[POSIX] Remove dlopen and friends from Starboard (youtube#6488)

This PR removes the usage of dlopen, dlclose, dlsym, dladdr, and dlerror
from Starboard for linux-evergreen platforms. There are a lot of issues
supporting these symbols for evergreen, so we have decided to remove
them.

Removal of these symbols is either done through disabling the code that
builds them through GN flags using `is_starboard` or is done by blocking
out code that calls these symbols using `!BUILDFLAG(IS_STARBOARD)`.

With this change, base::unittest
ElfReaderTestWithCurrentImage.ReadElfBuildId and
cdm_service_broker_unittest were disabled due to these tests using these
symbols.

Bug: 412456510
Bug: 420913744

Author: johnedocampo

base/BUILD.gn

@@ -1670,6 +1670,11 @@ component("base") {
         "profiler/thread_delegate_posix.cc",
         "profiler/thread_delegate_posix.h",
       ]
+
+      if (is_starboard) {
+        sources -= ["native_library_posix.cc"]
+        sources += ["native_library_starboard.cc"]
+      }
     }
 
     if (is_posix && !is_android) {

base/debug/elf_reader_unittest.cc

@@ -193,8 +193,15 @@ TEST(ElfReaderTestWithCurrentElfImage, ReadElfBuildId) {
     EXPECT_FALSE(IsAsciiLower(c));
   }
 }
+// ReadElfBuildId is disabled on Starboard configurations due to its
+// reliance on dladdr, which Starboard does not support.
+#if BUILDFLAG(IS_STARBOARD)
+#define MAYBE_ReadElfBuildId DISABLED_ReadElfBuildId
+#else
+#define MAYBE_ReadElfBuildId ReadElfBuildId
+#endif
 
-TEST(ElfReaderTestWithCurrentImage, ReadElfBuildId) {
+TEST(ElfReaderTestWithCurrentImage, MAYBE_ReadElfBuildId) {
 #if BUILDFLAG(IS_ANDROID)
   // On Android the library loader memory maps the full so file.
   const char kLibraryName[] = "libbase_unittests__library";

base/files/scoped_file_linux.cc

@@ -83,6 +83,7 @@ bool IsFDOwned(int fd) {
 
 using LibcCloseFuncPtr = int (*)(int);
 
+#if !BUILDFLAG(IS_STARBOARD)
 // Load the libc close symbol to forward to from the close wrapper.
 LibcCloseFuncPtr LoadCloseSymbol() {
 #if defined(THREAD_SANITIZER)
@@ -95,7 +96,6 @@ LibcCloseFuncPtr LoadCloseSymbol() {
 #endif
 }
 
-#if !BUILDFLAG(IS_STARBOARD)
 extern "C" {
 
 NO_SANITIZE("cfi-icall")

base/native_library_starboard.cc

@@ -0,0 +1,47 @@
+// Copyright 2025 The Cobalt Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/native_library.h"
+
+#include "base/notreached.h"
+#include "base/strings/strcat.h"
+#include "base/strings/string_util.h"
+
+namespace base {
+
+std::string NativeLibraryLoadError::ToString() const {
+  return message;
+}
+
+NativeLibrary LoadNativeLibraryWithOptions(const FilePath&,
+                                           const NativeLibraryOptions&,
+                                           NativeLibraryLoadError*) {
+  NOTREACHED() << "LoadNativeLibraryWithOptions called, but Starboard " 
+               << "does not support dlopen. This call will fail.";
+  return nullptr;
+}
+
+void UnloadNativeLibrary(NativeLibrary) {
+  NOTREACHED() << "UnloadNativeLibrary was called, but Starboard " 
+               << "does not support dlclose. This call will fail.";
+  return;
+}
+
+void* GetFunctionPointerFromNativeLibrary(NativeLibrary,
+                                          StringPiece) {
+  NOTREACHED() << "GetFunctionPointerFromNativeLibrary was called, "
+               << "but Starboard does not support dlsym. This call will fail.";
+  return nullptr;
+}
+
+std::string GetNativeLibraryName(StringPiece name) {
+  DCHECK(IsStringASCII(name));
+  return StrCat({"lib", name, ".so"});
+}
+
+std::string GetLoadableModuleName(StringPiece name) {
+  return GetNativeLibraryName(name);
+}
+
+}  // namespace base

content/browser/speech/tts_platform_impl.cc

@@ -24,10 +24,10 @@ TtsPlatform* TtsPlatform::GetInstance() {
 
 // This hack exists to ensure that Starboard does not make use of dl* symbols
 // for hermetic builds.
-if BUILDFLAG(ENABLE_COBALT_HERMETIC_HACKS) {
-  // TODO: (b/420913744) Add/Decide how to properly support the tts platform.
+// TODO: (b/420913744) Add/Decide how to properly support the tts platform.
+#if BUILDFLAG(ENABLE_COBALT_HERMETIC_HACKS)
   return nullptr;
-}
+#else
 
 #if BUILDFLAG(IS_CHROMEOS)
   // On Chrome OS, the platform TTS definition is provided by the content
@@ -37,14 +37,12 @@ if BUILDFLAG(ENABLE_COBALT_HERMETIC_HACKS) {
   // trying to do TTS on a platform where the content client implementation
   // is not provided, that's probably not intended. It's not important
   // if this is hit in something like a content-only unit test.
-  //
-  // TtsPlatformImpl relies on the library speech-dispatcher, which 
-  // Starboard does not support.
   NOTREACHED();
   return nullptr;
 #else
   return TtsPlatformImpl::GetInstance();
 #endif
+#endif
 }
 
 void TtsPlatformImpl::LoadBuiltInTtsEngine(BrowserContext* browser_context) {}

content/utility/BUILD.gn

@@ -143,6 +143,13 @@ source_set("utility") {
     deps += [ "//components/services/screen_ai:screen_ai_sandbox_hook" ]
   }
 
+  if (is_starboard) {
+    deps -= [ 
+      "//content/utility/speech:speech_recognition_sandbox_hook",
+      "//components/services/screen_ai:screen_ai_sandbox_hook",
+    ]
+  }
+
   if (enable_accessibility_service) {
     deps += [ "//services/accessibility:lib" ]
   }

content/utility/utility_main.cc

@@ -219,6 +219,7 @@ int UtilityMain(MainFunctionParams parameters) {
       pre_sandbox_hook = base::BindOnce(&printing::PrintBackendPreSandboxHook);
       break;
 #endif  // BUILDFLAG(ENABLE_OOP_PRINTING)
+#if !BUILDFLAG(IS_STARBOARD)
     case sandbox::mojom::Sandbox::kAudio:
       pre_sandbox_hook = base::BindOnce(&audio::AudioPreSandboxHook);
       break;
@@ -231,16 +232,13 @@ int UtilityMain(MainFunctionParams parameters) {
       pre_sandbox_hook = base::BindOnce(&screen_ai::ScreenAIPreSandboxHook);
       break;
 #endif
-#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS_ASH)
+#endif // !BUILDFLAG(IS_STARBOARD)
+#if BUILDFLAG(IS_LINUX) && !BUILDFLAG(IS_STARBOARD) || BUILDFLAG(IS_CHROMEOS_ASH)
     case sandbox::mojom::Sandbox::kHardwareVideoDecoding:
-#if BUILDFLAG(ENABLE_COBALT_HERMETIC_HACKS)
-      COBALT_LINKER_STUB();
-#else  // BUILDFLAG(ENABLE_COBALT_HERMETIC_HACKS)
       pre_sandbox_hook =
           base::BindOnce(&media::HardwareVideoDecodingPreSandboxHook);
-#endif  // BUILDFLAG(ENABLE_COBALT_HERMETIC_HACKS)
       break;
-#endif  // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_LINUX) && !BUILDFLAG(IS_STARBOARD) || BUILDFLAG(IS_CHROMEOS_ASH)
     case sandbox::mojom::Sandbox::kHardwareVideoEncoding:
       pre_sandbox_hook =
           base::BindOnce(&media::HardwareVideoEncodingPreSandboxHook);

media/gpu/sandbox/BUILD.gn

@@ -7,7 +7,7 @@ import("//media/gpu/args.gni")
 
 source_set("sandbox") {
   sources = []
-  if (is_linux || is_chromeos_ash) {
+  if (is_linux && !is_starboard || is_chromeos_ash) {
     sources += [
       "hardware_video_decoding_sandbox_hook_linux.cc",
       "hardware_video_decoding_sandbox_hook_linux.h",

media/mojo/services/BUILD.gn

@@ -291,6 +291,10 @@ source_set("unit_tests") {
       "mojo_cdm_helper_unittest.cc",
     ]
 
+    if (is_starboard) {
+      sources -= [ "cdm_service_broker_unittest.cc" ]
+    }
+
     deps += [
       "//media/cdm:cdm_api",
       "//media/cdm:cdm_paths",

services/audio/BUILD.gn

@@ -91,7 +91,7 @@ source_set("audio") {
     "//services/audio/public/mojom",
   ]
 
-  if (is_linux || is_chromeos) {
+  if (is_linux && !is_starboard || is_chromeos) {
     sources += [
       "audio_sandbox_hook_linux.cc",
       "audio_sandbox_hook_linux.h",