henrike@webrtc.org | f7795df | 2014-05-13 18:00:26 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2004 The WebRTC Project Authors. All rights reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | #include "webrtc/base/latebindingsymboltable.h" |
| 12 | |
| 13 | #if defined(WEBRTC_POSIX) |
| 14 | #include <dlfcn.h> |
| 15 | #endif |
| 16 | |
| 17 | #include "webrtc/base/logging.h" |
| 18 | |
| 19 | namespace rtc { |
| 20 | |
| 21 | #if defined(WEBRTC_POSIX) |
| 22 | static const DllHandle kInvalidDllHandle = NULL; |
| 23 | #else |
| 24 | #error Not implemented |
| 25 | #endif |
| 26 | |
| 27 | static const char *GetDllError() { |
| 28 | #if defined(WEBRTC_POSIX) |
| 29 | const char *err = dlerror(); |
| 30 | if (err) { |
| 31 | return err; |
| 32 | } else { |
| 33 | return "No error"; |
| 34 | } |
| 35 | #else |
| 36 | #error Not implemented |
| 37 | #endif |
| 38 | } |
| 39 | |
| 40 | static bool LoadSymbol(DllHandle handle, |
| 41 | const char *symbol_name, |
| 42 | void **symbol) { |
| 43 | #if defined(WEBRTC_POSIX) |
| 44 | *symbol = dlsym(handle, symbol_name); |
| 45 | const char *err = dlerror(); |
| 46 | if (err) { |
| 47 | LOG(LS_ERROR) << "Error loading symbol " << symbol_name << ": " << err; |
| 48 | return false; |
| 49 | } else if (!*symbol) { |
| 50 | // ELF allows for symbols to be NULL, but that should never happen for our |
| 51 | // usage. |
| 52 | LOG(LS_ERROR) << "Symbol " << symbol_name << " is NULL"; |
| 53 | return false; |
| 54 | } |
| 55 | return true; |
| 56 | #else |
| 57 | #error Not implemented |
| 58 | #endif |
| 59 | } |
| 60 | |
| 61 | LateBindingSymbolTable::LateBindingSymbolTable(const TableInfo *info, |
| 62 | void **table) |
| 63 | : info_(info), |
| 64 | table_(table), |
| 65 | handle_(kInvalidDllHandle), |
| 66 | undefined_symbols_(false) { |
| 67 | ClearSymbols(); |
| 68 | } |
| 69 | |
| 70 | LateBindingSymbolTable::~LateBindingSymbolTable() { |
| 71 | Unload(); |
| 72 | } |
| 73 | |
| 74 | bool LateBindingSymbolTable::IsLoaded() const { |
| 75 | return handle_ != kInvalidDllHandle; |
| 76 | } |
| 77 | |
| 78 | bool LateBindingSymbolTable::Load() { |
| 79 | ASSERT(info_->dll_name != NULL); |
| 80 | return LoadFromPath(info_->dll_name); |
| 81 | } |
| 82 | |
| 83 | bool LateBindingSymbolTable::LoadFromPath(const char *dll_path) { |
| 84 | if (IsLoaded()) { |
| 85 | return true; |
| 86 | } |
| 87 | if (undefined_symbols_) { |
| 88 | // We do not attempt to load again because repeated attempts are not |
| 89 | // likely to succeed and DLL loading is costly. |
| 90 | LOG(LS_ERROR) << "We know there are undefined symbols"; |
| 91 | return false; |
| 92 | } |
| 93 | |
| 94 | #if defined(WEBRTC_POSIX) |
| 95 | handle_ = dlopen(dll_path, |
| 96 | // RTLD_NOW front-loads symbol resolution so that errors are |
| 97 | // caught early instead of causing a process abort later. |
| 98 | // RTLD_LOCAL prevents other modules from automatically |
| 99 | // seeing symbol definitions in the newly-loaded tree. This |
| 100 | // is necessary for same-named symbols in different ABI |
| 101 | // versions of the same library to not explode. |
| 102 | RTLD_NOW|RTLD_LOCAL |
| 103 | #if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID) |
| 104 | // RTLD_DEEPBIND makes symbol dependencies in the |
| 105 | // newly-loaded tree prefer to resolve to definitions within |
| 106 | // that tree (the default on OS X). This is necessary for |
| 107 | // same-named symbols in different ABI versions of the same |
| 108 | // library to not explode. |
| 109 | |RTLD_DEEPBIND |
| 110 | #endif |
| 111 | ); // NOLINT |
| 112 | #else |
| 113 | #error Not implemented |
| 114 | #endif |
| 115 | |
| 116 | if (handle_ == kInvalidDllHandle) { |
| 117 | LOG(LS_WARNING) << "Can't load " << dll_path << ": " |
| 118 | << GetDllError(); |
| 119 | return false; |
| 120 | } |
| 121 | #if defined(WEBRTC_POSIX) |
| 122 | // Clear any old errors. |
| 123 | dlerror(); |
| 124 | #endif |
| 125 | for (int i = 0; i < info_->num_symbols; ++i) { |
| 126 | if (!LoadSymbol(handle_, info_->symbol_names[i], &table_[i])) { |
| 127 | undefined_symbols_ = true; |
| 128 | Unload(); |
| 129 | return false; |
| 130 | } |
| 131 | } |
| 132 | return true; |
| 133 | } |
| 134 | |
| 135 | void LateBindingSymbolTable::Unload() { |
| 136 | if (!IsLoaded()) { |
| 137 | return; |
| 138 | } |
| 139 | |
| 140 | #if defined(WEBRTC_POSIX) |
| 141 | if (dlclose(handle_) != 0) { |
| 142 | LOG(LS_ERROR) << GetDllError(); |
| 143 | } |
| 144 | #else |
| 145 | #error Not implemented |
| 146 | #endif |
| 147 | |
| 148 | handle_ = kInvalidDllHandle; |
| 149 | ClearSymbols(); |
| 150 | } |
| 151 | |
| 152 | void LateBindingSymbolTable::ClearSymbols() { |
| 153 | memset(table_, 0, sizeof(void *) * info_->num_symbols); |
| 154 | } |
| 155 | |
| 156 | } // namespace rtc |