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# -*- Python -*- vim: set syntax=python tabstop=4 expandtab cc=80:
#===----------------------------------------------------------------------===##
#
# The LLVM Compiler Infrastructure
#
# This file is dual licensed under the MIT and the University of Illinois Open
# Source Licenses. See LICENSE.TXT for details.
#
#===----------------------------------------------------------------------===##
"""
extract - A set of function that extract symbol lists from shared libraries.
"""
import distutils.spawn
import sys
import re
import libcxx.util
from libcxx.sym_check import util
extract_ignore_names = ['_init', '_fini']
class NMExtractor(object):
"""
NMExtractor - Extract symbol lists from libraries using nm.
"""
@staticmethod
def find_tool():
"""
Search for the nm executable and return the path.
"""
return distutils.spawn.find_executable('nm')
def __init__(self):
"""
Initialize the nm executable and flags that will be used to extract
symbols from shared libraries.
"""
self.nm_exe = self.find_tool()
if self.nm_exe is None:
# ERROR no NM found
print("ERROR: Could not find nm")
sys.exit(1)
self.flags = ['-P', '-g']
def extract(self, lib):
"""
Extract symbols from a library and return the results as a dict of
parsed symbols.
"""
cmd = [self.nm_exe] + self.flags + [lib]
out, _, exit_code = libcxx.util.executeCommandVerbose(cmd)
if exit_code != 0:
raise RuntimeError('Failed to run %s on %s' % (self.nm_exe, lib))
fmt_syms = (self._extract_sym(l)
for l in out.splitlines() if l.strip())
# Cast symbol to string.
final_syms = (repr(s) for s in fmt_syms if self._want_sym(s))
# Make unique and sort strings.
tmp_list = list(sorted(set(final_syms)))
# Cast string back to symbol.
return util.read_syms_from_list(tmp_list)
def _extract_sym(self, sym_str):
bits = sym_str.split()
# Everything we want has at least two columns.
if len(bits) < 2:
return None
new_sym = {
'name': bits[0],
'type': bits[1],
'is_defined': (bits[1].lower() != 'u')
}
new_sym['name'] = new_sym['name'].replace('@@', '@')
new_sym = self._transform_sym_type(new_sym)
# NM types which we want to save the size for.
if new_sym['type'] == 'OBJECT' and len(bits) > 3:
new_sym['size'] = int(bits[3], 16)
return new_sym
@staticmethod
def _want_sym(sym):
"""
Check that s is a valid symbol that we want to keep.
"""
if sym is None or len(sym) < 2:
return False
if sym['name'] in extract_ignore_names:
return False
bad_types = ['t', 'b', 'r', 'd', 'w']
return (sym['type'] not in bad_types
and sym['name'] not in ['__bss_start', '_end', '_edata'])
@staticmethod
def _transform_sym_type(sym):
"""
Map the nm single letter output for type to either FUNC or OBJECT.
If the type is not recognized it is left unchanged.
"""
func_types = ['T', 'W']
obj_types = ['B', 'D', 'R', 'V', 'S']
if sym['type'] in func_types:
sym['type'] = 'FUNC'
elif sym['type'] in obj_types:
sym['type'] = 'OBJECT'
return sym
class ReadElfExtractor(object):
"""
ReadElfExtractor - Extract symbol lists from libraries using readelf.
"""
@staticmethod
def find_tool():
"""
Search for the readelf executable and return the path.
"""
return distutils.spawn.find_executable('readelf')
def __init__(self):
"""
Initialize the readelf executable and flags that will be used to
extract symbols from shared libraries.
"""
self.tool = self.find_tool()
if self.tool is None:
# ERROR no NM found
print("ERROR: Could not find readelf")
sys.exit(1)
self.flags = ['--wide', '--symbols']
def extract(self, lib):
"""
Extract symbols from a library and return the results as a dict of
parsed symbols.
"""
cmd = [self.tool] + self.flags + [lib]
out, _, exit_code = libcxx.util.executeCommandVerbose(cmd)
if exit_code != 0:
raise RuntimeError('Failed to run %s on %s' % (self.nm_exe, lib))
dyn_syms = self.get_dynsym_table(out)
return self.process_syms(dyn_syms)
def process_syms(self, sym_list):
new_syms = []
for s in sym_list:
parts = s.split()
if not parts:
continue
assert len(parts) == 7 or len(parts) == 8 or len(parts) == 9
if len(parts) == 7:
continue
new_sym = {
'name': parts[7],
'size': int(parts[2]),
'type': parts[3],
'is_defined': (parts[6] != 'UND')
}
assert new_sym['type'] in ['OBJECT', 'FUNC', 'NOTYPE']
if new_sym['name'] in extract_ignore_names:
continue
if new_sym['type'] == 'NOTYPE':
continue
if new_sym['type'] == 'FUNC':
del new_sym['size']
new_syms += [new_sym]
return new_syms
def get_dynsym_table(self, out):
lines = out.splitlines()
start = -1
end = -1
for i in range(len(lines)):
if lines[i].startswith("Symbol table '.dynsym'"):
start = i + 2
if start != -1 and end == -1 and not lines[i].strip():
end = i + 1
assert start != -1
if end == -1:
end = len(lines)
return lines[start:end]
def extract_symbols(lib_file):
"""
Extract and return a list of symbols extracted from a dynamic library.
The symbols are extracted using NM. They are then filtered and formated.
Finally they symbols are made unique.
"""
if ReadElfExtractor.find_tool():
extractor = ReadElfExtractor()
else:
extractor = NMExtractor()
return extractor.extract(lib_file)
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