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 "$(git ls-files -u)" ||
  14         die "You are in the middle of a conflicted merge."
  15
  16 LF='
  17 '
  18
  19 all_strategies='recur recursive octopus resolve stupid ours subtree'
  20 default_twohead_strategies='recursive'
  21 default_octopus_strategies='octopus'
  22 no_trivial_merge_strategies='ours subtree'
  23 use_strategies=
  24
  25 index_merge=t
  26
  27 dropsave() {
  28         rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
  29                  "$GIT_DIR/MERGE_SAVE" || exit 1
  30 }
  31
  32 savestate() {
  33         # Stash away any local modifications.
  34         git diff-index -z --name-only $head |
  35         cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
  36 }
  37
  38 restorestate() {
  39         if test -f "$GIT_DIR/MERGE_SAVE"
  40         then
  41                 git reset --hard $head >/dev/null
  42                 cpio -iuv <"$GIT_DIR/MERGE_SAVE"
  43                 git update-index --refresh >/dev/null
  44         fi
  45 }
  46
  47 finish_up_to_date () {
  48         case "$squash" in
  49         t)
  50                 echo "$1 (nothing to squash)" ;;
  51         '')
  52                 echo "$1" ;;
  53         esac
  54         dropsave
  55 }
  56
  57 squash_message () {
  58         echo Squashed commit of the following:
  59         echo
  60         git log --no-merges ^"$head" $remote
  61 }
  62
  63 finish () {
  64         if test '' = "$2"
  65         then
  66                 rlogm="$GIT_REFLOG_ACTION"
  67         else
  68                 echo "$2"
  69                 rlogm="$GIT_REFLOG_ACTION: $2"
  70         fi
  71         case "$squash" in
  72         t)
  73                 echo "Squash commit -- not updating HEAD"
  74                 squash_message >"$GIT_DIR/SQUASH_MSG"
  75                 ;;
  76         '')
  77                 case "$merge_msg" in
  78                 '')
  79                         echo "No merge message -- not updating HEAD"
  80                         ;;
  81                 *)
  82                         git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
  83                         ;;
  84                 esac
  85                 ;;
  86         esac
  87         case "$1" in
  88         '')
  89                 ;;
  90         ?*)
  91                 if test "$show_diffstat" = t
  92                 then
  93                         # We want color (if set), but no pager
  94                         GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
  95                 fi
  96                 ;;
  97         esac
  98 }
  99
 100 merge_name () {
 101         remote="$1"
 102         rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
 103         bh=$(git show-ref -s --verify "refs/heads/$remote" 2>/dev/null)
 104         if test "$rh" = "$bh"
 105         then
 106                 echo "$rh               branch '$remote' of ."
 107         elif truname=$(expr "$remote" : '\(.*\)~[1-9][0-9]*$') &&
 108                 git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
 109         then
 110                 echo "$rh               branch '$truname' (early part) of ."
 111         elif test "$remote" = "FETCH_HEAD" -a -r "$GIT_DIR/FETCH_HEAD"
 112         then
 113                 sed -e 's/      not-for-merge   /               /' -e 1q \
 114                         "$GIT_DIR/FETCH_HEAD"
 115         else
 116                 echo "$rh               commit '$remote'"
 117         fi
 118 }
 119
 120 case "$#" in 0) usage ;; esac
 121
 122 have_message=
 123 while case "$#" in 0) break ;; esac
 124 do
 125         case "$1" in
 126         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
 127                 --no-summa|--no-summar|--no-summary)
 128                 show_diffstat=false ;;
 129         --summary)
 130                 show_diffstat=t ;;
 131         --sq|--squ|--squa|--squas|--squash)
 132                 squash=t no_commit=t ;;
 133         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
 134                 no_commit=t ;;
 135         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 136                 --strateg=*|--strategy=*|\
 137         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
 138                 case "$#,$1" in
 139                 *,*=*)
 140                         strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
 141                 1,*)
 142                         usage ;;
 143                 *)
 144                         strategy="$2"
 145                         shift ;;
 146                 esac
 147                 case " $all_strategies " in
 148                 *" $strategy "*)
 149                         use_strategies="$use_strategies$strategy " ;;
 150                 *)
 151                         die "available strategies are: $all_strategies" ;;
 152                 esac
 153                 ;;
 154         -m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
 155                 merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
 156                 have_message=t
 157                 ;;
 158         -m|--m|--me|--mes|--mess|--messa|--messag|--message)
 159                 shift
 160                 case "$#" in
 161                 1)      usage ;;
 162                 esac
 163                 merge_msg="$1"
 164                 have_message=t
 165                 ;;
 166         -*)     usage ;;
 167         *)      break ;;
 168         esac
 169         shift
 170 done
 171
 172 if test -z "$show_diffstat"; then
 173     test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
 174     test -z "$show_diffstat" && show_diffstat=t
 175 fi
 176
 177 # This could be traditional "merge <msg> HEAD <commit>..."  and the
 178 # way we can tell it is to see if the second token is HEAD, but some
 179 # people might have misused the interface and used a committish that
 180 # is the same as HEAD there instead.  Traditional format never would
 181 # have "-m" so it is an additional safety measure to check for it.
 182
 183 if test -z "$have_message" &&
 184         second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
 185         head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
 186         test "$second_token" = "$head_commit"
 187 then
 188         merge_msg="$1"
 189         shift
 190         head_arg="$1"
 191         shift
 192 elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 193 then
 194         # If the merged head is a valid one there is no reason to
 195         # forbid "git merge" into a branch yet to be born.  We do
 196         # the same for "git pull".
 197         if test 1 -ne $#
 198         then
 199                 echo >&2 "Can merge only exactly one commit into empty head"
 200                 exit 1
 201         fi
 202
 203         rh=$(git rev-parse --verify "$1^0") ||
 204                 die "$1 - not something we can merge"
 205
 206         git update-ref -m "initial pull" HEAD "$rh" "" &&
 207         git read-tree --reset -u HEAD
 208         exit
 209
 210 else
 211         # We are invoked directly as the first-class UI.
 212         head_arg=HEAD
 213
 214         # All the rest are the commits being merged; prepare
 215         # the standard merge summary message to be appended to
 216         # the given message.  If remote is invalid we will die
 217         # later in the common codepath so we discard the error
 218         # in this loop.
 219         merge_name=$(for remote
 220                 do
 221                         merge_name "$remote"
 222                 done | git fmt-merge-msg
 223         )
 224         merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
 225 fi
 226 head=$(git rev-parse --verify "$head_arg"^0) || usage
 227
 228 # All the rest are remote heads
 229 test "$#" = 0 && usage ;# we need at least one remote head.
 230 set_reflog_action "merge $*"
 231
 232 remoteheads=
 233 for remote
 234 do
 235         remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
 236             die "$remote - not something we can merge"
 237         remoteheads="${remoteheads}$remotehead "
 238         eval GITHEAD_$remotehead='"$remote"'
 239         export GITHEAD_$remotehead
 240 done
 241 set x $remoteheads ; shift
 242
 243 case "$use_strategies" in
 244 '')
 245         case "$#" in
 246         1)
 247                 var="`git config --get pull.twohead`"
 248                 if test -n "$var"
 249                 then
 250                         use_strategies="$var"
 251                 else
 252                         use_strategies="$default_twohead_strategies"
 253                 fi ;;
 254         *)
 255                 var="`git config --get pull.octopus`"
 256                 if test -n "$var"
 257                 then
 258                         use_strategies="$var"
 259                 else
 260                         use_strategies="$default_octopus_strategies"
 261                 fi ;;
 262         esac
 263         ;;
 264 esac
 265
 266 for s in $use_strategies
 267 do
 268         for nt in $no_trivial_merge_strategies
 269         do
 270                 case " $s " in
 271                 *" $nt "*)
 272                         index_merge=f
 273                         break
 274                         ;;
 275                 esac
 276         done
 277 done
 278
 279 case "$#" in
 280 1)
 281         common=$(git merge-base --all $head "$@")
 282         ;;
 283 *)
 284         common=$(git show-branch --merge-base $head "$@")
 285         ;;
 286 esac
 287 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 288
 289 case "$index_merge,$#,$common,$no_commit" in
 290 f,*)
 291         # We've been told not to try anything clever.  Skip to real merge.
 292         ;;
 293 ?,*,'',*)
 294         # No common ancestors found. We need a real merge.
 295         ;;
 296 ?,1,"$1",*)
 297         # If head can reach all the merge then we are up to date.
 298         # but first the most common case of merging one remote.
 299         finish_up_to_date "Already up-to-date."
 300         exit 0
 301         ;;
 302 ?,1,"$head",*)
 303         # Again the most common case of merging one remote.
 304         echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 305         git update-index --refresh 2>/dev/null
 306         msg="Fast forward"
 307         if test -n "$have_message"
 308         then
 309                 msg="$msg (no commit created; -m option ignored)"
 310         fi
 311         new_head=$(git rev-parse --verify "$1^0") &&
 312         git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
 313         finish "$new_head" "$msg" || exit
 314         dropsave
 315         exit 0
 316         ;;
 317 ?,1,?*"$LF"?*,*)
 318         # We are not doing octopus and not fast forward.  Need a
 319         # real merge.
 320         ;;
 321 ?,1,*,)
 322         # We are not doing octopus, not fast forward, and have only
 323         # one common.
 324         git update-index --refresh 2>/dev/null
 325         case " $use_strategies " in
 326         *' recursive '*|*' recur '*)
 327                 : run merge later
 328                 ;;
 329         *)
 330                 # See if it is really trivial.
 331                 git var GIT_COMMITTER_IDENT >/dev/null || exit
 332                 echo "Trying really trivial in-index merge..."
 333                 if git read-tree --trivial -m -u -v $common $head "$1" &&
 334                    result_tree=$(git write-tree)
 335                 then
 336                         echo "Wonderful."
 337                         result_commit=$(
 338                                 printf '%s\n' "$merge_msg" |
 339                                 git commit-tree $result_tree -p HEAD -p "$1"
 340                         ) || exit
 341                         finish "$result_commit" "In-index merge"
 342                         dropsave
 343                         exit 0
 344                 fi
 345                 echo "Nope."
 346         esac
 347         ;;
 348 *)
 349         # An octopus.  If we can reach all the remote we are up to date.
 350         up_to_date=t
 351         for remote
 352         do
 353                 common_one=$(git merge-base --all $head $remote)
 354                 if test "$common_one" != "$remote"
 355                 then
 356                         up_to_date=f
 357                         break
 358                 fi
 359         done
 360         if test "$up_to_date" = t
 361         then
 362                 finish_up_to_date "Already up-to-date. Yeeah!"
 363                 exit 0
 364         fi
 365         ;;
 366 esac
 367
 368 # We are going to make a new commit.
 369 git var GIT_COMMITTER_IDENT >/dev/null || exit
 370
 371 # At this point, we need a real merge.  No matter what strategy
 372 # we use, it would operate on the index, possibly affecting the
 373 # working tree, and when resolved cleanly, have the desired tree
 374 # in the index -- this means that the index must be in sync with
 375 # the $head commit.  The strategies are responsible to ensure this.
 376
 377 case "$use_strategies" in
 378 ?*' '?*)
 379     # Stash away the local changes so that we can try more than one.
 380     savestate
 381     single_strategy=no
 382     ;;
 383 *)
 384     rm -f "$GIT_DIR/MERGE_SAVE"
 385     single_strategy=yes
 386     ;;
 387 esac
 388
 389 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 390 merge_was_ok=
 391 for strategy in $use_strategies
 392 do
 393     test "$wt_strategy" = '' || {
 394         echo "Rewinding the tree to pristine..."
 395         restorestate
 396     }
 397     case "$single_strategy" in
 398     no)
 399         echo "Trying merge strategy $strategy..."
 400         ;;
 401     esac
 402
 403     # Remember which strategy left the state in the working tree
 404     wt_strategy=$strategy
 405
 406     git merge-$strategy $common -- "$head_arg" "$@"
 407     exit=$?
 408     if test "$no_commit" = t && test "$exit" = 0
 409     then
 410         merge_was_ok=t
 411         exit=1 ;# pretend it left conflicts.
 412     fi
 413
 414     test "$exit" = 0 || {
 415
 416         # The backend exits with 1 when conflicts are left to be resolved,
 417         # with 2 when it does not handle the given merge at all.
 418
 419         if test "$exit" -eq 1
 420         then
 421             cnt=`{
 422                 git diff-files --name-only
 423                 git ls-files --unmerged
 424             } | wc -l`
 425             if test $best_cnt -le 0 -o $cnt -le $best_cnt
 426             then
 427                 best_strategy=$strategy
 428                 best_cnt=$cnt
 429             fi
 430         fi
 431         continue
 432     }
 433
 434     # Automerge succeeded.
 435     result_tree=$(git write-tree) && break
 436 done
 437
 438 # If we have a resulting tree, that means the strategy module
 439 # auto resolved the merge cleanly.
 440 if test '' != "$result_tree"
 441 then
 442     parents=$(git show-branch --independent "$head" "$@" | sed -e 's/^/-p /')
 443     result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
 444     finish "$result_commit" "Merge made by $wt_strategy."
 445     dropsave
 446     exit 0
 447 fi
 448
 449 # Pick the result from the best strategy and have the user fix it up.
 450 case "$best_strategy" in
 451 '')
 452         restorestate
 453         case "$use_strategies" in
 454         ?*' '?*)
 455                 echo >&2 "No merge strategy handled the merge."
 456                 ;;
 457         *)
 458                 echo >&2 "Merge with strategy $use_strategies failed."
 459                 ;;
 460         esac
 461         exit 2
 462         ;;
 463 "$wt_strategy")
 464         # We already have its result in the working tree.
 465         ;;
 466 *)
 467         echo "Rewinding the tree to pristine..."
 468         restorestate
 469         echo "Using the $best_strategy to prepare resolving by hand."
 470         git-merge-$best_strategy $common -- "$head_arg" "$@"
 471         ;;
 472 esac
 473
 474 if test "$squash" = t
 475 then
 476         finish
 477 else
 478         for remote
 479         do
 480                 echo $remote
 481         done >"$GIT_DIR/MERGE_HEAD"
 482         printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
 483 fi
 484
 485 if test "$merge_was_ok" = t
 486 then
 487         echo >&2 \
 488         "Automatic merge went well; stopped before committing as requested"
 489         exit 0
 490 else
 491         {
 492             echo '
 493 Conflicts:
 494 '
 495                 git ls-files --unmerged |
 496                 sed -e 's/^[^   ]*      /       /' |
 497                 uniq
 498         } >>"$GIT_DIR/MERGE_MSG"
 499         git rerere
 500         die "Automatic merge failed; fix conflicts and then commit the result."
 501 fi