/* ldid - (Mach-O) Link-Loader Identity Editor
 * Copyright (C) 2007-2015  Jay Freeman (saurik)
*/

/* GNU Affero General Public License, Version 3 {{{ */
/*
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.

 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
**/
/* }}} */

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <map>
#include <sstream>
#include <string>
#include <vector>

#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdint.h>
#include <unistd.h>

#include <sys/mman.h>
#include <sys/stat.h>

#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/pkcs7.h>
#include <openssl/pkcs12.h>
#include <openssl/sha.h>

#include <plist/plist.h>

#include "ldid.hpp"

#define _assert___(line) \
    #line
#define _assert__(line) \
    _assert___(line)

#define _assert_(expr, format, ...) \
    do if (!(expr)) { \
        fprintf(stderr, "%s(%u): _assert(): " format "\n", __FILE__, __LINE__, ## __VA_ARGS__); \
        throw __FILE__ "(" _assert__(__LINE__) "): _assert(" #expr ")"; \
    } while (false)

#define _assert(expr) \
    _assert_(expr, "%s", #expr)

#define _syscall(expr) ({ \
    __typeof__(expr) _value; \
    do if ((long) (_value = (expr)) != -1) \
        break; \
    else switch (errno) { \
        case EINTR: \
            continue; \
        default: \
            _assert_(false, "errno=%u", errno); \
    } while (true); \
    _value; \
})

#define _trace() \
    fprintf(stderr, "_trace(%s:%u): %s\n", __FILE__, __LINE__, __FUNCTION__)

#define _not(type) \
    ((type) ~ (type) 0)

#define _packed \
    __attribute__((packed))

template <typename Type_>
struct Iterator_ {
    typedef typename Type_::const_iterator Result;
};

#define _foreach(item, list) \
    for (bool _stop(true); _stop; ) \
        for (const __typeof__(list) &_list = (list); _stop; _stop = false) \
            for (Iterator_<__typeof__(list)>::Result _item = _list.begin(); _item != _list.end(); ++_item) \
                for (bool _suck(true); _suck; _suck = false) \
                    for (const __typeof__(*_item) &item = *_item; _suck; _suck = false)

struct fat_header {
    uint32_t magic;
    uint32_t nfat_arch;
} _packed;

#define FAT_MAGIC 0xcafebabe
#define FAT_CIGAM 0xbebafeca

struct fat_arch {
    uint32_t cputype;
    uint32_t cpusubtype;
    uint32_t offset;
    uint32_t size;
    uint32_t align;
} _packed;

struct mach_header {
    uint32_t magic;
    uint32_t cputype;
    uint32_t cpusubtype;
    uint32_t filetype;
    uint32_t ncmds;
    uint32_t sizeofcmds;
    uint32_t flags;
} _packed;

#define MH_MAGIC 0xfeedface
#define MH_CIGAM 0xcefaedfe

#define MH_MAGIC_64 0xfeedfacf
#define MH_CIGAM_64 0xcffaedfe

#define MH_DYLDLINK   0x4

#define MH_OBJECT     0x1
#define MH_EXECUTE    0x2
#define MH_DYLIB      0x6
#define MH_BUNDLE     0x8
#define MH_DYLIB_STUB 0x9

struct load_command {
    uint32_t cmd;
    uint32_t cmdsize;
} _packed;

#define LC_REQ_DYLD           uint32_t(0x80000000)

#define LC_SEGMENT            uint32_t(0x01)
#define LC_SYMTAB             uint32_t(0x02)
#define LC_DYSYMTAB           uint32_t(0x0b)
#define LC_LOAD_DYLIB         uint32_t(0x0c)
#define LC_ID_DYLIB           uint32_t(0x0d)
#define LC_SEGMENT_64         uint32_t(0x19)
#define LC_UUID               uint32_t(0x1b)
#define LC_CODE_SIGNATURE     uint32_t(0x1d)
#define LC_SEGMENT_SPLIT_INFO uint32_t(0x1e)
#define LC_REEXPORT_DYLIB     uint32_t(0x1f | LC_REQ_DYLD)
#define LC_ENCRYPTION_INFO    uint32_t(0x21)
#define LC_DYLD_INFO          uint32_t(0x22)
#define LC_DYLD_INFO_ONLY     uint32_t(0x22 | LC_REQ_DYLD)
#define LC_ENCRYPTION_INFO_64 uint32_t(0x2c)

struct dylib {
    uint32_t name;
    uint32_t timestamp;
    uint32_t current_version;
    uint32_t compatibility_version;
} _packed;

struct dylib_command {
    uint32_t cmd;
    uint32_t cmdsize;
    struct dylib dylib;
} _packed;

struct uuid_command {
    uint32_t cmd;
    uint32_t cmdsize;
    uint8_t uuid[16];
} _packed;

struct symtab_command {
    uint32_t cmd;
    uint32_t cmdsize;
    uint32_t symoff;
    uint32_t nsyms;
    uint32_t stroff;
    uint32_t strsize;
} _packed;

struct dyld_info_command {
    uint32_t cmd;
    uint32_t cmdsize;
    uint32_t rebase_off;
    uint32_t rebase_size;
    uint32_t bind_off;
    uint32_t bind_size;
    uint32_t weak_bind_off;
    uint32_t weak_bind_size;
    uint32_t lazy_bind_off;
    uint32_t lazy_bind_size;
    uint32_t export_off;
    uint32_t export_size;
} _packed;

struct dysymtab_command {
    uint32_t cmd;
    uint32_t cmdsize;
    uint32_t ilocalsym;
    uint32_t nlocalsym;
    uint32_t iextdefsym;
    uint32_t nextdefsym;
    uint32_t iundefsym;
    uint32_t nundefsym;
    uint32_t tocoff;
    uint32_t ntoc;
    uint32_t modtaboff;
    uint32_t nmodtab;
    uint32_t extrefsymoff;
    uint32_t nextrefsyms;
    uint32_t indirectsymoff;
    uint32_t nindirectsyms;
    uint32_t extreloff;
    uint32_t nextrel;
    uint32_t locreloff;
    uint32_t nlocrel;
} _packed;

struct dylib_table_of_contents {
    uint32_t symbol_index;
    uint32_t module_index;
} _packed;

struct dylib_module {
    uint32_t module_name;
    uint32_t iextdefsym;
    uint32_t nextdefsym;
    uint32_t irefsym;
    uint32_t nrefsym;
    uint32_t ilocalsym;
    uint32_t nlocalsym;
    uint32_t iextrel;
    uint32_t nextrel;
    uint32_t iinit_iterm;
    uint32_t ninit_nterm;
    uint32_t objc_module_info_addr;
    uint32_t objc_module_info_size;
} _packed;

struct dylib_reference {
    uint32_t isym:24;
    uint32_t flags:8;
} _packed;

struct relocation_info {
    int32_t r_address;
    uint32_t r_symbolnum:24;
    uint32_t r_pcrel:1;
    uint32_t r_length:2;
    uint32_t r_extern:1;
    uint32_t r_type:4;
} _packed;

struct nlist {
    union {
        char *n_name;
        int32_t n_strx;
    } n_un;

    uint8_t n_type;
    uint8_t n_sect;
    uint8_t n_desc;
    uint32_t n_value;
} _packed;

struct segment_command {
    uint32_t cmd;
    uint32_t cmdsize;
    char segname[16];
    uint32_t vmaddr;
    uint32_t vmsize;
    uint32_t fileoff;
    uint32_t filesize;
    uint32_t maxprot;
    uint32_t initprot;
    uint32_t nsects;
    uint32_t flags;
} _packed;

struct segment_command_64 {
    uint32_t cmd;
    uint32_t cmdsize;
    char segname[16];
    uint64_t vmaddr;
    uint64_t vmsize;
    uint64_t fileoff;
    uint64_t filesize;
    uint32_t maxprot;
    uint32_t initprot;
    uint32_t nsects;
    uint32_t flags;
} _packed;

struct section {
    char sectname[16];
    char segname[16];
    uint32_t addr;
    uint32_t size;
    uint32_t offset;
    uint32_t align;
    uint32_t reloff;
    uint32_t nreloc;
    uint32_t flags;
    uint32_t reserved1;
    uint32_t reserved2;
} _packed;

struct section_64 {
    char sectname[16];
    char segname[16];
    uint64_t addr;
    uint64_t size;
    uint32_t offset;
    uint32_t align;
    uint32_t reloff;
    uint32_t nreloc;
    uint32_t flags;
    uint32_t reserved1;
    uint32_t reserved2;
} _packed;

struct linkedit_data_command {
    uint32_t cmd;
    uint32_t cmdsize;
    uint32_t dataoff;
    uint32_t datasize;
} _packed;

struct encryption_info_command {
    uint32_t cmd;
    uint32_t cmdsize;
    uint32_t cryptoff;
    uint32_t cryptsize;
    uint32_t cryptid;
} _packed;

#define BIND_OPCODE_MASK                             0xf0
#define BIND_IMMEDIATE_MASK                          0x0f
#define BIND_OPCODE_DONE                             0x00
#define BIND_OPCODE_SET_DYLIB_ORDINAL_IMM            0x10
#define BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB           0x20
#define BIND_OPCODE_SET_DYLIB_SPECIAL_IMM            0x30
#define BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM    0x40
#define BIND_OPCODE_SET_TYPE_IMM                     0x50
#define BIND_OPCODE_SET_ADDEND_SLEB                  0x60
#define BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB      0x70
#define BIND_OPCODE_ADD_ADDR_ULEB                    0x80
#define BIND_OPCODE_DO_BIND                          0x90
#define BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB            0xa0
#define BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED      0xb0
#define BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB 0xc0

inline void get(std::streambuf &stream, void *data, size_t size) {
    _assert(stream.sgetn(static_cast<char *>(data), size) == size);
}

inline void put(std::streambuf &stream, const void *data, size_t size) {
    _assert(stream.sputn(static_cast<const char *>(data), size) == size);
}

inline void pad(std::streambuf &stream, size_t size) {
    char padding[size];
    memset(padding, 0, size);
    put(stream, padding, size);
}

template <typename Type_>
Type_ Align(Type_ value, size_t align) {
    value += align - 1;
    value /= align;
    value *= align;
    return value;
}

static const uint8_t PageShift_(0x0c);
static const uint32_t PageSize_(1 << PageShift_);

static inline uint16_t Swap_(uint16_t value) {
    return
        ((value >>  8) & 0x00ff) |
        ((value <<  8) & 0xff00);
}

static inline uint32_t Swap_(uint32_t value) {
    value = ((value >>  8) & 0x00ff00ff) |
            ((value <<  8) & 0xff00ff00);
    value = ((value >> 16) & 0x0000ffff) |
            ((value << 16) & 0xffff0000);
    return value;
}

static inline uint64_t Swap_(uint64_t value) {
    value = (value & 0x00000000ffffffff) << 32 | (value & 0xffffffff00000000) >> 32;
    value = (value & 0x0000ffff0000ffff) << 16 | (value & 0xffff0000ffff0000) >> 16;
    value = (value & 0x00ff00ff00ff00ff) << 8  | (value & 0xff00ff00ff00ff00) >> 8;
    return value;
}

static inline int16_t Swap_(int16_t value) {
    return Swap_(static_cast<uint16_t>(value));
}

static inline int32_t Swap_(int32_t value) {
    return Swap_(static_cast<uint32_t>(value));
}

static inline int64_t Swap_(int64_t value) {
    return Swap_(static_cast<uint64_t>(value));
}

static bool little_(true);

static inline uint16_t Swap(uint16_t value) {
    return little_ ? Swap_(value) : value;
}

static inline uint32_t Swap(uint32_t value) {
    return little_ ? Swap_(value) : value;
}

static inline uint64_t Swap(uint64_t value) {
    return little_ ? Swap_(value) : value;
}

static inline int16_t Swap(int16_t value) {
    return Swap(static_cast<uint16_t>(value));
}

static inline int32_t Swap(int32_t value) {
    return Swap(static_cast<uint32_t>(value));
}

static inline int64_t Swap(int64_t value) {
    return Swap(static_cast<uint64_t>(value));
}

template <typename Target_>
class Pointer;

class Swapped {
  protected:
    bool swapped_;

    Swapped() :
        swapped_(false)
    {
    }

  public:
    Swapped(bool swapped) :
        swapped_(swapped)
    {
    }

    template <typename Type_>
    Type_ Swap(Type_ value) const {
        return swapped_ ? Swap_(value) : value;
    }
};

class Data :
    public Swapped
{
  private:
    void *base_;
    size_t size_;

  public:
    Data(void *base, size_t size) :
        base_(base),
        size_(size)
    {
    }

    void *GetBase() const {
        return base_;
    }

    size_t GetSize() const {
        return size_;
    }
};

class MachHeader :
    public Data
{
  private:
    bool bits64_;

    struct mach_header *mach_header_;
    struct load_command *load_command_;

  public:
    MachHeader(void *base, size_t size) :
        Data(base, size)
    {
        mach_header_ = (mach_header *) base;

        switch (Swap(mach_header_->magic)) {
            case MH_CIGAM:
                swapped_ = !swapped_;
            case MH_MAGIC:
                bits64_ = false;
            break;

            case MH_CIGAM_64:
                swapped_ = !swapped_;
            case MH_MAGIC_64:
                bits64_ = true;
            break;

            default:
                _assert(false);
        }

        void *post = mach_header_ + 1;
        if (bits64_)
            post = (uint32_t *) post + 1;
        load_command_ = (struct load_command *) post;

        _assert(
            Swap(mach_header_->filetype) == MH_EXECUTE ||
            Swap(mach_header_->filetype) == MH_DYLIB ||
            Swap(mach_header_->filetype) == MH_BUNDLE
        );
    }

    bool Bits64() const {
        return bits64_;
    }

    struct mach_header *operator ->() const {
        return mach_header_;
    }

    operator struct mach_header *() const {
        return mach_header_;
    }

    uint32_t GetCPUType() const {
        return Swap(mach_header_->cputype);
    }

    uint32_t GetCPUSubtype() const {
        return Swap(mach_header_->cpusubtype) & 0xff;
    }

    struct load_command *GetLoadCommand() const {
        return load_command_;
    }

    std::vector<struct load_command *> GetLoadCommands() const {
        std::vector<struct load_command *> load_commands;

        struct load_command *load_command = load_command_;
        for (uint32_t cmd = 0; cmd != Swap(mach_header_->ncmds); ++cmd) {
            load_commands.push_back(load_command);
            load_command = (struct load_command *) ((uint8_t *) load_command + Swap(load_command->cmdsize));
        }

        return load_commands;
    }

    std::vector<segment_command *> GetSegments(const char *segment_name) const {
        std::vector<struct segment_command *> segment_commands;

        _foreach (load_command, GetLoadCommands()) {
            if (Swap(load_command->cmd) == LC_SEGMENT) {
                segment_command *segment_command = reinterpret_cast<struct segment_command *>(load_command);
                if (strncmp(segment_command->segname, segment_name, 16) == 0)
                    segment_commands.push_back(segment_command);
            }
        }

        return segment_commands;
    }

    std::vector<segment_command_64 *> GetSegments64(const char *segment_name) const {
        std::vector<struct segment_command_64 *> segment_commands;

        _foreach (load_command, GetLoadCommands()) {
            if (Swap(load_command->cmd) == LC_SEGMENT_64) {
                segment_command_64 *segment_command = reinterpret_cast<struct segment_command_64 *>(load_command);
                if (strncmp(segment_command->segname, segment_name, 16) == 0)
                    segment_commands.push_back(segment_command);
            }
        }

        return segment_commands;
    }

    std::vector<section *> GetSections(const char *segment_name, const char *section_name) const {
        std::vector<section *> sections;

        _foreach (segment, GetSegments(segment_name)) {
            section *section = (struct section *) (segment + 1);

            uint32_t sect;
            for (sect = 0; sect != Swap(segment->nsects); ++sect) {
                if (strncmp(section->sectname, section_name, 16) == 0)
                    sections.push_back(section);
                ++section;
            }
        }

        return sections;
    }

    template <typename Target_>
    Pointer<Target_> GetPointer(uint32_t address, const char *segment_name = NULL) const {
        load_command *load_command = (struct load_command *) (mach_header_ + 1);
        uint32_t cmd;

        for (cmd = 0; cmd != Swap(mach_header_->ncmds); ++cmd) {
            if (Swap(load_command->cmd) == LC_SEGMENT) {
                segment_command *segment_command = (struct segment_command *) load_command;
                if (segment_name != NULL && strncmp(segment_command->segname, segment_name, 16) != 0)
                    goto next_command;

                section *sections = (struct section *) (segment_command + 1);

                uint32_t sect;
                for (sect = 0; sect != Swap(segment_command->nsects); ++sect) {
                    section *section = &sections[sect];
                    //printf("%s %u %p %p %u\n", segment_command->segname, sect, address, section->addr, section->size);
                    if (address >= Swap(section->addr) && address < Swap(section->addr) + Swap(section->size)) {
                        //printf("0x%.8x %s\n", address, segment_command->segname);
                        return Pointer<Target_>(this, reinterpret_cast<Target_ *>(address - Swap(section->addr) + Swap(section->offset) + (char *) mach_header_));
                    }
                }
            }

          next_command:
            load_command = (struct load_command *) ((char *) load_command + Swap(load_command->cmdsize));
        }

        return Pointer<Target_>(this);
    }

    template <typename Target_>
    Pointer<Target_> GetOffset(uint32_t offset) {
        return Pointer<Target_>(this, reinterpret_cast<Target_ *>(offset + (uint8_t *) mach_header_));
    }
};

class FatMachHeader :
    public MachHeader
{
  private:
    fat_arch *fat_arch_;

  public:
    FatMachHeader(void *base, size_t size, fat_arch *fat_arch) :
        MachHeader(base, size),
        fat_arch_(fat_arch)
    {
    }

    fat_arch *GetFatArch() const {
        return fat_arch_;
    }
};

class FatHeader :
    public Data
{
  private:
    fat_header *fat_header_;
    std::vector<FatMachHeader> mach_headers_;

  public:
    FatHeader(void *base, size_t size) :
        Data(base, size)
    {
        fat_header_ = reinterpret_cast<struct fat_header *>(base);

        if (Swap(fat_header_->magic) == FAT_CIGAM) {
            swapped_ = !swapped_;
            goto fat;
        } else if (Swap(fat_header_->magic) != FAT_MAGIC) {
            fat_header_ = NULL;
            mach_headers_.push_back(FatMachHeader(base, size, NULL));
        } else fat: {
            size_t fat_narch = Swap(fat_header_->nfat_arch);
            fat_arch *fat_arch = reinterpret_cast<struct fat_arch *>(fat_header_ + 1);
            size_t arch;
            for (arch = 0; arch != fat_narch; ++arch) {
                uint32_t arch_offset = Swap(fat_arch->offset);
                uint32_t arch_size = Swap(fat_arch->size);
                mach_headers_.push_back(FatMachHeader((uint8_t *) base + arch_offset, arch_size, fat_arch));
                ++fat_arch;
            }
        }
    }

    std::vector<FatMachHeader> &GetMachHeaders() {
        return mach_headers_;
    }

    bool IsFat() const {
        return fat_header_ != NULL;
    }

    struct fat_header *operator ->() const {
        return fat_header_;
    }

    operator struct fat_header *() const {
        return fat_header_;
    }
};

template <typename Target_>
class Pointer {
  private:
    const MachHeader *framework_;
    const Target_ *pointer_;

  public:
    Pointer(const MachHeader *framework = NULL, const Target_ *pointer = NULL) :
        framework_(framework),
        pointer_(pointer)
    {
    }

    operator const Target_ *() const {
        return pointer_;
    }

    const Target_ *operator ->() const {
        return pointer_;
    }

    Pointer<Target_> &operator ++() {
        ++pointer_;
        return *this;
    }

    template <typename Value_>
    Value_ Swap(Value_ value) {
        return framework_->Swap(value);
    }
};

#define CSMAGIC_REQUIREMENT            uint32_t(0xfade0c00)
#define CSMAGIC_REQUIREMENTS           uint32_t(0xfade0c01)
#define CSMAGIC_CODEDIRECTORY          uint32_t(0xfade0c02)
#define CSMAGIC_EMBEDDED_SIGNATURE     uint32_t(0xfade0cc0)
#define CSMAGIC_EMBEDDED_SIGNATURE_OLD uint32_t(0xfade0b02)
#define CSMAGIC_EMBEDDED_ENTITLEMENTS  uint32_t(0xfade7171)
#define CSMAGIC_DETACHED_SIGNATURE     uint32_t(0xfade0cc1)
#define CSMAGIC_BLOBWRAPPER            uint32_t(0xfade0b01)

#define CSSLOT_CODEDIRECTORY uint32_t(0x00000)
#define CSSLOT_INFOSLOT      uint32_t(0x00001)
#define CSSLOT_REQUIREMENTS  uint32_t(0x00002)
#define CSSLOT_RESOURCEDIR   uint32_t(0x00003)
#define CSSLOT_APPLICATION   uint32_t(0x00004)
#define CSSLOT_ENTITLEMENTS  uint32_t(0x00005)

#define CSSLOT_SIGNATURESLOT uint32_t(0x10000)

#define CS_HASHTYPE_SHA1 1

struct BlobIndex {
    uint32_t type;
    uint32_t offset;
} _packed;

struct Blob {
    uint32_t magic;
    uint32_t length;
} _packed;

struct SuperBlob {
    struct Blob blob;
    uint32_t count;
    struct BlobIndex index[];
} _packed;

struct CodeDirectory {
    uint32_t version;
    uint32_t flags;
    uint32_t hashOffset;
    uint32_t identOffset;
    uint32_t nSpecialSlots;
    uint32_t nCodeSlots;
    uint32_t codeLimit;
    uint8_t hashSize;
    uint8_t hashType;
    uint8_t spare1;
    uint8_t pageSize;
    uint32_t spare2;
} _packed;

extern "C" uint32_t hash(uint8_t *k, uint32_t length, uint32_t initval);

static void sha1(uint8_t *hash, const void *data, size_t size) {
    SHA1(static_cast<const uint8_t *>(data), size, hash);
}

struct CodesignAllocation {
    FatMachHeader mach_header_;
    uint32_t offset_;
    uint32_t size_;
    uint32_t limit_;
    uint32_t alloc_;
    uint32_t align_;

    CodesignAllocation(FatMachHeader mach_header, size_t offset, size_t size, size_t limit, size_t alloc, size_t align) :
        mach_header_(mach_header),
        offset_(offset),
        size_(size),
        limit_(limit),
        alloc_(alloc),
        align_(align)
    {
    }
};

class File {
  private:
    int file_;

  public:
    File() :
        file_(-1)
    {
    }

    ~File() {
        if (file_ != -1)
            _syscall(close(file_));
    }

    void open(const char *path, int flags) {
        _assert(file_ == -1);
        file_ = _syscall(::open(path, flags));
    }

    int file() const {
        return file_;
    }
};

class Map {
  private:
    File file_;
    void *data_;
    size_t size_;

    void clear() {
        if (data_ == NULL)
            return;
        _syscall(munmap(data_, size_));
        data_ = NULL;
        size_ = 0;
    }

  public:
    Map() :
        data_(NULL),
        size_(0)
    {
    }

    Map(const std::string &path, int oflag, int pflag, int mflag) :
        Map()
    {
        open(path, oflag, pflag, mflag);
    }

    Map(const std::string &path, bool edit) :
        Map()
    {
        open(path, edit);
    }

    ~Map() {
        clear();
    }

    bool empty() const {
        return data_ == NULL;
    }

    void open(const std::string &path, int oflag, int pflag, int mflag) {
        clear();

        file_.open(path.c_str(), oflag);
        int file(file_.file());

        struct stat stat;
        _syscall(fstat(file, &stat));
        size_ = stat.st_size;

        data_ = _syscall(mmap(NULL, size_, pflag, mflag, file, 0));
    }

    void open(const std::string &path, bool edit) {
        if (edit)
            open(path, O_RDWR, PROT_READ | PROT_WRITE, MAP_SHARED);
        else
            open(path, O_RDONLY, PROT_READ, MAP_PRIVATE);
    }

    void *data() const {
        return data_;
    }

    size_t size() const {
        return size_;
    }

    operator std::string() const {
        return std::string(static_cast<char *>(data_), size_);
    }
};

namespace ldid {

static void Allocate(const void *idata, size_t isize, std::streambuf &output, const Functor<size_t (size_t)> &allocate, const Functor<size_t (std::streambuf &output, size_t, const std::string &, const char *)> &save) {
    FatHeader source(const_cast<void *>(idata), isize);

    size_t offset(0);
    if (source.IsFat())
        offset += sizeof(fat_header) + sizeof(fat_arch) * source.Swap(source->nfat_arch);

    std::vector<CodesignAllocation> allocations;
    _foreach (mach_header, source.GetMachHeaders()) {
        struct linkedit_data_command *signature(NULL);
        struct symtab_command *symtab(NULL);

        _foreach (load_command, mach_header.GetLoadCommands()) {
            uint32_t cmd(mach_header.Swap(load_command->cmd));
            if (false);
            else if (cmd == LC_CODE_SIGNATURE)
                signature = reinterpret_cast<struct linkedit_data_command *>(load_command);
            else if (cmd == LC_SYMTAB)
                symtab = reinterpret_cast<struct symtab_command *>(load_command);
        }

        size_t size;
        if (signature == NULL)
            size = mach_header.GetSize();
        else {
            size = mach_header.Swap(signature->dataoff);
            _assert(size <= mach_header.GetSize());
        }

        if (symtab != NULL) {
            auto end(mach_header.Swap(symtab->stroff) + mach_header.Swap(symtab->strsize));
            _assert(end <= size);
            _assert(end >= size - 0x10);
            size = end;
        }

        size_t alloc(allocate(size));

        auto *fat_arch(mach_header.GetFatArch());
        uint32_t align(fat_arch == NULL ? 0 : source.Swap(fat_arch->align));
        offset = Align(offset, 1 << align);

        uint32_t limit(size);
        if (alloc != 0)
            limit = Align(limit, 0x10);

        allocations.push_back(CodesignAllocation(mach_header, offset, size, limit, alloc, align));
        offset += size + alloc;
        offset = Align(offset, 0x10);
    }

    size_t position(0);

    if (source.IsFat()) {
        fat_header fat_header;
        fat_header.magic = Swap(FAT_MAGIC);
        fat_header.nfat_arch = Swap(uint32_t(allocations.size()));
        put(output, &fat_header, sizeof(fat_header));
        position += sizeof(fat_header);

        _foreach (allocation, allocations) {
            auto &mach_header(allocation.mach_header_);

            fat_arch fat_arch;
            fat_arch.cputype = Swap(mach_header->cputype);
            fat_arch.cpusubtype = Swap(mach_header->cpusubtype);
            fat_arch.offset = Swap(allocation.offset_);
            fat_arch.size = Swap(allocation.limit_ + allocation.alloc_);
            fat_arch.align = Swap(allocation.align_);
            put(output, &fat_arch, sizeof(fat_arch));
            position += sizeof(fat_arch);
        }
    }

    _foreach (allocation, allocations) {
        auto &mach_header(allocation.mach_header_);

        pad(output, allocation.offset_ - position);
        position = allocation.offset_;

        std::vector<std::string> commands;

        _foreach (load_command, mach_header.GetLoadCommands()) {
            std::string copy(reinterpret_cast<const char *>(load_command), load_command->cmdsize);

            switch (mach_header.Swap(load_command->cmd)) {
                case LC_CODE_SIGNATURE:
                    continue;
                break;

                case LC_SEGMENT: {
                    auto segment_command(reinterpret_cast<struct segment_command *>(&copy[0]));
                    if (strncmp(segment_command->segname, "__LINKEDIT", 16) != 0)
                        break;
                    size_t size(mach_header.Swap(allocation.limit_ + allocation.alloc_ - mach_header.Swap(segment_command->fileoff)));
                    segment_command->filesize = size;
                    segment_command->vmsize = Align(size, PageSize_);
                } break;

                case LC_SEGMENT_64: {
                    auto segment_command(reinterpret_cast<struct segment_command_64 *>(&copy[0]));
                    if (strncmp(segment_command->segname, "__LINKEDIT", 16) != 0)
                        break;
                    size_t size(mach_header.Swap(allocation.limit_ + allocation.alloc_ - mach_header.Swap(segment_command->fileoff)));
                    segment_command->filesize = size;
                    segment_command->vmsize = Align(size, PageSize_);
                } break;
            }

            commands.push_back(copy);
        }

        if (allocation.alloc_ != 0) {
            linkedit_data_command signature;
            signature.cmd = mach_header.Swap(LC_CODE_SIGNATURE);
            signature.cmdsize = mach_header.Swap(uint32_t(sizeof(signature)));
            signature.dataoff = mach_header.Swap(allocation.limit_);
            signature.datasize = mach_header.Swap(allocation.alloc_);
            commands.push_back(std::string(reinterpret_cast<const char *>(&signature), sizeof(signature)));
        }

        size_t begin(position);

        uint32_t after(0);
        _foreach(command, commands)
            after += command.size();

        std::stringbuf altern;

        struct mach_header header(*mach_header);
        header.ncmds = mach_header.Swap(uint32_t(commands.size()));
        header.sizeofcmds = mach_header.Swap(after);
        put(output, &header, sizeof(header));
        put(altern, &header, sizeof(header));
        position += sizeof(header);

        if (mach_header.Bits64()) {
            auto pad(mach_header.Swap(uint32_t(0)));
            put(output, &pad, sizeof(pad));
            put(altern, &pad, sizeof(pad));
            position += sizeof(pad);
        }

        _foreach(command, commands) {
            put(output, command.data(), command.size());
            put(altern, command.data(), command.size());
            position += command.size();
        }

        uint32_t before(mach_header.Swap(mach_header->sizeofcmds));
        if (before > after) {
            pad(output, before - after);
            pad(altern, before - after);
            position += before - after;
        }

        auto top(reinterpret_cast<char *>(mach_header.GetBase()));

        std::string overlap(altern.str());
        overlap.append(top + overlap.size(), Align(overlap.size(), 0x1000) - overlap.size());

        put(output, top + (position - begin), allocation.size_ - (position - begin));
        position = begin + allocation.size_;

        pad(output, allocation.limit_ - allocation.size_);
        position += allocation.limit_ - allocation.size_;

        size_t saved(save(output, allocation.limit_, overlap, top));
        if (allocation.alloc_ > saved)
            pad(output, allocation.alloc_ - saved);
        position += allocation.alloc_;
    }
}

}

typedef std::map<uint32_t, std::string> Blobs;

static void insert(Blobs &blobs, uint32_t slot, const std::stringbuf &buffer) {
    auto value(buffer.str());
    std::swap(blobs[slot], value);
}

static void insert(Blobs &blobs, uint32_t slot, uint32_t magic, const std::stringbuf &buffer) {
    auto value(buffer.str());
    Blob blob;
    blob.magic = Swap(magic);
    blob.length = Swap(uint32_t(sizeof(blob) + value.size()));
    value.insert(0, reinterpret_cast<char *>(&blob), sizeof(blob));
    std::swap(blobs[slot], value);
}

static size_t put(std::streambuf &output, uint32_t magic, const Blobs &blobs) {
    size_t total(0);
    _foreach (blob, blobs)
        total += blob.second.size();

    struct SuperBlob super;
    super.blob.magic = Swap(magic);
    super.blob.length = Swap(uint32_t(sizeof(SuperBlob) + blobs.size() * sizeof(BlobIndex) + total));
    super.count = Swap(uint32_t(blobs.size()));
    put(output, &super, sizeof(super));

    size_t offset(sizeof(SuperBlob) + sizeof(BlobIndex) * blobs.size());

    _foreach (blob, blobs) {
        BlobIndex index;
        index.type = Swap(blob.first);
        index.offset = Swap(uint32_t(offset));
        put(output, &index, sizeof(index));
        offset += blob.second.size();
    }

    _foreach (blob, blobs)
        put(output, blob.second.data(), blob.second.size());

    return offset;
}

class Buffer {
  private:
    BIO *bio_;

  public:
    Buffer(BIO *bio) :
        bio_(bio)
    {
        _assert(bio_ != NULL);
    }

    Buffer() :
        bio_(BIO_new(BIO_s_mem()))
    {
    }

    Buffer(const char *data, size_t size) :
        Buffer(BIO_new_mem_buf(const_cast<char *>(data), size))
    {
    }

    Buffer(const std::string &data) :
        Buffer(data.data(), data.size())
    {
    }

    Buffer(PKCS7 *pkcs) :
        Buffer()
    {
        _assert(i2d_PKCS7_bio(bio_, pkcs) != 0);
    }

    ~Buffer() {
        BIO_free_all(bio_);
    }

    operator BIO *() const {
        return bio_;
    }

    explicit operator std::string() const {
        char *data;
        auto size(BIO_get_mem_data(bio_, &data));
        return std::string(data, size);
    }
};

class Stuff {
  private:
    PKCS12 *value_;
    EVP_PKEY *key_;
    X509 *cert_;
    STACK_OF(X509) *ca_;

  public:
    Stuff(BIO *bio) :
        value_(d2i_PKCS12_bio(bio, NULL)),
        ca_(NULL)
    {
        _assert(value_ != NULL);
        _assert(PKCS12_parse(value_, "", &key_, &cert_, &ca_) != 0);
        _assert(key_ != NULL);
        _assert(cert_ != NULL);
    }

    Stuff(const std::string &data) :
        Stuff(Buffer(data))
    {
    }

    ~Stuff() {
        sk_X509_pop_free(ca_, X509_free);
        X509_free(cert_);
        EVP_PKEY_free(key_);
        PKCS12_free(value_);
    }

    operator PKCS12 *() const {
        return value_;
    }

    operator EVP_PKEY *() const {
        return key_;
    }

    operator X509 *() const {
        return cert_;
    }

    operator STACK_OF(X509) *() const {
        return ca_;
    }
};

class Signature {
  private:
    PKCS7 *value_;

  public:
    Signature(const Stuff &stuff, const Buffer &data) :
        value_(PKCS7_sign(stuff, stuff, stuff, data, PKCS7_BINARY | PKCS7_DETACHED))
    {
        _assert(value_ != NULL);
    }

    ~Signature() {
        PKCS7_free(value_);
    }

    operator PKCS7 *() const {
        return value_;
    }
};

static void Commit(const std::string &path, const std::string &temp) {
    struct stat info;
    _syscall(stat(path.c_str(), &info));
#ifndef __WIN32__
    _syscall(chown(temp.c_str(), info.st_uid, info.st_gid));
#endif
    _syscall(chmod(temp.c_str(), info.st_mode));
    _syscall(unlink(path.c_str()));
    _syscall(rename(temp.c_str(), path.c_str()));
}

namespace ldid {

void Sign(const void *idata, size_t isize, std::streambuf &output, const std::string &identifier, const std::string &entitlements, const std::string &key, const Slots &slots) {
    Allocate(idata, isize, output, fun([&](size_t size) -> size_t {
        size_t alloc(sizeof(struct SuperBlob));

        uint32_t special(0);

        special = std::max(special, CSSLOT_REQUIREMENTS);
        alloc += sizeof(struct BlobIndex);
        alloc += 0xc;

        if (!entitlements.empty()) {
            special = std::max(special, CSSLOT_ENTITLEMENTS);
            alloc += sizeof(struct BlobIndex);
            alloc += sizeof(struct Blob);
            alloc += entitlements.size();
        }

        special = std::max(special, CSSLOT_CODEDIRECTORY);
        alloc += sizeof(struct BlobIndex);
        alloc += sizeof(struct Blob);
        alloc += sizeof(struct CodeDirectory);
        alloc += identifier.size() + 1;

        if (!key.empty()) {
            alloc += sizeof(struct BlobIndex);
            alloc += sizeof(struct Blob);
            // XXX: this is just a "sufficiently large number"
            alloc += 0x3000;
        }

        _foreach (slot, slots)
            special = std::max(special, slot.first);

        uint32_t normal((size + PageSize_ - 1) / PageSize_);
        alloc = Align(alloc + (special + normal) * SHA_DIGEST_LENGTH, 16);
        return alloc;
    }), fun([&](std::streambuf &output, size_t limit, const std::string &overlap, const char *top) -> size_t {
        Blobs blobs;

        if (true) {
            std::stringbuf data;

            Blobs requirements;
            put(data, CSMAGIC_REQUIREMENTS, requirements);

            insert(blobs, CSSLOT_REQUIREMENTS, data);
        }

        if (!entitlements.empty()) {
            std::stringbuf data;
            put(data, entitlements.data(), entitlements.size());
            insert(blobs, CSSLOT_ENTITLEMENTS, CSMAGIC_EMBEDDED_ENTITLEMENTS, data);
        }

        if (true) {
            std::stringbuf data;

            uint32_t special(0);
            _foreach (blob, blobs)
                special = std::max(special, blob.first);
            _foreach (slot, slots)
                special = std::max(special, slot.first);
            uint32_t normal((limit + PageSize_ - 1) / PageSize_);

            CodeDirectory directory;
            directory.version = Swap(uint32_t(0x00020001));
            directory.flags = Swap(uint32_t(0));
            directory.hashOffset = Swap(uint32_t(sizeof(Blob) + sizeof(CodeDirectory) + identifier.size() + 1 + SHA_DIGEST_LENGTH * special));
            directory.identOffset = Swap(uint32_t(sizeof(Blob) + sizeof(CodeDirectory)));
            directory.nSpecialSlots = Swap(special);
            directory.codeLimit = Swap(uint32_t(limit));
            directory.nCodeSlots = Swap(normal);
            directory.hashSize = SHA_DIGEST_LENGTH;
            directory.hashType = CS_HASHTYPE_SHA1;
            directory.spare1 = 0x00;
            directory.pageSize = PageShift_;
            directory.spare2 = Swap(uint32_t(0));
            put(data, &directory, sizeof(directory));

            put(data, identifier.c_str(), identifier.size() + 1);

            uint8_t storage[special + normal][SHA_DIGEST_LENGTH];
            uint8_t (*hashes)[SHA_DIGEST_LENGTH] = storage + special;

            memset(storage, 0, sizeof(*storage) * special);

            _foreach (blob, blobs) {
                auto local(reinterpret_cast<const Blob *>(&blob.second[0]));
                sha1((uint8_t *) (hashes - blob.first), local, Swap(local->length));
            }

            _foreach (slot, slots) {
                _assert(sizeof(*hashes) == slot.second.size());
                memcpy(hashes - slot.first, slot.second.data(), slot.second.size());
            }

            if (normal != 1)
                for (size_t i = 0; i != normal - 1; ++i)
                    sha1(hashes[i], (PageSize_ * i < overlap.size() ? overlap.data() : top) + PageSize_ * i, PageSize_);
            if (normal != 0)
                sha1(hashes[normal - 1], top + PageSize_ * (normal - 1), ((limit - 1) % PageSize_) + 1);

            put(data, storage, sizeof(storage));

            insert(blobs, CSSLOT_CODEDIRECTORY, CSMAGIC_CODEDIRECTORY, data);
        }

        if (!key.empty()) {
            std::stringbuf data;
            const std::string &sign(blobs[CSSLOT_CODEDIRECTORY]);

            Stuff stuff(key);
            Buffer bio(sign);

            Signature signature(stuff, sign);
            Buffer result(signature);
            std::string value(result);
            put(data, value.data(), value.size());

            insert(blobs, CSSLOT_SIGNATURESLOT, CSMAGIC_BLOBWRAPPER, data);
        }

        return put(output, CSMAGIC_EMBEDDED_SIGNATURE, blobs);
    }));
}

static void Unsign(void *idata, size_t isize, std::streambuf &output) {
    Allocate(idata, isize, output, fun([](size_t size) -> size_t {
        return 0;
    }), fun([](std::streambuf &output, size_t limit, const std::string &overlap, const char *top) -> size_t {
        return 0;
    }));
}

}

int main(int argc, char *argv[]) {
    OpenSSL_add_all_algorithms();

    union {
        uint16_t word;
        uint8_t byte[2];
    } endian = {1};

    little_ = endian.byte[0];

    bool flag_r(false);
    bool flag_e(false);

    bool flag_T(false);

    bool flag_S(false);
    bool flag_s(false);

    bool flag_D(false);

    bool flag_A(false);
    bool flag_a(false);

    uint32_t flag_CPUType(_not(uint32_t));
    uint32_t flag_CPUSubtype(_not(uint32_t));

    const char *flag_I(NULL);

    bool timeh(false);
    uint32_t timev(0);

    Map entitlements;
    Map key;
    ldid::Slots slots;

    std::vector<std::string> files;

    if (argc == 1) {
        fprintf(stderr, "usage: %s -S[entitlements.xml] <binary>\n", argv[0]);
        fprintf(stderr, "   %s -e MobileSafari\n", argv[0]);
        fprintf(stderr, "   %s -S cat\n", argv[0]);
        fprintf(stderr, "   %s -Stfp.xml gdb\n", argv[0]);
        exit(0);
    }

    for (int argi(1); argi != argc; ++argi)
        if (argv[argi][0] != '-')
            files.push_back(argv[argi]);
        else switch (argv[argi][1]) {
            case 'r':
                _assert(!flag_s);
                _assert(!flag_S);
                flag_r = true;
            break;

            case 'e': flag_e = true; break;

            case 'E': {
                const char *slot = argv[argi] + 2;
                const char *colon = strchr(slot, ':');
                _assert(colon != NULL);
                Map file(colon + 1, O_RDONLY, PROT_READ, MAP_PRIVATE);
                char *arge;
                unsigned number(strtoul(slot, &arge, 0));
                _assert(arge == colon);
                std::string &hash(slots[number]);
                hash.resize(SHA_DIGEST_LENGTH);
                sha1(reinterpret_cast<uint8_t *>(&hash[0]), file.data(), file.size());
            } break;

            case 'D': flag_D = true; break;

            case 'a': flag_a = true; break;

            case 'A':
                _assert(!flag_A);
                flag_A = true;
                if (argv[argi][2] != '\0') {
                    const char *cpu = argv[argi] + 2;
                    const char *colon = strchr(cpu, ':');
                    _assert(colon != NULL);
                    char *arge;
                    flag_CPUType = strtoul(cpu, &arge, 0);
                    _assert(arge == colon);
                    flag_CPUSubtype = strtoul(colon + 1, &arge, 0);
                    _assert(arge == argv[argi] + strlen(argv[argi]));
                }
            break;

            case 's':
                _assert(!flag_r);
                _assert(!flag_S);
                flag_s = true;
            break;

            case 'S':
                _assert(!flag_r);
                _assert(!flag_s);
                flag_S = true;
                if (argv[argi][2] != '\0') {
                    const char *xml = argv[argi] + 2;
                    entitlements.open(xml, O_RDONLY, PROT_READ, MAP_PRIVATE);
                }
            break;

            case 'K':
                key.open(argv[argi] + 2, O_RDONLY, PROT_READ, MAP_PRIVATE);
            break;

            case 'T': {
                flag_T = true;
                if (argv[argi][2] == '-')
                    timeh = true;
                else {
                    char *arge;
                    timev = strtoul(argv[argi] + 2, &arge, 0);
                    _assert(arge == argv[argi] + strlen(argv[argi]));
                }
            } break;

            case 'I': {
                flag_I = argv[argi] + 2;
            } break;

            default:
                goto usage;
            break;
        }

    _assert(flag_S || key.empty());
    _assert(flag_S || flag_I == NULL);

    if (files.empty()) usage: {
        exit(0);
    }

    size_t filei(0), filee(0);
    _foreach (file, files) try {
        std::string path(file);

        if (flag_S || flag_r) {
            Map input(path, O_RDONLY, PROT_READ, MAP_PRIVATE);

            std::string dir;
            std::string base;

            size_t slash(path.rfind('/'));
            if (slash == std::string::npos)
                base = path;
            else {
                dir = path.substr(0, slash + 1);
                base = path.substr(slash + 1);
            }

            std::string temp(dir + "." + base + ".cs");
            std::filebuf output;
            _assert(output.open(temp.c_str(), std::ios::out | std::ios::trunc | std::ios::binary) == &output);

            if (flag_r)
                ldid::Unsign(input.data(), input.size(), output);
            else {
                std::string identifier(flag_I ?: base.c_str());
                ldid::Sign(input.data(), input.size(), output, identifier, entitlements, key, slots);
            }

            Commit(path, temp);
        }

        Map mapping(path, flag_T || flag_s);
        FatHeader fat_header(mapping.data(), mapping.size());

        _foreach (mach_header, fat_header.GetMachHeaders()) {
            struct linkedit_data_command *signature(NULL);
            struct encryption_info_command *encryption(NULL);

            if (flag_A) {
                if (mach_header.GetCPUType() != flag_CPUType)
                    continue;
                if (mach_header.GetCPUSubtype() != flag_CPUSubtype)
                    continue;
            }

            if (flag_a)
                printf("cpu=0x%x:0x%x\n", mach_header.GetCPUType(), mach_header.GetCPUSubtype());

            _foreach (load_command, mach_header.GetLoadCommands()) {
                uint32_t cmd(mach_header.Swap(load_command->cmd));

                if (false);
                else if (cmd == LC_CODE_SIGNATURE)
                    signature = reinterpret_cast<struct linkedit_data_command *>(load_command);
                else if (cmd == LC_ENCRYPTION_INFO || cmd == LC_ENCRYPTION_INFO_64)
                    encryption = reinterpret_cast<struct encryption_info_command *>(load_command);
                else if (cmd == LC_ID_DYLIB) {
                    volatile struct dylib_command *dylib_command(reinterpret_cast<struct dylib_command *>(load_command));

                    if (flag_T) {
                        uint32_t timed;

                        if (!timeh)
                            timed = timev;
                        else {
                            dylib_command->dylib.timestamp = 0;
                            timed = hash(reinterpret_cast<uint8_t *>(mach_header.GetBase()), mach_header.GetSize(), timev);
                        }

                        dylib_command->dylib.timestamp = mach_header.Swap(timed);
                    }
                }
            }

            if (flag_D) {
                _assert(encryption != NULL);
                encryption->cryptid = mach_header.Swap(0);
            }

            if (flag_e) {
                _assert(signature != NULL);

                uint32_t data = mach_header.Swap(signature->dataoff);

                uint8_t *top = reinterpret_cast<uint8_t *>(mach_header.GetBase());
                uint8_t *blob = top + data;
                struct SuperBlob *super = reinterpret_cast<struct SuperBlob *>(blob);

                for (size_t index(0); index != Swap(super->count); ++index)
                    if (Swap(super->index[index].type) == CSSLOT_ENTITLEMENTS) {
                        uint32_t begin = Swap(super->index[index].offset);
                        struct Blob *entitlements = reinterpret_cast<struct Blob *>(blob + begin);
                        fwrite(entitlements + 1, 1, Swap(entitlements->length) - sizeof(*entitlements), stdout);
                    }
            }

            if (flag_s) {
                _assert(signature != NULL);

                uint32_t data = mach_header.Swap(signature->dataoff);

                uint8_t *top = reinterpret_cast<uint8_t *>(mach_header.GetBase());
                uint8_t *blob = top + data;
                struct SuperBlob *super = reinterpret_cast<struct SuperBlob *>(blob);

                for (size_t index(0); index != Swap(super->count); ++index)
                    if (Swap(super->index[index].type) == CSSLOT_CODEDIRECTORY) {
                        uint32_t begin = Swap(super->index[index].offset);
                        struct CodeDirectory *directory = reinterpret_cast<struct CodeDirectory *>(blob + begin);

                        uint8_t (*hashes)[SHA_DIGEST_LENGTH] = reinterpret_cast<uint8_t (*)[SHA_DIGEST_LENGTH]>(blob + begin + Swap(directory->hashOffset));
                        uint32_t pages = Swap(directory->nCodeSlots);

                        if (pages != 1)
                            for (size_t i = 0; i != pages - 1; ++i)
                                sha1(hashes[i], top + PageSize_ * i, PageSize_);
                        if (pages != 0)
                            sha1(hashes[pages - 1], top + PageSize_ * (pages - 1), ((data - 1) % PageSize_) + 1);
                    }
            }
        }

        ++filei;
    } catch (const char *) {
        ++filee;
        ++filei;
    }

    return filee;
}