brew/Library/Homebrew/cmd/upgrade.rb

require 'cmd/install'
require 'cmd/outdated'

module Homebrew extend self
  def upgrade
    Homebrew.perform_preinstall_checks

    if ARGV.named.empty?
      outdated = Homebrew.outdated_brews
      exit 0 if outdated.empty?
    else
      outdated = ARGV.formulae.select do |f|
        if f.installed?
          onoe "#{f}-#{f.installed_version} already installed"
          false
        elsif not f.rack.directory? or f.rack.subdirs.empty?
          onoe "#{f} not installed"
          false
        else
          true
        end
      end
      exit 1 if outdated.empty?
    end

    unless upgrade_pinned?
      pinned = outdated.select(&:pinned?)
      outdated -= pinned
    end

    unless outdated.empty?
      oh1 "Upgrading #{outdated.length} outdated package#{plural(outdated.length)}, with result:"
      puts outdated.map{ |f| "#{f.name} #{f.pkg_version}" } * ", "
    else
      oh1 "No packages to upgrade"
    end

    unless upgrade_pinned? || pinned.empty?
      oh1 "Not upgrading #{pinned.length} pinned package#{plural(pinned.length)}:"
      puts pinned.map{ |f| "#{f.name} #{f.pkg_version}" } * ", "
    end

    outdated.each { |f| upgrade_formula(f) }
  end

  def upgrade_pinned?
    not ARGV.named.empty?
  end

  def upgrade_formula f
    outdated_keg = Keg.new(f.linked_keg.resolved_path) if f.linked_keg.directory?

    fi = FormulaInstaller.new(f)
    fi.options             = Tab.for_formula(f).used_options
    fi.build_from_source   = ARGV.build_from_source?
    fi.verbose             = ARGV.verbose?
    fi.verbose           &&= :quieter if ARGV.quieter?
    fi.debug               = ARGV.debug?
    fi.prelude

    oh1 "Upgrading #{f.name}"

    # first we unlink the currently active keg for this formula otherwise it is
    # possible for the existing build to interfere with the build we are about to
    # do! Seriously, it happens!
    outdated_keg.unlink if outdated_keg

    fi.install
    fi.caveats
    fi.finish

    # If the formula was pinned, and we were force-upgrading it, unpin and
    # pin it again to get a symlink pointing to the correct keg.
    if f.pinned?
      f.unpin
      f.pin
    end
  rescue FormulaInstallationAlreadyAttemptedError
    # We already attempted to upgrade f as part of the dependency tree of
    # another formula. In that case, don't generate an error, just move on.
  rescue CannotInstallFormulaError => e
    ofail e
  rescue BuildError => e
    e.dump
    puts
    Homebrew.failed = true
  rescue DownloadError => e
    ofail e
  ensure
    # restore previous installation state if build failed
    outdated_keg.link if outdated_keg and not f.installed? rescue nil
  end

end