from elf import Elf64, Elf64_Phdr, Elf64_Shdr, TextSegment, DataSegment
from elf import SStrtab, SSymtab, SProgBits, SNobits, Dynamic, Interpreter
from errors import *
+from ctypes import CDLL
from ctypes.util import find_library
import struct
self.output = Elf64()
self.global_symbols = {}
self.undefined_symbols = set()
+ self.common_symbols = set()
def add_object(self, filename):
"""Find out the globally available symbols, as well as the globally
undefined ones (which should be found in external libraries."""
- # Gather the "extern" symbols from each input files.
+ # Gather the "extern" and common symbols from each input files.
for i in self.objs:
self.undefined_symbols.update(i.undefined_symbols)
+ self.common_symbols.update(i.common_symbols)
# Make a dict with all the symbols declared globally.
# Key is the symbol name, value will later be set to the final
# Find out which symbols aren't really defined anywhere
self.undefined_symbols.difference_update(self.global_symbols)
+ # A symbol declared as COMMON in one object may very well have been
+ # defined in another. In this case, it will be present in the
+ # global_symbols.
+ # Take a copy because we can't change the set's size inside the loop
+ for i in self.common_symbols.copy():
+ if i[0] in self.global_symbols:
+ self.common_symbols.remove(i)
+
def build_external(self, with_jump=False, align_jump=False):
"""
bss_shdr = Elf64_Shdr()
bss_shdr.sh_type = SHT_NOBITS
bss_shdr.sh_flags = (SHF_WRITE | SHF_ALLOC)
- bss_shdr.sh_size = len(symbols) * 8
bss_shdr.content = BinArray("")
fo.shdrs.append(bss_shdr)
fo.sections['.bss'] = bss_shdr
fo.global_symbols['_bold__functions_hash'] = (data_shdr, 0)
fo.global_symbols['_bold__functions_pointers'] = (bss_shdr, 0)
+ # The COMMON symbols. Assign an offset in .bss, declare as global.
+ bss_common_offset = len(symbols) * 8
+ for s_name, s_size, s_alignment in self.common_symbols:
+ padding = (s_alignment - (bss_common_offset % s_alignment)) % s_alignment
+ bss_common_offset += padding
+ fo.global_symbols[s_name] = (bss_shdr, bss_common_offset)
+ bss_common_offset += s_size
+
+ bss_shdr.sh_size = bss_common_offset
+
for n, i in enumerate(symbols):
# The hash is always in .data
h = "_bold__hash_%s" % i
self.shlibs.append(fullname)
+ def check_external(self):
+ """Verify that all globally undefined symbols are present in shared
+ libraries."""
+ libs = []
+ for libname in self.shlibs:
+ libs.append(CDLL(libname))
+
+ for symbol in self.undefined_symbols:
+ # Hackish ! Eek!
+ if symbol.startswith('_bold__'):
+ continue
+ found = False
+ for lib in libs:
+ if hasattr(lib, symbol):
+ found = True
+ break
+ if not found:
+ raise UndefinedSymbol(symbol)
+
+
def link(self):
"""Do the actual linking."""
# Prepare two segments. One for .text, the other for .data + .bss