157 lines
4.1 KiB
C++
157 lines
4.1 KiB
C++
/*
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* Copyright 2004 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/base/latebindingsymboltable.h"
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#if defined(WEBRTC_POSIX)
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#include <dlfcn.h>
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#endif
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#include "webrtc/base/logging.h"
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namespace rtc {
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#if defined(WEBRTC_POSIX)
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static const DllHandle kInvalidDllHandle = NULL;
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#else
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#error Not implemented
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#endif
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static const char *GetDllError() {
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#if defined(WEBRTC_POSIX)
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const char *err = dlerror();
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if (err) {
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return err;
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} else {
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return "No error";
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}
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#else
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#error Not implemented
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#endif
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}
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static bool LoadSymbol(DllHandle handle,
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const char *symbol_name,
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void **symbol) {
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#if defined(WEBRTC_POSIX)
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*symbol = dlsym(handle, symbol_name);
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const char *err = dlerror();
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if (err) {
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LOG(LS_ERROR) << "Error loading symbol " << symbol_name << ": " << err;
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return false;
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} else if (!*symbol) {
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// ELF allows for symbols to be NULL, but that should never happen for our
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// usage.
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LOG(LS_ERROR) << "Symbol " << symbol_name << " is NULL";
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return false;
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}
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return true;
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#else
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#error Not implemented
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#endif
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}
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LateBindingSymbolTable::LateBindingSymbolTable(const TableInfo *info,
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void **table)
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: info_(info),
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table_(table),
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handle_(kInvalidDllHandle),
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undefined_symbols_(false) {
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ClearSymbols();
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}
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LateBindingSymbolTable::~LateBindingSymbolTable() {
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Unload();
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}
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bool LateBindingSymbolTable::IsLoaded() const {
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return handle_ != kInvalidDllHandle;
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}
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bool LateBindingSymbolTable::Load() {
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ASSERT(info_->dll_name != NULL);
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return LoadFromPath(info_->dll_name);
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}
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bool LateBindingSymbolTable::LoadFromPath(const char *dll_path) {
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if (IsLoaded()) {
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return true;
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}
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if (undefined_symbols_) {
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// We do not attempt to load again because repeated attempts are not
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// likely to succeed and DLL loading is costly.
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LOG(LS_ERROR) << "We know there are undefined symbols";
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return false;
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}
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#if defined(WEBRTC_POSIX)
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handle_ = dlopen(dll_path,
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// RTLD_NOW front-loads symbol resolution so that errors are
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// caught early instead of causing a process abort later.
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// RTLD_LOCAL prevents other modules from automatically
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// seeing symbol definitions in the newly-loaded tree. This
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// is necessary for same-named symbols in different ABI
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// versions of the same library to not explode.
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RTLD_NOW|RTLD_LOCAL
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#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID) && defined(RTLD_DEEPBIND)
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// RTLD_DEEPBIND makes symbol dependencies in the
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// newly-loaded tree prefer to resolve to definitions within
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// that tree (the default on OS X). This is necessary for
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// same-named symbols in different ABI versions of the same
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// library to not explode.
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|RTLD_DEEPBIND
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#endif
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); // NOLINT
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#else
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#error Not implemented
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#endif
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if (handle_ == kInvalidDllHandle) {
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LOG(LS_WARNING) << "Can't load " << dll_path << ": "
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<< GetDllError();
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return false;
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}
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#if defined(WEBRTC_POSIX)
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// Clear any old errors.
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dlerror();
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#endif
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for (int i = 0; i < info_->num_symbols; ++i) {
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if (!LoadSymbol(handle_, info_->symbol_names[i], &table_[i])) {
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undefined_symbols_ = true;
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Unload();
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return false;
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}
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}
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return true;
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}
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void LateBindingSymbolTable::Unload() {
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if (!IsLoaded()) {
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return;
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}
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#if defined(WEBRTC_POSIX)
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if (dlclose(handle_) != 0) {
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LOG(LS_ERROR) << GetDllError();
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}
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#else
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#error Not implemented
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#endif
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handle_ = kInvalidDllHandle;
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ClearSymbols();
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}
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void LateBindingSymbolTable::ClearSymbols() {
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memset(table_, 0, sizeof(void *) * info_->num_symbols);
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}
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} // namespace rtc
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