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//===- MachOObject.cpp - Mach-O Object File Wrapper -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Object/MachOObject.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/System/Host.h"
#include "llvm/System/SwapByteOrder.h"
using namespace llvm;
using namespace llvm::object;
/* Translation Utilities */
template<typename T>
static void SwapValue(T &Value) {
Value = sys::SwapByteOrder(Value);
}
template<typename T>
static void SwapStruct(T &Value);
template<typename T>
static void ReadInMemoryStruct(const MachOObject &MOO,
StringRef Buffer, uint64_t Base,
InMemoryStruct<T> &Res) {
typedef T struct_type;
uint64_t Size = sizeof(struct_type);
// Check that the buffer contains the expected data.
if (Base + Size > Buffer.size()) {
Res = 0;
return;
}
// Check whether we can return a direct pointer.
struct_type *Ptr = (struct_type *) (Buffer.data() + Base);
if (!MOO.isSwappedEndian()) {
Res = Ptr;
return;
}
// Otherwise, copy the struct and translate the values.
Res = *Ptr;
SwapStruct(*Res);
}
/* *** */
MachOObject::MachOObject(MemoryBuffer *Buffer_, bool IsLittleEndian_,
bool Is64Bit_)
: Buffer(Buffer_), IsLittleEndian(IsLittleEndian_), Is64Bit(Is64Bit_),
IsSwappedEndian(IsLittleEndian != sys::isLittleEndianHost()),
LoadCommands(0), NumLoadedCommands(0) {
// Load the common header.
memcpy(&Header, Buffer->getBuffer().data(), sizeof(Header));
if (IsSwappedEndian) {
SwapValue(Header.Magic);
SwapValue(Header.CPUType);
SwapValue(Header.CPUSubtype);
SwapValue(Header.FileType);
SwapValue(Header.NumLoadCommands);
SwapValue(Header.SizeOfLoadCommands);
SwapValue(Header.Flags);
}
if (is64Bit()) {
memcpy(&Header64Ext, Buffer->getBuffer().data() + sizeof(Header),
sizeof(Header64Ext));
if (IsSwappedEndian) {
SwapValue(Header64Ext.Reserved);
}
}
// Create the load command array if sane.
if (getHeader().NumLoadCommands < (1 << 20))
LoadCommands = new LoadCommandInfo[getHeader().NumLoadCommands];
}
MachOObject::~MachOObject() {
delete LoadCommands;
}
MachOObject *MachOObject::LoadFromBuffer(MemoryBuffer *Buffer,
std::string *ErrorStr) {
// First, check the magic value and initialize the basic object info.
bool IsLittleEndian = false, Is64Bit = false;
StringRef Magic = Buffer->getBuffer().slice(0, 4);
if (Magic == "\xFE\xED\xFA\xCE") {
} else if (Magic == "\xCE\xFA\xED\xFE") {
IsLittleEndian = true;
} else if (Magic == "\xFE\xED\xFA\xCF") {
Is64Bit = true;
} else if (Magic == "\xCF\xFA\xED\xFE") {
IsLittleEndian = true;
Is64Bit = true;
} else {
if (ErrorStr) *ErrorStr = "not a Mach object file (invalid magic)";
return 0;
}
// Ensure that the at least the full header is present.
unsigned HeaderSize = Is64Bit ? macho::Header64Size : macho::Header32Size;
if (Buffer->getBufferSize() < HeaderSize) {
if (ErrorStr) *ErrorStr = "not a Mach object file (invalid header)";
return 0;
}
OwningPtr<MachOObject> Object(new MachOObject(Buffer, IsLittleEndian,
Is64Bit));
// Check for bogus number of load commands.
if (Object->getHeader().NumLoadCommands >= (1 << 20)) {
if (ErrorStr) *ErrorStr = "not a Mach object file (unreasonable header)";
return 0;
}
if (ErrorStr) *ErrorStr = "";
return Object.take();
}
const MachOObject::LoadCommandInfo &
MachOObject::getLoadCommandInfo(unsigned Index) const {
assert(Index < getHeader().NumLoadCommands && "Invalid index!");
// Load the command, if necessary.
if (Index >= NumLoadedCommands) {
uint64_t Offset;
if (Index == 0) {
Offset = getHeaderSize();
} else {
const LoadCommandInfo &Prev = getLoadCommandInfo(Index - 1);
Offset = Prev.Offset + Prev.Command.Size;
}
LoadCommandInfo &Info = LoadCommands[Index];
memcpy(&Info.Command, Buffer->getBuffer().data() + Offset,
sizeof(macho::LoadCommand));
if (IsSwappedEndian) {
SwapValue(Info.Command.Type);
SwapValue(Info.Command.Size);
}
Info.Offset = Offset;
NumLoadedCommands = Index + 1;
}
return LoadCommands[Index];
}
template<>
static void SwapStruct(macho::SegmentLoadCommand &Value) {
SwapValue(Value.Type);
SwapValue(Value.Size);
SwapValue(Value.VMAddress);
SwapValue(Value.VMSize);
SwapValue(Value.FileOffset);
SwapValue(Value.FileSize);
SwapValue(Value.MaxVMProtection);
SwapValue(Value.InitialVMProtection);
SwapValue(Value.NumSections);
SwapValue(Value.Flags);
}
void MachOObject::ReadSegmentLoadCommand(const LoadCommandInfo &LCI,
InMemoryStruct<macho::SegmentLoadCommand> &Res) const {
ReadInMemoryStruct(*this, Buffer->getBuffer(), LCI.Offset, Res);
}
template<>
static void SwapStruct(macho::Segment64LoadCommand &Value) {
SwapValue(Value.Type);
SwapValue(Value.Size);
SwapValue(Value.VMAddress);
SwapValue(Value.VMSize);
SwapValue(Value.FileOffset);
SwapValue(Value.FileSize);
SwapValue(Value.MaxVMProtection);
SwapValue(Value.InitialVMProtection);
SwapValue(Value.NumSections);
SwapValue(Value.Flags);
}
void MachOObject::ReadSegment64LoadCommand(const LoadCommandInfo &LCI,
InMemoryStruct<macho::Segment64LoadCommand> &Res) const {
ReadInMemoryStruct(*this, Buffer->getBuffer(), LCI.Offset, Res);
}
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