# -*- Python -*- vim: set syntax=python tabstop=4 expandtab cc=80:
# ===----------------------------------------------------------------------===##
#
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#
# ===----------------------------------------------------------------------===##
"""
extract - A set of function that extract symbol lists from shared libraries.
"""
import os.path
from os import environ
import re
import shutil
import subprocess
import sys
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 shutil.which("nm")
def __init__(self, static_lib):
"""
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.static_lib = static_lib
self.flags = ["-P", "-g"]
if sys.platform.startswith("aix"):
# AIX nm demangles symbols by default, so suppress that.
self.flags.append("-C")
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 = subprocess.check_output(cmd).decode()
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 shutil.which("readelf")
def __init__(self, static_lib):
"""
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)
# TODO: Support readelf for reading symbols from archives
assert not static_lib and "RealElf does not yet support static libs"
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 = subprocess.check_output(cmd).decode()
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", "TLS"]
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)):
# Accept both GNU and ELF Tool Chain readelf format. Some versions
# of ELF Tool Chain readelf use ( ) around the symbol table name
# instead of ' ', and omit the blank line before the heading.
if re.match(r"Symbol table ['(].dynsym[')]", lines[i]):
start = i + 2
elif start != -1 and end == -1:
if not lines[i].strip():
end = i + 1
if lines[i].startswith("Symbol table ("):
end = i
assert start != -1
if end == -1:
end = len(lines)
return lines[start:end]
class AIXDumpExtractor(object):
"""
AIXDumpExtractor - Extract symbol lists from libraries using AIX dump.
"""
@staticmethod
def find_tool():
"""
Search for the dump executable and return the path.
"""
return shutil.which("dump")
def __init__(self, static_lib):
"""
Initialize the dump executable and flags that will be used to
extract symbols from shared libraries.
"""
# TODO: Support dump for reading symbols from static libraries
assert not static_lib and "static libs not yet supported with dump"
self.tool = self.find_tool()
if self.tool is None:
print("ERROR: Could not find dump")
sys.exit(1)
self.flags = ["-n", "-v"]
object_mode = environ.get("OBJECT_MODE")
if object_mode == "32":
self.flags += ["-X32"]
elif object_mode == "64":
self.flags += ["-X64"]
else:
self.flags += ["-X32_64"]
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 = subprocess.check_output(cmd).decode()
loader_syms = self.get_loader_symbol_table(out)
return self.process_syms(loader_syms)
def process_syms(self, sym_list):
new_syms = []
for s in sym_list:
parts = s.split()
if not parts:
continue
assert len(parts) == 8 or len(parts) == 7
if len(parts) == 7:
continue
new_sym = {
"name": parts[7],
"type": "FUNC" if parts[4] == "DS" else "OBJECT",
"is_defined": (parts[5] != "EXTref"),
"storage_mapping_class": parts[4],
"import_export": parts[3],
}
if new_sym["name"] in extract_ignore_names:
continue
new_syms += [new_sym]
return new_syms
def get_loader_symbol_table(self, out):
lines = out.splitlines()
return filter(lambda n: re.match(r"^\[[0-9]+\]", n), lines)
@staticmethod
def is_shared_lib(lib):
"""
Check for the shared object flag in XCOFF headers of the input file or
library archive.
"""
dump = AIXDumpExtractor.find_tool()
if dump is None:
print("ERROR: Could not find dump")
sys.exit(1)
cmd = [dump, "-X32_64", "-ov", lib]
out = subprocess.check_output(cmd).decode()
return out.find("SHROBJ") != -1
def is_static_library(lib_file):
"""
Determine if a given library is static or shared.
"""
if sys.platform.startswith("aix"):
# An AIX library could be both, but for simplicity assume it isn't.
return not AIXDumpExtractor.is_shared_lib(lib_file)
else:
_, ext = os.path.splitext(lib_file)
return ext == ".a"
def extract_symbols(lib_file, static_lib=None):
"""
Extract and return a list of symbols extracted from a static or dynamic
library. The symbols are extracted using dump, nm or readelf. They are
then filtered and formated. Finally the symbols are made unique.
"""
if static_lib is None:
static_lib = is_static_library(lib_file)
if sys.platform.startswith("aix"):
extractor = AIXDumpExtractor(static_lib=static_lib)
elif ReadElfExtractor.find_tool() and not static_lib:
extractor = ReadElfExtractor(static_lib=static_lib)
else:
extractor = NMExtractor(static_lib=static_lib)
return extractor.extract(lib_file)
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