Refactoring keg_relocate to use ELFShim#interpreter

Library/Homebrew/extend/os/linux/keg_relocate.rb

@@ -27,6 +27,7 @@ def change_rpath(file, old_prefix, new_prefix)
     # patchelf requires that the ELF file have a .dynstr section.
     # Skip ELF files that do not have a .dynstr section.
     return if ["cannot find section .dynstr", "strange: no string table"].include?(old_rpath)
+
     unless $CHILD_STATUS.success?
       raise ErrorDuringExecution.new(cmd_rpath, status: $CHILD_STATUS, output: [[:stderr, old_rpath]])
     end
@@ -41,15 +42,15 @@ def change_rpath(file, old_prefix, new_prefix)
     new_rpath = rpath.join(":")
     cmd = [patchelf, "--force-rpath", "--set-rpath", new_rpath]
 
-    if file.with_interpreter?
-      old_interpreter = Utils.safe_popen_read(patchelf, "--print-interpreter", file).strip
-      new_interpreter = if File.readable? "#{new_prefix}/lib/ld.so"
-        "#{new_prefix}/lib/ld.so"
-      else
-        old_interpreter.sub old_prefix, new_prefix
-      end
-      cmd << "--set-interpreter" << new_interpreter if old_interpreter != new_interpreter
+    old_interpreter = file.interpreter
+    new_interpreter = if old_interpreter.nil?
+      nil
+    elsif File.readable? "#{new_prefix}/lib/ld.so"
+      "#{new_prefix}/lib/ld.so"
+    else
+      old_interpreter.sub old_prefix, new_prefix
     end
+    cmd << "--set-interpreter" << new_interpreter if old_interpreter != new_interpreter
 
     return if old_rpath == new_rpath && old_interpreter == new_interpreter
 

Library/Homebrew/os/linux/elf.rb

@@ -68,28 +68,24 @@ def binary_executable?
     elf_type == :executable
   end
 
-  def with_interpreter?
-    return @with_interpreter if defined? @with_interpreter
+  def interpreter
+    return @interpreter if defined? @interpreter
 
-    @with_interpreter = if binary_executable?
-      true
-    elsif dylib?
-      if HOMEBREW_PATCHELF_RB
-        begin
-          patchelf_patcher.interpreter.present?
-        rescue PatchELF::PatchError => e
-          opoo e unless e.to_s.start_with? "No interpreter found"
-          false
-        end
-      elsif which "readelf"
-        Utils.popen_read("readelf", "-l", to_path).include?(" INTERP ")
-      elsif which "file"
-        Utils.popen_read("file", "-L", "-b", to_path).include?(" interpreter ")
-      else
-        raise "Please install either readelf (from binutils) or file."
+    @interpreter = if HOMEBREW_PATCHELF_RB
+      begin
+        patchelf_patcher.interpreter
+      rescue PatchELF::PatchError => e
+        opoo e unless e.to_s.start_with? "No interpreter found"
+        nil
       end
+    elsif (patchelf = DevelopmentTools.locate "patchelf")
+      interp = Utils.popen_read(patchelf, "--print-interpreter", to_s, err: :out).strip
+      $CHILD_STATUS.success? ? interp : nil
+    elsif (file = DevelopmentTools.locate("file"))
+      output = Utils.popen_read(file, "-L", "-b", to_s, err: :out).strip
+      output[/^ELF.*, interpreter (.+?), /, 1]
     else
-      false
+      raise "Please install either patchelf or file."
     end
   end