1/* 2 * Copyright (C) 2011 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' 14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS 17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 23 * THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26#include "config.h" 27#include "DynamicLinkerEnvironmentExtractor.h" 28 29#include "EnvironmentVariables.h" 30#include <mach-o/loader.h> 31#include <mach-o/swap.h> 32#include <wtf/OwnPtr.h> 33#include <wtf/text/WTFString.h> 34 35namespace WebKit { 36 37DynamicLinkerEnvironmentExtractor::DynamicLinkerEnvironmentExtractor(NSString *executablePath, cpu_type_t architecture) 38 : m_executablePath(executablePath) 39 , m_architecture(architecture) 40{ 41 NSData *mainExecutableData = [NSData dataWithContentsOfFile:m_executablePath.get() options:NSDataReadingMappedIfSafe error:0]; 42 if (!mainExecutableData) 43 return; 44 45 const void* mainExecutableBytes = [mainExecutableData bytes]; 46 size_t length = [mainExecutableData length]; 47 if (length < sizeof(uint32_t)) 48 return; 49 50 uint32_t magicValue = *static_cast<const uint32_t*>(mainExecutableBytes); 51 if (magicValue == FAT_MAGIC || magicValue == FAT_CIGAM) { 52 processFatFile(mainExecutableBytes, length); 53 return; 54 } 55 56 processSingleArchitecture(mainExecutableBytes, length); 57} 58 59#define DEFINE_BYTE_SWAPPER(type) inline type byteSwapIfNeeded(const type& data, bool shouldByteSwap) \ 60{ \ 61 type swapped = data; \ 62 if (shouldByteSwap) \ 63 swap_##type(&swapped, NX_UnknownByteOrder); \ 64 return swapped; \ 65} 66 67DEFINE_BYTE_SWAPPER(load_command) 68DEFINE_BYTE_SWAPPER(dylinker_command) 69DEFINE_BYTE_SWAPPER(mach_header) 70DEFINE_BYTE_SWAPPER(mach_header_64) 71 72#undef DEFINE_BYTE_SWAPPER 73 74void DynamicLinkerEnvironmentExtractor::processEnvironmentVariable(const char* environmentString) 75{ 76 const char* equalsLocation = strchr(environmentString, '='); 77 if (!equalsLocation) 78 return; 79 80 size_t nameLength = equalsLocation - environmentString; 81 String name(environmentString, nameLength); 82 83 // LC_DYLD_ENVIRONMENT only respects DYLD_*_PATH variables. 84 if (!name.startsWith("DYLD_") || !name.endsWith("_PATH")) 85 return; 86 87 CString value(equalsLocation + 1); 88 m_extractedVariables.append(std::make_pair(name.latin1(), value)); 89} 90 91size_t DynamicLinkerEnvironmentExtractor::processLoadCommand(const void* data, size_t length, bool shouldByteSwap) 92{ 93 if (length < sizeof(load_command)) 94 return 0; 95 96 const load_command* rawLoadCommand = static_cast<const load_command*>(data); 97 load_command loadCommand = byteSwapIfNeeded(*rawLoadCommand, shouldByteSwap); 98 99 if (length < loadCommand.cmdsize) 100 return 0; 101 102 if (loadCommand.cmd == LC_DYLD_ENVIRONMENT) { 103 if (length < sizeof(dylinker_command)) 104 return 0; 105 106 dylinker_command environmentCommand = byteSwapIfNeeded(*reinterpret_cast<const dylinker_command*>(rawLoadCommand), shouldByteSwap); 107 if (loadCommand.cmdsize < environmentCommand.name.offset) 108 return 0; 109 110 size_t environmentStringLength = loadCommand.cmdsize - environmentCommand.name.offset; 111 Vector<char, 256> environmentString; 112 environmentString.reserveCapacity(environmentStringLength + 1); 113 environmentString.append(reinterpret_cast<const char*>(rawLoadCommand) + environmentCommand.name.offset, environmentStringLength); 114 environmentString.append(0); 115 116 processEnvironmentVariable(environmentString.data()); 117 } 118 119 return loadCommand.cmdsize; 120} 121 122void DynamicLinkerEnvironmentExtractor::processLoadCommands(const void* data, size_t length, int32_t numberOfCommands, bool shouldByteSwap) 123{ 124 const void* dataRemaining = data; 125 size_t lengthRemaining = length; 126 for (int i = 0; i < numberOfCommands; i++) { 127 size_t commandLength = processLoadCommand(dataRemaining, lengthRemaining, shouldByteSwap); 128 if (!commandLength || lengthRemaining < commandLength) 129 return; 130 131 dataRemaining = static_cast<const char*>(dataRemaining) + commandLength; 132 lengthRemaining -= commandLength; 133 } 134} 135 136void DynamicLinkerEnvironmentExtractor::processSingleArchitecture(const void* data, size_t length) 137{ 138 if (length < sizeof(mach_header)) 139 return; 140 141 const mach_header* header = static_cast<const mach_header*>(data); 142 if (header->magic == MH_MAGIC || header->magic == MH_CIGAM) { 143 bool shouldByteSwap = header->magic == MH_CIGAM; 144 mach_header swappedHeader = byteSwapIfNeeded(*header, shouldByteSwap); 145 if (swappedHeader.cputype == m_architecture) 146 processLoadCommands(static_cast<const char*>(data) + sizeof(*header), length - sizeof(*header), swappedHeader.ncmds, shouldByteSwap); 147 return; 148 } 149 150 if (length < sizeof(mach_header_64)) 151 return; 152 153 const mach_header_64* header64 = static_cast<const mach_header_64*>(data); 154 bool shouldByteSwap = header->magic == MH_CIGAM_64; 155 mach_header_64 swappedHeader64 = byteSwapIfNeeded(*header64, shouldByteSwap); 156 if (swappedHeader64.cputype == m_architecture) 157 processLoadCommands(static_cast<const char*>(data) + sizeof(*header64), length - sizeof(*header64), swappedHeader64.ncmds, shouldByteSwap); 158} 159 160void DynamicLinkerEnvironmentExtractor::processFatFile(const void* data, size_t length) 161{ 162 if (length < sizeof(fat_header)) 163 return; 164 165 const fat_header* header = static_cast<const fat_header*>(data); 166 167 size_t numberOfArchitectures = OSSwapBigToHostInt32(header->nfat_arch); 168 169 // Ensure that we have enough data remaining for numberOfArchitectures fat_arch structs. 170 if ((length - sizeof(fat_header)) / sizeof(fat_arch) < numberOfArchitectures) 171 return; 172 173 const fat_arch* archs = reinterpret_cast<const fat_arch*>(reinterpret_cast<const char*>(data) + sizeof(*header)); 174 for (uint32_t i = 0; i < numberOfArchitectures; i++) { 175 uint32_t architectureOffset = OSSwapBigToHostInt32(archs[i].offset); 176 uint32_t architectureSize = OSSwapBigToHostInt32(archs[i].size); 177 if (length < architectureOffset + architectureSize) 178 return; 179 180 processSingleArchitecture(static_cast<const char*>(data) + architectureOffset, architectureSize); 181 } 182} 183 184void DynamicLinkerEnvironmentExtractor::getExtractedEnvironmentVariables(EnvironmentVariables& environmentVariables) const 185{ 186 size_t extractedVariableCount = m_extractedVariables.size(); 187 for (size_t i = 0; i < extractedVariableCount; ++i) { 188 const CString& name = m_extractedVariables[i].first; 189 190 // Preserve any existing environment variable by this name so that it will take 191 // precedence over what we extracted from the executable file. 192 if (environmentVariables.get(name.data())) 193 continue; 194 195 environmentVariables.set(name.data(), m_extractedVariables[i].second.data()); 196 } 197} 198 199} // namespace WebKit 200