From cd3be4af882f4967d37ac36b9e90cbe94c259a4a Mon Sep 17 00:00:00 2001
From: John Anderson <panic@semiosix.com>
Date: Wed, 26 Sep 2018 14:27:17 +0200
Subject: [PATCH] extconf.rb now knows how to find /usr/lib/modsecurity which
 is the default location

---
 .gitignore                      |  1 +
 ext/msc_intervention/extconf.rb | 78 ++++++++++++++++++++++++++++++++-
 lib/rodsec/version.rb           |  2 +-
 lib/rodsec/wrapper.rb           |  4 +-
 rodsec.gemspec                  |  2 +-
 5 files changed, 83 insertions(+), 4 deletions(-)

diff --git a/.gitignore b/.gitignore
index 5118842..ae42770 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@
 
 # local c extensions
 lib/rodsec/*.so
+lib/rodsec/modsec_lib.rb
diff --git a/ext/msc_intervention/extconf.rb b/ext/msc_intervention/extconf.rb
index 2034aab..cf18294 100644
--- a/ext/msc_intervention/extconf.rb
+++ b/ext/msc_intervention/extconf.rb
@@ -1,5 +1,81 @@
 require 'mkmf'
-pkg_config 'modsecurity'
+
+MODSECURITY_LIB_NAME = 'modsecurity'
+SO_FUNC = 'msc_init'
+
+def so_name
+  @so_name ||= "lib#{MODSECURITY_LIB_NAME}.#{CONFIG['DLEXT']}"
+end
+
+def intervention_header_name
+  @intervention_header_name ||= 'modsecurity/intervention.h'
+end
+
+# raise an exception if one of the paths doesn't exist
+def confirm_include_lib include_dir, lib_dir
+  File.realpath(File.join include_dir, intervention_header_name)
+  File.realpath(File.join lib_dir, so_name)
+end
+
+def create_modsec_lib_rb so_lib_path, dst_ruby_file: 'modsec_lib.rb'
+  puts "runtime loads #{so_lib_path}"
+
+  # create a direct path to the library, because it's often in a nonstandard location
+  ruby_lib_dir = File.join CONFIG['srcdir'], '..', '..', 'lib', 'rodsec'
+  File.open File.join(ruby_lib_dir,dst_ruby_file), 'w' do |io|
+    io.write <<~EOS
+      # Generated by extconf.rb
+      module Rodsec
+        MODSECURITY_SO_PATH = '#{so_lib_path}'
+      end
+    EOS
+  end
+end
+
+def find_header_and_library include_dir, lib_dir
+  ok = true
+  ok &&= find_header intervention_header_name, include_dir
+  ok &&= find_library MODSECURITY_LIB_NAME, SO_FUNC, lib_dir
+  ok or abort
+end
+
+STANDARD_DIRS = [
+  %w[/usr/local/include /usr/local/lib],
+  %w[/usr/include       /usr/lib],
+]
+
+# get the user config, or failing that the default ModSecurity installation paths
+custom_dirs = dir_config 'modsecurity', '/usr/local/modsecurity'
+
+found_dirs = ([custom_dirs] + STANDARD_DIRS).find do |(include_dir, lib_dir)|
+  # try to find files from config
+  begin
+    confirm_include_lib include_dir, lib_dir
+    [include_dir, lib_dir]
+  rescue
+    puts "#{[include_dir, lib_dir]} not found. Continuing..."
+  end
+end
+
+unless found_dirs
+  puts 'Cannot locate libmodsecurity.so'
+  abort
+end
+
+so_lib_path =
+if found_dirs == custom_dirs
+  # we have custom dirs, set a specific path for the dlload in Wrapper
+  File.join found_dirs.last, so_name
+else
+  # standard dirs, so do not use a specific path in Wrapper
+  so_name
+end
+
+# create the file so Wrapper knows where to load the .so
+create_modsec_lib_rb so_lib_path
+
+# finally, use find_header and find_library to add the paths to the Makefile
+find_header_and_library *found_dirs
 
 # don't need piles of debug info. Or maybe we do. Dunno.
 CONFIG['debugflags'] = ''
diff --git a/lib/rodsec/version.rb b/lib/rodsec/version.rb
index bf52b67..3b9dfef 100644
--- a/lib/rodsec/version.rb
+++ b/lib/rodsec/version.rb
@@ -1,3 +1,3 @@
 module Rodsec
-  VERSION = '0.0.1'
+  VERSION = '0.0.2'
 end
diff --git a/lib/rodsec/wrapper.rb b/lib/rodsec/wrapper.rb
index 0f2da57..47343eb 100644
--- a/lib/rodsec/wrapper.rb
+++ b/lib/rodsec/wrapper.rb
@@ -1,13 +1,15 @@
 require 'fiddle'
 require 'fiddle/import'
 
+require_relative 'modsec_lib.rb'
+
 module Rodsec
   module Wrapper
     extend Fiddle::Importer
 
     dlext = RbConfig::CONFIG['DLEXT']
     msc_intervention = dlopen File.join __dir__, "msc_intervention.#{dlext}"
-    dlload msc_intervention, "libmodsecurity.#{dlext}"
+    dlload msc_intervention, MODSECURITY_SO_PATH
 
     ###########################
     # from modsecurity/modsecurity.h
diff --git a/rodsec.gemspec b/rodsec.gemspec
index f9db4f8..9dc379c 100644
--- a/rodsec.gemspec
+++ b/rodsec.gemspec
@@ -23,7 +23,7 @@ Gem::Specification.new do |spec|
   end
 
   spec.files         = `git ls-files -z`.split("\x0").reject do |f|
-    f.match(%r{^(test|spec(?!/config)|features)/})
+    f.match(%r{^(test|spec(?!/config)|features|modsec_lib)/})
   end
   spec.bindir        = 'exe'
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }