From 787b471618b8f10de261e572cf5b91d4b863f026 Mon Sep 17 00:00:00 2001
From: Roland Walker <walker@pobox.com>
Date: Tue, 3 Jun 2014 11:39:58 -0400
Subject: [PATCH 1/2] isolate ErrorDuringExecution rescue

it only should be rescued for the `curl` invocation
---
 lib/cask/source/uri.rb | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/cask/source/uri.rb b/lib/cask/source/uri.rb
index 34ffc0a0f7..3f6dffe9b6 100644
--- a/lib/cask/source/uri.rb
+++ b/lib/cask/source/uri.rb
@@ -14,10 +14,12 @@ class Cask::Source::URI
     path = HOMEBREW_CACHE_CASKS.join(File.basename(uri))
     ohai "Downloading #{uri}"
     odebug "Download target -> #{path.to_s}"
-    curl(uri, '-o', path.to_s)
+    begin
+      curl(uri, '-o', path.to_s)
+    rescue ErrorDuringExecution
+      raise CaskUnavailableError.new uri
+    end
     Cask::Source::PathSlashOptional.new(path).load
-  rescue ErrorDuringExecution
-    raise CaskUnavailableError, uri
   end
 
   def to_s

From c082b5521a4d7cf673b88b55028a70b2d0ad3b4b Mon Sep 17 00:00:00 2001
From: Roland Walker <walker@pobox.com>
Date: Tue, 3 Jun 2014 11:42:32 -0400
Subject: [PATCH 2/2] Improve error checking and messages on Cask load

Other Cask sources ultimately invoke the `load` method in the
abstract class Cask::Source::PathBase, so these changes apply
to all other sources.
---
 lib/cask/source/path_base.rb | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/lib/cask/source/path_base.rb b/lib/cask/source/path_base.rb
index 8c03e9cf15..ff62fb8346 100644
--- a/lib/cask/source/path_base.rb
+++ b/lib/cask/source/path_base.rb
@@ -15,8 +15,23 @@ class Cask::Source::PathBase
   end
 
   def load
-    require path
-    Cask.const_get(cask_class_name).new
+    raise CaskError.new "File '#{path}' does not exist"      unless path.exist?
+    raise CaskError.new "File '#{path}' is not readable"     unless path.readable?
+    raise CaskError.new "File '#{path}' is not a plain file" unless path.file?
+    begin
+      require path
+    rescue CaskError, StandardError, ScriptError => e
+      # bug: e.message.concat doesn't work with CaskError exceptions
+      e.message.concat(" while loading '#{path}'")
+      raise e
+    end
+    begin
+      Cask.const_get(cask_class_name).new
+    rescue CaskError, StandardError, ScriptError => e
+      # bug: e.message.concat doesn't work with CaskError exceptions
+      e.message.concat(" while instantiating '#{cask_class_name}' from '#{path}'")
+      raise e
+    end
   end
 
   def cask_class_name