Fuchsia: Add a Fuchsia-specific NativeLibrary impl library.

native_library_fuchsia uses the Fuchsia-specific dlopen_vmo() function
instead of dlopen() as on other POSIX builds.

The library is package-aware, resolving full library paths differently
if the process is running inside a packaged namespace.

Bug: 798847
Change-Id: I1f4e0769e8b94bff65704df4dcfd73c622df13bc
Reviewed-on: https://chromium-review.googlesource.com/1003060Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550302}

base/BUILD.gn

@@ -1301,6 +1301,7 @@ jumbo_component("base") {
       "debug/stack_trace_posix.cc",
       "message_loop/message_pump_libevent.cc",
       "message_loop/message_pump_libevent.h",
+      "native_library_posix.cc",
       "posix/unix_domain_socket.cc",
       "posix/unix_domain_socket.h",
       "process/kill_posix.cc",
@@ -1327,6 +1328,7 @@ jumbo_component("base") {
       "memory/shared_memory_handle_fuchsia.cc",
       "message_loop/message_pump_fuchsia.cc",
       "message_loop/message_pump_fuchsia.h",
+      "native_library_fuchsia.cc",
       "process/kill_fuchsia.cc",
       "process/launch_fuchsia.cc",
       "process/memory_fuchsia.cc",

base/native_library_fuchsia.cc

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// 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 <fcntl.h>
+#include <fdio/io.h>
+#include <stdio.h>
+#include <zircon/dlfcn.h>
+#include <zircon/status.h>
+#include <zircon/syscalls.h>
+
+#include "base/base_paths_fuchsia.h"
+#include "base/files/file.h"
+#include "base/files/file_path.h"
+#include "base/fuchsia/fuchsia_logging.h"
+#include "base/fuchsia/scoped_zx_handle.h"
+#include "base/logging.h"
+#include "base/path_service.h"
+#include "base/posix/safe_strerror.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/threading/thread_restrictions.h"
+
+namespace base {
+
+std::string NativeLibraryLoadError::ToString() const {
+  return message;
+}
+
+NativeLibrary LoadNativeLibraryWithOptions(const FilePath& library_path,
+                                           const NativeLibraryOptions& options,
+                                           NativeLibraryLoadError* error) {
+  std::vector<base::FilePath::StringType> components;
+  library_path.GetComponents(&components);
+  if (components.size() != 1u) {
+    NOTREACHED() << "library_path is a path, should be a filename: "
+                 << library_path.MaybeAsASCII();
+    return nullptr;
+  }
+
+  // Fuchsia libraries must live under the "lib" directory, which may be located
+  // in /system/lib or /pkg/lib depending on whether the executable is running
+  // inside a package.
+  // TODO(https://crbug.com/805057): Remove the non-package codepath when bootfs
+  // is deprecated.
+  FilePath computed_path = base::GetPackageRoot();
+  if (computed_path.empty()) {
+    CHECK(PathService::Get(DIR_EXE, &computed_path));
+  }
+  computed_path = computed_path.AppendASCII("lib").Append(components[0]);
+  base::File library(computed_path,
+                     base::File::FLAG_OPEN | base::File::FLAG_READ);
+  if (!library.IsValid()) {
+    if (error) {
+      error->message = base::StringPrintf(
+          "open library: %s",
+          base::File::ErrorToString(library.error_details()).c_str());
+    }
+    return nullptr;
+  }
+
+  base::ScopedZxHandle vmo;
+  zx_status_t status =
+      fdio_get_vmo_clone(library.GetPlatformFile(), vmo.receive());
+  if (status != ZX_OK) {
+    if (error) {
+      error->message = base::StringPrintf("fdio_get_vmo_clone: %s",
+                                          zx_status_get_string(status));
+    }
+    return nullptr;
+  }
+  NativeLibrary result = dlopen_vmo(vmo.get(), RTLD_LAZY | RTLD_LOCAL);
+  return result;
+}
+
+void UnloadNativeLibrary(NativeLibrary library) {
+  // dlclose() is a no-op on Fuchsia, so do nothing here.
+}
+
+void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
+                                          StringPiece name) {
+  return dlsym(library, name.data());
+}
+
+std::string GetNativeLibraryName(StringPiece name) {
+  return base::StringPrintf("lib%s.so", name.as_string().c_str());
+}
+
+std::string GetLoadableModuleName(StringPiece name) {
+  return GetNativeLibraryName(name);
+}
+
+}  // namespace base

base/native_library_unittest.cc

@@ -77,7 +77,12 @@ class TestLibrary {
   explicit TestLibrary(const NativeLibraryOptions& options)
     : library_(nullptr) {
     base::FilePath exe_path;
+
+#if !defined(OS_FUCHSIA)
+    // Libraries do not sit alongside the executable in Fuchsia. NativeLibrary
+    // is aware of this and is able to resolve library paths correctly.
     CHECK(base::PathService::Get(base::DIR_EXE, &exe_path));
+#endif
 
     library_ = LoadNativeLibraryWithOptions(
         exe_path.AppendASCII(kTestLibraryName), options, nullptr);

testing/buildbot/filters/fuchsia.base_unittests.filter

@@ -18,8 +18,6 @@
 -FileProxyTest.SetTimes
 -FileUtilProxyTest.Touch
 -FileUtilTest.FileToFILE
--NativeLibraryTest.LoadLibrary
--NativeLibraryTest.LoadLibraryPreferOwnSymbols
 -PlatformThreadTest.ThreadPriorityCurrentThread
 -ProcessMemoryDumpTest.CountResidentBytes
 -ProcessMemoryDumpTest.CountResidentBytesInSharedMemory
@@ -28,6 +26,11 @@
 -SysInfoTest.AmountOfMem
 -SysInfoTest.AmountOfTotalDiskSpace
 
+# Remove this filter once the migration to packages is complete.
+# See crbug.com/805057.
+-NativeLibraryTest.LoadLibrary
+-NativeLibraryTest.LoadLibraryPreferOwnSymbols
+
 # These tests are affected by an issue with cloning namespace entries from
 # inside a package. See https://crbug.com/826018
 -ProcessUtilTest.CloneAlternateDir