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/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "DynamicLinkerEnvironmentExtractor.h"
#include "EnvironmentVariables.h"
#include <mach-o/loader.h>
#include <mach-o/swap.h>
#include <wtf/OwnPtr.h>
#include <wtf/PassOwnPtr.h>
#include <wtf/text/WTFString.h>
namespace WebKit {
DynamicLinkerEnvironmentExtractor::DynamicLinkerEnvironmentExtractor(NSString *executablePath, cpu_type_t architecture)
: m_executablePath(executablePath)
, m_architecture(architecture)
{
NSData *mainExecutableData = [NSData dataWithContentsOfFile:m_executablePath.get() options:NSDataReadingMappedIfSafe error:0];
if (!mainExecutableData)
return;
const void* mainExecutableBytes = [mainExecutableData bytes];
size_t length = [mainExecutableData length];
if (length < sizeof(uint32_t))
return;
uint32_t magicValue = *static_cast<const uint32_t*>(mainExecutableBytes);
if (magicValue == FAT_MAGIC || magicValue == FAT_CIGAM) {
processFatFile(mainExecutableBytes, length);
return;
}
processSingleArchitecture(mainExecutableBytes, length);
}
#define DEFINE_BYTE_SWAPPER(type) inline type byteSwapIfNeeded(const type& data, bool shouldByteSwap) \
{ \
type swapped = data; \
if (shouldByteSwap) \
swap_##type(&swapped, NX_UnknownByteOrder); \
return swapped; \
}
DEFINE_BYTE_SWAPPER(load_command)
DEFINE_BYTE_SWAPPER(dylinker_command)
DEFINE_BYTE_SWAPPER(mach_header)
DEFINE_BYTE_SWAPPER(mach_header_64)
#undef DEFINE_BYTE_SWAPPER
void DynamicLinkerEnvironmentExtractor::processEnvironmentVariable(const char* environmentString)
{
const char* equalsLocation = strchr(environmentString, '=');
if (!equalsLocation)
return;
size_t nameLength = equalsLocation - environmentString;
String name(environmentString, nameLength);
// LC_DYLD_ENVIRONMENT only respects DYLD_*_PATH variables.
if (!name.startsWith("DYLD_") || !name.endsWith("_PATH"))
return;
CString value(equalsLocation + 1);
m_extractedVariables.append(std::make_pair(name.latin1(), value));
}
size_t DynamicLinkerEnvironmentExtractor::processLoadCommand(const void* data, size_t length, bool shouldByteSwap)
{
if (length < sizeof(load_command))
return 0;
const load_command* rawLoadCommand = static_cast<const load_command*>(data);
load_command loadCommand = byteSwapIfNeeded(*rawLoadCommand, shouldByteSwap);
if (length < loadCommand.cmdsize)
return 0;
if (loadCommand.cmd == LC_DYLD_ENVIRONMENT) {
if (length < sizeof(dylinker_command))
return 0;
dylinker_command environmentCommand = byteSwapIfNeeded(*reinterpret_cast<const dylinker_command*>(rawLoadCommand), shouldByteSwap);
if (loadCommand.cmdsize < environmentCommand.name.offset)
return 0;
size_t environmentStringLength = loadCommand.cmdsize - environmentCommand.name.offset;
Vector<char, 256> environmentString;
environmentString.reserveCapacity(environmentStringLength + 1);
environmentString.append(reinterpret_cast<const char*>(rawLoadCommand) + environmentCommand.name.offset, environmentStringLength);
environmentString.append(0);
processEnvironmentVariable(environmentString.data());
}
return loadCommand.cmdsize;
}
void DynamicLinkerEnvironmentExtractor::processLoadCommands(const void* data, size_t length, int32_t numberOfCommands, bool shouldByteSwap)
{
const void* dataRemaining = data;
size_t lengthRemaining = length;
for (int i = 0; i < numberOfCommands; i++) {
size_t commandLength = processLoadCommand(dataRemaining, lengthRemaining, shouldByteSwap);
if (!commandLength || lengthRemaining < commandLength)
return;
dataRemaining = static_cast<const char*>(dataRemaining) + commandLength;
lengthRemaining -= commandLength;
}
}
void DynamicLinkerEnvironmentExtractor::processSingleArchitecture(const void* data, size_t length)
{
if (length < sizeof(mach_header))
return;
const mach_header* header = static_cast<const mach_header*>(data);
if (header->magic == MH_MAGIC || header->magic == MH_CIGAM) {
bool shouldByteSwap = header->magic == MH_CIGAM;
mach_header swappedHeader = byteSwapIfNeeded(*header, shouldByteSwap);
if (swappedHeader.cputype == m_architecture)
processLoadCommands(static_cast<const char*>(data) + sizeof(*header), length - sizeof(*header), swappedHeader.ncmds, shouldByteSwap);
return;
}
if (length < sizeof(mach_header_64))
return;
const mach_header_64* header64 = static_cast<const mach_header_64*>(data);
bool shouldByteSwap = header->magic == MH_CIGAM_64;
mach_header_64 swappedHeader64 = byteSwapIfNeeded(*header64, shouldByteSwap);
if (swappedHeader64.cputype == m_architecture)
processLoadCommands(static_cast<const char*>(data) + sizeof(*header64), length - sizeof(*header64), swappedHeader64.ncmds, shouldByteSwap);
}
void DynamicLinkerEnvironmentExtractor::processFatFile(const void* data, size_t length)
{
if (length < sizeof(fat_header))
return;
const fat_header* header = static_cast<const fat_header*>(data);
size_t numberOfArchitectures = OSSwapBigToHostInt32(header->nfat_arch);
// Ensure that we have enough data remaining for numberOfArchitectures fat_arch structs.
if ((length - sizeof(fat_header)) / sizeof(fat_arch) < numberOfArchitectures)
return;
const fat_arch* archs = reinterpret_cast<const fat_arch*>(reinterpret_cast<const char*>(data) + sizeof(*header));
for (uint32_t i = 0; i < numberOfArchitectures; i++) {
uint32_t architectureOffset = OSSwapBigToHostInt32(archs[i].offset);
uint32_t architectureSize = OSSwapBigToHostInt32(archs[i].size);
if (length < architectureOffset + architectureSize)
return;
processSingleArchitecture(static_cast<const char*>(data) + architectureOffset, architectureSize);
}
}
void DynamicLinkerEnvironmentExtractor::getExtractedEnvironmentVariables(EnvironmentVariables& environmentVariables) const
{
size_t extractedVariableCount = m_extractedVariables.size();
for (size_t i = 0; i < extractedVariableCount; ++i) {
const CString& name = m_extractedVariables[i].first;
// Preserve any existing environment variable by this name so that it will take
// precedence over what we extracted from the executable file.
if (environmentVariables.get(name.data()))
continue;
environmentVariables.set(name.data(), m_extractedVariables[i].second.data());
}
}
} // namespace WebKit
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