Elf2Mac: Clean up code and prepare for segments
This commit is contained in:
Wolfgang Thaller
parent
a6bc7b5de6
commit
6a3e6863c5
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@ -35,6 +35,8 @@
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#include <vector>
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#include <fstream>
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#include <iostream>
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#include <sstream>
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#include <memory>
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#include <boost/algorithm/string/predicate.hpp>
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@ -42,105 +44,184 @@ using std::string;
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using std::unordered_map;
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using std::vector;
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using std::ofstream;
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using std::shared_ptr;
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using std::make_shared;
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using std::unique_ptr;
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unordered_map<string, Elf_Scn*> codeSections;
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unordered_map<string, Elf_Scn*> relaSections;
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Elf_Scn* dataSection;
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Elf_Scn* bssSection;
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Elf_Scn *symtabSection;
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size_t sectionHeaderStringTableIdx;
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size_t mainStringTableIdx;
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void ElfToFlt(string input, string output)
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class Symtab;
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std::vector<int> relocs;
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unique_ptr<Symtab> symtab;
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class Symtab
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{
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public:
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Elf_Scn *elfsec;
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Elf_Data *data;
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Symtab(Elf_Scn *elfsec);
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GElf_Sym GetSym(int idx);
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};
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Symtab::Symtab(Elf_Scn *elfsec)
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: elfsec(elfsec)
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{
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data = elf_getdata(elfsec, NULL);
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}
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GElf_Sym Symtab::GetSym(int idx)
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{
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GElf_Sym sym;
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auto res = gelf_getsym(data, idx, &sym);
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assert(res != 0);
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return sym;
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}
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class Section
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{
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public:
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Elf_Scn *elfsec, *relasec;
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Elf_Data *data;
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Section(int idx, Elf_Scn *elfsec);
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void SetRela(Elf_Scn *scn);
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uint32_t GetSize();
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string GetData();
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string GetAbsRelocations();
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};
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Section::Section(int idx, Elf_Scn *elfsec)
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: elfsec(elfsec), relasec(NULL)
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{
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data = elf_getdata(elfsec, NULL);
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}
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void Section::SetRela(Elf_Scn *scn)
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{
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relasec = scn;
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}
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uint32_t Section::GetSize()
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{
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return data->d_size;
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}
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string Section::GetData()
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{
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return string((char*)data->d_buf, (char*)data->d_buf + data->d_size);
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}
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string Section::GetAbsRelocations()
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{
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if(!relasec)
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return "";
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std::ostringstream out;
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std::vector<int> relocs;
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GElf_Shdr shdr;
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gelf_getshdr(relasec, &shdr);
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int nRela = shdr.sh_size / shdr.sh_entsize;
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Elf_Data *data = elf_getdata(relasec, NULL);
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for(int i = 0; i < nRela; i++)
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{
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GElf_Rela rela;
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gelf_getrela(data, i, &rela);
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//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);
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int symidx = GELF_R_SYM(rela.r_info);
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if(symidx == 0)
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continue;
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GElf_Sym sym = symtab->GetSym(symidx);
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if(sym.st_shndx == SHN_UNDEF)
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continue;
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if(GELF_R_TYPE(rela.r_info) == R_68K_32)
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relocs.push_back(rela.r_offset);
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}
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std::sort(relocs.begin(), relocs.end());
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for(int reloc : relocs)
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longword(out, reloc);
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return out.str();
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}
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unordered_map<string, shared_ptr<Section>> sections;
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void GrokELF(string input)
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{
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std::cout << "************ ELF2FLT\n";
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if(elf_version ( EV_CURRENT ) == EV_NONE)
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errx(EXIT_FAILURE , "ELF library initialization failed: %s", elf_errmsg( -1));
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int fd = open(input.c_str(), O_RDONLY, 0);
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Elf *e = elf_begin(fd, ELF_C_READ, NULL);
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Elf *elf = elf_begin(fd, ELF_C_READ, NULL);
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size_t shstrndx;
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elf_getshdrstrndx(e, &shstrndx);
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elf_getshdrstrndx(elf, §ionHeaderStringTableIdx);
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GElf_Ehdr ehdr;
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gelf_getehdr(e, &ehdr);
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gelf_getehdr(elf, &ehdr);
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Elf_Scn *symtab = NULL;
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int nSyms;
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unordered_map<string, Elf_Scn*> progbits;
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for(Elf_Scn *scn = NULL; (scn = elf_nextscn(e, scn)) != NULL;)
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int idx = 0;
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for(Elf_Scn *scn = NULL; (scn = elf_nextscn(elf, scn)) != NULL;idx++)
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{
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GElf_Shdr shdr;
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gelf_getshdr(scn, &shdr);
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if(shdr.sh_type == SHT_SYMTAB)
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std::string name = elf_strptr(elf, sectionHeaderStringTableIdx, shdr.sh_name);
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//printf("section: %s\n", name.c_str());
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if(shdr.sh_type == SHT_SYMTAB
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&& !symtab)
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{
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symtab = scn;
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nSyms = shdr.sh_size / shdr.sh_entsize;
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break;
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symtab.reset(new Symtab(scn));
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}
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if(shdr.sh_type == SHT_STRTAB)
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{
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if(name == ".strtab")
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mainStringTableIdx = idx;
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}
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}
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Elf_Data *symtabData = elf_getdata(symtab, NULL);
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std::vector<int> relocs;
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for(Elf_Scn *scn = NULL; (scn = elf_nextscn(e, scn)) != NULL;)
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{
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GElf_Shdr shdr;
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gelf_getshdr(scn, &shdr);
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std::string name = elf_strptr(e, shstrndx, shdr.sh_name);
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printf("section: %s\n", name.c_str());
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if(shdr.sh_type == SHT_RELA
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&& !bssSection) // ignore everything after bss, that's just debug info
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{
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printf("(rela)\n");
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int nRela = shdr.sh_size / shdr.sh_entsize;
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Elf_Data *data = elf_getdata(scn, NULL);
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for(int i = 0; i < nRela; i++)
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{
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GElf_Rela rela;
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gelf_getrela(data, i, &rela);
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GElf_Sym sym;
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if(gelf_getsym(symtabData, GELF_R_SYM(rela.r_info),&sym) != 0)
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{
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if(sym.st_shndx == SHN_UNDEF)
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continue;
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}
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if(GELF_R_TYPE(rela.r_info) == R_68K_32)
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relocs.push_back(rela.r_offset);
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//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);
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}
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if(boost::algorithm::starts_with(name,".rela."))
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{
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relaSections[name.substr(5)] = scn;
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string progbitsName = name.substr(5);
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relaSections[progbitsName] = scn;
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assert(sections.find(progbitsName) != sections.end());
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sections[progbitsName]->SetRela(scn);
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}
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}
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if(shdr.sh_type == SHT_PROGBITS
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&& !bssSection) // ignore everything after bss, that's just debug info
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{
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codeSections[name] = scn;
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printf("(progbits)\n");
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sections.emplace(name, make_shared<Section>(idx, scn));
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}
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if(shdr.sh_type == SHT_NOBITS)
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{
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bssSection = scn;
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printf("(nobits)\n");
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}
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}
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}
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/*for(int i = 0; i < nSyms; i++)
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{
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GElf_Sym sym;
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if(gelf_getsym(symtabData, i, &sym) == 0)
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printf("computer says no.\n");
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printf("%s at %x\n", elf_strptr(e, shstrndx-1, sym.st_name), (unsigned) sym.st_value);
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}*/
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std::sort(relocs.begin(), relocs.end());
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void ElfToFlt(string input, string output)
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{
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GrokELF(input);
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GElf_Shdr text_shdr, data_shdr, bss_shdr;
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gelf_getshdr(codeSections[".text"], &text_shdr);
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@ -149,19 +230,12 @@ void ElfToFlt(string input, string output)
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ofstream out(output);
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Elf_Data *data = elf_getdata(codeSections[".text"], NULL);
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out << string((char*)data->d_buf, (char*)data->d_buf + data->d_size);
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out << sections[".text"]->GetData();
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out << sections[".data"]->GetData();
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while(out.tellp() < /*0x40 + */data_shdr.sh_addr)
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byte(out, 0x00);
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data = elf_getdata(codeSections[".data"], NULL);
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out << string((char*)data->d_buf, (char*)data->d_buf + data->d_size);
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while(out.tellp() < /*0x40 +*/ bss_shdr.sh_addr)
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byte(out, 0x00);
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for(int reloc : relocs)
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longword(out, reloc);
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longword(out, -1); // not part of the FLT specification: terminate reloc list
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out << sections[".text"]->GetAbsRelocations();
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out << sections[".data"]->GetAbsRelocations();
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longword(out, -1);
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}
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string argvZero;
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@ -276,3 +350,5 @@ int main(int argc, char *argv[])
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}
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return 0;
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}
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@ -61,6 +61,10 @@ SECTIONS
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KEEP(*(.eh_frame))
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KEEP(*(.gcc_except_table))
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KEEP(*(.gcc_except_table.*))
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/* NOTE: Elf2Mac expects the sections to be contiguous,
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so include the alignment before the end of this section.
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*/
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. = ALIGN(0x4) ;
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_etext = . ;
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}
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