/*
* This is used by the sliding function to read and execute
* the compressed reloc table.
*/
static void rebaseCompressed(struct dyld_info_command* dyldInfo,
macho_segment_command* linkEdit,
uintptr_t slide,
macho_segment_command** segments,
int segCount)
{
/*
* HARD MODE!!!
*/
const uint8_t* base = (uint8_t*)((linkEdit->vmaddr + slide) - linkEdit->fileoff);
const uint8_t* start = addUintPtr2(dyldInfo->rebase_off, base);
const uint8_t* end = addUintPtr3(dyldInfo->rebase_size, dyldInfo->rebase_off, base);
const uint8_t* p = start;
/*
* If you want a better documented version of this code, see 'MachObject.cpp'
*/
uint8_t type = 0;
int segmentIndex = 0;
uintptr_t address = (segments[0]->vmaddr + slide);
uintptr_t segmentEndAddress = (segments[0]->vmaddr + slide + segments[0]->vmsize);
uint32_t count;
uint32_t skip;
bool done = false;
while ( !done && (p < end) ) {
uint8_t immediate = *p & REBASE_IMMEDIATE_MASK;
uint8_t opcode = *p & REBASE_OPCODE_MASK;
++p;
switch (opcode) {
case REBASE_OPCODE_DONE:
done = true;
break;
case REBASE_OPCODE_SET_TYPE_IMM:
type = immediate;
break;
case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
segmentIndex = immediate;
if (segmentIndex > segCount)
lnk::ldbg::printText("LNK_RELOC_ERROR: baaaad whatever \n");
address = (segments[segmentIndex]->vmaddr + slide) + read_uleb128(p, end);
segmentEndAddress = (segments[segmentIndex]->vmaddr + segments[segmentIndex]->vmsize + slide);
break;
case REBASE_OPCODE_ADD_ADDR_ULEB:
address += read_uleb128(p, end);
break;
case REBASE_OPCODE_ADD_ADDR_IMM_SCALED:
address += immediate*sizeof(uintptr_t);
break;
case REBASE_OPCODE_DO_REBASE_IMM_TIMES:
for (int i=0; i < immediate; ++i) {
if ( address >= segmentEndAddress )
lnk::ldbg::printText("LNK_RELOC_ERROR: baaaad REBASE_OPCODE_DO_REBASE_IMM_TIMES \n");
rebaseAt(address, slide, type);
address += sizeof(uintptr_t);
}
break;
case REBASE_OPCODE_DO_REBASE_ULEB_TIMES:
count = read_uleb128(p, end);
for (uint32_t i=0; i < count; ++i) {
if ( address >= segmentEndAddress )
lnk::ldbg::printText("LNK_RELOC_ERROR: baaaad REBASE_OPCODE_DO_REBASE_ULEB_TIMES \n");
rebaseAt(address, slide, type);
address += sizeof(uintptr_t);
}
break;
case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB:
if ( address >= segmentEndAddress )
lnk::ldbg::printText("LNK_RELOC_ERROR: baaaad REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB \n");
rebaseAt(address, slide, type);
address += read_uleb128(p, end) + sizeof(uintptr_t);
break;
case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB:
count = read_uleb128(p, end);
skip = read_uleb128(p, end);
for (uint32_t i=0; i < count; ++i) {
if ( address >= segmentEndAddress )
lnk::ldbg::printText("LNK_RELOC_ERROR: baaaad REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB \n");
rebaseAt(address, slide, type);
address += skip + sizeof(uintptr_t);
}
break;
default:
_printAbrt();
}
}
}
void MachObject::readRebase(const uint8_t* start, const uint8_t* end)
{
/* aaaa!!!! */;
uint8_t type = 0;
int segmentIndex = 0;
uintptr_t address = segActualLoadAddr(0);
uintptr_t segmentEndAddress = segActualEndAddr(0);
uint32_t count;
uint32_t skip;
const uint8_t* p = start;
bool done = false;
while ( !done && (p < end) ) {
uint8_t immediate = *p & REBASE_IMMEDIATE_MASK;
uint8_t opcode = *p & REBASE_OPCODE_MASK;
++p;
switch (opcode) {
case REBASE_OPCODE_DONE:
done = true;
break;
case REBASE_OPCODE_SET_TYPE_IMM:
type = immediate;
break;
case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
segmentIndex = immediate;
if (segmentIndex > fSegmentsCount)
lnk::halt("baaaad seg count for rebase!");
address = segActualLoadAddr(segmentIndex) + read_uleb128(p, end);
segmentEndAddress = segActualEndAddr(segmentIndex);
break;
case REBASE_OPCODE_ADD_ADDR_ULEB:
address += read_uleb128(p, end);
break;
case REBASE_OPCODE_ADD_ADDR_IMM_SCALED:
address += immediate*sizeof(uintptr_t);
break;
case REBASE_OPCODE_DO_REBASE_IMM_TIMES:
for (int i=0; i < immediate; ++i) {
if ( address >= segmentEndAddress )
throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
this->rebaseAt(address, fSlide, type);
address += sizeof(uintptr_t);
}
break;
case REBASE_OPCODE_DO_REBASE_ULEB_TIMES:
count = read_uleb128(p, end);
for (uint32_t i=0; i < count; ++i) {
if ( address >= segmentEndAddress )
throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
this->rebaseAt(address, fSlide, type);
address += sizeof(uintptr_t);
}
break;
case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB:
if ( address >= segmentEndAddress )
throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
this->rebaseAt(address, fSlide, type);
address += read_uleb128(p, end) + sizeof(uintptr_t);
break;
case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB:
count = read_uleb128(p, end);
skip = read_uleb128(p, end);
for (uint32_t i=0; i < count; ++i) {
if ( address >= segmentEndAddress )
throwBadBindingAddress(address, segmentEndAddress, segmentIndex, start, end, p);
rebaseAt(address, fSlide, type);
address += skip + sizeof(uintptr_t);
}
break;
default:
lnk::halt("invalid opcode %d for rebase", *p);
break;
}
}
}
