Revision b7d8c91822101ff9de07075e9b1f02e18c2725da authored by Brad King on 04 March 2020, 13:50:44 UTC, committed by Brad King on 04 March 2020, 13:50:44 UTC
1 parent 75d5232
cmMachO.cxx
/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file Copyright.txt or https://cmake.org/licensing for details. */
#include "cmMachO.h"
#include <cstddef>
#include <string>
#include <vector>
#include <cm/memory>
#include "cmsys/FStream.hxx"
#include "cmAlgorithms.h"
// Include the Mach-O format information system header.
#include <mach-o/fat.h>
#include <mach-o/loader.h>
/**
https://developer.apple.com/library/mac/documentation/
DeveloperTools/Conceptual/MachORuntime/index.html
A Mach-O file has 3 major regions: header, load commands and segments.
Data Structures are provided from <mach-o/loader.h> which
correspond to the file structure.
The header can be either a struct mach_header or struct mach_header_64.
One can peek at the first 4 bytes to identify the type of header.
Following is the load command region which starts with
struct load_command, and is followed by n number of load commands.
In the case of a universal binary (an archive of multiple Mach-O files),
the file begins with a struct fat_header and is followed by multiple
struct fat_arch instances. The struct fat_arch indicates the offset
for each Mach-O file.
*/
namespace {
// peek in the file
template <typename T>
bool peek(cmsys::ifstream& fin, T& v)
{
std::streampos p = fin.tellg();
if (!fin.read(reinterpret_cast<char*>(&v), sizeof(T))) {
return false;
}
fin.seekg(p);
return fin.good();
}
// read from the file and fill a data structure
template <typename T>
bool read(cmsys::ifstream& fin, T& v)
{
return !!fin.read(reinterpret_cast<char*>(&v), sizeof(T));
}
// read from the file and fill multiple data structures where
// the vector has been resized
template <typename T>
bool read(cmsys::ifstream& fin, std::vector<T>& v)
{
// nothing to read
if (v.empty()) {
return true;
}
return !!fin.read(reinterpret_cast<char*>(&v[0]), sizeof(T) * v.size());
}
}
// Contains header and load commands for a single Mach-O file
class cmMachOHeaderAndLoadCommands
{
public:
// A load_command and its associated data
struct RawLoadCommand
{
uint32_t type(const cmMachOHeaderAndLoadCommands* m) const
{
if (this->LoadCommand.size() < sizeof(load_command)) {
return 0;
}
const load_command* cmd =
reinterpret_cast<const load_command*>(&this->LoadCommand[0]);
return m->swap(cmd->cmd);
}
std::vector<char> LoadCommand;
};
cmMachOHeaderAndLoadCommands(bool _swap)
: Swap(_swap)
{
}
virtual ~cmMachOHeaderAndLoadCommands() = default;
virtual bool read_mach_o(cmsys::ifstream& fin) = 0;
const std::vector<RawLoadCommand>& load_commands() const
{
return this->LoadCommands;
}
uint32_t swap(uint32_t v) const
{
if (this->Swap) {
char* c = reinterpret_cast<char*>(&v);
std::swap(c[0], c[3]);
std::swap(c[1], c[2]);
}
return v;
}
protected:
bool read_load_commands(uint32_t ncmds, uint32_t sizeofcmds,
cmsys::ifstream& fin);
bool Swap;
std::vector<RawLoadCommand> LoadCommands;
};
// Implementation for reading Mach-O header and load commands.
// This is 32 or 64 bit arch specific.
template <typename T>
class cmMachOHeaderAndLoadCommandsImpl : public cmMachOHeaderAndLoadCommands
{
public:
cmMachOHeaderAndLoadCommandsImpl(bool _swap)
: cmMachOHeaderAndLoadCommands(_swap)
{
}
bool read_mach_o(cmsys::ifstream& fin) override
{
if (!read(fin, this->Header)) {
return false;
}
this->Header.cputype = swap(this->Header.cputype);
this->Header.cpusubtype = swap(this->Header.cpusubtype);
this->Header.filetype = swap(this->Header.filetype);
this->Header.ncmds = swap(this->Header.ncmds);
this->Header.sizeofcmds = swap(this->Header.sizeofcmds);
this->Header.flags = swap(this->Header.flags);
return read_load_commands(this->Header.ncmds, this->Header.sizeofcmds,
fin);
}
protected:
T Header;
};
bool cmMachOHeaderAndLoadCommands::read_load_commands(uint32_t ncmds,
uint32_t sizeofcmds,
cmsys::ifstream& fin)
{
uint32_t size_read = 0;
this->LoadCommands.resize(ncmds);
for (uint32_t i = 0; i < ncmds; i++) {
load_command lc;
if (!peek(fin, lc)) {
return false;
}
lc.cmd = swap(lc.cmd);
lc.cmdsize = swap(lc.cmdsize);
size_read += lc.cmdsize;
RawLoadCommand& c = this->LoadCommands[i];
c.LoadCommand.resize(lc.cmdsize);
if (!read(fin, c.LoadCommand)) {
return false;
}
}
if (size_read != sizeofcmds) {
this->LoadCommands.clear();
return false;
}
return true;
}
class cmMachOInternal
{
public:
cmMachOInternal(const char* fname);
~cmMachOInternal();
// read a Mach-O file
bool read_mach_o(uint32_t file_offset);
// the file we are reading
cmsys::ifstream Fin;
// The archs in the universal binary
// If the binary is not a universal binary, this will be empty.
std::vector<fat_arch> FatArchs;
// the error message while parsing
std::string ErrorMessage;
// the list of Mach-O's
std::vector<cmMachOHeaderAndLoadCommands*> MachOList;
};
cmMachOInternal::cmMachOInternal(const char* fname)
: Fin(fname)
{
// Quit now if the file could not be opened.
if (!this->Fin || !this->Fin.get()) {
this->ErrorMessage = "Error opening input file.";
return;
}
if (!this->Fin.seekg(0)) {
this->ErrorMessage = "Error seeking to beginning of file.";
return;
}
// Read the binary identification block.
uint32_t magic = 0;
if (!peek(this->Fin, magic)) {
this->ErrorMessage = "Error reading Mach-O identification.";
return;
}
// Verify the binary identification.
if (!(magic == MH_CIGAM || magic == MH_MAGIC || magic == MH_CIGAM_64 ||
magic == MH_MAGIC_64 || magic == FAT_CIGAM || magic == FAT_MAGIC)) {
this->ErrorMessage = "File does not have a valid Mach-O identification.";
return;
}
if (magic == FAT_MAGIC || magic == FAT_CIGAM) {
// this is a universal binary
fat_header header;
if (!read(this->Fin, header)) {
this->ErrorMessage = "Error reading fat header.";
return;
}
// read fat_archs
this->FatArchs.resize(OSSwapBigToHostInt32(header.nfat_arch));
if (!read(this->Fin, this->FatArchs)) {
this->ErrorMessage = "Error reading fat header archs.";
return;
}
// parse each Mach-O file
for (const auto& arch : this->FatArchs) {
if (!this->read_mach_o(OSSwapBigToHostInt32(arch.offset))) {
return;
}
}
} else {
// parse Mach-O file at the beginning of the file
this->read_mach_o(0);
}
}
cmMachOInternal::~cmMachOInternal()
{
for (auto& i : this->MachOList) {
delete i;
}
}
bool cmMachOInternal::read_mach_o(uint32_t file_offset)
{
if (!this->Fin.seekg(file_offset)) {
this->ErrorMessage = "Failed to locate Mach-O content.";
return false;
}
uint32_t magic;
if (!peek(this->Fin, magic)) {
this->ErrorMessage = "Error reading Mach-O identification.";
return false;
}
cmMachOHeaderAndLoadCommands* f = nullptr;
if (magic == MH_CIGAM || magic == MH_MAGIC) {
bool swap = false;
if (magic == MH_CIGAM) {
swap = true;
}
f = new cmMachOHeaderAndLoadCommandsImpl<mach_header>(swap);
} else if (magic == MH_CIGAM_64 || magic == MH_MAGIC_64) {
bool swap = false;
if (magic == MH_CIGAM_64) {
swap = true;
}
f = new cmMachOHeaderAndLoadCommandsImpl<mach_header_64>(swap);
}
if (f && f->read_mach_o(this->Fin)) {
this->MachOList.push_back(f);
} else {
delete f;
this->ErrorMessage = "Failed to read Mach-O header.";
return false;
}
return true;
}
//============================================================================
// External class implementation.
cmMachO::cmMachO(const char* fname)
: Internal(cm::make_unique<cmMachOInternal>(fname))
{
}
cmMachO::~cmMachO() = default;
std::string const& cmMachO::GetErrorMessage() const
{
return this->Internal->ErrorMessage;
}
bool cmMachO::Valid() const
{
return !this->Internal->MachOList.empty();
}
bool cmMachO::GetInstallName(std::string& install_name)
{
if (this->Internal->MachOList.empty()) {
return false;
}
// grab the first Mach-O and get the install name from that one
cmMachOHeaderAndLoadCommands* macho = this->Internal->MachOList[0];
for (size_t i = 0; i < macho->load_commands().size(); i++) {
const cmMachOHeaderAndLoadCommands::RawLoadCommand& cmd =
macho->load_commands()[i];
uint32_t lc_cmd = cmd.type(macho);
if (lc_cmd == LC_ID_DYLIB || lc_cmd == LC_LOAD_WEAK_DYLIB ||
lc_cmd == LC_LOAD_DYLIB) {
if (sizeof(dylib_command) < cmd.LoadCommand.size()) {
uint32_t namelen = cmd.LoadCommand.size() - sizeof(dylib_command);
install_name.assign(&cmd.LoadCommand[sizeof(dylib_command)], namelen);
return true;
}
}
}
return false;
}
void cmMachO::PrintInfo(std::ostream& /*os*/) const
{
}
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...