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