Print DMG EULA when --verbose.

Library/Homebrew/cask/lib/hbc/artifact/nested_container.rb

@@ -16,7 +16,7 @@ module Hbc
         end
 
         ohai "Extracting nested container #{source.basename}"
-        container.new(@cask, source, @command).extract
+        container.new(@cask, source, @command, verbose: verbose?).extract
         FileUtils.remove_entry_secure(source)
       end
     end

Library/Homebrew/cask/lib/hbc/container/base.rb

@@ -1,11 +1,16 @@
 module Hbc
   class Container
     class Base
-      def initialize(cask, path, command, nested: false)
+      def initialize(cask, path, command, nested: false, verbose: false)
         @cask = cask
         @path = path
         @command = command
         @nested = nested
+        @verbose = verbose
+      end
+
+      def verbose?
+        @verbose
       end
 
       def extract_nested_inside(dir)
@@ -32,7 +37,7 @@ module Hbc
         return false unless container
 
         ohai "Extracting nested container #{source.basename}"
-        container.new(@cask, source, @command, nested: true).extract
+        container.new(@cask, source, @command, nested: true, verbose: verbose?).extract
 
         true
       end

Library/Homebrew/cask/lib/hbc/container/dmg.rb

@@ -31,11 +31,27 @@ module Hbc
         Dir.mktmpdir do |unpack_dir|
           cdr_path = Pathname.new(unpack_dir).join("#{path.basename(".dmg")}.cdr")
 
+          without_eula = @command.run("/usr/bin/hdiutil",
+                                 args:  ["attach", "-plist", "-nobrowse", "-readonly", "-noidme", "-mountrandom", unpack_dir, path],
+                                 input: "qn\n",
+                                 print_stderr: false)
+
+          # If mounting without agreeing to EULA succeeded, there is none.
+          plist = if without_eula.success?
+            without_eula.plist
+          else
             @command.run!("/usr/bin/hdiutil", args: ["convert", "-quiet", "-format", "UDTO", "-o", cdr_path, path])
 
-          plist = @command.run!("/usr/bin/hdiutil",
-                                args:  ["attach", "-plist", "-nobrowse", "-readonly", "-noidme", "-mountrandom", unpack_dir, cdr_path],
-                                input: "qy\n").plist
+            with_eula = @command.run!("/usr/bin/hdiutil",
+                          args: ["attach", "-plist", "-nobrowse", "-readonly", "-noidme", "-mountrandom", unpack_dir, cdr_path])
+
+            if verbose? && !(eula_text = without_eula.stdout).empty?
+              ohai "Software License Agreement for '#{path}':"
+              puts eula_text
+            end
+
+            with_eula.plist
+          end
 
           yield mounts_from_plist(plist)
         end

Library/Homebrew/cask/lib/hbc/installer.rb

@@ -165,7 +165,7 @@ module Hbc
       end
 
       odebug "Using container class #{container} for #{@downloaded_path}"
-      container.new(@cask, @downloaded_path, @command).extract
+      container.new(@cask, @downloaded_path, @command, verbose: verbose?).extract
     end
 
     def install_artifacts