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/PassOwnPtr.h> 34#include <wtf/text/WTFString.h> 35 36namespace WebKit { 37 38DynamicLinkerEnvironmentExtractor::DynamicLinkerEnvironmentExtractor(NSString *executablePath, cpu_type_t architecture) 39 : m_executablePath(executablePath) 40 , m_architecture(architecture) 41{ 42 NSData *mainExecutableData = [NSData dataWithContentsOfFile:m_executablePath.get() options:NSDataReadingMappedIfSafe error:0]; 43 if (!mainExecutableData) 44 return; 45 46 const void* mainExecutableBytes = [mainExecutableData bytes]; 47 size_t length = [mainExecutableData length]; 48 if (length < sizeof(uint32_t)) 49 return; 50 51 uint32_t magicValue = *static_cast<const uint32_t*>(mainExecutableBytes); 52 if (magicValue == FAT_MAGIC || magicValue == FAT_CIGAM) { 53 processFatFile(mainExecutableBytes, length); 54 return; 55 } 56 57 processSingleArchitecture(mainExecutableBytes, length); 58} 59 60#define DEFINE_BYTE_SWAPPER(type) inline type byteSwapIfNeeded(const type& data, bool shouldByteSwap) \ 61{ \ 62 type swapped = data; \ 63 if (shouldByteSwap) \ 64 swap_##type(&swapped, NX_UnknownByteOrder); \ 65 return swapped; \ 66} 67 68DEFINE_BYTE_SWAPPER(load_command) 69DEFINE_BYTE_SWAPPER(dylinker_command) 70DEFINE_BYTE_SWAPPER(mach_header) 71DEFINE_BYTE_SWAPPER(mach_header_64) 72 73#undef DEFINE_BYTE_SWAPPER 74 75void DynamicLinkerEnvironmentExtractor::processEnvironmentVariable(const char* environmentString) 76{ 77 const char* equalsLocation = strchr(environmentString, '='); 78 if (!equalsLocation) 79 return; 80 81 size_t nameLength = equalsLocation - environmentString; 82 String name(environmentString, nameLength); 83 84 // LC_DYLD_ENVIRONMENT only respects DYLD_*_PATH variables. 85 if (!name.startsWith("DYLD_") || !name.endsWith("_PATH")) 86 return; 87 88 CString value(equalsLocation + 1); 89 m_extractedVariables.append(std::make_pair(name.latin1(), value)); 90} 91 92size_t DynamicLinkerEnvironmentExtractor::processLoadCommand(const void* data, size_t length, bool shouldByteSwap) 93{ 94 if (length < sizeof(load_command)) 95 return 0; 96 97 const load_command* rawLoadCommand = static_cast<const load_command*>(data); 98 load_command loadCommand = byteSwapIfNeeded(*rawLoadCommand, shouldByteSwap); 99 100 if (length < loadCommand.cmdsize) 101 return 0; 102 103 if (loadCommand.cmd == LC_DYLD_ENVIRONMENT) { 104 if (length < sizeof(dylinker_command)) 105 return 0; 106 107 dylinker_command environmentCommand = byteSwapIfNeeded(*reinterpret_cast<const dylinker_command*>(rawLoadCommand), shouldByteSwap); 108 if (loadCommand.cmdsize < environmentCommand.name.offset) 109 return 0; 110 111 size_t environmentStringLength = loadCommand.cmdsize - environmentCommand.name.offset; 112 Vector<char, 256> environmentString; 113 environmentString.reserveCapacity(environmentStringLength + 1); 114 environmentString.append(reinterpret_cast<const char*>(rawLoadCommand) + environmentCommand.name.offset, environmentStringLength); 115 environmentString.append(0); 116 117 processEnvironmentVariable(environmentString.data()); 118 } 119 120 return loadCommand.cmdsize; 121} 122 123void DynamicLinkerEnvironmentExtractor::processLoadCommands(const void* data, size_t length, int32_t numberOfCommands, bool shouldByteSwap) 124{ 125 const void* dataRemaining = data; 126 size_t lengthRemaining = length; 127 for (int i = 0; i < numberOfCommands; i++) { 128 size_t commandLength = processLoadCommand(dataRemaining, lengthRemaining, shouldByteSwap); 129 if (!commandLength || lengthRemaining < commandLength) 130 return; 131 132 dataRemaining = static_cast<const char*>(dataRemaining) + commandLength; 133 lengthRemaining -= commandLength; 134 } 135} 136 137void DynamicLinkerEnvironmentExtractor::processSingleArchitecture(const void* data, size_t length) 138{ 139 if (length < sizeof(mach_header)) 140 return; 141 142 const mach_header* header = static_cast<const mach_header*>(data); 143 if (header->magic == MH_MAGIC || header->magic == MH_CIGAM) { 144 bool shouldByteSwap = header->magic == MH_CIGAM; 145 mach_header swappedHeader = byteSwapIfNeeded(*header, shouldByteSwap); 146 if (swappedHeader.cputype == m_architecture) 147 processLoadCommands(static_cast<const char*>(data) + sizeof(*header), length - sizeof(*header), swappedHeader.ncmds, shouldByteSwap); 148 return; 149 } 150 151 if (length < sizeof(mach_header_64)) 152 return; 153 154 const mach_header_64* header64 = static_cast<const mach_header_64*>(data); 155 bool shouldByteSwap = header->magic == MH_CIGAM_64; 156 mach_header_64 swappedHeader64 = byteSwapIfNeeded(*header64, shouldByteSwap); 157 if (swappedHeader64.cputype == m_architecture) 158 processLoadCommands(static_cast<const char*>(data) + sizeof(*header64), length - sizeof(*header64), swappedHeader64.ncmds, shouldByteSwap); 159} 160 161void DynamicLinkerEnvironmentExtractor::processFatFile(const void* data, size_t length) 162{ 163 if (length < sizeof(fat_header)) 164 return; 165 166 const fat_header* header = static_cast<const fat_header*>(data); 167 168 size_t numberOfArchitectures = OSSwapBigToHostInt32(header->nfat_arch); 169 170 // Ensure that we have enough data remaining for numberOfArchitectures fat_arch structs. 171 if ((length - sizeof(fat_header)) / sizeof(fat_arch) < numberOfArchitectures) 172 return; 173 174 const fat_arch* archs = reinterpret_cast<const fat_arch*>(reinterpret_cast<const char*>(data) + sizeof(*header)); 175 for (uint32_t i = 0; i < numberOfArchitectures; i++) { 176 uint32_t architectureOffset = OSSwapBigToHostInt32(archs[i].offset); 177 uint32_t architectureSize = OSSwapBigToHostInt32(archs[i].size); 178 if (length < architectureOffset + architectureSize) 179 return; 180 181 processSingleArchitecture(static_cast<const char*>(data) + architectureOffset, architectureSize); 182 } 183} 184 185void DynamicLinkerEnvironmentExtractor::getExtractedEnvironmentVariables(EnvironmentVariables& environmentVariables) const 186{ 187 size_t extractedVariableCount = m_extractedVariables.size(); 188 for (size_t i = 0; i < extractedVariableCount; ++i) { 189 const CString& name = m_extractedVariables[i].first; 190 191 // Preserve any existing environment variable by this name so that it will take 192 // precedence over what we extracted from the executable file. 193 if (environmentVariables.get(name.data())) 194 continue; 195 196 environmentVariables.set(name.data(), m_extractedVariables[i].second.data()); 197 } 198} 199 200} // namespace WebKit 201