git-merge.sh

   1 #!/bin/sh
   2 #
   3 # Copyright (c) 2005 Junio C Hamano
   4 #
   5
   6 USAGE='[-n] [--summary] [--no-commit] [--squash] [-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" $remote
  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                         ;;
  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 '$remote'"
 132         fi
 133 }
 134
 135 case "$#" in 0) usage ;; esac
 136
 137 have_message=
 138 while test $# != 0
 139 do
 140         case "$1" in
 141         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
 142                 --no-summa|--no-summar|--no-summary)
 143                 show_diffstat=false ;;
 144         --summary)
 145                 show_diffstat=t ;;
 146         --sq|--squ|--squa|--squas|--squash)
 147                 squash=t no_commit=t ;;
 148         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
 149                 no_commit=t ;;
 150         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 151                 --strateg=*|--strategy=*|\
 152         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
 153                 case "$#,$1" in
 154                 *,*=*)
 155                         strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
 156                 1,*)
 157                         usage ;;
 158                 *)
 159                         strategy="$2"
 160                         shift ;;
 161                 esac
 162                 case " $all_strategies " in
 163                 *" $strategy "*)
 164                         use_strategies="$use_strategies$strategy " ;;
 165                 *)
 166                         die "available strategies are: $all_strategies" ;;
 167                 esac
 168                 ;;
 169         -m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
 170                 merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
 171                 have_message=t
 172                 ;;
 173         -m|--m|--me|--mes|--mess|--messa|--messag|--message)
 174                 shift
 175                 case "$#" in
 176                 1)      usage ;;
 177                 esac
 178                 merge_msg="$1"
 179                 have_message=t
 180                 ;;
 181         -*)     usage ;;
 182         *)      break ;;
 183         esac
 184         shift
 185 done
 186
 187 if test -z "$show_diffstat"; then
 188     test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
 189     test -z "$show_diffstat" && show_diffstat=t
 190 fi
 191
 192 # This could be traditional "merge <msg> HEAD <commit>..."  and the
 193 # way we can tell it is to see if the second token is HEAD, but some
 194 # people might have misused the interface and used a committish that
 195 # is the same as HEAD there instead.  Traditional format never would
 196 # have "-m" so it is an additional safety measure to check for it.
 197
 198 if test -z "$have_message" &&
 199         second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
 200         head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
 201         test "$second_token" = "$head_commit"
 202 then
 203         merge_msg="$1"
 204         shift
 205         head_arg="$1"
 206         shift
 207 elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 208 then
 209         # If the merged head is a valid one there is no reason to
 210         # forbid "git merge" into a branch yet to be born.  We do
 211         # the same for "git pull".
 212         if test 1 -ne $#
 213         then
 214                 echo >&2 "Can merge only exactly one commit into empty head"
 215                 exit 1
 216         fi
 217
 218         rh=$(git rev-parse --verify "$1^0") ||
 219                 die "$1 - not something we can merge"
 220
 221         git update-ref -m "initial pull" HEAD "$rh" "" &&
 222         git read-tree --reset -u HEAD
 223         exit
 224
 225 else
 226         # We are invoked directly as the first-class UI.
 227         head_arg=HEAD
 228
 229         # All the rest are the commits being merged; prepare
 230         # the standard merge summary message to be appended to
 231         # the given message.  If remote is invalid we will die
 232         # later in the common codepath so we discard the error
 233         # in this loop.
 234         merge_name=$(for remote
 235                 do
 236                         merge_name "$remote"
 237                 done | git fmt-merge-msg
 238         )
 239         merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
 240 fi
 241 head=$(git rev-parse --verify "$head_arg"^0) || usage
 242
 243 # All the rest are remote heads
 244 test "$#" = 0 && usage ;# we need at least one remote head.
 245 set_reflog_action "merge $*"
 246
 247 remoteheads=
 248 for remote
 249 do
 250         remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
 251             die "$remote - not something we can merge"
 252         remoteheads="${remoteheads}$remotehead "
 253         eval GITHEAD_$remotehead='"$remote"'
 254         export GITHEAD_$remotehead
 255 done
 256 set x $remoteheads ; shift
 257
 258 case "$use_strategies" in
 259 '')
 260         case "$#" in
 261         1)
 262                 var="`git config --get pull.twohead`"
 263                 if test -n "$var"
 264                 then
 265                         use_strategies="$var"
 266                 else
 267                         use_strategies="$default_twohead_strategies"
 268                 fi ;;
 269         *)
 270                 var="`git config --get pull.octopus`"
 271                 if test -n "$var"
 272                 then
 273                         use_strategies="$var"
 274                 else
 275                         use_strategies="$default_octopus_strategies"
 276                 fi ;;
 277         esac
 278         ;;
 279 esac
 280
 281 for s in $use_strategies
 282 do
 283         for ss in $no_fast_forward_strategies
 284         do
 285                 case " $s " in
 286                 *" $ss "*)
 287                         allow_fast_forward=f
 288                         break
 289                         ;;
 290                 esac
 291         done
 292         for ss in $no_trivial_strategies
 293         do
 294                 case " $s " in
 295                 *" $ss "*)
 296                         allow_trivial_merge=f
 297                         break
 298                         ;;
 299                 esac
 300         done
 301 done
 302
 303 case "$#" in
 304 1)
 305         common=$(git merge-base --all $head "$@")
 306         ;;
 307 *)
 308         common=$(git show-branch --merge-base $head "$@")
 309         ;;
 310 esac
 311 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 312
 313 case "$allow_fast_forward,$#,$common,$no_commit" in
 314 ?,*,'',*)
 315         # No common ancestors found. We need a real merge.
 316         ;;
 317 ?,1,"$1",*)
 318         # If head can reach all the merge then we are up to date.
 319         # but first the most common case of merging one remote.
 320         finish_up_to_date "Already up-to-date."
 321         exit 0
 322         ;;
 323 t,1,"$head",*)
 324         # Again the most common case of merging one remote.
 325         echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 326         git update-index --refresh 2>/dev/null
 327         msg="Fast forward"
 328         if test -n "$have_message"
 329         then
 330                 msg="$msg (no commit created; -m option ignored)"
 331         fi
 332         new_head=$(git rev-parse --verify "$1^0") &&
 333         git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
 334         finish "$new_head" "$msg" || exit
 335         dropsave
 336         exit 0
 337         ;;
 338 ?,1,?*"$LF"?*,*)
 339         # We are not doing octopus and not fast forward.  Need a
 340         # real merge.
 341         ;;
 342 ?,1,*,)
 343         # We are not doing octopus, not fast forward, and have only
 344         # one common.
 345         git update-index --refresh 2>/dev/null
 346         case "$allow_trivial_merge" in
 347         t)
 348                 # See if it is really trivial.
 349                 git var GIT_COMMITTER_IDENT >/dev/null || exit
 350                 echo "Trying really trivial in-index merge..."
 351                 if git read-tree --trivial -m -u -v $common $head "$1" &&
 352                    result_tree=$(git write-tree)
 353                 then
 354                         echo "Wonderful."
 355                         result_commit=$(
 356                                 printf '%s\n' "$merge_msg" |
 357                                 git commit-tree $result_tree -p HEAD -p "$1"
 358                         ) || exit
 359                         finish "$result_commit" "In-index merge"
 360                         dropsave
 361                         exit 0
 362                 fi
 363                 echo "Nope."
 364         esac
 365         ;;
 366 *)
 367         # An octopus.  If we can reach all the remote we are up to date.
 368         up_to_date=t
 369         for remote
 370         do
 371                 common_one=$(git merge-base --all $head $remote)
 372                 if test "$common_one" != "$remote"
 373                 then
 374                         up_to_date=f
 375                         break
 376                 fi
 377         done
 378         if test "$up_to_date" = t
 379         then
 380                 finish_up_to_date "Already up-to-date. Yeeah!"
 381                 exit 0
 382         fi
 383         ;;
 384 esac
 385
 386 # We are going to make a new commit.
 387 git var GIT_COMMITTER_IDENT >/dev/null || exit
 388
 389 # At this point, we need a real merge.  No matter what strategy
 390 # we use, it would operate on the index, possibly affecting the
 391 # working tree, and when resolved cleanly, have the desired tree
 392 # in the index -- this means that the index must be in sync with
 393 # the $head commit.  The strategies are responsible to ensure this.
 394
 395 case "$use_strategies" in
 396 ?*' '?*)
 397     # Stash away the local changes so that we can try more than one.
 398     savestate
 399     single_strategy=no
 400     ;;
 401 *)
 402     rm -f "$GIT_DIR/MERGE_SAVE"
 403     single_strategy=yes
 404     ;;
 405 esac
 406
 407 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 408 merge_was_ok=
 409 for strategy in $use_strategies
 410 do
 411     test "$wt_strategy" = '' || {
 412         echo "Rewinding the tree to pristine..."
 413         restorestate
 414     }
 415     case "$single_strategy" in
 416     no)
 417         echo "Trying merge strategy $strategy..."
 418         ;;
 419     esac
 420
 421     # Remember which strategy left the state in the working tree
 422     wt_strategy=$strategy
 423
 424     git-merge-$strategy $common -- "$head_arg" "$@"
 425     exit=$?
 426     if test "$no_commit" = t && test "$exit" = 0
 427     then
 428         merge_was_ok=t
 429         exit=1 ;# pretend it left conflicts.
 430     fi
 431
 432     test "$exit" = 0 || {
 433
 434         # The backend exits with 1 when conflicts are left to be resolved,
 435         # with 2 when it does not handle the given merge at all.
 436
 437         if test "$exit" -eq 1
 438         then
 439             cnt=`{
 440                 git diff-files --name-only
 441                 git ls-files --unmerged
 442             } | wc -l`
 443             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 444             then
 445                 best_strategy=$strategy
 446                 best_cnt=$cnt
 447             fi
 448         fi
 449         continue
 450     }
 451
 452     # Automerge succeeded.
 453     result_tree=$(git write-tree) && break
 454 done
 455
 456 # If we have a resulting tree, that means the strategy module
 457 # auto resolved the merge cleanly.
 458 if test '' != "$result_tree"
 459 then
 460     parents=$(git show-branch --independent "$head" "$@" | sed -e 's/^/-p /')
 461     result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
 462     finish "$result_commit" "Merge made by $wt_strategy."
 463     dropsave
 464     exit 0
 465 fi
 466
 467 # Pick the result from the best strategy and have the user fix it up.
 468 case "$best_strategy" in
 469 '')
 470         restorestate
 471         case "$use_strategies" in
 472         ?*' '?*)
 473                 echo >&2 "No merge strategy handled the merge."
 474                 ;;
 475         *)
 476                 echo >&2 "Merge with strategy $use_strategies failed."
 477                 ;;
 478         esac
 479         exit 2
 480         ;;
 481 "$wt_strategy")
 482         # We already have its result in the working tree.
 483         ;;
 484 *)
 485         echo "Rewinding the tree to pristine..."
 486         restorestate
 487         echo "Using the $best_strategy to prepare resolving by hand."
 488         git-merge-$best_strategy $common -- "$head_arg" "$@"
 489         ;;
 490 esac
 491
 492 if test "$squash" = t
 493 then
 494         finish
 495 else
 496         for remote
 497         do
 498                 echo $remote
 499         done >"$GIT_DIR/MERGE_HEAD"
 500         printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
 501 fi
 502
 503 if test "$merge_was_ok" = t
 504 then
 505         echo >&2 \
 506         "Automatic merge went well; stopped before committing as requested"
 507         exit 0
 508 else
 509         {
 510             echo '
 511 Conflicts:
 512 '
 513                 git ls-files --unmerged |
 514                 sed -e 's/^[^   ]*      /       /' |
 515                 uniq
 516         } >>"$GIT_DIR/MERGE_MSG"
 517         git rerere
 518         die "Automatic merge failed; fix conflicts and then commit the result."
 519 fi