Setup ld_library_path argument for crashtracker

ext/datadog_profiling_native_extension/crashtracker.c

@@ -21,6 +21,7 @@ static VALUE _native_start_or_update_on_fork(int argc, VALUE *argv, DDTRACE_UNUS
 
   VALUE exporter_configuration = rb_hash_fetch(options, ID2SYM(rb_intern("exporter_configuration")));
   VALUE path_to_crashtracking_receiver_binary = rb_hash_fetch(options, ID2SYM(rb_intern("path_to_crashtracking_receiver_binary")));
+  VALUE ld_library_path = rb_hash_fetch(options, ID2SYM(rb_intern("ld_library_path")));
   VALUE tags_as_array = rb_hash_fetch(options, ID2SYM(rb_intern("tags_as_array")));
   VALUE action = rb_hash_fetch(options, ID2SYM(rb_intern("action")));
   VALUE start_action = ID2SYM(rb_intern("start"));
@@ -29,6 +30,7 @@ static VALUE _native_start_or_update_on_fork(int argc, VALUE *argv, DDTRACE_UNUS
   ENFORCE_TYPE(exporter_configuration, T_ARRAY);
   ENFORCE_TYPE(tags_as_array, T_ARRAY);
   ENFORCE_TYPE(path_to_crashtracking_receiver_binary, T_STRING);
+  ENFORCE_TYPE(ld_library_path, T_STRING);
   ENFORCE_TYPE(action, T_SYMBOL);
 
   if (action != start_action && action != update_on_fork_action) rb_raise(rb_eArgError, "Unexpected action: %+"PRIsVALUE, action);
@@ -63,14 +65,14 @@ static VALUE _native_start_or_update_on_fork(int argc, VALUE *argv, DDTRACE_UNUS
     .tags = &tags,
   };
 
-  ddog_prof_EnvVar ld_library_path = {
+  ddog_prof_EnvVar ld_library_path_env = {
     .key = DDOG_CHARSLICE_C("LD_LIBRARY_PATH"),
-    .val = DDOG_CHARSLICE_C("FIXME"), // FIXME
+    .val = char_slice_from_ruby_string(ld_library_path),
   };
 
   ddog_prof_CrashtrackerReceiverConfig receiver_config = {
     .args = {},
-    .env = {.ptr = &ld_library_path, .len = 1},
+    .env = {.ptr = &ld_library_path_env, .len = 1},
     .path_to_receiver_binary = char_slice_from_ruby_string(path_to_crashtracking_receiver_binary),
     .optional_stderr_filename = {},
     .optional_stdout_filename = {},

lib/datadog/profiling/crashtracker.rb

@@ -2,6 +2,17 @@
 
 require 'libdatadog'
 
+# Temporary, this should be moved to libdatadog
+module Libdatadog
+  def self.ld_library_path
+    pkgconfig_folder = self.pkgconfig_folder
+
+    return unless pkgconfig_folder
+
+    File.absolute_path("#{pkgconfig_folder}/../")
+  end
+end
+
 module Datadog
   module Profiling
     # Used to report Ruby VM crashes.
@@ -15,18 +26,20 @@ module Profiling
     class Crashtracker
       private
 
-      attr_reader :exporter_configuration, :tags_as_array, :path_to_crashtracking_receiver_binary
+      attr_reader :exporter_configuration, :tags_as_array, :path_to_crashtracking_receiver_binary, :ld_library_path
 
       public
 
       def initialize(
         exporter_configuration:,
         tags:,
-        path_to_crashtracking_receiver_binary: Libdatadog.path_to_crashtracking_receiver_binary
+        path_to_crashtracking_receiver_binary: Libdatadog.path_to_crashtracking_receiver_binary,
+        ld_library_path: Libdatadog.ld_library_path
       )
         @exporter_configuration = exporter_configuration
         @tags_as_array = tags.to_a
         @path_to_crashtracking_receiver_binary = path_to_crashtracking_receiver_binary
+        @ld_library_path = ld_library_path
       end
 
       def start
@@ -56,11 +69,19 @@ def start_or_update_on_fork(action:)
           return
         end
 
+        unless ld_library_path
+          Datadog.logger.warn(
+            "Cannot #{action} profiling crash tracking as no ld_library_path was found"
+          )
+          return
+        end
+
         begin
           self.class._native_start_or_update_on_fork(
             action: action,
             exporter_configuration: exporter_configuration,
             path_to_crashtracking_receiver_binary: path_to_crashtracking_receiver_binary,
+            ld_library_path: ld_library_path,
             tags_as_array: tags_as_array,
           )
           Datadog.logger.debug("Crash tracking #{action} successful")

sig/datadog/profiling/crashtracker.rbs

@@ -8,13 +8,15 @@ module Datadog
       attr_reader exporter_configuration: exporter_configuration_array
       attr_reader tags_as_array: ::Array[[::String, ::String]]
       attr_reader path_to_crashtracking_receiver_binary: ::String
+      attr_reader ld_library_path: ::String
 
       public
 
       def initialize: (
         exporter_configuration: exporter_configuration_array,
         tags: ::Hash[::String, ::String],
         ?path_to_crashtracking_receiver_binary: ::String,
+        ?ld_library_path: ::String,
       ) -> void
 
       def start: -> void
@@ -28,8 +30,9 @@ module Datadog
       def self._native_start_or_update_on_fork: (
         action: :start | :update_on_fork,
         exporter_configuration: exporter_configuration_array,
-        tags_as_array: ::Array[[::String, ::String]],
         path_to_crashtracking_receiver_binary: ::String,
+        ld_library_path: ::String,
+        tags_as_array: ::Array[[::String, ::String]],
       ) -> void
 
       def self._native_stop: -> void

spec/datadog/profiling/crashtracker_spec.rb

@@ -43,6 +43,22 @@
       end
     end
 
+    context 'when ld_library_path is nil' do
+      subject(:crashtracker) do
+        described_class.new(
+          exporter_configuration: exporter_configuration,
+          tags: { 'tag1' => 'value1', 'tag2' => 'value2' },
+          ld_library_path: nil
+        )
+      end
+
+      it 'logs a warning' do
+        expect(Datadog.logger).to receive(:warn).with(/no ld_library_path was found/)
+
+        start
+      end
+    end
+
     it 'starts the crash tracker' do
       start
 

vendor/rbs/libdatadog/0/libdatadog.rbs

@@ -1,4 +1,5 @@
 module Libdatadog
   def self.path_to_crashtracking_receiver_binary: () -> ::String?
+  def self.ld_library_path: () -> ::String?
   def self.pkgconfig_folder: () -> ::String?
 end