From c95b8f3664299ff60fa06073ab0ad77f4d5ed3d0 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@oriontransfer.co.nz>
Date: Fri, 24 Jun 2022 21:32:38 +1200
Subject: Add support for passing ABI version to `FFI.map_library_name`.

---
 lib/ffi/library.rb   | 59 +++++++++++++++++++++++++++++++++++++++++++---------
 spec/ffi/ffi_spec.rb |  9 ++++++++
 2 files changed, 58 insertions(+), 10 deletions(-)

diff --git a/lib/ffi/library.rb b/lib/ffi/library.rb
index 43b2bfe..c2628ab 100644
--- a/lib/ffi/library.rb
+++ b/lib/ffi/library.rb
@@ -31,6 +31,53 @@
 module FFI
   CURRENT_PROCESS = USE_THIS_PROCESS_AS_LIBRARY = Object.new
 
+  class LibraryPath < ::Struct.new(:name, :abi_number, :root)
+    PATTERN = /(#{Platform::LIBPREFIX})?(?<name>.*?)(\.|\z)/
+
+    def self.wrap(value)
+      # We allow instances of LibraryPath to pass through transparently:
+      return value if value.is_a?(self)
+
+      # We special case a library named 'c' to be the standard C library:
+      return Library::LIBC if value == 'c'
+
+      # If provided a relative file name we convert it into a library path:
+      if value && File.basename(value) == value
+        if match = PATTERN.match(value)
+          return self.new(match[:name])
+        end
+      end
+
+      # Otherwise, we assume it's a full path to a library:
+      return value
+    end
+
+    def full_name
+      # If the abi_number is given, we format it specifically according to platform rules:
+      if abi_number
+        if Platform.windows?
+          "#{Platform::LIBPREFIX}#{name}-#{abi_number}.#{Platform::LIBSUFFIX}"
+        elsif Platform.mac?
+          "#{Platform::LIBPREFIX}#{name}.#{abi_number}.#{Platform::LIBSUFFIX}"
+        else # Linux? BSD? etc.
+          "#{Platform::LIBPREFIX}#{name}.#{Platform::LIBSUFFIX}.#{abi_number}"
+        end
+      else
+        # Otherwise we just use a generic format:
+        "#{Platform::LIBPREFIX}#{name}.#{Platform::LIBSUFFIX}"
+      end
+    end
+
+    def to_s
+      if root
+        # If the root path is given, we generate the full path:
+        File.join(root, full_name)
+      else
+        full_name
+      end
+    end
+  end
+
   # @param [#to_s] lib library name
   # @return [String] library name formatted for current platform
   # Transform a generic library name to a platform library name
@@ -41,17 +88,9 @@ module FFI
   #  # Windows
   #  FFI.map_library_name 'c'     # -> "msvcrt.dll"
   #  FFI.map_library_name 'jpeg'  # -> "jpeg.dll"
-  def self.map_library_name(lib)
+  def self.map_library_name(value)
     # Mangle the library name to reflect the native library naming conventions
-    lib = Library::LIBC if lib == 'c'
-
-    if lib && File.basename(lib) == lib
-      lib = Platform::LIBPREFIX + lib unless lib =~ /^#{Platform::LIBPREFIX}/
-      r = Platform::IS_WINDOWS || Platform::IS_MAC ? "\\.#{Platform::LIBSUFFIX}$" : "\\.so($|\\.[1234567890]+)"
-      lib += ".#{Platform::LIBSUFFIX}" unless lib =~ /#{r}/
-    end
-
-    lib
+    LibraryPath.wrap(value).to_s
   end
 
   # Exception raised when a function is not found in libraries
diff --git a/spec/ffi/ffi_spec.rb b/spec/ffi/ffi_spec.rb
index 4de5310..608cd99 100644
--- a/spec/ffi/ffi_spec.rb
+++ b/spec/ffi/ffi_spec.rb
@@ -24,6 +24,15 @@ describe "FFI" do
       expect(FFI.map_library_name('c')).to eq(FFI::Library::LIBC)
     end
 
+    it "should return library path with abi version" do
+      expect(FFI.map_library_name(FFI::LibraryPath.new('vips', 42))).to be =~ /#{prefix}vips.*42/
+    end
+
+    it "should return library path with root" do
+      root = "/non/existant/root"
+
+      expect(FFI.map_library_name(FFI::LibraryPath.new('vips', 42, root))).to be =~ /#{root}/#{prefix}vips.*42/
+    end
   end
 
   describe "VERSION" do
-- 
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