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"""
Class to read the symbol table from a Mach-O header
"""
from macholib.mach_o import *
__all__ = ['SymbolTable']
# XXX: Does not support 64-bit, probably broken anyway
class SymbolTable(object):
def __init__(self, macho, openfile=None):
if openfile is None:
openfile = open
self.macho = macho.headers[0]
self.symtab = macho.getSymbolTableCommand()
self.dysymtab = macho.getDynamicSymbolTableCommand()
fh = openfile(self.macho.filename, 'rb')
try:
if self.symtab is not None:
self.readSymbolTable(fh)
if self.dysymtab is not None:
self.readDynamicSymbolTable(fh)
finally:
fh.close()
def readSymbolTable(self, fh):
cmd = self.symtab
fh.seek(cmd.stroff)
strtab = fh.read(cmd.strsize)
fh.seek(cmd.symoff)
nlists = []
for i in xrange(cmd.nsyms):
cmd = nlist.from_fileobj(fh)
if cmd.n_un == 0:
nlists.append((cmd, ''))
else:
nlists.append((cmd, strtab[cmd.n_un:strtab.find(b'\x00', cmd.n_un)]))
self.nlists = nlists
def readDynamicSymbolTable(self, fh):
cmd = self.dysymtab
nlists = self.nlists
self.localsyms = nlists[cmd.ilocalsym:cmd.ilocalsym+cmd.nlocalsym]
self.extdefsyms = nlists[cmd.iextdefsym:cmd.iextdefsym+cmd.nextdefsym]
self.undefsyms = nlists[cmd.iundefsym:cmd.iundefsym+cmd.nundefsym]
#if cmd.tocoff == 0:
# self.toc = None
#else:
# self.toc = self.readtoc(fh, cmd.tocoff, cmd.ntoc)
#if cmd.modtaboff == 0:
# self.modtab = None
#else:
# self.modtab = self.readmodtab(fh, cmd.modtaboff, cmd.nmodtab)
if cmd.extrefsymoff == 0:
self.extrefsym = None
else:
self.extrefsym = self.readsym(fh, cmd.extrefsymoff, cmd.nextrefsyms)
#if cmd.indirectsymoff == 0:
# self.indirectsym = None
#else:
# self.indirectsym = self.readsym(fh, cmd.indirectsymoff, cmd.nindirectsyms)
#if cmd.extreloff == 0:
# self.extrel = None
#else:
# self.extrel = self.readrel(fh, cmd.extreloff, cmd.nextrel)
#if cmd.locreloff == 0:
# self.locrel = None
#else:
# self.locrel = self.readrel(fh, cmd.locreloff, cmd.nlocrel)
def readtoc(self, fh, off, n):
#print 'toc', off, n
fh.seek(off)
return [dylib_table_of_contents.from_fileobj(fh) for i in xrange(n)]
def readmodtab(self, fh, off, n):
#print 'modtab', off, n
fh.seek(off)
return [dylib_module.from_fileobj(fh) for i in xrange(n)]
def readsym(self, fh, off, n):
#print 'sym', off, n
fh.seek(off)
refs = []
for i in xrange(n):
ref = dylib_reference.from_fileobj(fh)
isym, flags = divmod(ref.isym_flags, 256)
refs.append((self.nlists[isym], flags))
return refs
def readrel(self, fh, off, n):
#print 'rel', off, n
fh.seek(off)
return [relocation_info.from_fileobj(fh) for i in xrange(n)]
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