[apple/ld64.git] / src / other / rebase.cpp

/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*- 
 *
 * Copyright (c) 2006-2008 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <mach/mach.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <vector>
#include <set>


#include "MachOFileAbstraction.hpp"
#include "Architectures.hpp"

static bool verbose = false;

__attribute__((noreturn))
void throwf(const char* format, ...) 
{
        va_list list;
        char*   p;
        va_start(list, format);
        vasprintf(&p, format, list);
        va_end(list);
        
        const char*     t = p;
        throw t;
}


class AbstractRebaser
{
public:
        virtual cpu_type_t                                                      getArchitecture() const = 0;
        virtual uint64_t                                                        getBaseAddress() const = 0;
        virtual uint64_t                                                        getVMSize() const = 0;
        virtual void                                                            setBaseAddress(uint64_t) = 0;
};


template <typename A>
class Rebaser : public AbstractRebaser
{
public:
                                                                                                Rebaser(const void* machHeader);
        virtual                                                                         ~Rebaser() {}

        virtual cpu_type_t                                                      getArchitecture() const;
        virtual uint64_t                                                        getBaseAddress() const;
        virtual uint64_t                                                        getVMSize() const;
        virtual void                                                            setBaseAddress(uint64_t);

private:
        typedef typename A::P                                   P;
        typedef typename A::P::E                                E;
        typedef typename A::P::uint_t                   pint_t;
        
        struct vmmap { pint_t vmaddr; pint_t vmsize; pint_t fileoff; };
        
        void                                                                            setRelocBase();
        void                                                                            buildSectionTable();
        void                                                                            adjustLoadCommands();
        void                                                                            adjustSymbolTable();
        void                                                                            adjustDATA();
        void                                                                            doLocalRelocation(const macho_relocation_info<P>* reloc);
        pint_t*                                                                         mappedAddressForVMAddress(uint32_t vmaddress);
        void                                                                            rebaseAt(int segIndex, uint64_t offset, uint8_t type);
        
        const macho_header<P>*                                          fHeader;
        pint_t                                                                          fOrignalVMRelocBaseAddress;
        pint_t                                                                          fSlide;
        std::vector<vmmap>                                                      fVMMApping;
};



class MultiArchRebaser
{
public:
                                                                                                MultiArchRebaser(const char* path, bool writable=false);
                                                                                                ~MultiArchRebaser();

        const std::vector<AbstractRebaser*>&            getArchs() const { return fRebasers; }
        void                                                                            commit();

private:
        std::vector<AbstractRebaser*>                           fRebasers;
        void*                                                                           fMappingAddress;
        uint64_t                                                                        fFileSize;
};



MultiArchRebaser::MultiArchRebaser(const char* path, bool writable)
 : fMappingAddress(0), fFileSize(0)
{
        // map in whole file
        int fd = ::open(path, (writable ? O_RDWR : O_RDONLY), 0);
        if ( fd == -1 )
                throwf("can't open file %s, errno=%d", path, errno);
        struct stat stat_buf;
        if ( fstat(fd, &stat_buf) == -1)
                throwf("can't stat open file %s, errno=%d", path, errno);
        if ( stat_buf.st_size < 20 )
                throwf("file too small %s", path);
        const int prot = writable ? (PROT_READ | PROT_WRITE) : PROT_READ;
        const int flags = writable ? (MAP_FILE | MAP_SHARED) : (MAP_FILE | MAP_PRIVATE);
        uint8_t* p = (uint8_t*)::mmap(NULL, stat_buf.st_size, prot, flags, fd, 0);
        if ( p == (uint8_t*)(-1) )
                throwf("can't map file %s, errno=%d", path, errno);
        ::close(fd);

        // if fat file, process each architecture
        const fat_header* fh = (fat_header*)p;
        const mach_header* mh = (mach_header*)p;
        if ( fh->magic == OSSwapBigToHostInt32(FAT_MAGIC) ) {
                // Fat header is always big-endian
                const struct fat_arch* archs = (struct fat_arch*)(p + sizeof(struct fat_header));
                for (unsigned long i=0; i < OSSwapBigToHostInt32(fh->nfat_arch); ++i) {
                        uint32_t fileOffset = OSSwapBigToHostInt32(archs[i].offset);
                        try {
                                switch ( OSSwapBigToHostInt32(archs[i].cputype) ) {
                                        case CPU_TYPE_POWERPC:
                                                fRebasers.push_back(new Rebaser<ppc>(&p[fileOffset]));
                                                break;
                                        case CPU_TYPE_POWERPC64:
                                                fRebasers.push_back(new Rebaser<ppc64>(&p[fileOffset]));
                                                break;
                                        case CPU_TYPE_I386:
                                                fRebasers.push_back(new Rebaser<x86>(&p[fileOffset]));
                                                break;
                                        case CPU_TYPE_X86_64:
                                                fRebasers.push_back(new Rebaser<x86_64>(&p[fileOffset]));
                                                break;
                                        case CPU_TYPE_ARM:
                                                fRebasers.push_back(new Rebaser<arm>(&p[fileOffset]));
                                                break;
                                        default:
                                                throw "unknown file format";
                                }
                        }
                        catch (const char* msg) {
                                fprintf(stderr, "rebase warning: %s for %s\n", msg, path);
                        }
                }
        }
        else {
                try {
                        if ( (OSSwapBigToHostInt32(mh->magic) == MH_MAGIC) && (OSSwapBigToHostInt32(mh->cputype) == CPU_TYPE_POWERPC)) {
                                fRebasers.push_back(new Rebaser<ppc>(mh));
                        }
                        else if ( (OSSwapBigToHostInt32(mh->magic) == MH_MAGIC_64) && (OSSwapBigToHostInt32(mh->cputype) == CPU_TYPE_POWERPC64)) {
                                fRebasers.push_back(new Rebaser<ppc64>(mh));
                        }
                        else if ( (OSSwapLittleToHostInt32(mh->magic) == MH_MAGIC) && (OSSwapLittleToHostInt32(mh->cputype) == CPU_TYPE_I386)) {
                                fRebasers.push_back(new Rebaser<x86>(mh));
                        }
                        else if ( (OSSwapLittleToHostInt32(mh->magic) == MH_MAGIC_64) && (OSSwapLittleToHostInt32(mh->cputype) == CPU_TYPE_X86_64)) {
                                fRebasers.push_back(new Rebaser<x86_64>(mh));
                        }
                        else if ( (OSSwapLittleToHostInt32(mh->magic) == MH_MAGIC) && (OSSwapLittleToHostInt32(mh->cputype) == CPU_TYPE_ARM)) {
                                fRebasers.push_back(new Rebaser<arm>(mh));
                        }
                        else {
                                throw "unknown file format";
                        }
                }
                catch (const char* msg) {
                        fprintf(stderr, "rebase warning: %s for %s\n", msg, path);
                }
        }
        
        fMappingAddress = p;
        fFileSize = stat_buf.st_size;
}


MultiArchRebaser::~MultiArchRebaser()
{
        ::munmap(fMappingAddress, fFileSize);
}

void MultiArchRebaser::commit()
{
        ::msync(fMappingAddress, fFileSize, MS_ASYNC); 
}



template <typename A>
Rebaser<A>::Rebaser(const void* machHeader)
 :      fHeader((const macho_header<P>*)machHeader)
{
        switch ( fHeader->filetype() ) {
                case MH_DYLIB:
                        if ( (fHeader->flags() & MH_SPLIT_SEGS) != 0 )
                                throw "split-seg dylibs cannot be rebased";
                        break;
                case MH_BUNDLE:
                        break;
                default:
                        throw "file is not a dylib or bundle";
        }
                
}

template <> cpu_type_t Rebaser<ppc>::getArchitecture()    const { return CPU_TYPE_POWERPC; }
template <> cpu_type_t Rebaser<ppc64>::getArchitecture()  const { return CPU_TYPE_POWERPC64; }
template <> cpu_type_t Rebaser<x86>::getArchitecture()    const { return CPU_TYPE_I386; }
template <> cpu_type_t Rebaser<x86_64>::getArchitecture() const { return CPU_TYPE_X86_64; }
template <> cpu_type_t Rebaser<arm>::getArchitecture() const { return CPU_TYPE_ARM; }

template <typename A>
uint64_t Rebaser<A>::getBaseAddress() const
{
        uint64_t lowestSegmentAddress = LLONG_MAX;
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
                        const macho_segment_command<P>* segCmd = (const macho_segment_command<P>*)cmd;
                        if ( segCmd->vmaddr() < lowestSegmentAddress ) {
                                lowestSegmentAddress = segCmd->vmaddr();
                        }
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }
        return lowestSegmentAddress;
}

template <typename A>
uint64_t Rebaser<A>::getVMSize() const
{
        const macho_segment_command<P>* highestSegmentCmd = NULL; 
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
                        const macho_segment_command<P>* segCmd = (const macho_segment_command<P>*)cmd;
                        if ( (highestSegmentCmd == NULL) || (segCmd->vmaddr() > highestSegmentCmd->vmaddr()) ) {
                                highestSegmentCmd = segCmd;
                        }
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }
        
        return ((highestSegmentCmd->vmaddr() + highestSegmentCmd->vmsize() - this->getBaseAddress() + 4095) & (-4096));
}


template <typename A>
void Rebaser<A>::setBaseAddress(uint64_t addr)
{
        // calculate slide
        fSlide = addr - this->getBaseAddress();
        
        // compute base address for relocations
        this->setRelocBase();
        
        // build cache of section index to section 
        this->buildSectionTable();
                
        // update load commands
        this->adjustLoadCommands();
        
        // update symbol table  
        this->adjustSymbolTable();
        
        // update writable segments that have internal pointers
        this->adjustDATA();
}

template <typename A>
void Rebaser<A>::adjustLoadCommands()
{
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                switch ( cmd->cmd() ) {
                        case LC_ID_DYLIB:
                                if ( (fHeader->flags() & MH_PREBOUND) != 0 ) {
                                        // clear timestamp so that any prebound clients are invalidated
                                        macho_dylib_command<P>* dylib  = (macho_dylib_command<P>*)cmd;
                                        dylib->set_timestamp(1);
                                }
                                break;
                        case LC_LOAD_DYLIB:
                        case LC_LOAD_WEAK_DYLIB:
                        case LC_REEXPORT_DYLIB:
                        case LC_LOAD_UPWARD_DYLIB:
                                if ( (fHeader->flags() & MH_PREBOUND) != 0 ) {
                                        // clear expected timestamps so that this image will load with invalid prebinding 
                                        macho_dylib_command<P>* dylib  = (macho_dylib_command<P>*)cmd;
                                        dylib->set_timestamp(2);
                                }
                                break;
                        case macho_routines_command<P>::CMD:
                                // update -init command
                                {
                                        macho_routines_command<P>* routines = (macho_routines_command<P>*)cmd;
                                        routines->set_init_address(routines->init_address() + fSlide);
                                }
                                break;
                        case macho_segment_command<P>::CMD:
                                // update segment commands
                                {
                                        macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
                                        seg->set_vmaddr(seg->vmaddr() + fSlide);
                                        macho_section<P>* const sectionsStart = (macho_section<P>*)((char*)seg + sizeof(macho_segment_command<P>));
                                        macho_section<P>* const sectionsEnd = &sectionsStart[seg->nsects()];
                                        for(macho_section<P>* sect = sectionsStart; sect < sectionsEnd; ++sect) {
                                                sect->set_addr(sect->addr() + fSlide);
                                        }
                                }
                                break;
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }
}


template <typename A>
void Rebaser<A>::buildSectionTable()
{
        // build vector of sections
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
                        const macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
                        vmmap mapping;
                        mapping.vmaddr = seg->vmaddr();
                        mapping.vmsize = seg->vmsize();
                        mapping.fileoff = seg->fileoff();
                        fVMMApping.push_back(mapping);
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }       
}


template <typename A>
void Rebaser<A>::adjustSymbolTable()
{
        const macho_dysymtab_command<P>* dysymtab = NULL;
        macho_nlist<P>* symbolTable = NULL;
        const char* strings = NULL;

        // get symbol table info
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                switch (cmd->cmd()) {
                        case LC_SYMTAB:
                                {
                                        const macho_symtab_command<P>* symtab = (macho_symtab_command<P>*)cmd;
                                        symbolTable = (macho_nlist<P>*)(((uint8_t*)fHeader) + symtab->symoff());
                                        strings = (char*)(((uint8_t*)fHeader) + symtab->stroff());
                }    
                                break;
                        case LC_DYSYMTAB:
                                dysymtab = (macho_dysymtab_command<P>*)cmd;
                                break;
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }       

        // walk all exports and slide their n_value
        macho_nlist<P>* lastExport = &symbolTable[dysymtab->iextdefsym()+dysymtab->nextdefsym()];
        for (macho_nlist<P>* entry = &symbolTable[dysymtab->iextdefsym()]; entry < lastExport; ++entry) {
                if ( (entry->n_type() & N_TYPE) == N_SECT )
                        entry->set_n_value(entry->n_value() + fSlide);
        }

        // walk all local symbols and slide their n_value
        macho_nlist<P>* lastLocal = &symbolTable[dysymtab->ilocalsym()+dysymtab->nlocalsym()];
        for (macho_nlist<P>* entry = &symbolTable[dysymtab->ilocalsym()]; entry < lastLocal; ++entry) {
                if ( ((entry->n_type() & N_STAB) == 0) && ((entry->n_type() & N_TYPE) == N_SECT) ) {
                        entry->set_n_value(entry->n_value() + fSlide);
                }
                else if ( entry->n_type() & N_STAB ) {
                        // some stabs need to be slid too
                        switch ( entry->n_type() ) {
                                case N_FUN:
                                        // don't slide end-of-function FUN which is FUN with no string
                                        if ( (entry->n_strx() == 0) || (strings[entry->n_strx()] == '\0') )
                                                break;
                                case N_BNSYM:
                                case N_STSYM:
                                case N_LCSYM:
                                        entry->set_n_value(entry->n_value() + fSlide);
                                        break;
                        }
                }
        }
        
        // FIXME ¥¥¥ adjust dylib_module if it exists
}

static uint64_t read_uleb128(const uint8_t*& p, const uint8_t* end)
{
        uint64_t result = 0;
        int              bit = 0;
        do {
                if (p == end)
                        throwf("malformed uleb128");

                uint64_t slice = *p & 0x7f;

                if (bit >= 64 || slice << bit >> bit != slice)
                        throwf("uleb128 too big");
                else {
                        result |= (slice << bit);
                        bit += 7;
                }
        } 
        while (*p++ & 0x80);
        return result;
}

template <typename A>
void Rebaser<A>::rebaseAt(int segIndex, uint64_t offset, uint8_t type)
{
        //fprintf(stderr, "rebaseAt(seg=%d, offset=0x%08llX, type=%d\n", segIndex, offset, type);
        static int lastSegIndex = -1;
        static uint8_t* lastSegMappedStart = NULL;
        if ( segIndex != lastSegIndex ) {
                const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
                const uint32_t cmd_count = fHeader->ncmds();
                const macho_load_command<P>* cmd = cmds;
                int segCount = 0;
                for (uint32_t i = 0; i < cmd_count; ++i) {
                        if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
                                if ( segIndex == segCount ) {
                                        const macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
                                        lastSegMappedStart = (uint8_t*)fHeader + seg->fileoff();
                                        lastSegIndex = segCount;
                                        break;
                                }
                                ++segCount;
                        }
                        cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
                }       
        }
        
        pint_t* locationToFix = (pint_t*)(lastSegMappedStart+offset);
        uint32_t* locationToFix32 = (uint32_t*)(lastSegMappedStart+offset);
        switch (type) {
                case REBASE_TYPE_POINTER:
                        P::setP(*locationToFix, A::P::getP(*locationToFix) + fSlide);
                        break;
                case REBASE_TYPE_TEXT_ABSOLUTE32:
                        E::set32(*locationToFix32, E::get32(*locationToFix32) + fSlide);
                        break;
                default:
                        throwf("bad rebase type %d", type);
        }
}


template <typename A>
void Rebaser<A>::adjustDATA()
{
        const macho_dysymtab_command<P>* dysymtab = NULL;
        const macho_dyld_info_command<P>* dyldInfo = NULL;

        // get symbol table info
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                switch (cmd->cmd()) {
                        case LC_DYSYMTAB:
                                dysymtab = (macho_dysymtab_command<P>*)cmd;
                                break;
                        case LC_DYLD_INFO:
                        case LC_DYLD_INFO_ONLY:
                                dyldInfo = (macho_dyld_info_command<P>*)cmd;
                                break;
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }       

        // use new encoding of rebase info if present
        if ( dyldInfo != NULL ) {
                if ( dyldInfo->rebase_size() != 0 ) {
                        const uint8_t* p = (uint8_t*)fHeader + dyldInfo->rebase_off();
                        const uint8_t* end = &p[dyldInfo->rebase_size()];
                        
                        uint8_t type = 0;
                        uint64_t offset = 0;
                        uint32_t count;
                        uint32_t skip;
                        int segIndex;
                        bool done = false;
                        while ( !done && (p < end) ) {
                                uint8_t immediate = *p & REBASE_IMMEDIATE_MASK;
                                uint8_t opcode = *p & REBASE_OPCODE_MASK;
                                ++p;
                                switch (opcode) {
                                        case REBASE_OPCODE_DONE:
                                                done = true;
                                                break;
                                        case REBASE_OPCODE_SET_TYPE_IMM:
                                                type = immediate;
                                                break;
                                        case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
                                                segIndex = immediate;
                                                offset = read_uleb128(p, end);
                                                break;
                                        case REBASE_OPCODE_ADD_ADDR_ULEB:
                                                offset += read_uleb128(p, end);
                                                break;
                                        case REBASE_OPCODE_ADD_ADDR_IMM_SCALED:
                                                offset += immediate*sizeof(pint_t);
                                                break;
                                        case REBASE_OPCODE_DO_REBASE_IMM_TIMES:
                                                for (int i=0; i < immediate; ++i) {
                                                        rebaseAt(segIndex, offset, type);
                                                        offset += sizeof(pint_t);
                                                }
                                                break;
                                        case REBASE_OPCODE_DO_REBASE_ULEB_TIMES:
                                                count = read_uleb128(p, end);
                                                for (uint32_t i=0; i < count; ++i) {
                                                        rebaseAt(segIndex, offset, type);
                                                        offset += sizeof(pint_t);
                                                }
                                                break;
                                        case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB:
                                                rebaseAt(segIndex, offset, type);
                                                offset += read_uleb128(p, end) + sizeof(pint_t);
                                                break;
                                        case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB:
                                                count = read_uleb128(p, end);
                                                skip = read_uleb128(p, end);
                                                for (uint32_t i=0; i < count; ++i) {
                                                        rebaseAt(segIndex, offset, type);
                                                        offset += skip + sizeof(pint_t);
                                                }
                                                break;
                                        default:
                                                throwf("bad rebase opcode %d", *p);
                                }
                        }       
                                
                
                
                }
        }
        else {
                // walk all local relocations and slide every pointer
                const macho_relocation_info<P>* const relocsStart = (macho_relocation_info<P>*)(((uint8_t*)fHeader) + dysymtab->locreloff());
                const macho_relocation_info<P>* const relocsEnd = &relocsStart[dysymtab->nlocrel()];
                for (const macho_relocation_info<P>* reloc=relocsStart; reloc < relocsEnd; ++reloc) {
                        this->doLocalRelocation(reloc);
                }
                
                // walk non-lazy-pointers and slide the ones that are LOCAL
                cmd = cmds;
                for (uint32_t i = 0; i < cmd_count; ++i) {
                        if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
                                const macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
                                const macho_section<P>* const sectionsStart = (macho_section<P>*)((char*)seg + sizeof(macho_segment_command<P>));
                                const macho_section<P>* const sectionsEnd = &sectionsStart[seg->nsects()];
                                const uint32_t* const indirectTable = (uint32_t*)(((uint8_t*)fHeader) + dysymtab->indirectsymoff());
                                for(const macho_section<P>* sect = sectionsStart; sect < sectionsEnd; ++sect) {
                                        if ( (sect->flags() & SECTION_TYPE) == S_NON_LAZY_SYMBOL_POINTERS ) {
                                                const uint32_t indirectTableOffset = sect->reserved1();
                                                uint32_t pointerCount = sect->size() / sizeof(pint_t);
                                                pint_t* nonLazyPointer = (pint_t*)(((uint8_t*)fHeader) + sect->offset());
                                                for (uint32_t i=0; i < pointerCount; ++i, ++nonLazyPointer) {
                                                        if ( E::get32(indirectTable[indirectTableOffset + i]) == INDIRECT_SYMBOL_LOCAL ) {
                                                                P::setP(*nonLazyPointer, A::P::getP(*nonLazyPointer) + fSlide);
                                                        }
                                                }
                                        }
                                }
                        }
                        cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
                }       
        }
}


template <typename A>
typename A::P::uint_t* Rebaser<A>::mappedAddressForVMAddress(uint32_t vmaddress)
{
        for(typename std::vector<vmmap>::iterator it = fVMMApping.begin(); it != fVMMApping.end(); ++it) {
                //fprintf(stderr, "vmaddr=0x%08lX, vmsize=0x%08lX\n", it->vmaddr, it->vmsize);
                if ( (vmaddress >= it->vmaddr) && (vmaddress < (it->vmaddr+it->vmsize)) ) {
                        return (pint_t*)((vmaddress - it->vmaddr) + it->fileoff + (uint8_t*)fHeader);
                }
        }
        throwf("reloc address 0x%08X not found", vmaddress);
}


template <>
void Rebaser<x86_64>::doLocalRelocation(const macho_relocation_info<x86_64::P>* reloc)
{
        if ( reloc->r_type() == X86_64_RELOC_UNSIGNED ) {
                pint_t* addr = mappedAddressForVMAddress(reloc->r_address() + fOrignalVMRelocBaseAddress);
                P::setP(*addr, P::getP(*addr) + fSlide);
        }
        else {
                throw "invalid relocation type";
        }
}

template <>
void Rebaser<ppc>::doLocalRelocation(const macho_relocation_info<P>* reloc)
{
        if ( (reloc->r_address() & R_SCATTERED) == 0 ) {
                if ( reloc->r_type() == GENERIC_RELOC_VANILLA ) {
                        pint_t* addr = mappedAddressForVMAddress(reloc->r_address() + fOrignalVMRelocBaseAddress);
                        P::setP(*addr, P::getP(*addr) + fSlide);
                }
        }
        else {
                throw "cannot rebase final linked image with scattered relocations";
        }
}

template <>
void Rebaser<x86>::doLocalRelocation(const macho_relocation_info<P>* reloc)
{
        if ( (reloc->r_address() & R_SCATTERED) == 0 ) {
                if ( reloc->r_type() == GENERIC_RELOC_VANILLA ) {
                        pint_t* addr = mappedAddressForVMAddress(reloc->r_address() + fOrignalVMRelocBaseAddress);
                        P::setP(*addr, P::getP(*addr) + fSlide);
                }
        }
        else {
                macho_scattered_relocation_info<P>* sreloc = (macho_scattered_relocation_info<P>*)reloc;
                if ( sreloc->r_type() == GENERIC_RELOC_PB_LA_PTR ) {
                        sreloc->set_r_value( sreloc->r_value() + fSlide );
                }
                else {
                        throw "cannot rebase final linked image with scattered relocations";
                }
        }
}

#if SUPPORT_ARCH_arm_any
template <>
void Rebaser<arm>::doLocalRelocation(const macho_relocation_info<P>* reloc)
{
        if ( (reloc->r_address() & R_SCATTERED) == 0 ) {
                if ( reloc->r_type() == ARM_RELOC_VANILLA ) {
                        pint_t* addr = mappedAddressForVMAddress(reloc->r_address() + fOrignalVMRelocBaseAddress);
                        P::setP(*addr, P::getP(*addr) + fSlide);
                }
        }
        else {
                macho_scattered_relocation_info<P>* sreloc = (macho_scattered_relocation_info<P>*)reloc;
                if ( sreloc->r_type() == ARM_RELOC_PB_LA_PTR ) {
                        sreloc->set_r_value( sreloc->r_value() + fSlide );
                }
                else {
                        throw "cannot rebase final linked image with scattered relocations";
                }
        }
}
#endif

template <typename A>
void Rebaser<A>::doLocalRelocation(const macho_relocation_info<P>* reloc)
{
        if ( (reloc->r_address() & R_SCATTERED) == 0 ) {
                if ( reloc->r_type() == GENERIC_RELOC_VANILLA ) {
                        pint_t* addr = mappedAddressForVMAddress(reloc->r_address() + fOrignalVMRelocBaseAddress);
                        P::setP(*addr, P::getP(*addr) + fSlide);
                }
        }
        else {
                throw "cannot rebase final linked image with scattered relocations";
        }
}


template <typename A>
void Rebaser<A>::setRelocBase()
{
        // reloc addresses are from the start of the mapped file (base address)
        fOrignalVMRelocBaseAddress = this->getBaseAddress();
        //fprintf(stderr, "fOrignalVMRelocBaseAddress=0x%08X\n", fOrignalVMRelocBaseAddress);
}

template <>
void Rebaser<ppc64>::setRelocBase()
{
        // reloc addresses either:
        // 1) from the base address if no writable segment is > 4GB from base address
        // 2) from start of first writable segment
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
                        const macho_segment_command<P>* segCmd = (const macho_segment_command<P>*)cmd;
                        if ( segCmd->initprot() & VM_PROT_WRITE ) {
                                if ( (segCmd->vmaddr() + segCmd->vmsize() - this->getBaseAddress()) > 0x100000000ULL ) {
                                        // found writable segment with address > 4GB past base address
                                        fOrignalVMRelocBaseAddress = segCmd->vmaddr();
                                        return;
                                }
                        }
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }
        // just use base address
        fOrignalVMRelocBaseAddress = this->getBaseAddress();
}

template <>
void Rebaser<x86_64>::setRelocBase()
{
        // reloc addresses are always based from the start of the first writable segment
        const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
        const uint32_t cmd_count = fHeader->ncmds();
        const macho_load_command<P>* cmd = cmds;
        for (uint32_t i = 0; i < cmd_count; ++i) {
                if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
                        const macho_segment_command<P>* segCmd = (const macho_segment_command<P>*)cmd;
                        if ( segCmd->initprot() & VM_PROT_WRITE ) {
                                fOrignalVMRelocBaseAddress = segCmd->vmaddr();
                                return;
                        }
                }
                cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
        }
        throw "no writable segment";
}


static void copyFile(const char* srcFile, const char* dstFile)
{
        // open files 
        int src = open(srcFile, O_RDONLY);      
        if ( src == -1 )
                throwf("can't open file %s, errno=%d", srcFile, errno);
        struct stat stat_buf;
        if ( fstat(src, &stat_buf) == -1)
                throwf("can't stat open file %s, errno=%d", srcFile, errno);
                
        // create new file with all same permissions to hold copy of dylib 
        ::unlink(dstFile);
        int dst = open(dstFile, O_CREAT | O_RDWR | O_TRUNC, stat_buf.st_mode);  
        if ( dst == -1 )
                throwf("can't create temp file %s, errnor=%d", dstFile, errno);

        // mark source as "don't cache"
        (void)fcntl(src, F_NOCACHE, 1);
        // we want to cache the dst because we are about to map it in and modify it
        
        // copy permission bits
        if ( chmod(dstFile, stat_buf.st_mode & 07777) == -1 )
                throwf("can't chmod temp file %s, errno=%d", dstFile, errno);
        if ( chown(dstFile, stat_buf.st_uid, stat_buf.st_gid) == -1)
                throwf("can't chown temp file %s, errno=%d", dstFile, errno);
                  
        // copy contents
        ssize_t len;
        const uint32_t kBufferSize = 128*1024;
        static uint8_t* buffer = NULL;
        if ( buffer == NULL ) {
                vm_address_t addr = 0;
                if ( vm_allocate(mach_task_self(), &addr, kBufferSize, true /*find range*/) == KERN_SUCCESS )
                        buffer = (uint8_t*)addr;
                else
                        throw "can't allcoate copy buffer";
        }
        while ( (len = read(src, buffer, kBufferSize)) > 0 ) {
                if ( write(dst, buffer, len) == -1 )
                        throwf("write failure copying feil %s, errno=%d", dstFile, errno);
        }
                
        // close files 
        int result1 = close(dst);
        int result2 = close(src);
        if ( (result1 != 0) || (result2 != 0) )
                throw "can't close file";
}


// scan dylibs and collect size info
// calculate new base address for each dylib
// rebase each file
//              copy to temp and mmap
//              update content
//              unmap/flush
//              rename

struct archInfo {
        cpu_type_t      arch;
        uint64_t        vmSize;
        uint64_t        orgBase;
        uint64_t        newBase;
};

struct fileInfo
{
        fileInfo(const char* p) : path(p) {}
        
        const char*                             path;
        std::vector<archInfo>   archs;
};

//
// add archInfos to fileInfo for every slice of a fat file
// for ppc, there may be duplicate architectures (with different sub-types)
//
static void setSizes(fileInfo& info, const std::set<cpu_type_t>& onlyArchs)
{
        const MultiArchRebaser mar(info.path);
        const std::vector<AbstractRebaser*>&    rebasers = mar.getArchs();
        for(std::set<cpu_type_t>::iterator ait=onlyArchs.begin(); ait != onlyArchs.end(); ++ait) {
                for(std::vector<AbstractRebaser*>::const_iterator rit=rebasers.begin(); rit != rebasers.end(); ++rit) {
                        AbstractRebaser* rebaser = *rit;
                        if ( rebaser->getArchitecture() == *ait ) {
                                archInfo ai;
                                ai.arch = *ait;
                                ai.vmSize = rebaser->getVMSize();
                                ai.orgBase = rebaser->getBaseAddress();
                                ai.newBase = 0;
                                //fprintf(stderr, "base=0x%llX, size=0x%llX\n", ai.orgBase, ai.vmSize);
                                info.archs.push_back(ai);
                        }
                }
        }
}

static const char* nameForArch(cpu_type_t arch)
{
        switch( arch ) {
                case CPU_TYPE_POWERPC:
                        return "ppc";
                case CPU_TYPE_POWERPC64:
                        return "ppca64";
                case CPU_TYPE_I386:
                        return "i386";
                case CPU_TYPE_X86_64:
                        return "x86_64";
                case CPU_TYPE_ARM:
                        return "arm";
        }
        return "unknown";
}

static void rebase(const fileInfo& info)
{
        // generate temp file name
        char realFilePath[PATH_MAX];
        if ( realpath(info.path, realFilePath) == NULL ) {
                throwf("realpath() failed on %s, errno=%d", info.path, errno);
        }
        const char* tempPath;
        asprintf((char**)&tempPath, "%s_rebase", realFilePath);

        // copy whole file to temp file 
        copyFile(info.path, tempPath);
        
        try {
                // rebase temp file
                MultiArchRebaser mar(tempPath, true);
                const std::vector<AbstractRebaser*>&    rebasers = mar.getArchs();
                for(std::vector<archInfo>::const_iterator fait=info.archs.begin(); fait != info.archs.end(); ++fait) {
                        for(std::vector<AbstractRebaser*>::const_iterator rit=rebasers.begin(); rit != rebasers.end(); ++rit) {
                                if ( (*rit)->getArchitecture() == fait->arch ) {
                                        (*rit)->setBaseAddress(fait->newBase);
                                        if ( verbose )
                                                printf("%8s 0x%0llX -> 0x%0llX  %s\n", nameForArch(fait->arch), fait->orgBase, fait->newBase, info.path);
                                }
                        }       
                }
                
                // flush temp file out to disk
                mar.commit();
                
                // rename
                int result = rename(tempPath, info.path);
                if ( result != 0 ) {
                        throwf("can't swap temporary rebased file: rename(%s,%s) returned errno=%d", tempPath, info.path, errno);
                }
                
                // make sure every really gets out to disk
                ::sync();
        }
        catch (const char* msg) {
                // delete temp file
                ::unlink(tempPath);
                
                // throw exception with file name added
                const char* newMsg;
                asprintf((char**)&newMsg, "%s for file %s", msg, info.path);
                throw newMsg;
        }
}

static uint64_t totalVMSize(cpu_type_t arch, std::vector<fileInfo>& files)
{
        uint64_t totalSize = 0;
        for(std::vector<fileInfo>::iterator fit=files.begin(); fit != files.end(); ++fit) {
                fileInfo& fi = *fit;
                for(std::vector<archInfo>::iterator fait=fi.archs.begin(); fait != fi.archs.end(); ++fait) {
                        if ( fait->arch == arch )
                                totalSize += fait->vmSize;
                }
        }       
        return totalSize;
}

static uint64_t startAddress(cpu_type_t arch, std::vector<fileInfo>& files, uint64_t lowAddress, uint64_t highAddress)
{
        if ( lowAddress != 0 ) 
                return lowAddress;
        else if ( highAddress != 0 ) {
                uint64_t totalSize = totalVMSize(arch, files);
                if ( highAddress < totalSize )
                        throwf("cannot use -high_address 0x%X because total size of images is greater: 0x%X", highAddress, totalSize);
                return highAddress - totalSize;
        }
        else {
                if ( (arch == CPU_TYPE_I386) || (arch == CPU_TYPE_POWERPC) ) {
                        // place dylibs below dyld
                        uint64_t topAddr = 0x8FE00000;
                        uint64_t totalSize = totalVMSize(arch, files);
                        if ( totalSize > topAddr )
                                throwf("total size of images (0x%X) does not fit below 0x8FE00000", totalSize);
                        return topAddr - totalSize;
                }
                else if ( arch == CPU_TYPE_POWERPC64 ) {
                        return 0x200000000ULL;
                }
                else if ( arch == CPU_TYPE_X86_64 ) {
                        return 0x200000000ULL;
                }
                else if ( arch == CPU_TYPE_ARM ) {
                        // place dylibs below dyld
                        uint64_t topAddr = 0x2FE00000;
                        uint64_t totalSize = totalVMSize(arch, files);
                        if ( totalSize > topAddr )
                                throwf("total size of images (0x%X) does not fit below 0x2FE00000", totalSize);
                        return topAddr - totalSize;
                }
                else
                        throw "unknown architecture";
        }
}

static void usage()
{
        fprintf(stderr, "rebase [-low_address] [-high_address] [-v] [-arch <arch>] files...\n");
}


int main(int argc, const char* argv[])
{
        std::vector<fileInfo> files;
        std::set<cpu_type_t> onlyArchs;
        uint64_t lowAddress = 0;
        uint64_t highAddress = 0;

        try {
                // parse command line options
                char* endptr;
                for(int i=1; i < argc; ++i) {
                        const char* arg = argv[i];
                        if ( arg[0] == '-' ) {
                                if ( strcmp(arg, "-v") == 0 ) {
                                        verbose = true;
                                }
                                else if ( strcmp(arg, "-low_address") == 0 ) {
                                        lowAddress = strtoull(argv[++i], &endptr, 16);
                                }
                                else if ( strcmp(arg, "-high_address") == 0 ) {
                                        highAddress = strtoull(argv[++i], &endptr, 16);
                                }
                                else if ( strcmp(arg, "-arch") == 0 ) {
                                        const char* archName = argv[++i];
                                        if ( archName == NULL )
                                                throw "-arch missing architecture name";
                                        bool found = false;
                                        for (const ArchInfo* t=archInfoArray; t->archName != NULL; ++t) {
                                                if ( strcmp(t->archName,archName) == 0 ) {
                                                        onlyArchs.insert(t->cpuType);
                                                        found = true;
                                                }
                                        }
                                        if ( !found )
                                                throwf("unknown architecture %s", archName);
                                }
                                else {
                                        usage();
                                        throwf("unknown option: %s\n", arg);
                                }
                        }
                        else {
                                files.push_back(fileInfo(arg));
                        }
                }
                
                if ( files.size() == 0 )
                        throw "no files specified";
                
                // use all architectures if no restrictions specified
                if ( onlyArchs.size() == 0 ) {
                        onlyArchs.insert(CPU_TYPE_POWERPC);
                        onlyArchs.insert(CPU_TYPE_POWERPC64);
                        onlyArchs.insert(CPU_TYPE_I386);
                        onlyArchs.insert(CPU_TYPE_X86_64);
                        onlyArchs.insert(CPU_TYPE_ARM);
                }
                
                // scan files and collect sizes
                for(std::vector<fileInfo>::iterator it=files.begin(); it != files.end(); ++it) {
                        setSizes(*it, onlyArchs);
                }
                                
                // assign new base address for each arch
                for(std::set<cpu_type_t>::iterator ait=onlyArchs.begin(); ait != onlyArchs.end(); ++ait) {
                        cpu_type_t arch = *ait;
                        uint64_t baseAddress = startAddress(arch, files, lowAddress, highAddress);
                        for(std::vector<fileInfo>::iterator fit=files.begin(); fit != files.end(); ++fit) {
                                fileInfo& fi = *fit;
                                for(std::vector<archInfo>::iterator fait=fi.archs.begin(); fait != fi.archs.end(); ++fait) {
                                        if ( fait->arch == arch ) {
                                                fait->newBase = baseAddress;
                                                baseAddress += fait->vmSize; 
                                                baseAddress = (baseAddress + 4095) & (-4096);  // page align
                                        }
                                }
                        }
                }
                
                // rebase each file if it contains something rebaseable
                for(std::vector<fileInfo>::iterator it=files.begin(); it != files.end(); ++it) {
                        fileInfo& fi = *it;
                        if ( fi.archs.size() > 0 )
                                rebase(fi);
                }
                
        }
        catch (const char* msg) {
                fprintf(stderr, "rebase failed: %s\n", msg);
                return 1;
        }
        
        return 0;
}