407 lines
16 KiB
C++
407 lines
16 KiB
C++
/**************************** mac2mac.cpp *****************************
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* Author: Agner Fog
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* Date created: 2008-05-25
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* Last modified: 2008-05-25
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* Project: objconv
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* Module: mac2mac.cpp
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* Description:
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* Module for changing symbol names in Mach-O file
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*
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* Copyright 2008 GNU General Public License http://www.gnu.org/licenses
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*****************************************************************************/
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#include "stdafx.h"
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// All functions in this module are templated to make two versions: 32 and 64 bits.
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// See instantiations at the end of this file.
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// Constructor
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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CMAC2MAC<MACSTRUCTURES>::CMAC2MAC() {
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// Initialize everything
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memset(this, 0, sizeof(*this));
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}
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// Convert()
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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void CMAC2MAC<MACSTRUCTURES>::Convert() {
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MakeSymbolTable(); // Remake symbol tables and string tables
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MakeBinaryFile(); // Put everyting together into ToFile
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ChangeSegments(); // Modify section names and relocation table symbol indices
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*this << ToFile; // Take over new file buffer
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}
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// MakeSymbolTable()
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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void CMAC2MAC<MACSTRUCTURES>::MakeSymbolTable() {
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// Remake symbol tables and string table
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int OldScope = 0; // Old scope of symbol. 0=local, 1=public, 2=external
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int NewScope; // New scope of symbol. 0=local, 1=public, 2=external
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uint32 symi; // Old index of symbol
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const char * Name1; // Old symbol name
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const char * Name2; // New symbol name
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int action; // Action to take on symbol
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int SymType; // Symbol type
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int SymDesc; // Symbol descriptor
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uint8 Section; // Symbol section
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// pointer to symbol table
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TMAC_nlist * symp = (TMAC_nlist*)(this->Buf() + this->SymTabOffset);
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// pointer to string table
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char * strtab = (char*)(this->Buf() + this->StringTabOffset);
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// loop through symbol table
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for (symi = 0; symi < this->SymTabNumber; symi++, symp++) {
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// Check indices for first symbol of each scope category
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if (symi == this->iextdefsym && this->nextdefsym) OldScope = 1;
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if (symi == this->iundefsym && this->nundefsym) OldScope = 2;
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NewScope = OldScope;
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if (symp->n_strx >= this->StringTabSize) {
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// Index out of range
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err.submit(2112); continue;
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}
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// Get symbol name
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Name1 = strtab + symp->n_strx;
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// Get type, descriptor and section
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SymType = symp->n_type; // Symbol type
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SymDesc = symp->n_desc; // Symbol descriptor
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Section = symp->n_sect; // Symbol section
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// Check if any change required for this symbol
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action = cmd.SymbolChange(Name1, &Name2, SYMT_LOCAL + OldScope);
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switch (action) {
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case SYMA_NOCHANGE:
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// No change
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break;
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case SYMA_MAKE_WEAK:
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// Make symbol weak
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if (cmd.OutputType == FILETYPE_COFF) {
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// PE/COFF format does not support weak publics
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err.submit(2200);
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}
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// Make weak
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if (OldScope == 1) {
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SymDesc |= MAC_N_WEAK_DEF; // Weak public. Allowed only in coalesced (communal) section
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}
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else if (OldScope == 2) {
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SymDesc |= MAC_N_WEAK_REF; // Weak external
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}
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else {
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err.submit(1020, Name1); // Local symbol
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}
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break;
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case SYMA_MAKE_LOCAL:
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// Make public symbol local, make external symbol ignored
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if (OldScope == 1) {
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NewScope = 0; // Public changed to local
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SymType &= ~MAC_N_EXT;
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}
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else if (OldScope == 2) {
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Section = MAC_NO_SECT; // External symbol. Set to 0
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SymDesc = 0;
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SymType = MAC_N_UNDF;
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}
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else err.submit(1021, Name1);
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break;
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case SYMA_CHANGE_NAME:
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// Change name of symbol
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Name1 = Name2; Name2 = 0;
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break;
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case SYMA_ALIAS:
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// Make alias and keep old name
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if (OldScope != 1) {
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err.submit(1022, Name1); break;
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}
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// Make alias
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NewSymbols[1].AddSymbol(-1, Name2, SymType, SymDesc, Section, symp->n_value);
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break;
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default:
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err.submit(9000); // unknown error
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}
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// Store symbol, possibly modified
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NewSymbols[NewScope].AddSymbol(symi, Name1, SymType, SymDesc, Section, symp->n_value);
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}
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// Put everything into symbol table and string table
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if (this->SymTabNumber) {
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NewStringTable.SetDataSize(1); // First record must indicate empty string (see nlist.n_un in Mach-O File Format Reference)
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}
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for (NewScope = 0; NewScope < 3; NewScope++) {
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NewSymbols[NewScope].SortList(); // Sort each list alphabetically
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NewSymbols[NewScope].StoreList(&NewSymbolTable, &NewStringTable);
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}
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// Indices to local, public and external symbols
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NewIlocalsym = 0; // index to local symbols
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NewNlocalsym = NewSymbols[0].GetNumEntries(); // number of local symbols
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NewIextdefsym = NewNlocalsym; // index to public symbols
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NewNextdefsym = NewSymbols[1].GetNumEntries();// number of public symbols
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NewIundefsym = NewNlocalsym + NewNextdefsym; // index to external symbols
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NewNundefsym = NewSymbols[2].GetNumEntries(); // number of external symbols
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// Calculate difference in size of new tables versus old tables
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// (this calculation is moved to MakeBinaryFile)
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// SizeDifference = NewSymbolTable.GetDataSize + NewStringTable.GetDataSize()
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// - this->SymTabNumber * sizeof(TMAC_nlist) - this->StringTabSize;
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}
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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int CMAC2MAC<MACSTRUCTURES>::NewSymbolIndex(int32 OldIndex) {
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// Convert subfunction: Translate old to new symbol index
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int NewIndex;
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int Scope;
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// Search for symbol in all scopes
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for (Scope = 0; Scope < 3; Scope++) {
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NewIndex = NewSymbols[Scope].TranslateIndex(OldIndex);
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if (NewIndex >= 0) {
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// OldIndex found. Add offset into appropriate table
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if (Scope == 1) NewIndex += NewIextdefsym;
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else if (Scope == 2) NewIndex += NewIundefsym;
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return NewIndex;
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}
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}
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//err.submit(2031);
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return -1;
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}
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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uint32 CMAC2MAC<MACSTRUCTURES>::NewFileOffset(uint32 OldOffset) {
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// Convert subfunction: Translate old to new file offset
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if (OldOffset <= NewSymtabOffset) {
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// Before symbol table. No change
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return OldOffset;
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}
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if (OldOffset >= OldTablesEnd) {
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// After string table. Add size difference
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return OldOffset + SizeDifference;
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}
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// Between symbol table and string table.
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// The possibility of something between these two tables has not been accounted for
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err.submit(2052);
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return 0;
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}
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// MakeBinaryFile()
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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void CMAC2MAC<MACSTRUCTURES>::MakeBinaryFile() {
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uint32 OldSymtabEnd; // End of old symbol table
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uint32 OldStringtabEnd; // End of old string table
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const int WordSize = sizeof(MInt) * 8; // Word size, 32 or 64 bits
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// Offset to symbol table and string table
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NewSymtabOffset = this->SymTabOffset;
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if (this->StringTabOffset && this->StringTabOffset < NewSymtabOffset) NewSymtabOffset = this->StringTabOffset;
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if (NewSymtabOffset == 0) NewSymtabOffset = this->GetDataSize();
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// Copy all headers and all data until TablesOffset
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ToFile.Push(this->Buf(), NewSymtabOffset);
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ToFile.Align(WordSize/8);
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NewSymtabOffset = ToFile.GetDataSize();
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// Copy new symbol table
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ToFile.Push(NewSymbolTable.Buf(), NewSymbolTable.GetDataSize());
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// Copy new string table
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NewStringtabOffset = ToFile.GetDataSize();
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ToFile.Push(NewStringTable.Buf(), NewStringTable.GetDataSize());
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ToFile.Align(2);
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NewStringtabEnd = ToFile.GetDataSize();
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// Find end of old tables
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OldSymtabEnd = this->SymTabOffset + this->SymTabNumber * sizeof(TMAC_nlist);
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OldStringtabEnd = this->StringTabOffset + this->StringTabSize;
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OldTablesEnd = OldStringtabEnd;
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if (OldSymtabEnd > OldTablesEnd) OldTablesEnd = OldSymtabEnd;
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if (OldTablesEnd == 0) OldTablesEnd = this->GetDataSize();
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// Size difference between new and old tables
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SizeDifference = NewStringtabEnd - OldTablesEnd;
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// Is there anything in the old file after these tables?
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if (OldTablesEnd && this->GetDataSize() > OldTablesEnd) {
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// There is something after these tables. Copy it
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ToFile.Push(this->Buf() + OldTablesEnd, this->GetDataSize() - OldTablesEnd);
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}
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}
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// ChangeSegments()
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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void CMAC2MAC<MACSTRUCTURES>::ChangeSegments() {
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// Convert subfunction: Change section names if needed and adjust all relocation tables
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uint32 FileOffset; // Current offset into file
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uint32 lcmd; // Load command
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uint32 cmdsize = 0; // Command size
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uint32 icmd; // Loop counter
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int action; // Name change action
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char * Name1; // Old name
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const char * Name2; // New name
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FileOffset = sizeof(TMAC_header);
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// Loop through file commands
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for (icmd = 1; icmd <= this->FileHeader.ncmds; icmd++, FileOffset += cmdsize) {
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lcmd = ((MAC_load_command*)(ToFile.Buf() + FileOffset)) -> cmd;
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cmdsize = ((MAC_load_command*)(ToFile.Buf() + FileOffset)) -> cmdsize;
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// Interpret specific command type
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switch(lcmd) {
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case MAC_LC_SEGMENT: { // 32-bit segment
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MAC_segment_command_32 * sh = (MAC_segment_command_32*)(ToFile.Buf() + FileOffset);
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Name1 = sh->segname;
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// Check if any change required for this symbol
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action = cmd.SymbolChange(Name1, &Name2, SYMT_SECTION);
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if (action == SYMA_CHANGE_NAME) {
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// Change segment name
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if (strlen(Name2) > 16) err.submit(1040);
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strncpy(Name1, Name2, 16);
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}
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// Change section names and relocations in all sections under this segment
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ChangeSections(FileOffset + sizeof(MAC_segment_command_32), sh->nsects);
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break;}
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case MAC_LC_SEGMENT_64: { // 64-bit segment
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MAC_segment_command_64 * sh = (MAC_segment_command_64*)(ToFile.Buf() + FileOffset);
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Name1 = sh->segname;
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// Check if any change required for this symbol
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action = cmd.SymbolChange(Name1, &Name2, SYMT_SECTION);
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if (action == SYMA_CHANGE_NAME) {
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// Change segment name
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if (strlen(Name2) > 16) err.submit(1040);
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strncpy(Name1, Name2, 16);
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}
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// Change section names and relocations in all sections under this segment
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ChangeSections(FileOffset + sizeof(MAC_segment_command_64), sh->nsects);
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break;}
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case MAC_LC_SYMTAB: { // Symbol table header
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MAC_symtab_command * sh = (MAC_symtab_command*)(ToFile.Buf() + FileOffset);
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// Change table addresses
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sh->symoff = NewSymtabOffset;
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sh->nsyms = NewSymbolTable.GetDataSize() / sizeof(TMAC_nlist);
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sh->stroff = NewStringtabOffset;
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sh->strsize = NewStringtabEnd - NewStringtabOffset;
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break;}
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case MAC_LC_DYSYMTAB: { // dynamic link-edit symbol table
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MAC_dysymtab_command * sh = (MAC_dysymtab_command*)(ToFile.Buf() + FileOffset);
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// Change indices to symbol tables
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sh->ilocalsym = NewIlocalsym;
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sh->nlocalsym = NewNlocalsym;
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sh->iextdefsym = NewIextdefsym;
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sh->nextdefsym = NewNextdefsym;
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sh->iundefsym = NewIundefsym;
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sh->nundefsym = NewNundefsym;
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// Change table addresses
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sh->tocoff = NewFileOffset(sh->tocoff);
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sh->modtaboff = NewFileOffset(sh->modtaboff);
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sh->extrefsymoff = NewFileOffset(sh->extrefsymoff);
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sh->indirectsymoff = NewFileOffset(sh->indirectsymoff);
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sh->extreloff = NewFileOffset(sh->extreloff);
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sh->locreloff = NewFileOffset(sh->locreloff);
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if (sh->nindirectsyms) {
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// Change symbol indices in import table
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ChangeImportTable(sh->indirectsymoff, sh->nindirectsyms);
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}
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break;}
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}
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}
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}
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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void CMAC2MAC<MACSTRUCTURES>::ChangeSections(uint32 HeaderOffset, uint32 Num) {
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// Convert subfunction: Change section names and relocation records if needed
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int action; // Name change action
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char * Name1; // Old name
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const char * Name2; // New name
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uint32 isec1; // Section index
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TMAC_section * secp; // Pointer to section header
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uint32 irel; // Relocation index
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MAC_relocation_info * relp; // Pointer to relocation record
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// Loop through section headers
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for (isec1 = 0; isec1 < Num; isec1++) {
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// Find section header
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secp = (TMAC_section*)(ToFile.Buf() + HeaderOffset + isec1*sizeof(TMAC_section));
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// Segment name
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Name1 = secp->segname;
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action = cmd.SymbolChange(Name1, &Name2, SYMT_SECTION);
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if (action == SYMA_CHANGE_NAME) {
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// Change segment name
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if (strlen(Name2) > 16) err.submit(1040);
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strncpy(Name1, Name2, 16);
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}
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// Section name
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Name1 = secp->sectname;
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action = cmd.SymbolChange(Name1, &Name2, SYMT_SECTION);
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if (action == SYMA_CHANGE_NAME) {
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// Change section name
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if (strlen(Name2) > 16) err.submit(1040);
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strncpy(Name1, Name2, 16);
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}
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// Update file offset
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secp->offset = NewFileOffset(secp->offset);
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if (secp->nreloc) {
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// This section has relocations
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// Update relocations offset
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secp->reloff = NewFileOffset(secp->reloff);
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// Pointer to relocation records
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relp = (MAC_relocation_info*)(ToFile.Buf() + secp->reloff);
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// Loop through relocations, if any
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for (irel = 0; irel < secp->nreloc; irel++, relp++) {
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// Only non-scattered r_extern relocations have symbol index
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if (!(relp->r_address & R_SCATTERED) && relp->r_extern) {
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// Update symbol index
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relp->r_symbolnum = NewSymbolIndex(relp->r_symbolnum);
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}
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}
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}
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}
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}
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template <class TMAC_header, class TMAC_segment_command, class TMAC_section, class TMAC_nlist, class MInt>
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void CMAC2MAC<MACSTRUCTURES>::ChangeImportTable(uint32 FileOffset, uint32 Num) {
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// Convert subfunction: Change symbol indices in import table if needed
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uint32 i; // Index
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uint32 * p; // pointer to current entry
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// Find first entry
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p = (uint32*)(ToFile.Buf() + FileOffset);
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// Loop through table
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for (i = 0; i < Num; i++, p++) {
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// Translate symbol index
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*p = NewSymbolIndex(*p);
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}
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}
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// Make template instances for 32 and 64 bits
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template class CMAC2MAC<MAC32STRUCTURES>;
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template class CMAC2MAC<MAC64STRUCTURES>;
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