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