1 files changed, 178 insertions, 0 deletions
diff --git a/Library/Homebrew/linkage_checker.rb b/Library/Homebrew/linkage_checker.rb
new file mode 100644
index 000000000..cf6c12f22
--- /dev/null
+++ b/Library/Homebrew/linkage_checker.rb
@@ -0,0 +1,178 @@
+require "set"
+require "keg"
+require "formula"
+
+class LinkageChecker
+  attr_reader :keg, :formula
+  attr_reader :brewed_dylibs, :system_dylibs, :broken_dylibs, :variable_dylibs
+  attr_reader :undeclared_deps, :unnecessary_deps, :reverse_links
+
+  def initialize(keg, formula = nil)
+    @keg = keg
+    @formula = formula || resolve_formula(keg)
+    @brewed_dylibs = Hash.new { |h, k| h[k] = Set.new }
+    @system_dylibs = Set.new
+    @broken_dylibs = Set.new
+    @variable_dylibs = Set.new
+    @indirect_deps = []
+    @undeclared_deps = []
+    @reverse_links = Hash.new { |h, k| h[k] = Set.new }
+    @unnecessary_deps = []
+    check_dylibs
+  end
+
+  def check_dylibs
+    @keg.find do |file|
+      next if file.symlink? || file.directory?
+      next unless file.dylib? || file.binary_executable? || file.mach_o_bundle?
+
+      # weakly loaded dylibs may not actually exist on disk, so skip them
+      # when checking for broken linkage
+      file.dynamically_linked_libraries(except: :LC_LOAD_WEAK_DYLIB).each do |dylib|
+        @reverse_links[dylib] << file
+        if dylib.start_with? "@"
+          @variable_dylibs << dylib
+        else
+          begin
+            owner = Keg.for Pathname.new(dylib)
+          rescue NotAKegError
+            @system_dylibs << dylib
+          rescue Errno::ENOENT
+            next if harmless_broken_link?(dylib)
+            @broken_dylibs << dylib
+          else
+            tap = Tab.for_keg(owner).tap
+            f = if tap.nil? || tap.core_tap?
+              owner.name
+            else
+              "#{tap}/#{owner.name}"
+            end
+            @brewed_dylibs[f] << dylib
+          end
+        end
+      end
+    end
+
+    @indirect_deps, @undeclared_deps, @unnecessary_deps = check_undeclared_deps if formula
+  end
+
+  def check_undeclared_deps
+    filter_out = proc do |dep|
+      next true if dep.build?
+      next false unless dep.optional? || dep.recommended?
+      formula.build.without?(dep)
+    end
+    declared_deps = formula.deps.reject { |dep| filter_out.call(dep) }.map(&:name)
+    recursive_deps = keg.to_formula.runtime_dependencies.map { |dep| dep.to_formula.full_name }
+    declared_dep_names = declared_deps.map { |dep| dep.split("/").last }
+    indirect_deps = []
+    undeclared_deps = []
+    @brewed_dylibs.each_key do |full_name|
+      name = full_name.split("/").last
+      next if name == formula.name
+      if recursive_deps.include?(name)
+        indirect_deps << full_name unless declared_dep_names.include?(name)
+      else
+        undeclared_deps << full_name
+      end
+    end
+    sort_by_formula_full_name!(indirect_deps)
+    sort_by_formula_full_name!(undeclared_deps)
+    unnecessary_deps = declared_dep_names.reject do |full_name|
+      name = full_name.split("/").last
+      next true if Formula[name].bin.directory?
+      @brewed_dylibs.keys.map { |x| x.split("/").last }.include?(name)
+    end
+    [indirect_deps, undeclared_deps, unnecessary_deps]
+  end
+
+  def sort_by_formula_full_name!(arr)
+    arr.sort! do |a, b|
+      if a.include?("/") && !b.include?("/")
+        1
+      elsif !a.include?("/") && b.include?("/")
+        -1
+      else
+        a <=> b
+      end
+    end
+  end
+
+  def display_normal_output
+    display_items "System libraries", @system_dylibs
+    display_items "Homebrew libraries", @brewed_dylibs
+    display_items "Indirect dependencies with linkage", @indirect_deps
+    display_items "Variable-referenced libraries", @variable_dylibs
+    display_items "Missing libraries", @broken_dylibs
+    display_items "Undeclared dependencies with linkage", @undeclared_deps
+    display_items "Dependencies with no linkage", @unnecessary_deps
+  end
+
+  def display_reverse_output
+    return if @reverse_links.empty?
+    sorted = @reverse_links.sort
+    sorted.each do |dylib, files|
+      puts dylib
+      files.each do |f|
+        unprefixed = f.to_s.strip_prefix "#{@keg}/"
+        puts "  #{unprefixed}"
+      end
+      puts unless dylib == sorted.last[0]
+    end
+  end
+
+  def display_test_output
+    display_items "Missing libraries", @broken_dylibs
+    display_items "Possible unnecessary dependencies", @unnecessary_deps
+    puts "No broken dylib links" if @broken_dylibs.empty?
+  end
+
+  def broken_dylibs?
+    !@broken_dylibs.empty?
+  end
+
+  def undeclared_deps?
+    !@undeclared_deps.empty?
+  end
+
+  def unnecessary_deps?
+    !@unnecessary_deps.empty?
+  end
+
+  private
+
+  # Whether or not dylib is a harmless broken link, meaning that it's
+  # okay to skip (and not report) as broken.
+  def harmless_broken_link?(dylib)
+    # libgcc_s_* is referenced by programs that use the Java Service Wrapper,
+    # and is harmless on x86(_64) machines
+    [
+      "/usr/lib/libgcc_s_ppc64.1.dylib",
+      "/opt/local/lib/libgcc/libgcc_s.1.dylib",
+    ].include?(dylib)
+  end
+
+  # Display a list of things.
+  # Things may either be an array, or a hash of (label -> array)
+  def display_items(label, things)
+    return if things.empty?
+    puts "#{label}:"
+    if things.is_a? Hash
+      things.sort.each do |list_label, list|
+        list.sort.each do |item|
+          puts "  #{item} (#{list_label})"
+        end
+      end
+    else
+      things.sort.each do |item|
+        puts "  #{item}"
+      end
+    end
+  end
+
+  def resolve_formula(keg)
+    Formulary.from_keg(keg)
+  rescue FormulaUnavailableError
+    opoo "Formula unavailable: #{keg.name}"
+  end
+end