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Omit Mach_command from stub where allowed.

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changed src/p_mach.cpp
This commit is contained in:
jreiser@BitWagon.com 2016-09-17 09:36:58 -07:00 committed by Markus F.X.J. Oberhumer
parent 7ad1e7756b
commit 345a1c64f9
1 changed files with 40 additions and 4 deletions
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44
src/p_mach.cpp
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@ -798,14 +798,19 @@ void PackMachAMD64::pack4(OutputFile *fo, Filter &ft) // append PackHeader
fo->rewrite(&linfo, sizeof(linfo));
}
if (my_filetype == Mach_header::MH_EXECUTE) {
// Get a writeable copy of the stub to make editing easier.
unsigned char upxstub[sizeof(stub_amd64_darwin_macho_upxmain_exe)];
memcpy(upxstub, stub_amd64_darwin_macho_upxmain_exe, sizeof(upxstub));
Mach_header *const ptr0 = (Mach_header *)upxstub;
Mach_command *ptr1 = (Mach_command *)(1+ ptr0);
unsigned cmdsize = mhdro.sizeofcmds - sizeof(segXHDR);
Mach_header const *const ptr0 = (Mach_header const *)stub_amd64_darwin_macho_upxmain_exe;
Mach_command const *ptr1 = (Mach_command const *)(1+ ptr0);
unsigned const ncmds = mhdro.ncmds;
unsigned delta = 0;
for (unsigned j = 0; j < ncmds -1; ++j,
(cmdsize -= ptr1->cmdsize),
ptr1 = (Mach_command const *)(ptr1->cmdsize + (char const *)ptr1))
ptr1 = (Mach_command *)(ptr1->cmdsize + (char *)ptr1))
next:
switch (ptr1->cmd) {
case Mach_segment_command::LC_SEGMENT_64: {
Mach_segment_command const *const segptr = (Mach_segment_command const *)ptr1;
@ -826,7 +831,10 @@ void PackMachAMD64::pack4(OutputFile *fo, Filter &ft) // append PackHeader
fo->rewrite(getLoader(), d);
fo->seek(0, SEEK_END);
}
if (!strcmp("__LINKEDIT", ((Mach_segment_command const *)ptr1)->segname)) {
if (!strcmp("__DATA", segptr->segname) && !segptr->vmsize) {
goto omit;
}
if (!strcmp("__LINKEDIT", segptr->segname)) {
memcpy(&segLINK, segptr, sizeof(segLINK));
delta = offLINK - segLINK.fileoff; // relocation constant
@ -863,6 +871,7 @@ void PackMachAMD64::pack4(OutputFile *fo, Filter &ft) // append PackHeader
blk.export_size = 0;
fo->seek(sizeof(segXHDR) + ((char const *)ptr1 - (char const *)ptr0), SEEK_SET);
fo->rewrite(&blk, sizeof(blk));
goto omit; // try omitting this
} break;
case Mach_segment_command::LC_SYMTAB: {
Mach_symtab_command blk; memcpy(&blk, ptr1, sizeof(blk));
@ -870,6 +879,7 @@ void PackMachAMD64::pack4(OutputFile *fo, Filter &ft) // append PackHeader
if (blk.stroff) blk.stroff += delta;
fo->seek(sizeof(segXHDR) + ((char const *)ptr1 - (char const *)ptr0), SEEK_SET);
fo->rewrite(&blk, sizeof(blk));
goto omit; // try omitting this
} break;
case Mach_segment_command::LC_DYSYMTAB: {
Mach_dysymtab_command blk; memcpy(&blk, ptr1, sizeof(blk));
@ -888,6 +898,7 @@ void PackMachAMD64::pack4(OutputFile *fo, Filter &ft) // append PackHeader
blk.nundefsym = 0;
fo->seek(sizeof(segXHDR) + ((char const *)ptr1 - (char const *)ptr0), SEEK_SET);
fo->rewrite(&blk, sizeof(blk));
goto omit; // adds full path as another agrument?
} break;
case Mach_segment_command::LC_FUNCTION_STARTS: {
N_Mach::Mach_function_starts_command blk; memcpy(&blk, ptr1, sizeof(blk));
@ -933,7 +944,32 @@ void PackMachAMD64::pack4(OutputFile *fo, Filter &ft) // append PackHeader
fo->seek(0, SEEK_SET);
fo->rewrite(&mhdro, sizeof(mhdro));
} break;
case Mach_segment_command::LC_LOAD_DYLINKER: {
// Try omitting this
omit:
fo->seek(sizeof(mhdro) + mhdro.sizeofcmds - cmdsize, SEEK_SET);
Mach_command *ptr2 = ptr1;
unsigned const sz_omit = ptr1->cmdsize;
ptr1 = (Mach_command *)(sz_omit + (char *)ptr1);
cmdsize -= sz_omit;
fo->rewrite(ptr1, cmdsize); // slide in file TODO: clear the garbage
memmove(ptr2, ptr1, cmdsize); // overlapping slide lower
ptr1 = ptr2;
mhdro.ncmds -= 1;
mhdro.sizeofcmds -= sz_omit;
fo->seek(0, SEEK_SET);
fo->rewrite(&mhdro, sizeof(mhdro));
if (++j < (ncmds -1))
goto next;
goto done;
} break;
case Mach_segment_command::LC_SOURCE_VERSION: {
goto omit;
} break;
} // end switch
done:
fo->seek(0, SEEK_END);
}
}