import argparse

import collections

import logging

import os

import re

import shutil

import subprocess

import sys

import tempfile

PROJECT_ROOT = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))

Violation = collections.namedtuple('Violation', ['file', 'object', 'symbol'])

class Ignores(collections.namedtuple('Ignores',

['ignore_files', 'ignore_objects', 'ignore_symbols'])):

def is_ignored(self, violation):

return any(re.search(ignore_file, violation.file) is not None for ignore_file in

self.ignore_files) or any(

re.search(ignore_object, violation.object) is not None for ignore_object in

self.ignore_objects) or any(

re.search(ignore_symbol, violation.symbol) is not None for ignore_symbol in

self.ignore_symbols)

def filter_out_static_symbols(violations):

files = {v.file for v in violations}

files = [(f if os.path.isabs(f) else os.path.join('demo', f)) for f in files]

static_symbols = set()

if len(files) > 0:

for entry in subprocess.run(['nm', '--portability'] + files, universal_newlines=True,

stdout=subprocess.PIPE, check=True).stdout.splitlines():

columns = entry.split()

# second column of nm output specifies symbol type

# it's supposed to be a single letter, see man nm for details

# lowercase generally means the symbol has internal linkage

if len(columns) >= 2 and re.search(r'[a-z]', columns[1]) is not None:

static_symbols.add(columns[0])

return {v for v in violations if v.symbol not in static_symbols}

def find_unused_code(jobs, ignores):

# check installed versions

subprocess.run(['gcc', '--version'], text=True, check=True)

subprocess.run(['ld', '-v'], text=True, check=True)

subprocess.run(['cmake', '--version'], text=True, check=True)

DEVCONFIG_OUT_FNAME = 'devconfig.out'

MAKE_OUT_FNAME = 'make.out'

UNUSED_SECTIONS_FNAME = 'unused-sections'

logging.info('configuring: %s/%s', os.getcwd(), DEVCONFIG_OUT_FNAME)

with open(DEVCONFIG_OUT_FNAME, 'w') as out:

subprocess.run([os.path.join(PROJECT_ROOT, 'devconfig'), '--without-memcheck',

'-DCMAKE_C_FLAGS=-ffunction-sections -fdata-sections',

'-DCMAKE_EXE_LINKER_FLAGS=-Wl,--gc-sections -Wl,--print-gc-sections -Wl,--gc-keep-exported',

'-DWITH_AVS_CRYPTO_PKI_ENGINE=OFF', '-DWITH_STATIC_ANALYSIS=OFF'],

stdout=out, stderr=out, check=True)

with open('CMakeCache.txt', 'r') as f:

cmake_binary_candidates = [line for line in f.readlines() if line.startswith('CMAKE_COMMAND')]

assert len(cmake_binary_candidates) == 1

cmake_binary = cmake_binary_candidates[0].split('=')[-1].strip()

logging.info('compiling: %s/%s', os.getcwd(), MAKE_OUT_FNAME)

with open(MAKE_OUT_FNAME, 'w') as out:

subprocess.run([cmake_binary, '--build', '.', '--', '-j%d' % (jobs,)], stdout=out, stderr=out,

check=True)

# examples of lines we're looking for in ld output:

#

### GNU ld 2.26.1 on Ubuntu 16.04

# /usr/bin/ld: Removing unused section '.rodata.AVS_NET_EPROTO' in file '../output/lib/libavs_net.a(net_impl.c.o)'

# /usr/bin/ld: Removing unused section '.data' in file '/usr/lib/gcc/x86_64-linux-gnu/5/crtbegin.o'

#

### GNU ld 2.31.1 on Ubuntu 18.10 (lowercase r in "removing")

# /usr/bin/ld: removing unused section '.rodata.AVS_NET_EPROTO' in file '../output/lib/libavs_net.a(net_impl.c.o)'

# /usr/bin/ld: removing unused section '.data' in file '/usr/lib/gcc/x86_64-linux-gnu/5/crtbegin.o'

#

violations = set()

with open(MAKE_OUT_FNAME, 'r') as f:

for line in f:

match = re.search(r'removing unused section (.*) in file (.*)$', line.strip(),

re.IGNORECASE)

if match is None:

continue

symbol = match.group(1).strip().strip("'")

# drop .$SECTION. prefix

symbol = re.sub(r'^\.(data|rodata|text)\.(rel\.ro\.local\.)?', '', symbol, 1)

file_obj = match.group(2).strip().strip("'")

match = re.fullmatch(r'(.*)\((.*)\)', file_obj)

if match is not None:

violations.add(Violation(file=match.group(1), object=match.group(2), symbol=symbol))

else:

violations.add(Violation(file=file_obj, object=file_obj, symbol=symbol))

violations = {v for v in violations if not ignores.is_ignored(v)}

violations = filter_out_static_symbols(violations)

if len(violations) == 0:

return 0

logging.error('unused symbols found:')

# Column formatting, adapted from https://stackoverflow.com/a/12065663

widths = [max(map(len, col)) for col in zip(*violations)]

with open(UNUSED_SECTIONS_FNAME, 'w') as f:

for violation in sorted(violations):

line = ' '.join((val.ljust(width) for val, width in zip(violation, widths)))

print(line, file=f)

logging.error(line)

return 1

if __name__ == '__main__':

parser = argparse.ArgumentParser(description="Find unused exported symbols in the codebase")

parser.add_argument('-j', '--jobs', type=int, help='run build in N parallel jobs',

default=os.cpu_count())

parser.add_argument('-s', '--ignore-symbol', action='append',

help='do not report unused symbols matching REGEX')

parser.add_argument('-o', '--ignore-object', action='append',

help='do not report unused symbols from object files matching REGEX')

parser.add_argument('-f', '--ignore-file', action='append',

help='do not report unused symbols from files matching REGEX')

parser.add_argument('--preserve-tmpdir', action='store_true',

help='do not delete temporary directory after finishing')

args = parser.parse_args()

logging.getLogger().setLevel(logging.DEBUG)

for file in args.ignore_file:

logging.debug('ignoring file: %s', file)

for obj in args.ignore_object:

logging.debug('ignoring object file: %s', obj)

for sym in args.ignore_symbol:

logging.debug('ignoring symbol: %s', sym)

tmpdir = tempfile.mkdtemp()

try:

os.chdir(tmpdir)

sys.exit(find_unused_code(args.jobs, Ignores(args.ignore_file, args.ignore_object,

args.ignore_symbol)))

finally:

if not args.preserve_tmpdir:

shutil.rmtree(tmpdir)