try to warn about ffi startup failures

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## master
 
+* try to catch and warn about ffi startup failures [paulschreiber] 
+
 ## Version 2.3.0 (2025-12-10)
 
 * move library_name out of the global namespace and into FFI [jcupitt]

README.md

@@ -30,6 +30,11 @@ gem install ruby-vips
 
 Or include `gem "ruby-vips"` in your gemfile.
 
+ruby-vips uses FFI to call into the libvips binary, and this needs
+write-execute permission to construct function wrappers. If ruby-vips fails to
+start, check your systemd settings and make sure `MemoryDenyWriteExecute` is not
+enabled, see https://github.com/libvips/ruby-vips/issues/439.
+
 ## Install on Windows
 
 The gemspec will pull in the msys libvips for you, so all you need is:

VERSION

@@ -1 +1 @@
-2.3.0
+2.3.1

lib/vips.rb

@@ -52,6 +52,14 @@ module Vips
     @@is_unified = true
   rescue FFI::NotFoundError
     @@is_unified = false
+  rescue RuntimeError
+    $stderr.puts "ruby-vips RuntimeError"
+    $stderr.puts "\tFFI has been able to load a library, but unable to call"
+    $stderr.puts "\ta known function in that library. You may have"
+    $stderr.puts "\twrite-execute protection enabled, preventing FFI from"
+    $stderr.puts "\tmaking wrappers for function dispatch."
+    $stderr.puts "\tSee https://github.com/libvips/ruby-vips/issues/439"
+    raise
   end
 
   def self.unified?

lib/vips/version.rb

@@ -1,3 +1,3 @@
 module Vips
-  VERSION = "2.3.0"
+  VERSION = "2.3.1"
 end