" in
  80                 '')
  81                         echo "No merge message -- not updating HEAD"
  82                         ;;
  83                 *)
  84                         git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
  85                         git gc --auto
  86                         ;;
  87                 esac
  88                 ;;
  89         esac
  90         case "$1" in
  91         '')
  92                 ;;
  93         ?*)
  94                 if test "$show_diffstat" = t
  95                 then
  96                         # We want color (if set), but no pager
  97                         GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
  98                 fi
  99                 ;;
 100         esac
 101
 102         # Run a post-merge hook
 103         if test -x "$GIT_DIR"/hooks/post-merge
 104         then
 105             case "$squash" in
 106             t)
 107                 "$GIT_DIR"/hooks/post-merge 1
 108                 ;;
 109             '')
 110                 "$GIT_DIR"/hooks/post-merge 0
 111                 ;;
 112             esac
 113         fi
 114 }
 115
 116 merge_name () {
 117         remote="$1"
 118         rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
 119         bh=$(git show-ref -s --verify "refs/heads/$remote" 2>/dev/null)
 120         if test "$rh" = "$bh"
 121         then
 122                 echo "$rh               branch '$remote' of ."
 123         elif truname=$(expr "$remote" : '\(.*\)~[1-9][0-9]*$') &&
 124                 git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
 125         then
 126                 echo "$rh               branch '$truname' (early part) of ."
 127         elif test "$remote" = "FETCH_HEAD" -a -r "$GIT_DIR/FETCH_HEAD"
 128         then
 129                 sed -e 's/      not-for-merge   /               /' -e 1q \
 130                         "$GIT_DIR/FETCH_HEAD"
 131         else
 132                 echo "$rh               commit '$remote'"
 133         fi
 134 }
 135
 136 parse_option () {
 137         case "$1" in
 138         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
 139                 --no-summa|--no-summar|--no-summary)
 140                 show_diffstat=false ;;
 141         --summary)
 142                 show_diffstat=t ;;
 143         --sq|--squ|--squa|--squas|--squash)
 144                 allow_fast_forward=t squash=t no_commit=t ;;
 145         --no-sq|--no-squ|--no-squa|--no-squas|--no-squash)
 146                 allow_fast_forward=t squash= no_commit= ;;
 147         --c|--co|--com|--comm|--commi|--commit)
 148                 allow_fast_forward=t squash= no_commit= ;;
 149         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
 150                 allow_fast_forward=t squash= no_commit=t ;;
 151         --ff)
 152                 allow_fast_forward=t squash= no_commit= ;;
 153         --no-ff)
 154                 allow_fast_forward=false squash= no_commit= ;;
 155         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 156                 --strateg=*|--strategy=*|\
 157         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
 158                 case "$#,$1" in
 159                 *,*=*)
 160                         strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
 161                 1,*)
 162                         usage ;;
 163                 *)
 164                         strategy="$2"
 165                         shift ;;
 166                 esac
 167                 case " $all_strategies " in
 168                 *" $strategy "*)
 169                         use_strategies="$use_strategies$strategy " ;;
 170                 *)
 171                         die "available strategies are: $all_strategies" ;;
 172                 esac
 173                 ;;
 174         -m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
 175                 merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
 176                 have_message=t
 177                 ;;
 178         -m|--m|--me|--mes|--mess|--messa|--messag|--message)
 179                 shift
 180                 case "$#" in
 181                 1)      usage ;;
 182                 esac
 183                 merge_msg="$1"
 184                 have_message=t
 185                 ;;
 186         -*)     usage ;;
 187         *)      return 1 ;;
 188         esac
 189         shift
 190         args_left=$#
 191 }
 192
 193 parse_config () {
 194         while test $# -gt 0
 195         do
 196                 parse_option "$@" || usage
 197                 while test $args_left -lt $#
 198                 do
 199                         shift
 200                 done
 201         done
 202 }
 203
 204 test $# != 0 || usage
 205
 206 have_message=
 207
 208 if branch=$(git-symbolic-ref -q HEAD)
 209 then
 210         mergeopts=$(git config "branch.${branch#refs/heads/}.mergeoptions")
 211         if test -n "$mergeopts"
 212         then
 213                 parse_config $mergeopts
 214         fi
 215 fi
 216
 217 while parse_option "$@"
 218 do
 219         while test $args_left -lt $#
 220         do
 221                 shift
 222         done
 223 done
 224
 225 if test -z "$show_diffstat"; then
 226     test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
 227     test -z "$show_diffstat" && show_diffstat=t
 228 fi
 229
 230 # This could be traditional "merge <msg> HEAD <commit>..."  and the
 231 # way we can tell it is to see if the second token is HEAD, but some
 232 # people might have misused the interface and used a committish that
 233 # is the same as HEAD there instead.  Traditional format never would
 234 # have "-m" so it is an additional safety measure to check for it.
 235
 236 if test -z "$have_message" &&
 237         second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
 238         head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
 239         test "$second_token" = "$head_commit"
 240 then
 241         merge_msg="$1"
 242         shift
 243         head_arg="$1"
 244         shift
 245 elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 246 then
 247         # If the merged head is a valid one there is no reason to
 248         # forbid "git merge" into a branch yet to be born.  We do
 249         # the same for "git pull".
 250         if test 1 -ne $#
 251         then
 252                 echo >&2 "Can merge only exactly one commit into empty head"
 253                 exit 1
 254         fi
 255
 256         rh=$(git rev-parse --verify "$1^0") ||
 257                 die "$1 - not something we can merge"
 258
 259         git update-ref -m "initial pull" HEAD "$rh" "" &&
 260         git read-tree --reset -u HEAD
 261         exit
 262
 263 else
 264         # We are invoked directly as the first-class UI.
 265         head_arg=HEAD
 266
 267         # All the rest are the commits being merged; prepare
 268         # the standard merge summary message to be appended to
 269         # the given message.  If remote is invalid we will die
 270         # later in the common codepath so we discard the error
 271         # in this loop.
 272         merge_name=$(for remote
 273                 do
 274                         merge_name "$remote"
 275                 done | git fmt-merge-msg
 276         )
 277         merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
 278 fi
 279 head=$(git rev-parse --verify "$head_arg"^0) || usage
 280
 281 # All the rest are remote heads
 282 test "$#" = 0 && usage ;# we need at least one remote head.
 283 set_reflog_action "merge $*"
 284
 285 remoteheads=
 286 for remote
 287 do
 288         remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
 289             die "$remote - not something we can merge"
 290         remoteheads="${remoteheads}$remotehead "
 291         eval GITHEAD_$remotehead='"$remote"'
 292         export GITHEAD_$remotehead
 293 done
 294 set x $remoteheads ; shift
 295
 296 case "$use_strategies" in
 297 '')
 298         case "$#" in
 299         1)
 300                 var="`git config --get pull.twohead`"
 301                 if test -n "$var"
 302                 then
 303                         use_strategies="$var"
 304                 else
 305                         use_strategies="$default_twohead_strategies"
 306                 fi ;;
 307         *)
 308                 var="`git config --get pull.octopus`"
 309                 if test -n "$var"
 310                 then
 311                         use_strategies="$var"
 312                 else
 313                         use_strategies="$default_octopus_strategies"
 314                 fi ;;
 315         esac
 316         ;;
 317 esac
 318
 319 for s in $use_strategies
 320 do
 321         for ss in $no_fast_forward_strategies
 322         do
 323                 case " $s " in
 324                 *" $ss "*)
 325                         allow_fast_forward=f
 326                         break
 327                         ;;
 328                 esac
 329         done
 330         for ss in $no_trivial_strategies
 331         do
 332                 case " $s " in
 333                 *" $ss "*)
 334                         allow_trivial_merge=f
 335                         break
 336                         ;;
 337                 esac
 338         done
 339 done
 340
 341 case "$#" in
 342 1)
 343         common=$(git merge-base --all $head "$@")
 344         ;;
 345 *)
 346         common=$(git show-branch --merge-base $head "$@")
 347         ;;
 348 esac
 349 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 350
 351 case "$allow_fast_forward,$#,$common,$no_commit" in
 352 ?,*,'',*)
 353         # No common ancestors found. We need a real merge.
 354         ;;
 355 ?,1,"$1",*)
 356         # If head can reach all the merge then we are up to date.
 357         # but first the most common case of merging one remote.
 358         finish_up_to_date "Already up-to-date."
 359         exit 0
 360         ;;
 361 t,1,"$head",*)
 362         # Again the most common case of merging one remote.
 363         echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 364         git update-index --refresh 2>/dev/null
 365         msg="Fast forward"
 366         if test -n "$have_message"
 367         then
 368                 msg="$msg (no commit created; -m option ignored)"
 369         fi
 370         new_head=$(git rev-parse --verify "$1^0") &&
 371         git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
 372         finish "$new_head" "$msg" || exit
 373         dropsave
 374         exit 0
 375         ;;
 376 ?,1,?*"$LF"?*,*)
 377         # We are not doing octopus and not fast forward.  Need a
 378         # real merge.
 379         ;;
 380 ?,1,*,)
 381         # We are not doing octopus, not fast forward, and have only
 382         # one common.
 383         git update-index --refresh 2>/dev/null
 384         case "$allow_trivial_merge" in
 385         t)
 386                 # See if it is really trivial.
 387                 git var GIT_COMMITTER_IDENT >/dev/null || exit
 388                 echo "Trying really trivial in-index merge..."
 389                 if git read-tree --trivial -m -u -v $common $head "$1" &&
 390                    result_tree=$(git write-tree)
 391                 then
 392                         echo "Wonderful."
 393                         result_commit=$(
 394                                 printf '%s\n' "$merge_msg" |
 395                                 git commit-tree $result_tree -p HEAD -p "$1"
 396                         ) || exit
 397                         finish "$result_commit" "In-index merge"
 398                         dropsave
 399                         exit 0
 400                 fi
 401                 echo "Nope."
 402         esac
 403         ;;
 404 *)
 405         # An octopus.  If we can reach all the remote we are up to date.
 406         up_to_date=t
 407         for remote
 408         do
 409                 common_one=$(git merge-base --all $head $remote)
 410                 if test "$common_one" != "$remote"
 411                 then
 412                         up_to_date=f
 413                         break
 414                 fi
 415         done
 416         if test "$up_to_date" = t
 417         then
 418                 finish_up_to_date "Already up-to-date. Yeeah!"
 419                 exit 0
 420         fi
 421         ;;
 422 esac
 423
 424 # We are going to make a new commit.
 425 git var GIT_COMMITTER_IDENT >/dev/null || exit
 426
 427 # At this point, we need a real merge.  No matter what strategy
 428 # we use, it would operate on the index, possibly affecting the
 429 # working tree, and when resolved cleanly, have the desired tree
 430 # in the index -- this means that the index must be in sync with
 431 # the $head commit.  The strategies are responsible to ensure this.
 432
 433 case "$use_strategies" in
 434 ?*' '?*)
 435     # Stash away the local changes so that we can try more than one.
 436     savestate
 437     single_strategy=no
 438     ;;
 439 *)
 440     rm -f "$GIT_DIR/MERGE_SAVE"
 441     single_strategy=yes
 442     ;;
 443 esac
 444
 445 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 446 merge_was_ok=
 447 for strategy in $use_strategies
 448 do
 449     test "$wt_strategy" = '' || {
 450         echo "Rewinding the tree to pristine..."
 451         restorestate
 452     }
 453     case "$single_strategy" in
 454     no)
 455         echo "Trying merge strategy $strategy..."
 456         ;;
 457     esac
 458
 459     # Remember which strategy left the state in the working tree
 460     wt_strategy=$strategy
 461
 462     git-merge-$strategy $common -- "$head_arg" "$@"
 463     exit=$?
 464     if test "$no_commit" = t && test "$exit" = 0
 465     then
 466         merge_was_ok=t
 467         exit=1 ;# pretend it left conflicts.
 468     fi
 469
 470     test "$exit" = 0 || {
 471
 472         # The backend exits with 1 when conflicts are left to be resolved,
 473         # with 2 when it does not handle the given merge at all.
 474
 475         if test "$exit" -eq 1
 476         then
 477             cnt=`{
 478                 git diff-files --name-only
 479                 git ls-files --unmerged
 480             } | wc -l`
 481             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 482             then
 483                 best_strategy=$strategy
 484                 best_cnt=$cnt
 485             fi
 486         fi
 487         continue
 488     }
 489
 490     # Automerge succeeded.
 491     result_tree=$(git write-tree) && break
 492 done
 493
 494 # If we have a resulting tree, that means the strategy module
 495 # auto resolved the merge cleanly.
 496 if test '' != "$result_tree"
 497 then
 498     if test "$allow_fast_forward" = "t"
 499     then
 500         parents=$(git show-branch --independent "$head" "$@")
 501     else
 502         parents=$(git rev-parse "$head" "$@")
 503     fi
 504     parents=$(echo "$parents" | sed -e 's/^/-p /')
 505     result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
 506     finish "$result_commit" "Merge made by $wt_strategy."
 507     dropsave
 508     exit 0
 509 fi
 510
 511 # Pick the result from the best strategy and have the user fix it up.
 512 case "$best_strategy" in
 513 '')
 514         restorestate
 515         case "$use_strategies" in
 516         ?*' '?*)
 517                 echo >&2 "No merge strategy handled the merge."
 518                 ;;
 519         *)
 520                 echo >&2 "Merge with strategy $use_strategies failed."
 521                 ;;
 522         esac
 523         exit 2
 524         ;;
 525 "$wt_strategy")
 526         # We already have its result in the working tree.
 527         ;;
 528 *)
 529         echo "Rewinding the tree to pristine..."
 530         restorestate
 531         echo "Using the $best_strategy to prepare resolving by hand."
 532         git-merge-$best_strategy $common -- "$head_arg" "$@"
 533         ;;
 534 esac
 535
 536 if test "$squash" = t
 537 then
 538         finish
 539 else
 540         for remote
 541         do
 542                 echo $remote
 543         done >"$GIT_DIR/MERGE_HEAD"
 544         printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
 545 fi
 546
 547 if test "$merge_was_ok" = t
 548 then
 549         echo >&2 \
 550         "Automatic merge went well; stopped before committing as requested"
 551         exit 0
 552 else
 553         {
 554             echo '
 555 Conflicts:
 556 '
 557                 git ls-files --unmerged |
 558                 sed -e 's/^[^   ]*      /       /' |
 559                 uniq
 560         } >>"$GIT_DIR/MERGE_MSG"
 561         git rerere
 562         die "Automatic merge failed; fix conflicts and then commit the result."
 563 fi