Ensure gem install and bundle install give the same result.

- This workaround is required until Ruby gems has a post_gem_install hook

Signed-off-by: Hedgehog <hedgehogshiatus@gmail.com>

ext/geminstall_hook/extconf.rb

@@ -0,0 +1,97 @@
+require 'fileutils'
+
+# methods used in gem installation hooks
+# Source: Victor Costan (http://blog.costan.us/2008/11/post-install-post-update-scripts-for.html)
+module ::Fog
+  module GeminstallHook
+    # called by ensure_on_path for Windows systems
+    def self.ensure_on_windows_path(bin_file)
+      bat_file = File.expand_path(File.join(ENV["WINDIR"],
+                                  File.basename(bin_file) + ".bat"))
+      begin
+        File.open(bat_file, 'w') do |f|
+          f.write <<END_BATCH
+@ECHO OFF
+IF NOT "%~f0" == "~f0" GOTO :WinNT
+@"ruby.exe" "#{File.expand_path(bin_file)}" %1 %2 %3 %4 %5 %6 %7 %8 %9
+GOTO :EOF
+:WinNT
+@"ruby.exe" "#{File.expand_path(bin_file)}" %*
+END_BATCH
+        end
+      #rescue
+        # if anything goes wrong we probably don't have permissions (hi Vista?)
+      end
+    end
+
+    # called by ensure_on_path for UNIX systems
+    def self.ensure_on_unix_path(bin_file)
+      path = "/usr/bin/#{File.basename bin_file}"
+      begin
+        # using a link so the gem can be updated and the link still works
+        FileUtils.ln_s(bin_file, path, :force)
+      rescue
+        # if anything goes wrong we probably don't have permissions
+        # oh well at least we tried
+      end
+    end
+
+    # ensures that bin_file can be invoked from a shell
+    def self.ensure_on_path(bin_script)
+      caller_trace = Kernel.caller.first
+      caller_match = /^(.*)\:\d+\:in /.match(caller_trace) ||
+                     /^(.*)\:\d+$/.match(caller_trace)
+      bin_file = File.expand_path caller_match[1] + '/../../../bin/' + bin_script
+      # this is a cheat to get the binary in the right place on stubborn Debians
+      if RUBY_PLATFORM =~ /win/ and RUBY_PLATFORM !~ /darwin/
+        ensure_on_windows_path bin_file
+      else
+        ensure_on_unix_path bin_file
+      end
+    end
+
+    # tricks rubygems into believeing that the extension compiled and worked out
+    def self.emulate_extension_install(extension_name)
+      File.open('Makefile', 'w') { |f| f.write "all:\n\ninstall:\n\n" }
+      File.open('make', 'w') do |f|
+        f.write '#!/bin/sh'
+      end
+      ::FileUtils.chmod 0711, 'make', :verbose => true
+      File.open(extension_name + '.so', 'w') {}
+      File.open(extension_name + '.dll', 'w') {}
+      File.open('nmake.bat', 'w') { |f| }
+    end
+
+    def self.sh(cmd, &block)
+      out, code = sh_with_code(cmd, &block)
+      code == 0 ? out : raise(out.empty? ? "Running `#{cmd}' failed. Run this command directly for more detailed output." : out)
+    end
+
+    def self.sh_with_code(cmd, &block)
+      cmd << " 2>&1"
+      outbuf = ''
+      Dir.chdir(self.gemfile_dir) {
+        outbuf = `#{cmd}`
+        if $? == 0
+          block.call(outbuf) if block
+        end
+      }
+      [outbuf, $?]
+    end
+
+    def self.gemfile_dir
+      File.expand_path(File.join(File.dirname(__FILE__), '..', '..') )
+    end
+  end
+end
+
+::Fog::GeminstallHook.ensure_on_path 'fog'
+begin
+  ::Fog::GeminstallHook.sh('bundle install --without bdd benchmark cukes debug development rspec shindo metrics')
+rescue => err
+  $stderr.puts "Run `bundle install` to install gems missing from common or rake groups"
+  $stderr.puts caller.join("\n")
+  exit err.status_code
+else
+  ::Fog::GeminstallHook.emulate_extension_install 'geminstall_hook'
+end