Let runner implement the engine ABI for the engine worker.

centipede/BUILD

@@ -984,35 +984,6 @@ cc_library(
     # This has no dependency and only uses string, pair and vector.
 )
 
-cc_library(
-    name = "engine_worker",
-    srcs = [
-        "engine_worker.cc",
-    ],
-    hdrs = ["engine_worker_abi.h"],
-    deps = [
-        ":engine_abi",
-        ":execution_metadata",
-        ":feature",
-        ":runner_request",
-        ":runner_result",
-        ":runner_utils",
-        ":shared_memory_blob_sequence",
-        "@abseil-cpp//absl/base:nullability",
-        "@com_google_fuzztest//common:defs",
-    ],
-)
-
-cc_library(
-    name = "engine_controller_with_subprocess",
-    srcs = ["engine_controller_with_subprocess.cc"],
-    hdrs = ["engine_controller_abi.h"],
-    deps = [
-        "@com_google_fuzztest//centipede:engine_abi",
-        "@com_google_fuzztest//fuzztest/internal:escaping",
-    ],
-)
-
 # The runner library is special:
 #   * It must not be instrumented with asan, sancov, etc.
 #   * It must not have heavy dependencies, and ideally not at all.
@@ -1033,8 +1004,6 @@ RUNNER_SOURCES_NO_MAIN = [
     "runner_dl_info.cc",
     "runner_dl_info.h",
     "runner_interface.h",
-    "runner_utils.cc",
-    "runner_utils.h",
     "sancov_callbacks.cc",
     "sancov_interceptors.cc",
     "sancov_object_array.cc",
@@ -1081,11 +1050,12 @@ RUNNER_DEPS = [
     ":knobs",
     ":mutation_data",
     ":rolling_hash",
-    ":engine_abi",
     ":runner_cmp_trace",
-    ":runner_fork_server",
     ":runner_request",
     ":runner_result",
+    ":runner_utils",
+    ":engine_abi",
+    ":engine_worker",
     ":shared_memory_blob_sequence",
     "@com_google_fuzztest//common:defs",
     "@abseil-cpp//absl/base:core_headers",
@@ -1094,6 +1064,37 @@ RUNNER_DEPS = [
     "@abseil-cpp//absl/types:span",
 ]
 
+cc_library(
+    name = "engine_worker",
+    srcs = [
+        "engine_worker.cc",
+    ],
+    hdrs = ["engine_worker_abi.h"],
+    copts = RUNNER_COPTS,
+    deps = [
+        ":engine_abi",
+        ":execution_metadata",
+        ":feature",
+        ":runner_fork_server",
+        ":runner_request",
+        ":runner_result",
+        ":runner_utils",
+        ":shared_memory_blob_sequence",
+        "@abseil-cpp//absl/base:nullability",
+        "@com_google_fuzztest//common:defs",
+    ],
+)
+
+cc_library(
+    name = "engine_controller_with_subprocess",
+    srcs = ["engine_controller_with_subprocess.cc"],
+    hdrs = ["engine_controller_abi.h"],
+    deps = [
+        "@com_google_fuzztest//centipede:engine_abi",
+        "@com_google_fuzztest//fuzztest/internal:escaping",
+    ],
+)
+
 # A fuzz target needs to link with this library in order to run with Centipede.
 # The fuzz target must provide its own main().
 #

centipede/engine_worker.cc

@@ -46,6 +46,9 @@
 
 namespace fuzztest::internal {
 
+// Defined in the fork server library.
+extern void ForkServerCallMeVeryEarly();
+
 namespace {
 
 // Logging needs to be signal-safe and thread-safe.
@@ -309,6 +312,9 @@ inline std::string_view ToStringView(const std::vector<uint8_t>& bytes) {
 static int persistent_mode_socket;
 
 __attribute__((constructor(200))) void WorkerInitEarly() {
+  // Make sure fork server is started if needed.
+  ForkServerCallMeVeryEarly();
+
   const char* persistent_mode_socket_path =
       GetWorkerFlags().GetStringFlag(kWorkerPersistentModeSocketPathFlagHeader);
   if (persistent_mode_socket_path == nullptr) return;