[PROF-9257] Fix incorrect platform detection for x86_64-linux-gnu/aarch64-linux-gnu

ruby/lib/libdatadog.rb

@@ -9,24 +9,7 @@ def self.available_binaries
   end
 
   def self.pkgconfig_folder(pkgconfig_file_name = "datadog_profiling_with_rpath.pc")
-    current_platform = Gem::Platform.local.to_s
-
-    if RbConfig::CONFIG["arch"].include?("-musl") && !current_platform.include?("-musl")
-      # Fix/workaround for https://github.com/DataDog/dd-trace-rb/issues/2222
-      #
-      # Old versions of rubygems (for instance 3.0.3) don't properly detect alternative libc implementations on Linux;
-      # in particular for our case, they don't detect musl. (For reference, Rubies older than 2.7 may have shipped with
-      # an affected version of rubygems).
-      # In such cases, we fall back to use RbConfig::CONFIG['arch'] instead.
-      #
-      # Why not use RbConfig::CONFIG['arch'] always? Because Gem::Platform.local.to_s does some normalization we want
-      # in other situations -- for instance, it turns `x86_64-linux-gnu` to `x86_64-linux`. So for now we only add this
-      # workaround in a specific situation where we actually know it is wrong.
-      #
-      # See also https://github.com/rubygems/rubygems/pull/2922 and https://github.com/rubygems/rubygems/pull/4082
-
-      current_platform = RbConfig::CONFIG["arch"]
-    end
+    current_platform = self.current_platform
 
     return unless available_binaries.include?(current_platform)
 
@@ -40,4 +23,37 @@ def self.pkgconfig_folder(pkgconfig_file_name = "datadog_profiling_with_rpath.pc
   private_class_method def self.vendor_directory
     ENV["LIBDATADOG_VENDOR_OVERRIDE"] || "#{__dir__}/../vendor/libdatadog-#{Libdatadog::LIB_VERSION}/"
   end
+
+  def self.current_platform
+    platform = Gem::Platform.local.to_s
+
+    if platform.end_with?("-gnu")
+      # In some cases on Linux with glibc the platform includes a -gnu suffix. We normalize it to not have the suffix.
+      #
+      # Note: This should be platform = platform.delete_suffix("-gnu") but it doesn't work on legacy Rubies; once
+      # dd-trace-rb 2.0 is out we can simplify this.
+      #
+      platform = platform[0..-5]
+    end
+
+    if RbConfig::CONFIG["arch"].include?("-musl") && !platform.include?("-musl")
+      # Fix/workaround for https://github.com/datadog/dd-trace-rb/issues/2222
+      #
+      # Old versions of rubygems (for instance 3.0.3) don't properly detect alternative libc implementations on Linux;
+      # in particular for our case, they don't detect musl. (For reference, Rubies older than 2.7 may have shipped with
+      # an affected version of rubygems).
+      # In such cases, we fall back to use RbConfig::CONFIG['arch'] instead.
+      #
+      # Why not use RbConfig::CONFIG['arch'] always? Because Gem::Platform.local.to_s does some normalization that seemed
+      # useful in the past, although part of it got removed in https://github.com/rubygems/rubygems/pull/5852.
+      # For now we only add this workaround in a specific situation where we actually know it is wrong, but in the
+      # future it may be worth re-evaluating if we should move away from `Gem::Platform` altogether.
+      #
+      # See also https://github.com/rubygems/rubygems/pull/2922 and https://github.com/rubygems/rubygems/pull/4082
+
+      RbConfig::CONFIG["arch"]
+    else
+      platform
+    end
+  end
 end

ruby/lib/libdatadog/version.rb

@@ -4,7 +4,7 @@ module Libdatadog
   # Current libdatadog version
   LIB_VERSION = "6.0.0"
 
-  GEM_MAJOR_VERSION = "1"
+  GEM_MAJOR_VERSION = "2"
   GEM_MINOR_VERSION = "0"
   GEM_PRERELEASE_VERSION = "" # remember to include dot prefix, if needed!
   private_constant :GEM_MAJOR_VERSION, :GEM_MINOR_VERSION, :GEM_PRERELEASE_VERSION

ruby/spec/libdatadog_spec.rb

@@ -89,6 +89,7 @@ def create_dummy_pkgconfig_file(pkgconfig_folder)
           # Fix for https://github.com/DataDog/dd-trace-rb/issues/2222
 
           before do
+            allow(RbConfig::CONFIG).to receive(:[]).and_call_original
             allow(RbConfig::CONFIG).to receive(:[]).with("arch").and_return("x86_64-linux-musl")
             allow(Gem::Platform).to receive(:local).and_return("x86_64-linux")
 
@@ -101,6 +102,18 @@ def create_dummy_pkgconfig_file(pkgconfig_folder)
             expect(Libdatadog.pkgconfig_folder).to eq "#{temporary_directory}/x86_64-linux-musl/some/folder/containing/the/pkgconfig/file"
           end
         end
+
+        context "when platform ends with -gnu" do
+          let(:pkgconfig_folder) { "#{temporary_directory}/aarch64-linux/some/folder/containing/the/pkgconfig/file" }
+
+          before do
+            allow(Gem::Platform).to receive(:local).and_return(Gem::Platform.new("aarch64-linux-gnu"))
+          end
+
+          it "chops off the -gnu suffix and returns the folder containing the pkgconfig file for the non-gnu variant" do
+            expect(Libdatadog.pkgconfig_folder).to eq pkgconfig_folder
+          end
+        end
       end
 
       context "but not for the current platform" do