find libzmq in /usr/lib and respect LD_LIBRARY_PATH

Author: paddor

lib/cztop/poller/zmq.rb

@@ -9,11 +9,21 @@ module Poller::ZMQ
     POLLERR = 4
 
     extend ::FFI::Library
-    lib_name  = 'libzmq'
-    lib_dirs  = ['/usr/local/lib', '/opt/local/lib', '/usr/lib64']
-    lib_dirs  = [*ENV['LIBZMQ_PATH'].split(':'), *lib_dirs] if ENV['LIBZMQ_PATH']
-    lib_paths = lib_dirs.map { |path| "#{path}/#{lib_name}.#{::FFI::Platform::LIBSUFFIX}" }
-    ffi_lib lib_paths + [lib_name]
+    lib_name      = 'libzmq'
+    major_version = '5'
+    lib_dirs      = ['/usr/local/lib', '/opt/local/lib', '/usr/lib64', '/usr/lib']
+    lib_dirs      = [*ENV['LD_LIBRARY_PATH'].split(':'), *lib_dirs] if ENV['LD_LIBRARY_PATH']
+    lib_dirs      = [*ENV["#{lib_name.upcase}_PATH"].split(':'), *lib_dirs] if ENV["#{lib_name.upcase}_PATH"]
+    lib_paths     = lib_dirs.map do |path|
+      [
+        "#{path}/#{lib_name}.#{::FFI::Platform::LIBSUFFIX}",
+        "#{path}/#{lib_name}.#{::FFI::Platform::LIBSUFFIX}.#{major_version}"
+      ]
+    end.flatten
+
+    lib_paths.concat [lib_name, "#{lib_name}.#{::FFI::Platform::LIBSUFFIX}.#{major_version}"]
+
+    ffi_lib lib_paths
 
     # This represents a +zmq_poller_event_t+ as in:
     #