/**************************** elf2mac.cpp *********************************
* Author: Agner Fog
* Date created: 2007-01-10
* Last modified: 2012-05-05
* Project: objconv
* Module: elf2mac.cpp
* Description:
* Module for converting ELF file to Mach-O file
*
* Copyright 2007-2012 GNU General Public License http://www.gnu.org/licenses
*****************************************************************************/
#include "stdafx.h"
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::CELF2MAC() {
// Constructor
memset(this, 0, sizeof(*this)); // Reset everything
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::Convert() {
// Do the conversion
// Some compilers require this-> for accessing members of template base class,
// according to the so-called two-phase lookup rule.
// Call the subfunctions
ToFile.SetFileType(FILETYPE_MACHO_LE); // Set type of new file
MakeFileHeader(); // Make file header
MakeSectionsIndex(); // Make sections index translation table
FindUnusedSymbols(); // Check if symbols used, remove unused symbols
MakeSymbolTable(); // Make symbol table and string tables
MakeSections(); // Make sections and relocation tables
MakeBinaryFile(); // Put sections together
*this << ToFile; // Take over new file buffer
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::MakeFileHeader() {
// Convert subfunction: Make file header and load segment command
TMAC_header NewHeader; // new file header
NewHeader.magic = (this->WordSize == 32) ? MAC_MAGIC_32 : MAC_MAGIC_64; // Mach magic number identifier
NewHeader.cputype = (this->WordSize == 32) ? MAC_CPU_TYPE_I386 : MAC_CPU_TYPE_X86_64;
NewHeader.cpusubtype = MAC_CPU_SUBTYPE_I386_ALL;
NewHeader.filetype = MAC_OBJECT;
NewHeader.ncmds = 3; // Three commands = segment, symbol table, dynsymtab
NewHeader.sizeofcmds = 0; // Set this later
NewHeader.flags = 0; // No flags needed
// put file header in OutFile
ToFile.Push(&NewHeader, sizeof(NewHeader));
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::MakeSectionsIndex() {
// Make sections index translation table and section offset table.
// We must make these tables before the sections, because they are needed for the
// symbol tables and relocation tables, and we must make the symbol tables before
// the relocation tables, and we must make the relocation tables together with the
// sections.
uint32 oldsec; // Section number in old file
uint32 newsec = 0; // Section number in new file
NewSectIndex. SetNum(this->NSections); // Allocate size for section index table
NewSectIndex. SetZero(); // Initialize
NewSectOffset.SetNum(this->NSections); // Allocate buffer for section offset table
NewSectOffset.SetZero(); // Initialize
MInt NewVirtualAddress = 0; // Virtual address of new section as specified in Mach-O file
// First loop through old sections
for (oldsec = 0; oldsec < this->NSections; oldsec++) {
NewSectIndex[oldsec] = 0;
NewSectOffset[oldsec] = 0;
// Get section name
const char * sname = "";
uint32 namei = this->SectionHeaders[oldsec].sh_name;
if (namei >= this->SecStringTableLen) {
err.submit(2112);
}
else sname = this->SecStringTable + namei;
if (cmd.DebugInfo == CMDL_DEBUG_STRIP) {
// Check for debug section names
if (strncmp(sname, ".note", 5) == 0
|| strncmp(sname, ".comment", 8) == 0
|| strncmp(sname, ".stab", 5) == 0
|| strncmp(sname, ".debug", 6) == 0) {
// Remove this section
this->SectionHeaders[oldsec].sh_type = SHT_REMOVE_ME;
cmd.CountDebugRemoved();
continue;
}
}
if (cmd.ExeptionInfo == CMDL_EXCEPTION_STRIP) {
// Check for exception section name
if (strncmp(sname, ".eh_frame", 9) == 0) {
// Remove this section
this->SectionHeaders[oldsec].sh_type = SHT_REMOVE_ME;
cmd.CountExceptionRemoved();
continue;
}
}
// Search for program data sections only
if (this->SectionHeaders[oldsec].sh_type != SHT_PROGBITS
&& this->SectionHeaders[oldsec].sh_type != SHT_NOBITS) {
// Has no data. Ignore
continue;
}
if (this->SectionHeaders[oldsec].sh_size == 0) {
// Remove empty section
// The linker has a bug with empty sections
continue;
}
// Section index translation table
NewSectIndex[oldsec] = newsec++;
// Calculate virtual memory address of section. This address does not have
// much to do with the final address, but it is needed in relocation entries.
// Alignment
int NewAlign = FloorLog2((uint32)this->SectionHeaders[oldsec].sh_addralign);
if (NewAlign > 12) NewAlign = 12; // What is the limit for highest alignment?
int AlignBy = 1 << NewAlign;
// Align memory address
NewVirtualAddress = (NewVirtualAddress + AlignBy - 1) & -(MInt)AlignBy;
// Virtual memory address of new section
NewSectOffset[oldsec] = NewVirtualAddress;
// Increment memory address
NewVirtualAddress += this->SectionHeaders[oldsec].sh_size;
// Fix v. 2.14: Align end of memory address by 4
NewVirtualAddress = (NewVirtualAddress + 3) & MInt(-4);
}
// Store number of sections in new file
NumSectionsNew = newsec;
// Calculate file offset of first raw data
RawDataOffset = sizeof(TMAC_header)
+ sizeof(TMAC_segment_command)
+ NumSectionsNew * sizeof(TMAC_section)
+ sizeof(MAC_symtab_command)
+ sizeof(MAC_dysymtab_command);
// Align end of memory address by 4
NewVirtualAddress = (NewVirtualAddress + 3) & MInt(-4);
// Make segment command
TMAC_segment_command NewSegment;
memset(&NewSegment, 0, sizeof(NewSegment));
NewSegment.cmd = (this->WordSize == 32) ? MAC_LC_SEGMENT : MAC_LC_SEGMENT_64;
NewSegment.cmdsize = sizeof(TMAC_segment_command) + NumSectionsNew * sizeof(TMAC_section);
NewSegment.fileoff = RawDataOffset;
NewSegment.nsects = NumSectionsNew;
NewSegment.maxprot = NewSegment.initprot = 7; // 1=read, 2=write, 4=execute
NewSegment.vmsize = NewVirtualAddress;
NewSegment.filesize = 0; // Changed later
// put segment command in OutFile
CommandOffset = ToFile.Push(&NewSegment, sizeof(NewSegment));
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::MakeSymbolTable() {
// Convert subfunction: Symbol table and string tables
uint32 oldsec; // Section number in old file
TELF_SectionHeader OldHeader; // Old section header
int FoundSymTab = 0; // Found symbol table
int8 * strtab; // Old symbol string table
int8 * symtab; // Old symbol table
uint32 symtabsize; // Size of old symbol table
int8 * symtabend; // End of old symbol table
uint32 entrysize; // Size of each entry in old symbol table
TELF_Symbol OldSym; // Old symbol table record
uint32 OldSymI; // Symbol index in old symbol table
const char * symname; // Symbol name
int NewSection = 0; // New section index
int NewType; // New symbol type
int NewDesc; // New symbol reference type
MInt Value; // Symbol value
uint32 Scope; // 0: Local, 1: Public, 2: External
// Loop through old sections to find symbol table
for (oldsec = 0; oldsec < this->NSections; oldsec++) {
// Search for program data sections only
if (this->SectionHeaders[oldsec].sh_type == SHT_SYMTAB
|| this->SectionHeaders[oldsec].sh_type == SHT_DYNSYM) {
FoundSymTab++;
// Copy symbol table header for convenience
OldHeader = this->SectionHeaders[oldsec];
// Find associated string table
if (OldHeader.sh_link >= (uint32)(this->NSections)) {
err.submit(2035); OldHeader.sh_link = 0;
}
strtab = this->Buf() + (uint32)this->SectionHeaders[OldHeader.sh_link].sh_offset;
// Find old symbol table
entrysize = (uint32)OldHeader.sh_entsize;
if (entrysize < sizeof(TELF_Symbol)) {err.submit(2033); entrysize = sizeof(TELF_Symbol);}
symtab = this->Buf() + (uint32)OldHeader.sh_offset;
symtabsize = (uint32)OldHeader.sh_size;
symtabend = symtab + symtabsize;
if (NewSymTab[0].GetNumEntries() == 0) {
// make empty symbol record for index 0
NewSymTab[0].AddSymbol(0, "", 0, 0, 0, 0);
}
// Loop through old symbol table
for (OldSymI = 0; symtab < symtabend; symtab += entrysize, OldSymI++) {
if (OldSymI == 0) continue; // First symbol entry in ELF file is unused
// Copy 32 bit symbol table entry or convert 64 bit entry
OldSym = *(TELF_Symbol*)symtab;
// Old symbol type
int type = OldSym.st_type;
// Old symbol storage class = binding
int binding = OldSym.st_bind;
// Get symbol name
if (OldSym.st_name < this->SymbolStringTableSize) {
symname = strtab + OldSym.st_name;
}
else {
err.submit(2112); // String table corrupt
continue; // Ignore
}
if (symname == 0 || *symname == 0) {
// Symbol has no name. Give it a name
// Mac linker messes this up if the symbol doesn't have a unique name.
char tempbuf[80];
sprintf(tempbuf, "?unnamed%i", OldSymI);
int os = UnnamedSymbolsTable.PushString(tempbuf);
symname = UnnamedSymbolsTable.Buf() + os;
}
NewType = NewDesc = 0; // New symbol type
// Value = address
Value = OldSym.st_value;
// Section
if (OldSym.st_shndx == SHN_UNDEF) {
NewSection = 0; // External
}
else if ((int16)(OldSym.st_shndx) == SHN_ABS) {
NewType |= MAC_N_ABS; // Absolute symbol
NewDesc |= MAC_N_NO_DEAD_STRIP;
NewSection = 0;
}
else if ((int16)(OldSym.st_shndx) == SHN_COMMON) {
NewType |= MAC_N_ABS; // Common symbol. Translate to abs and make warning
NewDesc |= MAC_N_NO_DEAD_STRIP;
NewSection = 0;
err.submit(1053, symname); // Warning. Common symbol
}
else if (OldSym.st_shndx >= this->NSections) {
err.submit(2036, OldSym.st_shndx); // Special/unknown section index or out of range
}
else {
// Normal section index.
// Look up in section index translation table and add 1 because it is 1-based
NewSection = NewSectIndex[OldSym.st_shndx] + 1;
// Value must be absolute address. Add section address
Value += NewSectOffset[OldSym.st_shndx];
}
// Convert binding/storage class
switch (binding) {
case STB_LOCAL: // Local
Scope = S_LOCAL;
if (!(NewType & MAC_N_ABS)) NewType |= MAC_N_SECT;
break;
case STB_GLOBAL:
if (NewSection || (NewType & MAC_N_ABS)) {
// Public
Scope = S_PUBLIC;
NewType |= MAC_N_EXT;
if (!(NewType & MAC_N_ABS)) NewType |= MAC_N_SECT;
}
else {
// External
Scope = S_EXTERNAL;
NewType |= MAC_N_EXT;
}
NewDesc |= MAC_REF_FLAG_UNDEFINED_NON_LAZY;
break;
case STB_WEAK:
if (NewSection) {
// Weak public
Scope = S_PUBLIC;
NewType |= MAC_N_EXT | MAC_N_SECT;
NewDesc |= MAC_N_WEAK_DEF;
if (this->WordSize == 32) {
err.submit(1051, symname); // Weak public only allowed in coalesced section of MachO-32
}
}
else {
// Weak external
Scope = S_EXTERNAL;
NewType |= MAC_N_EXT;
NewDesc |= MAC_N_WEAK_REF;
}
break;
default:
Scope = S_LOCAL;
err.submit(2037, binding); // Other. Not supported
}
// Make record depending on type
switch (type) {
case STT_OBJECT: case STT_NOTYPE:
// Data object
break;
case STT_GNU_IFUNC:
err.submit(1063); // Warning: Gnu indirect function cannot be converted
// continue in next case:
case STT_FUNC:
// Function
break;
case STT_FILE:
// File name record. Ignore
continue;
case STT_SECTION:
// Section name record. (Has no name)
break;
case STT_COMMON:
default:
err.submit(2038, type); // Symbol type not supported
continue;
}
// Discard unused symbols
if (Scope != S_PUBLIC && !OldSymbolUsed[OldSymI]) continue;
// Store new symbol record in the appropriate table
if (Scope > 2) err.submit(9000);
NewSymTab[Scope].AddSymbol(OldSymI, symname, NewType, NewDesc, NewSection, Value);
// Store scope in OldSymbolScope
if (OldSymI < NumOldSymbols) {
OldSymbolScope[OldSymI] = Scope;
}
} // End OldSymI loop
}
} // End search for symbol table
if (FoundSymTab == 0) err.submit(2034); // Symbol table not found
if (FoundSymTab > 1) err.submit(1032); // More than one symbol table found
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::Elf2MacRelocations(Elf32_Shdr & OldRelHeader, MAC_section_32 & NewHeader, uint32 NewRawDataOffset, uint32 oldsec) {
// Convert 32-bit relocations from ELF to MAC
// (This function has two template instances, only the 32-bit instance is used)
Elf32_Rela OldRelocation; // Old relocation table entry
MAC_scattered_relocation_info scat; // Scattered relocation entry
memset(&scat, 0, sizeof(scat));
// Get pointer to old relocation table
int8 * reltab = this->Buf() + OldRelHeader.sh_offset;
int8 * reltabend = reltab + OldRelHeader.sh_size;
// Get entry size
uint32 entrysize = (uint32)OldRelHeader.sh_entsize;
uint32 expectedentrysize = (OldRelHeader.sh_type == SHT_REL) ? sizeof(Elf32_Rel) : sizeof(Elf32_Rela);
if (entrysize < expectedentrysize) {err.submit(2033); entrysize = expectedentrysize;}
// File pointer to relocations
NewHeader.reloff = NewRelocationTab.GetNumEntries()*sizeof(MAC_relocation_info); // Offset to first relocation table added later
// Loop through relocation table entries
for (; reltab < reltabend; reltab += entrysize) {
// Copy relocation entry with or without addend
OldRelocation.r_addend = 0;
memcpy(&OldRelocation, reltab, entrysize);
// Find inline addend
uint32 InlinePosition = (uint32)(NewRawDataOffset + OldRelocation.r_offset);
// Check that address is valid
if (InlinePosition >= this->GetDataSize()) {
// Address is invalid
err.submit(2032); break;
}
// Pointer to inline addend
int32 * piaddend = (int32*)(NewRawData.Buf() + InlinePosition);
// Add old addend if any
*piaddend += (int32)OldRelocation.r_addend;
// Define relocation parameters
uint32 r_address = 0; // section-relative offset to relocation source
uint32 r_symbolnum = 0; // symbol index if r_extern == 1 or section ordinal if r_extern == 0
// uint32 r_value = 0; // value of relocation target
// int r_scattered = 0; // use scattered relocation
int r_pcrel = 0; // self relative
int r_length = 2; // size of source: 0=byte, 1=2 bytes, 2=4 bytes, 3=8 bytes
int r_extern = 0; // public or external
int r_type = 0; // if not 0, machine specific relocation type
int Scope = 0; // Symbol scope: 0 = local, 1 = public, 2 = external
// source offset
r_address = (uint32)OldRelocation.r_offset;
// target scope
if (OldRelocation.r_sym < NumOldSymbols) {
Scope = OldSymbolScope[OldRelocation.r_sym];
}
// Get r_extern: 0 = local target referenced by address,
// 1 = external symbol referenced by symbol table index
switch (Scope) {
case S_LOCAL: // Local target must be referenced by address
r_extern = 0; break;
case S_PUBLIC: // Public target is optionally referenced by index or by address
r_extern = 0;
// r_extern = 1; is not allowed!
break;
case S_EXTERNAL: // External target is always referenced by index
r_extern = 1; break;
}
// Get zero-based index into NewSymTab[Scope]
int newindex = NewSymTab[Scope].TranslateIndex(OldRelocation.r_sym);
if (newindex < 0) {
// Symbol not found or wrong type
err.submit(2031);
break;
}
if (r_extern) {
// r_symbolnum is zero based index into combined symbol tables.
// Add number of entries in preceding NewSymTab tables to index
// into NewSymTab[Scope]
r_symbolnum = newindex + NumSymbols[Scope];
}
else {
// r_extern = 0. r_symbolnum = target section
r_symbolnum = NewSymTab[Scope][newindex].n_sect;
// Absolute address of target stored inline in source
*piaddend += (uint32)NewSymTab[Scope][newindex].n_value;
}
// Get relocation type and fix addend
switch(OldRelocation.r_type) {
case R_386_NONE: // Ignored
continue;
case R_386_IRELATIVE:
err.submit(1063); // Warning: Gnu indirect function cannot be converted
// continue in next case?:
case R_386_32: // 32-bit absolute virtual address
r_type = MAC32_RELOC_VANILLA;
break;
case R_386_PC32: // 32-bit self-relative
r_type = MAC32_RELOC_VANILLA;
r_pcrel = 1;
// Mach-O 32 bit format requires that self-relative addresses must have
// self-relative values already before relocation. Therefore
// the source address is subtracted.
// (The PC reference point is the end of the source = start
// of source + 4, but ELF files have the same offset so no further
// correction is needed when converting from ELF file).
// !! ToDo: Self-relative relocations plus offset to local symbol in a different section
// sometimes causes problems in Mac linker, perhaps because it fails to determine
// correctly which section the target is in. Use a relocation with a reference point
// instead. This probably occurs only in assembler-coded self-relative 32-bit code.
// (Use asmlib A_strtoupper and A_strcspn as test cases - they fail if dummy data
// at the end of .data section is removed)
*piaddend -= r_address + (uint32)NewHeader.addr;
break;
case R_UNSUPPORTED_IMAGEREL: // 32-bit image-relative
// This occurs only when converting from COFF (via ELF)
// Needs scattered relocation entry
scat.r_address = r_address;
scat.r_length = 2;
scat.r_pcrel = 0;
scat.r_scattered = 1;
scat.r_type = MAC32_RELOC_SECTDIFF;
scat.r_value = r_symbolnum;
// Store first entry of scattered pair
NewRelocationTab.Push(&scat, sizeof(scat));
NewHeader.nreloc++;
// Make subtractor record for image base
scat.r_type = MAC32_RELOC_PAIR;
scat.r_value = GetImagebaseSymbol();
// Store second entry of scattered pair
NewRelocationTab.Push(&scat, sizeof(scat));
NewHeader.nreloc++;
continue;
case R_386_GOT32: case R_386_GLOB_DAT: case R_386_GOTOFF: case R_386_GOTPC:
// Global offset table
err.submit(2042); // cannot convert position-independent code
err.ClearError(2042); // report this error only once
r_type = 0;
break;
case R_386_PLT32: case R_386_JMP_SLOT:
// procedure linkage table
err.submit(2043); // cannot convert import table
err.ClearError(2043); // report this error only once
r_type = 0;
break;
default: // Unknown or unsupported relocation method
err.submit(2030, OldRelocation.r_type);
r_type = 0; break;
}
if (!r_pcrel) {
// Warn for position dependent code.
// This warning is currently turned off in error.cpp.
err.submit(1050, this->SymbolName(OldRelocation.r_sym));
// Write this error only once
err.ClearError(1050);
}
// Make relocation entry
MAC_relocation_info rel;
memset(&rel, 0, sizeof(rel));
// Make non-scattered relocation entry
rel.r_address = r_address;
rel.r_symbolnum = r_symbolnum;
rel.r_pcrel = r_pcrel;
rel.r_length = r_length;
rel.r_extern = r_extern;
rel.r_type = r_type;
// Store relocation entry
NewRelocationTab.Push(&rel, sizeof(rel));
NewHeader.nreloc++;
// Remember that symbol is used
// if (SymbolsUsed && OldRelocation.r_type && NewRelocation.r_symbolnum < ?) {
// SymbolsUsed[NewRelocation.r_symbolnum]++;}
} // End of relocations loop
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::Elf2MacRelocations(Elf64_Shdr & OldRelHeader, MAC_section_64 & NewHeader, uint32 NewRawDataOffset, uint32 oldsec) {
// Convert 64-bit relocations from ELF to MAC
// (This function has two template instances, only the 64-bit instance is used)
// Make relocation entry for dummy subtractor
MAC_relocation_info relsub;
memset(&relsub, 0, sizeof(relsub));
Elf64_Rela OldRelocation; // Old relocation table entry
// Get pointer to old relocation table
int8 * reltab = this->Buf() + OldRelHeader.sh_offset;
int8 * reltabend = reltab + OldRelHeader.sh_size;
// Get entry size
uint32 entrysize = (uint32)OldRelHeader.sh_entsize;
uint32 expectedentrysize = (OldRelHeader.sh_type == SHT_REL) ? sizeof(Elf64_Rel) : sizeof(Elf64_Rela);
if (entrysize < expectedentrysize) {err.submit(2033); entrysize = expectedentrysize;}
// File pointer to relocations
NewHeader.reloff = NewRelocationTab.GetNumEntries()*sizeof(MAC_relocation_info); // Offset to first relocation table added later
// Loop through relocation table entries
for (; reltab < reltabend; reltab += entrysize) {
// Copy relocation entry with or without addend
OldRelocation.r_addend = 0;
memcpy(&OldRelocation, reltab, entrysize);
// Find inline addend
uint32 InlinePosition = (uint32)(NewRawDataOffset + OldRelocation.r_offset);
// Check that address is valid
if (InlinePosition >= this->GetDataSize()) {
// Address is invalid
err.submit(2032);
break;
}
// Pointer to inline addend
int32 * piaddend = (int32*)(NewRawData.Buf() + InlinePosition);
// Add old addend if any
*piaddend += (uint32)OldRelocation.r_addend;
// Define relocation parameters
uint32 r_address = 0; // section-relative offset to relocation source
uint32 r_symbolnum = 0; // symbol index if r_extern == 1 or section ordinal if r_extern == 0
// uint32 r_value = 0; // value of relocation target
// int r_scattered = 0; // scattered relocations not used in 64 bit
int r_pcrel = 0; // self relative
int r_length = 2; // size of source: 0=byte, 1=2 bytes, 2=4 bytes, 3=8 bytes
int r_extern = 0; // public or external
int r_type = 0; // if not 0, machine specific relocation type
int Scope = 0; // Symbol scope: 0 = local, 1 = public, 2 = external
// source offset
r_address = (uint32)OldRelocation.r_offset;
// target scope
if (OldRelocation.r_sym < NumOldSymbols) {
Scope = OldSymbolScope[OldRelocation.r_sym];
}
// Get r_extern: 0 = local target referenced by address,
// 1 = public or external symbol referenced by symbol table index
switch (Scope) {
case S_LOCAL: // Local target
// r_extern = 0; // Local target must be referenced by address
// Note: the description in reloc.h says that local targets are addressed
// relative to any preceding public target. If there is no preceding label
// then referenced by address in the segment. However, the Gnu compiler
// uses reference to a local symbol and sets r_extern = 1 to indicate that
// it refers to a symbol record, not to an address. I have chosen to use the
// latter method because it is simpler, though undocumented.
r_extern = 1;
break;
case S_PUBLIC: // Public target is optionally referenced by index or by address
r_extern = 1;
break;
case S_EXTERNAL: // External target is always referenced by index
r_extern = 1;
break;
}
// Get zero-based index into NewSymTab[Scope]
int newindex = NewSymTab[Scope].TranslateIndex(OldRelocation.r_sym);
if (newindex < 0) {
// Symbol not found or wrong type
err.submit(2031);
break;
}
// r_symbolnum is zero based index into combined symbol tables.
// Add number of entries in preceding NewSymTab tables to index
// into NewSymTab[Scope]
r_symbolnum = newindex + NumSymbols[Scope];
// Get relocation type and fix addend, 64 bit
switch(OldRelocation.r_type) {
case R_X86_64_NONE: // Ignored
continue;
case R_X86_64_64:
// 64-bit absolute virtual address
r_type = MAC64_RELOC_UNSIGNED; r_length = 3;
break;
case R_X86_64_IRELATIVE:
err.submit(1063); // Warning: Gnu indirect function cannot be converted
// continue in next case?:
case R_X86_64_32: case R_X86_64_32S: {
// 32-bit absolute virtual address
// Note: The linker doesn't accept a 32-bit absolute address
// Make address relative to the image base, and add the value of the image base to compensate
if (cmd.ImageBase == 0) {
// Default image base if not specified
cmd.ImageBase = 0x400000;
}
// Make subtractor relocation entry for image base
relsub.r_address = r_address;
relsub.r_symbolnum = GetImagebaseSymbol();
relsub.r_length = 2;
relsub.r_extern = 1;
relsub.r_type = MAC64_RELOC_SUBTRACTOR;
NewRelocationTab.Push(&relsub, sizeof(relsub));
NewHeader.nreloc++;
// Add image base to compensate for subtracted image base
*piaddend += cmd.ImageBase;
// Now we can add the address we really want:
r_type = MAC64_RELOC_UNSIGNED;
r_length = 2;
// Warn that image base must be set to the specified value
char ImageBaseHex[32];
sprintf(ImageBaseHex, "%X", cmd.ImageBase); // write value as hexadecimal
err.submit(1300, ImageBaseHex); err.ClearError(1300);
break;}
case R_X86_64_PC32: // 32-bit self-relative
r_type = MAC64_RELOC_BRANCH;
// MAC64_RELOC_SIGNED does the same, but the linker complains if external symbol
r_length = 2;
r_pcrel = 1;
// Difference between EIP-relative and self-relative relocation = size of address field
// Adjust inline addend for different relocation method:
*piaddend += 4;
break;
case R_UNSUPPORTED_IMAGEREL: // 32-bit image-relative
// This occurs only when converting from COFF (via ELF)
// Make subtractor relocation entry for image base
relsub.r_address = r_address;
relsub.r_symbolnum = GetImagebaseSymbol();
relsub.r_length = 2;
relsub.r_extern = 1;
relsub.r_type = MAC64_RELOC_SUBTRACTOR;
NewRelocationTab.Push(&relsub, sizeof(relsub));
NewHeader.nreloc++;
// Second record adds the target address
r_type = MAC64_RELOC_UNSIGNED;
r_length = 2;
break;
case R_X86_64_GLOB_DAT: case R_X86_64_GOTPCREL:
// Create 64-bit GOT entry??
r_type = MAC64_RELOC_GOT; r_length = 2;
break;
case R_X86_64_GOT32:
// 32-bit GOT entry
err.submit(2042); // cannot convert 32-bit GOT
err.ClearError(2042); // report this error only once
r_type = 0;
break;
case R_X86_64_PLT32: case R_X86_64_JUMP_SLOT:
// procedure linkage table
err.submit(2043); // cannot convert import table
err.ClearError(2043); // report this error only once
r_type = 0;
break;
case R_X86_64_COPY: case R_X86_64_RELATIVE:
default: // Unknown or unsupported relocation method
err.submit(2030, OldRelocation.r_type);
r_type = 0; break;
}
// Make relocation entry
MAC_relocation_info rel;
memset(&rel, 0, sizeof(rel));
// Make non-scattered relocation entry
rel.r_address = r_address;
rel.r_symbolnum = r_symbolnum;
rel.r_pcrel = r_pcrel;
rel.r_length = r_length;
rel.r_extern = r_extern;
rel.r_type = r_type;
// Store relocation entry
NewRelocationTab.Push(&rel, sizeof(rel));
NewHeader.nreloc++;
// Remember that symbol is used
// if (SymbolsUsed && OldRelocation.r_type && NewRelocation.r_symbolnum < ?) {
// SymbolsUsed[NewRelocation.r_symbolnum]++;}
} // End of relocations loop
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::MakeSections() {
// Convert subfunction: Make sections and relocation tables
uint32 oldsec; // Section number in old file
uint32 relsec; // Relocation section in old file
TMAC_section NewHeader; // New section header
TELF_SectionHeader OldHeader; // Old section header
TELF_SectionHeader OldRelHeader;// Old relocation section header
uint32 NewVirtualAddress = 0; // Virtual address of new section
uint32 NewRawDataOffset = 0; // Offset into NewRawData of section.
// NewRawDataOffset is different from NewVirtualAddress if alignment of sections in
// the object file is different from alignment of sections in memory
// Count cumulative number of symbols in each scope
NumSymbols[0] = 0;
NumSymbols[1] = NumSymbols[0] + NewSymTab[0].GetNumEntries();
NumSymbols[2] = NumSymbols[1] + NewSymTab[1].GetNumEntries();
NumSymbols[3] = NumSymbols[2] + NewSymTab[2].GetNumEntries();
if (NumSymbols[3] >= 0x1000000) err.submit(2051); // Too many symbols, max = 2^24
NewSectHeadOffset = ToFile.GetDataSize();
// Second loop through old sections
for (oldsec = 0; oldsec < this->NSections; oldsec++) {
// Copy old header for convenience
OldHeader = this->SectionHeaders[oldsec];
if (OldHeader.sh_size == 0) {
// Remove empty section
// The linker has a bug with empty sections
continue;
}
// Search for program data sections only
if (OldHeader.sh_type == SHT_PROGBITS || OldHeader.sh_type == SHT_NOBITS) {
// Reset new section header
memset(&NewHeader, 0, sizeof(NewHeader));
// Section name
const char * sname = "";
uint32 namei = OldHeader.sh_name;
if (namei >= this->SecStringTableLen) err.submit(2112);
else sname = this->SecStringTable + namei;
// Translate section name and truncate to 16 characters
if (!stricmp(sname,".text") || !stricmp(sname,"_text")) {
strcpy(NewHeader.sectname, "__text");
strcpy(NewHeader.segname, "__TEXT");
}
else if (!stricmp(sname,".data") || !stricmp(sname,"_data")) {
strcpy(NewHeader.sectname, "__data");
strcpy(NewHeader.segname, "__DATA");
}
else if (!strnicmp(sname+1,"bss", 3)) {
strcpy(NewHeader.sectname, "__bss");
strcpy(NewHeader.segname, "__DATA");
}
else if (!strnicmp(sname+1,"const", 5) || !strnicmp(sname+1,"rodata", 6)) {
strcpy(NewHeader.sectname, "__const");
strcpy(NewHeader.segname, "__DATA");
}
else if (!strnicmp(sname, ELF_CONSTRUCTOR_NAME, 5)) {
// Constructors
strcpy(NewHeader.sectname, MAC_CONSTRUCTOR_NAME);
strcpy(NewHeader.segname, "__DATA");
NewHeader.flags = MAC_S_MOD_INIT_FUNC_POINTERS;
}
else if (OldHeader.sh_flags & SHF_EXECINSTR) {
// Other code section
if (strlen(NewHeader.sectname) > 16) err.submit(1040, NewHeader.sectname); // Warning: name truncated
strncpy(NewHeader.sectname, sname, 16);
strcpy(NewHeader.segname, "__TEXT");
}
else {
// Other data section. Truncate name to 16 characters
if (strlen(NewHeader.sectname) > 16) err.submit(1040, NewHeader.sectname); // Warning: name truncated
strncpy(NewHeader.sectname, sname, 16);
strcpy(NewHeader.segname, "__DATA");
}
if (NewHeader.sectname[0] == '.') {
// Make sure name begins with '_'
NewHeader.sectname[0] = '_';
}
// Raw data
NewHeader.size = OldHeader.sh_size; // section size in file
// File to raw data for section
NewHeader.offset = NewRawData.GetDataSize() + RawDataOffset;
if (OldHeader.sh_size && OldHeader.sh_type != SHT_NOBITS) { // Not for .bss segment
// Copy raw data
NewRawDataOffset = NewRawData.Push(this->Buf()+(uint32)OldHeader.sh_offset, (uint32)OldHeader.sh_size);
NewRawData.Align(4);
}
// Section flags
if (OldHeader.sh_flags & SHF_EXECINSTR) {
NewHeader.flags |= MAC_S_ATTR_PURE_INSTRUCTIONS | MAC_S_ATTR_SOME_INSTRUCTIONS;
}
else if (OldHeader.sh_type == SHT_NOBITS) {
NewHeader.flags |= MAC_S_ZEROFILL; // .bss segment
}
// Alignment
NewHeader.align = FloorLog2((uint32)OldHeader.sh_addralign);
if (NewHeader.align > 12) NewHeader.align = 12; // What is the limit for highest alignment?
int AlignBy = 1 << NewHeader.align;
// Align memory address
NewVirtualAddress = (NewVirtualAddress + AlignBy - 1) & -AlignBy;
// Virtual memory address of new section
NewHeader.addr = NewVirtualAddress;
NewVirtualAddress += (uint32)OldHeader.sh_size;
// Find relocation table for this section by searching through all sections
for (relsec = 1; relsec < this->NSections; relsec++) {
// Get section header
OldRelHeader = this->SectionHeaders[relsec];
// Check if this is a relocations section referring to oldsec
if ((OldRelHeader.sh_type == SHT_REL || OldRelHeader.sh_type == SHT_RELA) // if section is relocation
&& OldRelHeader.sh_info == oldsec) { // and if section refers to current section
Elf2MacRelocations(OldRelHeader, NewHeader, NewRawDataOffset, oldsec);
}
} // End of search for relocation table
// Align raw data for next section
NewRawData.Align(4);
// Fix v. 2.14: adjust NewVirtualAddress to match above alignment
NewVirtualAddress = (NewVirtualAddress + 3) & MInt(-4);
// Store section header in file
ToFile.Push(&NewHeader, sizeof(NewHeader));
} // End of if section has program data
} // End of loop through old sections
} // End of function MakeSections
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::FindUnusedSymbols() {
// Check if symbols used, remove unused symbols
// Allocate table OldSymbolScope and OldSymbolUsed
NumOldSymbols = this->SymbolTableEntries;
if (NumOldSymbols > 0 && NumOldSymbols < 0x1000000) {
OldSymbolScope.SetNum(NumOldSymbols);
OldSymbolScope.SetZero();
OldSymbolUsed.SetNum(NumOldSymbols);
OldSymbolUsed.SetZero();
}
// Loop through section headers
for (uint32 sc = 0; sc < this->NSections; sc++) {
uint32 entrysize = uint32(this->SectionHeaders[sc].sh_entsize);
// printf("\n%2i Name: %-18s ", sc, SecStringTable + sheader.sh_name);
if ((this->SectionHeaders[sc].sh_type==SHT_REL || this->SectionHeaders[sc].sh_type==SHT_RELA)) {
// Relocation list
int8 * reltab = this->Buf() + uint32(this->SectionHeaders[sc].sh_offset);
int8 * reltabend = reltab + uint32(this->SectionHeaders[sc].sh_size);
uint32 expectedentrysize = this->SectionHeaders[sc].sh_type == SHT_RELA ?
sizeof(TELF_Relocation) : // Elf32_Rela, Elf64_Rela
sizeof(TELF_Relocation) - this->WordSize/8; // Elf32_Rel, Elf64_Rel
if (entrysize < expectedentrysize) {err.submit(2033); entrysize = expectedentrysize;}
// Loop through entries
for (; reltab < reltabend; reltab += entrysize) {
int isymbol = ((TELF_Relocation*)reltab)->r_sym;
// printf("\n>SymbolUsed: %i, Name: %s",isymbol,SymbolName(isymbol));
// Remember symbol used
OldSymbolUsed[isymbol]++;
}
}
}
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
void CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::MakeBinaryFile() {
// Convert subfunction: Putting sections together
// File header, segment command and section headers have been inserted.
int i;
// Update segment header for segment size in file
((TMAC_segment_command*)(ToFile.Buf()+CommandOffset))->filesize = NewRawData.GetDataSize();
// Make symbol table command
MAC_symtab_command symtab;
memset(&symtab, 0, sizeof(symtab));
symtab.cmd = MAC_LC_SYMTAB;
symtab.cmdsize = sizeof(symtab);
// symoff, nsyms, stroff, strsize inserted later
// Store symtab command
NewSymtabOffset = ToFile.Push(&symtab, sizeof(symtab));
// Make MAC_dysymtab_command command
MAC_dysymtab_command dysymtab;
memset(&dysymtab, 0, sizeof(dysymtab));
dysymtab.cmd = MAC_LC_DYSYMTAB;
dysymtab.cmdsize = sizeof(dysymtab);
dysymtab.ilocalsym = 0; // index to local symbols
dysymtab.nlocalsym = NewSymTab[0].GetNumEntries(); // number of local symbols
dysymtab.iextdefsym = dysymtab.nlocalsym; // index to externally defined symbols
dysymtab.nextdefsym = NewSymTab[1].GetNumEntries(); // number of externally defined symbols
dysymtab.iundefsym = dysymtab.iextdefsym + dysymtab.nextdefsym; // index to public symbols
dysymtab.nundefsym = NewSymTab[2].GetNumEntries(); // number of public symbols
// Store MAC_dysymtab_command command
ToFile.Push(&dysymtab, sizeof(dysymtab));
// Store section data
uint32 Current = ToFile.Push(NewRawData.Buf(), NewRawData.GetDataSize());
if (Current != RawDataOffset) err.submit(9000);
ToFile.Align(4);
// Store relocation tables
uint32 Reltabs = ToFile.Push(NewRelocationTab.Buf(), NewRelocationTab.GetDataSize());
// Initialize new string table. First string is empty
NewStringTable.Push(0, 1);
// Store symbol tables and make string table
// Tables are not sorted alphabetically yet. This will be done subsequently
// by CMAC2MAC
uint32 Symtabs = ToFile.GetDataSize();
uint32 NumSyms = 0;
for (i = 0; i < 3; i++) {
NumSyms += NewSymTab[i].GetNumEntries();
NewSymTab[i].StoreList(&ToFile, &NewStringTable);
}
// Store string table
uint32 StringTab = ToFile.Push(NewStringTable.Buf(), NewStringTable.GetDataSize());
// Set missing values in file header
((TMAC_header*)ToFile.Buf())->sizeofcmds = RawDataOffset - sizeof(TMAC_header);
// Adjust relocation offsets in section headers
TMAC_section* sectp = (TMAC_section*)(ToFile.Buf() + NewSectHeadOffset);
for (i = 0; i < NumSectionsNew; i++, sectp++) {
sectp->reloff += Reltabs;
}
// Set missing symoff, nsyms, stroff, strsize in symtab command
MAC_symtab_command * symtabp = (MAC_symtab_command*)(ToFile.Buf() + NewSymtabOffset);
symtabp->symoff = Symtabs;
symtabp->nsyms = NumSyms;
symtabp->stroff = StringTab;
symtabp->strsize = NewStringTable.GetDataSize();
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation,
class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
int CELF2MAC<ELFSTRUCTURES,MACSTRUCTURES>::GetImagebaseSymbol() {
// Get symbol table index of __mh_execute_header = image base
// Create this symbol table entry if it doesn't exist
const char * ImageBaseName = "__mh_execute_header";
static int ImagebaseSymbol = -1;
if (ImagebaseSymbol >= 0) {
// Found previously
return ImagebaseSymbol;
}
// Search for name among external symbols
int index2 = NewSymTab[2].Search(ImageBaseName);
if (index2 >= 0) {
// found
ImagebaseSymbol = index2 + NumSymbols[2];
return ImagebaseSymbol;
}
// Not found. Create symbol
NewSymTab[2].AddSymbol(NumOldSymbols, ImageBaseName, MAC_N_EXT, 0, 0, 0);
ImagebaseSymbol = NewSymTab[2].TranslateIndex(NumOldSymbols) + NumSymbols[2];
NumSymbols[3]++;
return ImagebaseSymbol;
}
// Make template instances for 32 and 64 bits
template class CELF2MAC<ELF32STRUCTURES,MAC32STRUCTURES>;
template class CELF2MAC<ELF64STRUCTURES,MAC64STRUCTURES>;