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