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Retro68/Elf2Mac/Elf2Mac.cc

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/*
Copyright 2017 Wolfgang Thaller.
This file is part of Retro68.
Retro68 is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Retro68 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with Retro68. If not, see <http://www.gnu.org/licenses/>.
*/
#include "Elf2Mac.h"
#include "ResourceFork.h"
#include "BinaryIO.h"
#include "ResourceFile.h"
#include <gelf.h>
#include <err.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string>
#include <unordered_map>
#include <map>
#include <vector>
#include <fstream>
#include <iostream>
#include <sstream>
#include <memory>
#include <boost/algorithm/string/predicate.hpp>
using std::string;
using std::unordered_map;
using std::map;
using std::vector;
using std::ofstream;
using std::shared_ptr;
using std::make_shared;
using std::unique_ptr;
using std::pair;
using std::make_pair;
size_t sectionHeaderStringTableIdx;
size_t mainStringTableIdx = (size_t)-1;
class Symtab;
class Section;
Elf *elf;
std::vector<int> relocs;
unique_ptr<Symtab> symtab;
unordered_map<string, shared_ptr<Section>> sections;
unordered_map<int, shared_ptr<Section>> sectionsByElfIndex;
std::vector<shared_ptr<Section>> codeSections;
shared_ptr<Section> dataSection, bssSection;
enum class SectionKind
{
undefined = -1,
code = 0,
data,
bss
};
enum class RelocBase
{
code = 0,
data,
bss,
jumptable,
code1
};
class Symbol : public GElf_Sym
{
public:
bool valid;
bool referencedExternally;
SectionKind sectionKind;
bool needsJT;
int jtIndex;
shared_ptr<Section> section;
Symbol();
Symbol(const GElf_Sym& sym);
string GetName();
};
class Symtab
{
public:
Elf_Scn *elfsec;
Elf_Data *data;
vector<Symbol> symbols;
map<pair<int,uint32_t>, int> symbolsByAddress;
Symtab(Elf_Scn *elfsec);
Symbol& GetSym(int idx);
int FindSym(int secidx, uint32_t addr);
};
class Reloc : public GElf_Rela
{
public:
RelocBase relocBase;
Reloc();
Reloc(const GElf_Rela& rela);
};
class Section
{
public:
string name;
int idx;
SectionKind kind;
Elf_Scn *elfsec, *relasec;
Elf_Data *data;
GElf_Shdr shdr;
uint32_t outputBase;
int codeID;
std::vector<Reloc> relocs;
std::vector<Symbol*> jtEntries;
int firstJTEntryIndex;
Section(string name, int idx, SectionKind kind, Elf_Scn *elfsec);
void SetRela(Elf_Scn *scn);
uint32_t GetSize();
string GetData();
string GetAbsRelocations(bool useOffsets, bool suppressTerminatingEntry = false);
void ScanRelocs();
void FixRelocs();
};
Symbol::Symbol()
: valid(false)
{
}
Symbol::Symbol(const GElf_Sym &sym)
: GElf_Sym(sym), valid(true),
referencedExternally(false),
sectionKind(SectionKind::undefined),
needsJT(false)
{
if(st_shndx != SHN_UNDEF && st_shndx < SHN_LORESERVE)
{
section = sectionsByElfIndex[st_shndx];
sectionKind = section->kind;
}
}
string Symbol::GetName()
{
return elf_strptr(elf, mainStringTableIdx, st_name);
}
Symtab::Symtab(Elf_Scn *elfsec)
: elfsec(elfsec)
{
data = elf_getdata(elfsec, NULL);
GElf_Shdr shdr;
gelf_getshdr(elfsec, &shdr);
int count = shdr.sh_size / shdr.sh_entsize;
symbols.reserve(count);
for(int i = 0; i < count; i++)
{
GElf_Sym sym;
auto res = gelf_getsym(data, i, &sym);
assert(res != 0);
symbols.emplace_back(sym);
if(sym.st_shndx != SHN_UNDEF && sym.st_shndx < SHN_LORESERVE)
symbolsByAddress[make_pair((int)sym.st_shndx,sym.st_value)] = i;
}
}
Symbol &Symtab::GetSym(int idx)
{
return symbols[idx];
}
int Symtab::FindSym(int secidx, uint32_t addr)
{
auto p = symbolsByAddress.find(make_pair(secidx, addr));
if(p != symbolsByAddress.end())
return p->second;
else
return -1;
}
Reloc::Reloc()
{
}
Reloc::Reloc(const GElf_Rela &rela)
: GElf_Rela(rela)
{
}
Section::Section(string name, int idx, SectionKind kind, Elf_Scn *elfsec)
: name(name), idx(idx), kind(kind), elfsec(elfsec), relasec(NULL),
codeID(-1), firstJTEntryIndex(0)
{
data = elf_getdata(elfsec, NULL);
gelf_getshdr(elfsec, &shdr);
outputBase = shdr.sh_addr;
}
void Section::SetRela(Elf_Scn *scn)
{
relasec = scn;
GElf_Shdr shdr;
gelf_getshdr(relasec, &shdr);
int nRela = shdr.sh_size / shdr.sh_entsize;
Elf_Data *data = elf_getdata(relasec, NULL);
for(int i = 0; i < nRela; i++)
{
GElf_Rela rela;
gelf_getrela(data, i, &rela);
relocs.push_back(rela);
}
std::sort(relocs.begin(), relocs.end(),
[](GElf_Rela& a, GElf_Rela& b) { return a.r_offset < b.r_offset; });
}
uint32_t Section::GetSize()
{
return data->d_size;
}
string Section::GetData()
{
return string((char*)data->d_buf, (char*)data->d_buf + data->d_size);
}
string Section::GetAbsRelocations(bool useOffsets, bool suppressTerminatingEntry)
{
std::ostringstream out;
for(auto& rela : relocs)
{
//printf("rel: %d %d %x %x\n", (int)GELF_R_TYPE(rela.r_info), (int)GELF_R_SYM(rela.r_info), (unsigned)rela.r_addend, (unsigned)rela.r_offset);
int symidx = GELF_R_SYM(rela.r_info);
if(symidx == 0)
continue;
Symbol& sym = symtab->GetSym(symidx);
if(sym.st_shndx == SHN_UNDEF || sym.st_shndx >= SHN_LORESERVE)
continue;
if(sym.sectionKind == SectionKind::undefined)
continue;
if(GELF_R_TYPE(rela.r_info) == R_68K_32)
{
assert(sym.sectionKind != SectionKind::undefined);
uint32_t offset = rela.r_offset;
if(useOffsets)
offset -= shdr.sh_addr;
std::cout << "RELA: " << std::hex << offset << " " << (int)rela.relocBase << std::dec << std::endl;
longword(out, offset | ((int)rela.relocBase << 24));
}
}
if(!suppressTerminatingEntry)
longword(out, -1);
return out.str();
}
void Section::ScanRelocs()
{
for(Reloc& rela : relocs)
{
int symidx = GELF_R_SYM(rela.r_info);
if(symidx == 0)
continue;
Symbol *sym = &symtab->GetSym(symidx);
if(sym->st_shndx == SHN_UNDEF)
continue;
if(rela.r_addend != 0)
{
int symidx2 = symtab->FindSym(sym->st_shndx, sym->st_value + rela.r_addend);
if(symidx2 != -1)
{
sym = &symtab->GetSym(symidx2);
rela.r_addend = 0;
rela.r_info = GELF_R_INFO(symidx2, GELF_R_TYPE(rela.r_info));
}
}
if(sym->st_shndx != idx)
sym->referencedExternally = true;
}
}
void Section::FixRelocs()
{
//bool first_reloc = true;
for(Reloc& rela : relocs)
{
if(GELF_R_TYPE(rela.r_info) != R_68K_32)
continue;
int symidx = GELF_R_SYM(rela.r_info);
if(symidx == 0)
continue;
Symbol& sym = symtab->GetSym(symidx);
if(sym.sectionKind == SectionKind::undefined)
continue;
RelocBase relocBase;
switch(sym.sectionKind)
{
case SectionKind::code:
relocBase = RelocBase::code;
if(sym.needsJT)
{
if(rela.r_addend == 0)
{
relocBase = RelocBase::jumptable;
}
else
{
if(sym.section.get() != this)
{
std::cerr << "Invalid ref from "
<< name << ":" << std::hex << rela.r_offset-shdr.sh_addr << std::dec
<< " to " << sym.section->name
<< "(" << sym.GetName() << ")"
<< "+" << rela.r_offset << std::endl;
}
assert(sym.section.get() == this);
}
}
else
assert(sym.section.get() == this);
break;
case SectionKind::data:
relocBase = RelocBase::data;
break;
case SectionKind::bss:
relocBase = RelocBase::bss;
break;
}
rela.relocBase = relocBase;
uint8_t *relocand = ((uint8_t*) data->d_buf + rela.r_offset - shdr.sh_addr);
/*if(first_reloc)
{
std::cout << "sec kind: " << (int)sym.sectionKind << std::endl;
std::cout << "reloc addr:" << rela.r_offset << std::endl;
}*/
if(relocBase == RelocBase::jumptable)
{
uint32_t dst = 0x20 + sym.jtIndex * 8 + 2;
relocand[0] = dst >> 24;
relocand[1] = dst >> 16;
relocand[2] = dst >> 8;
relocand[3] = dst;
}
else
{
uint32_t orig = (relocand[0] << 24) | (relocand[1] << 16) | (relocand[2] << 8) | relocand[3];
uint32_t dst = orig + sym.section->outputBase - sym.section->shdr.sh_addr;
relocand[0] = dst >> 24;
relocand[1] = dst >> 16;
relocand[2] = dst >> 8;
relocand[3] = dst;
}
}
}
void GrokELF(string input)
{
if(elf_version ( EV_CURRENT ) == EV_NONE)
errx(EXIT_FAILURE , "ELF library initialization failed: %s", elf_errmsg( -1));
int fd = open(input.c_str(), O_RDONLY, 0);
elf = elf_begin(fd, ELF_C_READ, NULL);
elf_getshdrstrndx(elf, &sectionHeaderStringTableIdx);
GElf_Ehdr ehdr;
gelf_getehdr(elf, &ehdr);
int idx = 1;
for(Elf_Scn *scn = NULL; (scn = elf_nextscn(elf, scn)) != NULL; idx++)
{
GElf_Shdr shdr;
gelf_getshdr(scn, &shdr);
std::string name = elf_strptr(elf, sectionHeaderStringTableIdx, shdr.sh_name);
//std::cout << "section #" << idx << ": " << name << std::endl;
if(shdr.sh_type == SHT_SYMTAB
&& !symtab)
{
symtab.reset(new Symtab(scn));
}
if(shdr.sh_type == SHT_STRTAB)
{
if(name == ".strtab")
mainStringTableIdx = idx;
}
if(shdr.sh_type == SHT_RELA
&& !bssSection) // ignore everything after bss, that's just debug info
{
if(boost::algorithm::starts_with(name,".rela."))
{
string progbitsName = name.substr(5);
assert(sections.find(progbitsName) != sections.end());
sections[progbitsName]->SetRela(scn);
}
}
if(shdr.sh_type == SHT_PROGBITS
&& !bssSection) // ignore everything after bss, that's just debug info
{
SectionKind kind = name == ".data" ? SectionKind::data : SectionKind::code;
auto section = make_shared<Section>(name, idx, kind, scn);
sections[name] = sectionsByElfIndex[idx] = section;
if(kind == SectionKind::data)
dataSection = section;
else if(kind == SectionKind::code)
codeSections.push_back(section);
}
if(shdr.sh_type == SHT_NOBITS)
{
// Currently, the bss section is used
// to know when to start skipping debug info sections.
// (What's the official way to distinguish a debug info section from a "real" section?)
bssSection = sections[name] = sectionsByElfIndex[idx] =
make_shared<Section>(name, idx, SectionKind::bss, scn);
}
}
std::sort(codeSections.begin(), codeSections.end(),
[](shared_ptr<Section> a, shared_ptr<Section> b) { return a->name < b->name; });
}
void FlatCode(std::ostream& out)
{
for(auto sec : codeSections)
out << sec->GetData();
out << dataSection->GetData();
for(auto sec : codeSections)
out << sec->GetAbsRelocations(false, true);
out << dataSection->GetAbsRelocations(false);
}
void FlatCode(string fn)
{
ofstream out(fn);
FlatCode(out);
}
std::string fromhex(std::string hex)
{
std::string bin;
int nibble;
bool haveNibble = false;
for(std::string::iterator p = hex.begin(); p != hex.end(); ++p)
{
if(std::isspace(*p))
continue;
assert(isdigit(*p) || (tolower(*p) >= 'a' && tolower(*p) <= 'f'));
int digit;
if(isdigit(*p))
digit = *p - '0';
else
digit = tolower(*p) - 'a' + 0xA;
if(haveNibble)
{
bin += (char) ((nibble << 4) | digit);
haveNibble = false;
}
else
{
nibble = digit;
haveNibble = true;
}
}
return bin;
}
void SingleSegmentApp(string output)
{
ResourceFile file(output);
Resources& rsrc = file.resources;
rsrc.addResource(Resource(ResType("CODE"), 0,
fromhex(
"00000028 00000000 00000008 00000020"
"0000 3F3C 0001 A9F0"
)
));
{
std::ostringstream code1;
word(code1, 0);
word(code1, 1);
FlatCode(code1);
rsrc.addResource(Resource(ResType("CODE"), 1,
code1.str()));
}
file.creator = ResType("????");
file.type = ResType("APPL");
file.write();
}
void MultiSegmentApp(string output)
{
ResourceFile file(output);
Resources& rsrc = file.resources;
for(auto namedSec : sections)
{
namedSec.second->ScanRelocs();
}
int jtEntryCount = 0;
unordered_map<int, vector<Symbol*>> jtEntries;
for(Symbol& sym : symtab->symbols)
{
if(sym.valid)
{
if(sym.referencedExternally && sym.sectionKind == SectionKind::code)
{
sym.needsJT = true;
sym.jtIndex = -1;
sym.section->jtEntries.push_back(&sym);
++jtEntryCount;
}
}
}
uint32_t data_and_bss_size = dataSection->shdr.sh_size + bssSection->shdr.sh_size;
{
std::ostringstream code0;
longword(code0, 0x20 + 8 * (jtEntryCount+2));
longword(code0, data_and_bss_size);
longword(code0, 8 * (jtEntryCount+2));
longword(code0, 0x20);
code0 << fromhex("0000 3F3C 0001 A9F0"); // jt entry for entrypoint
code0 << fromhex("0000 FFFF 0000 0000"); // 32-bit entries start from here
int jtIndex = 2;
int id = 1;
for(auto sec : codeSections)
{
sec->codeID = id;
sec->firstJTEntryIndex = jtIndex;
GElf_Shdr &shdr = sec->shdr;
for(Symbol* jtEntry : sec->jtEntries)
{
word(code0, id);
word(code0, 0xA9F0);
uint32_t offset = jtEntry->st_value - shdr.sh_addr;
if(id == 1)
offset += 4;
else
offset += 40;
longword(code0, offset);
jtEntry->jtIndex = jtIndex++;
//std::cout << "JT Entry " << jtEntry->jtIndex << ": " << jtEntry->GetName() << std::endl;
}
id++;
}
std::cout << "CODE 0: " << code0.str().size() << " bytes\n";
std::cout << "above A5: " << 0x20 + 8 * (jtEntryCount+2) << " bytes\n";
std::cout << "below A5: " << data_and_bss_size << " bytes\n";
std::cout << ".data: " << dataSection->shdr.sh_size << " bytes at A5-"
<< std::hex << data_and_bss_size << std::dec << "\n";
std::cout << ".bss: " << bssSection->shdr.sh_size << " bytes at A5-"
<< std::hex << bssSection->shdr.sh_size << std::dec << "\n";
rsrc.addResource(Resource(ResType("CODE"), 0, code0.str()));
}
for(auto sec : codeSections)
{
int id = sec->codeID;
if(id == 1)
sec->outputBase = 4; // standard 'CODE' header
else
sec->outputBase = 40; // far-model 'CODE' header
}
dataSection->outputBase = -data_and_bss_size;
bssSection->outputBase = -bssSection->shdr.sh_size;
for(auto namedSec : sections)
{
namedSec.second->FixRelocs();
}
for(auto sec : codeSections)
{
int id = sec->codeID;
std::ostringstream code;
if(id == 1)
{
word(code, 0);
word(code, 1);
}
else
{
word(code, 0xFFFF);
word(code, 0);
longword(code, 0);
longword(code, 0);
longword(code, 8 * sec->firstJTEntryIndex );
longword(code, sec->jtEntries.size());
longword(code, 0); // reloc info for A5
longword(code, 0); // assumed address for A5
longword(code, 0); // reloc info for code
longword(code, 0); // assumed address for start of code resource
longword(code, 0);
}
code << sec->GetData();
std::cout << "CODE " << id << ": " << code.str().size() << " bytes\n";
rsrc.addResource(Resource(ResType("CODE"), id,
code.str()));
rsrc.addResource(Resource(ResType("RELA"),id, sec->GetAbsRelocations(true)));
}
rsrc.addResource(Resource(ResType("DATA"),0, dataSection->GetData()));
rsrc.addResource(Resource(ResType("RELA"),0, dataSection->GetAbsRelocations(true)));
std::cout << "DATA 0: " << dataSection->shdr.sh_size << " bytes\n";
file.creator = ResType("????");
file.type = ResType("APPL");
file.write();
}
string argvZero;
void RealLD(vector<string> args)
{
vector<const char*> argv;
string realLD = argvZero + ".real";
argv.push_back(realLD.c_str());
for(string& s : args)
argv.push_back(s.c_str());
argv.push_back(NULL);
pid_t pid = fork();
if(pid < 0)
{
perror("unable to fork");
exit(-1);
}
else if(pid == 0)
{
execvp(argv[0], const_cast<char* const *> (argv.data()));
perror("exec failed");
exit(-1);
}
else
{
int wstatus;
int result = 0;
do
{
result = waitpid(pid, &wstatus, 0);
} while(result == -1 && errno == EINTR);
if(!WIFEXITED(wstatus))
{
errx(EXIT_FAILURE, "ld process did not exit properly");
}
else
{
int exitcode = WEXITSTATUS(wstatus);
if(exitcode)
exit(exitcode);
}
}
}
int main(int argc, char *argv[])
{
vector<string> args;
std::copy(argv + 1, argv+argc, std::back_inserter(args));
argvZero = argv[0];
if(boost::algorithm::ends_with(argv[0], "ld"))
{
string outputFile = "a.out";
bool elf2mac = false;
bool flatoutput = false;
bool segments = true;
vector<string> args2;
for(auto p = args.begin(), e = args.end(); p != e; ++p)
{
if(*p == "-o")
{
++p;
if(p == e)
errx(EXIT_FAILURE, "-o missing argument");
outputFile = *p;
}
else if(boost::algorithm::starts_with(*p, "-o"))
{
outputFile = (*p).substr(2);
}
else if(*p == "-elf2mac")
{
elf2mac = true;
}
else if(*p == "--mac-flat")
{
elf2mac = true;
flatoutput = true;
}
else if(*p == "--mac-segments")
{
elf2mac = true;
if(flatoutput)
errx(EXIT_FAILURE, "--mac-segments can't be used with --mac-flat");
++p;
if(p == e)
errx(EXIT_FAILURE, "--mac-segments missing argument");
//segmentMapFile = *p;
}
else
{
args2.push_back(*p);
}
}
if(elf2mac)
{
char tmpfile[] = "/tmp/ldscriptXXXXXX";
int fd = mkstemp(tmpfile);
if(fd < 0)
errx(EXIT_FAILURE, "can't create temp file");
{
ofstream out(tmpfile);
CreateLdScript(out, segments);
CreateLdScript(std::cout, segments);
}
args2.push_back("-o");
args2.push_back(outputFile + ".gdb");
args2.push_back("-T");
args2.push_back(tmpfile);
RealLD(args2);
unlink(tmpfile);
GrokELF(outputFile + ".gdb");
if(flatoutput)
FlatCode(outputFile);
else if(segments)
MultiSegmentApp(outputFile);
else
SingleSegmentApp(outputFile);
}
else
{
RealLD(args);
}
return 0;
}
else
{
if(argc != 2)
errx(EXIT_FAILURE, "usage : %s file-name ", argv[0]);
GrokELF(argv[1]);
MultiSegmentApp("out.bin");
}
return 0;
}
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