aboutsummaryrefslogtreecommitdiffstats
path: root/Library/Homebrew/cmd/update.sh
blob: 3f287340ff3f266de911ed9d2493cda6498cde2a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
#:  * `update` [`--merge`] [`--force`]:
#:    Fetch the newest version of Homebrew and all formulae from GitHub using
#:    `git`(1) and perform any necessary migrations.
#:
#:    If `--merge` is specified then `git merge` is used to include updates
#:    (rather than `git rebase`).
#:
#:    If `--force` (or `-f`) is specified then always do a slower, full update check even
#:    if unnecessary.

# Hide shellcheck complaint:
# shellcheck source=/dev/null
source "$HOMEBREW_LIBRARY/Homebrew/utils/lock.sh"

# Replaces the function in Library/Homebrew/brew.sh to cache the Git executable to
# provide speedup when using Git repeatedly (as update.sh does).
git() {
  if [[ -z "$GIT_EXECUTABLE" ]]
  then
    GIT_EXECUTABLE="$("$HOMEBREW_LIBRARY/Homebrew/shims/scm/git" --homebrew=print-path)"
  fi
  "$GIT_EXECUTABLE" "$@"
}

git_init_if_necessary() {
  if [[ -n "$HOMEBREW_MACOS" ]] || [[ -n "$HOMEBREW_FORCE_HOMEBREW_ORG" ]]
  then
    BREW_OFFICIAL_REMOTE="https://github.com/Homebrew/brew"
    CORE_OFFICIAL_REMOTE="https://github.com/Homebrew/homebrew-core"
  elif [[ -n "$HOMEBREW_LINUX" ]]
  then
    BREW_OFFICIAL_REMOTE="https://github.com/Linuxbrew/brew"
    CORE_OFFICIAL_REMOTE="https://github.com/Linuxbrew/homebrew-core"
  fi

  safe_cd "$HOMEBREW_REPOSITORY"
  if [[ ! -d ".git" ]]
  then
    set -e
    trap '{ rm -rf .git; exit 1; }' EXIT
    git init
    git config --bool core.autocrlf false
    git config remote.origin.url "$BREW_OFFICIAL_REMOTE"
    git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
    git fetch --force --depth=1 origin refs/heads/master:refs/remotes/origin/master
    git reset --hard origin/master
    SKIP_FETCH_BREW_REPOSITORY=1
    set +e
    trap - EXIT
  fi

  [[ -d "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core" ]] || return
  safe_cd "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core"
  if [[ ! -d ".git" ]]
  then
    set -e
    trap '{ rm -rf .git; exit 1; }' EXIT
    git init
    git config --bool core.autocrlf false
    git config remote.origin.url "$CORE_OFFICIAL_REMOTE"
    git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
    git fetch --force --depth=1 origin refs/heads/master:refs/remotes/origin/master
    git reset --hard origin/master
    SKIP_FETCH_CORE_REPOSITORY=1
    set +e
    trap - EXIT
  fi
}

rename_taps_dir_if_necessary() {
  local tap_dir
  local tap_dir_basename
  local tap_dir_hyphens
  local user
  local repo

  for tap_dir in "$HOMEBREW_LIBRARY"/Taps/*
  do
    [[ -d "$tap_dir/.git" ]] || continue
    tap_dir_basename="${tap_dir##*/}"
    if [[ "$tap_dir_basename" = *"-"* ]]
    then
      # only replace the *last* dash: yes, tap filenames suck
      user="$(echo "${tap_dir_basename%-*}" | tr "[:upper:]" "[:lower:]")"
      repo="$(echo "${tap_dir_basename:${#user}+1}" | tr "[:upper:]" "[:lower:]")"
      mkdir -p "$HOMEBREW_LIBRARY/Taps/$user"
      mv "$tap_dir" "$HOMEBREW_LIBRARY/Taps/$user/homebrew-$repo"

      tap_dir_hyphens="${tap_dir_basename//[^\-]}"
      if [[ ${#tap_dir_hyphens} -gt 1 ]]
      then
        echo "Homebrew changed the structure of Taps like <someuser>/<sometap>." >&2
        echo "So you may need to rename $HOMEBREW_LIBRARY/Taps/$user/homebrew-$repo manually." >&2
      fi
    else
      echo "Homebrew changed the structure of Taps like <someuser>/<sometap>. " >&2
      echo "$tap_dir is an incorrect Tap path." >&2
      echo "So you may need to rename it to $HOMEBREW_LIBRARY/Taps/<someuser>/homebrew-<sometap> manually." >&2
    fi
  done
}

repo_var() {
  local repo_var

  repo_var="$1"
  if [[ "$repo_var" = "$HOMEBREW_REPOSITORY" ]]
  then
    repo_var=""
  else
    repo_var="${repo_var#"$HOMEBREW_LIBRARY/Taps"}"
    repo_var="$(echo -n "$repo_var" | tr -C "A-Za-z0-9" "_" | tr "[:lower:]" "[:upper:]")"
  fi
  echo "$repo_var"
}

upstream_branch() {
  local upstream_branch

  upstream_branch="$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null)"
  upstream_branch="${upstream_branch#refs/remotes/origin/}"
  [[ -z "$upstream_branch" ]] && upstream_branch="master"
  echo "$upstream_branch"
}

read_current_revision() {
  git rev-parse -q --verify HEAD
}

pop_stash() {
  [[ -z "$STASHED" ]] && return
  if [[ -n "$HOMEBREW_VERBOSE" ]]
  then
    echo "Restoring your stashed changes to $DIR..."
    git stash pop
  else
    git stash pop "${QUIET_ARGS[@]}" 1>/dev/null
  fi
  unset STASHED
}

pop_stash_message() {
  [[ -z "$STASHED" ]] && return
  echo "To restore the stashed changes to $DIR run:"
  echo "  'cd $DIR && git stash pop'"
  unset STASHED
}

reset_on_interrupt() {
  if [[ "$INITIAL_BRANCH" != "$UPSTREAM_BRANCH" && -n "$INITIAL_BRANCH" ]]
  then
    git checkout "$INITIAL_BRANCH" "${QUIET_ARGS[@]}"
  fi

  if [[ -n "$INITIAL_REVISION" ]]
  then
    git rebase --abort &>/dev/null
    git merge --abort &>/dev/null
    git reset --hard "$INITIAL_REVISION" "${QUIET_ARGS[@]}"
  fi

  if [[ -n "$HOMEBREW_NO_UPDATE_CLEANUP" ]]
  then
    pop_stash
  else
    pop_stash_message
  fi

  exit 130
}

# Used for testing purposes, e.g., for testing formula migration after
# renaming it in the currently checked-out branch. To test run
# "brew update --simulate-from-current-branch"
simulate_from_current_branch() {
  local DIR
  local TAP_VAR
  local UPSTREAM_BRANCH
  local CURRENT_REVISION

  DIR="$1"
  cd "$DIR" || return
  TAP_VAR="$2"
  UPSTREAM_BRANCH="$3"
  CURRENT_REVISION="$4"

  INITIAL_REVISION="$(git rev-parse -q --verify "$UPSTREAM_BRANCH")"
  export HOMEBREW_UPDATE_BEFORE"$TAP_VAR"="$INITIAL_REVISION"
  export HOMEBREW_UPDATE_AFTER"$TAP_VAR"="$CURRENT_REVISION"
  if [[ "$INITIAL_REVISION" != "$CURRENT_REVISION" ]]
  then
    HOMEBREW_UPDATED="1"
  fi
  if ! git merge-base --is-ancestor "$INITIAL_REVISION" "$CURRENT_REVISION"
  then
    odie "Your $DIR HEAD is not a descendant of $UPSTREAM_BRANCH!"
  fi
}

merge_or_rebase() {
  if [[ -n "$HOMEBREW_VERBOSE" ]]
  then
    echo "Updating $DIR..."
  fi

  local DIR
  local TAP_VAR
  local UPSTREAM_BRANCH

  DIR="$1"
  cd "$DIR" || return
  TAP_VAR="$2"
  UPSTREAM_BRANCH="$3"
  unset STASHED

  trap reset_on_interrupt SIGINT

  if [[ "$DIR" = "$HOMEBREW_REPOSITORY" && -n "$HOMEBREW_UPDATE_TO_TAG" ]]
  then
    UPSTREAM_TAG="$(git tag --list |
                    sort --field-separator=. --key=1,1nr -k 2,2nr -k 3,3nr |
                    grep --max-count=1 '^[0-9]*\.[0-9]*\.[0-9]*$')"
  else
    UPSTREAM_TAG=""
  fi

  if [ -n "$UPSTREAM_TAG" ]
  then
    REMOTE_REF="refs/tags/$UPSTREAM_TAG"
    UPSTREAM_BRANCH="stable"
  else
    REMOTE_REF="origin/$UPSTREAM_BRANCH"
  fi

  if [[ -n "$(git status --untracked-files=all --porcelain 2>/dev/null)" ]]
  then
    if [[ -n "$HOMEBREW_VERBOSE" ]]
    then
      echo "Stashing uncommitted changes to $DIR..."
    fi
    git merge --abort &>/dev/null
    git rebase --abort &>/dev/null
    git reset --mixed "${QUIET_ARGS[@]}"
    if ! git -c "user.email=brew-update@localhost" \
             -c "user.name=brew update" \
             stash save --include-untracked "${QUIET_ARGS[@]}"
    then
      odie <<EOS
Could not 'git stash' in $DIR!
Please stash/commit manually if you need to keep your changes or, if not, run:
  cd $DIR
  git reset --hard origin/master
EOS
    fi
    git reset --hard "${QUIET_ARGS[@]}"
    STASHED="1"
  fi

  INITIAL_BRANCH="$(git symbolic-ref --short HEAD 2>/dev/null)"
  if [[ -n "$UPSTREAM_TAG" ]] ||
     [[ "$INITIAL_BRANCH" != "$UPSTREAM_BRANCH" && -n "$INITIAL_BRANCH" ]]
  then
    # Recreate and check out `#{upstream_branch}` if unable to fast-forward
    # it to `origin/#{@upstream_branch}`. Otherwise, just check it out.
    if [[ -z "$UPSTREAM_TAG" ]] &&
       git merge-base --is-ancestor "$UPSTREAM_BRANCH" "$REMOTE_REF" &>/dev/null
    then
      git checkout --force "$UPSTREAM_BRANCH" "${QUIET_ARGS[@]}"
    else
      git checkout --force -B "$UPSTREAM_BRANCH" "$REMOTE_REF" "${QUIET_ARGS[@]}"
    fi
  fi

  INITIAL_REVISION="$(read_current_revision)"
  export HOMEBREW_UPDATE_BEFORE"$TAP_VAR"="$INITIAL_REVISION"

  # ensure we don't munge line endings on checkout
  git config core.autocrlf false

  if [[ -z "$HOMEBREW_MERGE" ]]
  then
    git rebase "${QUIET_ARGS[@]}" "$REMOTE_REF"
  else
    git merge --no-edit --ff "${QUIET_ARGS[@]}" "$REMOTE_REF" \
      --strategy=recursive \
      --strategy-option=ours \
      --strategy-option=ignore-all-space
  fi

  CURRENT_REVISION="$(read_current_revision)"
  export HOMEBREW_UPDATE_AFTER"$TAP_VAR"="$CURRENT_REVISION"

  if [[ "$INITIAL_REVISION" != "$CURRENT_REVISION" ]]
  then
    HOMEBREW_UPDATED="1"
  fi

  trap '' SIGINT

  if [[ -n "$HOMEBREW_NO_UPDATE_CLEANUP" ]]
  then
    if [[ "$INITIAL_BRANCH" != "$UPSTREAM_BRANCH" && -n "$INITIAL_BRANCH" &&
          ! "$INITIAL_BRANCH" =~ ^v[0-9]+\.[0-9]+\.[0-9]|stable$ ]]
    then
      git checkout "$INITIAL_BRANCH" "${QUIET_ARGS[@]}"
    fi

    pop_stash
  else
    pop_stash_message
  fi

  trap - SIGINT
}

homebrew-update() {
  local option
  local DIR
  local UPSTREAM_BRANCH

  for option in "$@"
  do
    case "$option" in
      -\?|-h|--help|--usage)          brew help update; exit $? ;;
      --verbose)                      HOMEBREW_VERBOSE=1 ;;
      --debug)                        HOMEBREW_DEBUG=1 ;;
      --merge)                        HOMEBREW_MERGE=1 ;;
      --force)                        HOMEBREW_UPDATE_FORCE=1 ;;
      --simulate-from-current-branch) HOMEBREW_SIMULATE_FROM_CURRENT_BRANCH=1 ;;
      --preinstall)                   export HOMEBREW_UPDATE_PREINSTALL=1 ;;
      --*)                            ;;
      -*)
        [[ "$option" = *v* ]] && HOMEBREW_VERBOSE=1
        [[ "$option" = *d* ]] && HOMEBREW_DEBUG=1
        ;;
      *)
        odie <<EOS
This command updates brew itself, and does not take formula names.
Use 'brew upgrade $@' instead.
EOS
        ;;
    esac
  done

  if [[ -n "$HOMEBREW_DEBUG" ]]
  then
    set -x
  fi

  if [[ -z "$HOMEBREW_UPDATE_CLEANUP" && -z "$HOMEBREW_UPDATE_TO_TAG" ]]
  then
    if [[ -n "$HOMEBREW_DEVELOPER" || -n "$HOMEBREW_DEV_CMD_RUN" ]]
    then
      export HOMEBREW_NO_UPDATE_CLEANUP="1"
    else
      export HOMEBREW_UPDATE_TO_TAG="1"
    fi
  fi

  if [[ -z "$HOMEBREW_AUTO_UPDATE_SECS" ]]
  then
    HOMEBREW_AUTO_UPDATE_SECS="60"
  fi

  # check permissions
  if [[ -e "$HOMEBREW_CELLAR" && ! -w "$HOMEBREW_CELLAR" ]]
  then
    odie <<EOS
$HOMEBREW_CELLAR is not writable. You should change the
ownership and permissions of $HOMEBREW_CELLAR back to your
user account:
  sudo chown -R \$(whoami) $HOMEBREW_CELLAR
EOS
  fi

  if [[ ! -w "$HOMEBREW_REPOSITORY" ]]
  then
    odie <<EOS
$HOMEBREW_REPOSITORY is not writable. You should change the
ownership and permissions of $HOMEBREW_REPOSITORY back to your
user account:
  sudo chown -R \$(whoami) $HOMEBREW_REPOSITORY
EOS
  fi

  # we may want to use a Homebrew curl
  if [[ -n "$HOMEBREW_FORCE_BREWED_CURL" &&
      ! -x "$HOMEBREW_PREFIX/opt/curl/bin/curl" ]]
  then
    brew install curl
  fi

  if ! git --version &>/dev/null ||
       [[ -n "$HOMEBREW_SYSTEM_GIT_TOO_OLD" &&
        ! -x "$HOMEBREW_PREFIX/opt/git/bin/git" ]]
  then
    # we cannot install brewed git if homebrew/core is unavailable.
    [[ -d "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core" ]] && brew install git
    unset GIT_EXECUTABLE
    if ! git --version &>/dev/null
    then
      odie "Git must be installed and in your PATH!"
    fi
  fi
  export GIT_TERMINAL_PROMPT="0"
  export GIT_SSH_COMMAND="ssh -oBatchMode=yes"

  if [[ -z "$HOMEBREW_VERBOSE" ]]
  then
    QUIET_ARGS=(-q)
  else
    QUIET_ARGS=()
  fi

  # only allow one instance of brew update
  lock update

  git_init_if_necessary
  # rename Taps directories
  # this procedure will be removed in the future if it seems unnecessary
  rename_taps_dir_if_necessary

  safe_cd "$HOMEBREW_REPOSITORY"

  # kill all of subprocess on interrupt
  trap '{ /usr/bin/pkill -P $$; wait; exit 130; }' SIGINT

  local update_failed_file="$HOMEBREW_REPOSITORY/.git/UPDATE_FAILED"
  rm -f "$update_failed_file"

  for DIR in "$HOMEBREW_REPOSITORY" "$HOMEBREW_LIBRARY"/Taps/*/*
  do
    [[ -d "$DIR/.git" ]] || continue
    cd "$DIR" || continue

    if [[ -n "$HOMEBREW_VERBOSE" ]]
    then
      echo "Checking if we need to fetch $DIR..."
    fi

    TAP_VAR="$(repo_var "$DIR")"
    UPSTREAM_BRANCH_DIR="$(upstream_branch)"
    declare UPSTREAM_BRANCH"$TAP_VAR"="$UPSTREAM_BRANCH_DIR"
    declare PREFETCH_REVISION"$TAP_VAR"="$(git rev-parse -q --verify refs/remotes/origin/"$UPSTREAM_BRANCH_DIR")"

    # Force a full update if we don't have any tags.
    if [[ "$DIR" = "$HOMEBREW_REPOSITORY" && -z "$(git tag --list)" ]]
    then
      HOMEBREW_UPDATE_FORCE=1
    fi

    if [[ -z "$HOMEBREW_UPDATE_FORCE" ]]
    then
      [[ -n "$SKIP_FETCH_BREW_REPOSITORY" && "$DIR" = "$HOMEBREW_REPOSITORY" ]] && continue
      [[ -n "$SKIP_FETCH_CORE_REPOSITORY" && "$DIR" = "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core" ]] && continue
    fi

    # The upstream repository's default branch may not be master;
    # check refs/remotes/origin/HEAD to see what the default
    # origin branch name is, and use that. If not set, fall back to "master".
    # the refspec ensures that the default upstream branch gets updated
    (
      if [[ -n "$HOMEBREW_UPDATE_PREINSTALL" ]]
      then
        # Skip taps checked/fetched recently
        [[ -n "$(find "$DIR/.git/FETCH_HEAD" -type f -mtime -"${HOMEBREW_AUTO_UPDATE_SECS}"s 2>/dev/null)" ]] && exit
      fi

      UPSTREAM_REPOSITORY_URL="$(git config remote.origin.url)"
      if [[ "$UPSTREAM_REPOSITORY_URL" = "https://github.com/"* ]]
      then
        UPSTREAM_REPOSITORY="${UPSTREAM_REPOSITORY_URL#https://github.com/}"
        UPSTREAM_REPOSITORY="${UPSTREAM_REPOSITORY%.git}"

        if [[ "$DIR" = "$HOMEBREW_REPOSITORY" && -n "$HOMEBREW_UPDATE_TO_TAG" ]]
        then
          # Only try to `git fetch` when the upstream tags have changed
          # (so the API does not return 304: unmodified).
          GITHUB_API_ETAG="$(sed -n 's/^ETag: "\([a-f0-9]\{32\}\)".*/\1/p' ".git/GITHUB_HEADERS" 2>/dev/null)"
          GITHUB_API_ACCEPT="application/vnd.github.v3+json"
          GITHUB_API_ENDPOINT="tags"
        else
          # Only try to `git fetch` when the upstream branch is at a different SHA
          # (so the API does not return 304: unmodified).
          GITHUB_API_ETAG="$(git rev-parse "refs/remotes/origin/$UPSTREAM_BRANCH_DIR")"
          GITHUB_API_ACCEPT="application/vnd.github.v3.sha"
          GITHUB_API_ENDPOINT="commits/$UPSTREAM_BRANCH_DIR"
        fi

        UPSTREAM_SHA_HTTP_CODE="$("$HOMEBREW_CURL" --silent --max-time 3 \
           --output /dev/null --write-out "%{http_code}" \
           --dump-header "$DIR/.git/GITHUB_HEADERS" \
           --user-agent "$HOMEBREW_USER_AGENT_CURL" \
           --header "Accept: $GITHUB_API_ACCEPT" \
           --header "If-None-Match: \"$GITHUB_API_ETAG\"" \
           "https://api.github.com/repos/$UPSTREAM_REPOSITORY/$GITHUB_API_ENDPOINT")"

        # Touch FETCH_HEAD to confirm we've checked for an update.
        [[ -f "$DIR/.git/FETCH_HEAD" ]] && touch "$DIR/.git/FETCH_HEAD"
        [[ -z "$HOMEBREW_UPDATE_FORCE" ]] && [[ "$UPSTREAM_SHA_HTTP_CODE" = "304" ]] && exit
      elif [[ -n "$HOMEBREW_UPDATE_PREINSTALL" ]]
      then
        # Don't try to do a `git fetch` that may take longer than expected.
        exit
      fi

      if [[ -n "$HOMEBREW_VERBOSE" ]]
      then
        echo "Fetching $DIR..."
      fi

      if [[ -n "$HOMEBREW_UPDATE_PREINSTALL" ]]
      then
        git fetch --tags --force "${QUIET_ARGS[@]}" origin \
          "refs/heads/$UPSTREAM_BRANCH_DIR:refs/remotes/origin/$UPSTREAM_BRANCH_DIR" 2>/dev/null
      else
        if ! git fetch --tags --force "${QUIET_ARGS[@]}" origin \
          "refs/heads/$UPSTREAM_BRANCH_DIR:refs/remotes/origin/$UPSTREAM_BRANCH_DIR"
        then
          echo "Fetching $DIR failed!" >>"$update_failed_file"
        fi
      fi
    ) &
  done

  wait
  trap - SIGINT

  if [[ -f "$update_failed_file" ]]
  then
    onoe <"$update_failed_file"
    rm -f "$update_failed_file"
    export HOMEBREW_UPDATE_FAILED="1"
  fi

  for DIR in "$HOMEBREW_REPOSITORY" "$HOMEBREW_LIBRARY"/Taps/*/*
  do
    [[ -d "$DIR/.git" ]] || continue
    cd "$DIR" || continue

    TAP_VAR="$(repo_var "$DIR")"
    UPSTREAM_BRANCH_VAR="UPSTREAM_BRANCH$TAP_VAR"
    UPSTREAM_BRANCH="${!UPSTREAM_BRANCH_VAR}"
    CURRENT_REVISION="$(read_current_revision)"

    PREFETCH_REVISION_VAR="PREFETCH_REVISION$TAP_VAR"
    PREFETCH_REVISION="${!PREFETCH_REVISION_VAR}"
    POSTFETCH_REVISION="$(git rev-parse -q --verify refs/remotes/origin/"$UPSTREAM_BRANCH")"

    if [[ -n "$HOMEBREW_SIMULATE_FROM_CURRENT_BRANCH" ]]
    then
      simulate_from_current_branch "$DIR" "$TAP_VAR" "$UPSTREAM_BRANCH" "$CURRENT_REVISION"
    elif [[ -z "$HOMEBREW_UPDATE_FORCE" ]] &&
         [[ "$PREFETCH_REVISION" = "$POSTFETCH_REVISION" ]] &&
         [[ "$CURRENT_REVISION" = "$POSTFETCH_REVISION" ]]
    then
      export HOMEBREW_UPDATE_BEFORE"$TAP_VAR"="$CURRENT_REVISION"
      export HOMEBREW_UPDATE_AFTER"$TAP_VAR"="$CURRENT_REVISION"
    else
      merge_or_rebase "$DIR" "$TAP_VAR" "$UPSTREAM_BRANCH"
      [[ -n "$HOMEBREW_VERBOSE" ]] && echo
    fi
  done

  safe_cd "$HOMEBREW_REPOSITORY"

  if [[ -n "$HOMEBREW_UPDATED" ||
        -n "$HOMEBREW_UPDATE_FAILED" ||
        -n "$HOMEBREW_UPDATE_FORCE" ||
        -d "$HOMEBREW_LIBRARY/LinkedKegs" ||
        (-n "$HOMEBREW_DEVELOPER" && -z "$HOMEBREW_UPDATE_PREINSTALL") ]]
  then
    unset HOMEBREW_RUBY_PATH
    brew update-report "$@"
    return $?
  elif [[ -z "$HOMEBREW_UPDATE_PREINSTALL" ]]
  then
    echo "Already up-to-date."
  fi
}