Merge pull request #52 from chef/lcg/dlopen-extension

add DLopen extension

4 files changed, 105 insertions, 92 deletions

diff --git a/lib/ffi_yajl.rb b/lib/ffi_yajl.rb
index 7f39189..5edc4f6 100644
--- a/lib/ffi_yajl.rb
+++ b/lib/ffi_yajl.rb
@@ -19,10 +19,6 @@ elsif ENV['FORCE_FFI_YAJL'] == "ffi"
   require 'ffi_yajl/ffi'
 elsif RUBY_PLATFORM == "java"
   require 'ffi_yajl/ffi'
-elsif defined?(Yajl)
-  warn "the ffi-yajl and yajl-ruby gems have incompatible C libyajl libs and should not be loaded in the same Ruby VM"
-  warn "falling back to ffi which might work (or might not, no promises)"
-  require 'ffi_yajl/ffi'
 else
   begin
     require 'ffi_yajl/ext'
diff --git a/lib/ffi_yajl/ext.rb b/lib/ffi_yajl/ext.rb
index bc4d410..7ecf172 100644
--- a/lib/ffi_yajl/ext.rb
+++ b/lib/ffi_yajl/ext.rb
@@ -2,62 +2,14 @@ require 'rubygems'
 
 require 'ffi_yajl/encoder'
 require 'ffi_yajl/parser'
-require 'libyajl2'
+require 'ffi_yajl/ext/dlopen'
 require 'ffi_yajl/map_library_name'
 
 module FFI_Yajl
   extend FFI_Yajl::MapLibraryName
+  extend FFI_Yajl::Ext::Dlopen
 
-  libname = map_library_name
-  libpath = File.expand_path(File.join(Libyajl2.opt_path, libname))
-
-  #
-  # FFS, what exactly was so wrong with DL.dlopen that ruby had to get rid of it???
-  #
-
-  def self.try_fiddle_dlopen(libpath)
-    require 'fiddle'
-    if defined?(Fiddle) && Fiddle.respond_to?(:dlopen)
-      ::Fiddle.dlopen(libpath)
-      true
-    else
-      false
-    end
-  rescue LoadError
-    return false
-  end
-
-  def self.try_dl_dlopen(libpath)
-    require 'dl'
-    if defined?(DL) && DL.respond_to?(:dlopen)
-      ::DL.dlopen(libpath)
-      true
-    else
-      false
-    end
-  rescue LoadError
-    return false
-  end
-
-  def self.try_ffi_dlopen(libpath)
-    require 'ffi'
-    require 'rbconfig'
-    extend ::FFI::Library
-    ffi_lib 'dl'
-    attach_function 'dlopen', :dlopen, [:string, :int], :void
-    if  RbConfig::CONFIG['host_os'] =~ /linux/i
-      dlopen libpath, 0x102  # linux: RTLD_GLOBAL | RTLD_NOW
-    else
-      dlopen libpath, 0
-    end
-    true
-  rescue LoadError
-    return false
-  end
-
-  unless try_fiddle_dlopen(libpath) || try_dl_dlopen(libpath) || try_ffi_dlopen(libpath)
-    raise "cannot find dlopen via Fiddle, DL or FFI, what am I supposed to do?"
-  end
+  dlopen_yajl_library
 
   class Parser
     require 'ffi_yajl/ext/parser'
diff --git a/lib/ffi_yajl/ffi.rb b/lib/ffi_yajl/ffi.rb
index 32335ac..b38d5fb 100644
--- a/lib/ffi_yajl/ffi.rb
+++ b/lib/ffi_yajl/ffi.rb
@@ -16,15 +16,7 @@ module FFI_Yajl
 
   extend FFI_Yajl::MapLibraryName
 
-  libname = map_library_name
-  libpath = File.expand_path(File.join(Libyajl2.opt_path, libname))
-
-  if File.file?(libpath)
-    # use our vendored version of libyajl2 if we find it installed
-    ffi_lib libpath
-  else
-    ffi_lib 'yajl'
-  end
+  ffi_open_yajl_library
 
   class YajlCallbacks < ::FFI::Struct
     layout :yajl_null, :pointer,
diff --git a/lib/ffi_yajl/map_library_name.rb b/lib/ffi_yajl/map_library_name.rb
index 3518d07..8723424 100644
--- a/lib/ffi_yajl/map_library_name.rb
+++ b/lib/ffi_yajl/map_library_name.rb
@@ -1,37 +1,110 @@
+# Copyright (c) 2015 Lamont Granquist
+# Copyright (c) 2015 Chef Software, Inc.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-require 'ffi_yajl/platform'
+require 'libyajl2'
+
+# Mixin for use in finding the right yajl library on the system.  The 'caller'
+# needs to also mixin either the FFI module or the DLopen module.  Those are
+# deliberately not mixed in to avoid loading the dlopen module in the ffi
+# codepath (which fails on jruby which does not have that C extension).
 
 module FFI_Yajl
   module MapLibraryName
-    include FFI_Yajl::Platform
-    def map_library_name
-      # this is the right answer for the internally built libyajl on windows
-      return "libyajl.so" if windows?
-
-      # this is largely copied from the FFI.map_library_name algorithm, we most likely need
-      # the windows code eventually to support not using the embedded libyajl2-gem
-      libprefix =
-        case RbConfig::CONFIG['host_os'].downcase
-        when /mingw|mswin/
-          ''
-        when /cygwin/
-          'cyg'
-        else
-          'lib'
+
+    private
+
+    # Stub for tests to override the host_os
+    #
+    # @api private
+    # @return Array<String> lower case ruby host_os string
+    def host_os
+      RbConfig::CONFIG['host_os'].downcase
+    end
+
+    # Array of yajl library names on the platform.  Some platforms like Windows
+    # and Mac may have different names/extensions.
+    #
+    # @api private
+    # @return Array<String> Array of yajl library names for platform
+    def library_names
+      case host_os
+      when /mingw|mswin/
+        [ "libyajl.so", "yajl.dll" ]
+      when /cygwin/
+        [ "libyajl.so", "cygyajl.dll" ]
+      when /darwin/
+        [ "libyajl.bundle", "libyajl.dylib" ]
+      else
+        [ "libyajl.so" ]
+      end
+    end
+
+    # Array of yajl library names prepended with the libyajl2 path to use to
+    # load those directly and bypass the system libyajl by default.  Since
+    # these are full paths, this API checks to ensure that the file exists on
+    # the filesystem.  May return an empty array.
+    #
+    # @api private
+    # @return Array<String> Array of full paths to libyajl2 gem libraries
+    def expanded_library_names
+      library_names.map do |libname|
+        pathname = File.expand_path(File.join(Libyajl2.opt_path, libname))
+        pathname if File.file?(pathname)
+      end.compact
+    end
+
+    # Iterate across the expanded library names in the libyajl2-gem and then
+    # attempt to load the system libraries.  Uses the native dlopen extension
+    # that ships in this gem.
+    #
+    # @api private
+    def dlopen_yajl_library
+      found = false
+      ( expanded_library_names + library_names ).each do |libname|
+        begin
+          dlopen(libname)
+          found = true
+          break
+        rescue ArgumentError
         end
-      libsuffix =
-        case RbConfig::CONFIG['host_os'].downcase
-        when /darwin/
-          'bundle'
-        when /linux|bsd|solaris|sunos/
-          'so'
-        when /mingw|mswin|cygwin/
-          'dll'
-        else
-          # Punt and just assume a sane unix (i.e. anything but AIX)
-          'so'
+      end
+      raise "cannot find yajl library for platform" unless found
+    end
+
+    # Iterate across the expanded library names in the libyajl2-gem and attempt
+    # to load them.  If they are missing just use `ffi_lib 'yajl'` to accept
+    # the FFI default algorithm to find the library.
+    #
+    # @api private
+    def ffi_open_yajl_library
+      found = false
+      expanded_library_names.each do |libname|
+        begin
+          ffi_lib libname
+          found = true
+        rescue LoadError
         end
-      libprefix + "yajl" + ".#{libsuffix}"
+      end
+      ffi_lib 'yajl' unless found
     end
   end
 end