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# vim: set ts=8 sts=4 et sw=4 tw=79:
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#----------------------------------------------------------------------------
# All heap allocations in SpiderMonkey must go through js_malloc, js_calloc,
# js_realloc, and js_free. This is so that any embedder who uses a custom
# allocator (by defining JS_USE_CUSTOM_ALLOCATOR) will see all heap allocation
# go through that custom allocator.
#
# Therefore, the presence of any calls to "vanilla" allocation/free functions
# (e.g. malloc(), free()) is a bug.
#
# This script checks for the presence of such disallowed vanilla
# allocation/free function in SpiderMonkey when it's built as a library. It
# relies on |nm| from the GNU binutils, and so only works on Linux, but one
# platform is good enough to catch almost all violations.
#
# This checking is only 100% reliable in a JS_USE_CUSTOM_ALLOCATOR build in
# which the default definitions of js_malloc et al (in Utility.h) -- which call
# malloc et al -- are replaced with empty definitions. This is because the
# presence and possible inlining of the default js_malloc et al can cause
# malloc/calloc/realloc/free calls show up in unpredictable places.
#
# Unfortunately, that configuration cannot be tested on Mozilla's standard
# testing infrastructure. Instead, by default this script only tests that none
# of the other vanilla allocation/free functions (operator new, memalign, etc)
# are present. If given the --aggressive flag, it will also check for
# malloc/calloc/realloc/free.
#
# Note: We don't check for |operator delete| and |operator delete[]|. These
# can be present somehow due to virtual destructors, but this is not too
# because vanilla delete/delete[] calls don't make sense without corresponding
# vanilla new/new[] calls, and any explicit calls will be caught by Valgrind's
# mismatched alloc/free checking.
#----------------------------------------------------------------------------
from __future__ import print_function
import argparse
import re
import subprocess
import sys
# The obvious way to implement this script is to search for occurrences of
# malloc et al, succeed if none are found, and fail is some are found.
# However, "none are found" does not necessarily mean "none are present" --
# this script could be buggy. (Or the output format of |nm| might change in
# the future.)
#
# So jsutil.cpp deliberately contains a (never-called) function that contains a
# single use of all the vanilla allocation/free functions. And this script
# fails if it (a) finds uses of those functions in files other than jsutil.cpp,
# *or* (b) fails to find them in jsutil.cpp.
# Tracks overall success of the test.
has_failed = False
def fail(msg):
print('TEST-UNEXPECTED-FAIL | check_vanilla_allocations.py |', msg)
global has_failed
has_failed = True
def main():
parser = argparse.ArgumentParser()
parser.add_argument('--aggressive', action='store_true',
help='also check for malloc, calloc, realloc and free')
parser.add_argument('file', type=str,
help='name of the file to check')
args = parser.parse_args()
# Run |nm|. Options:
# -u: show only undefined symbols
# -C: demangle symbol names
# -A: show an object filename for each undefined symbol
cmd = ['nm', '-u', '-C', '-A', args.file]
lines = subprocess.check_output(cmd, universal_newlines=True,
stderr=subprocess.PIPE).split('\n')
# alloc_fns contains all the vanilla allocation/free functions that we look
# for. Regexp chars are escaped appropriately.
alloc_fns = [
# Matches |operator new(unsigned T)|, where |T| is |int| or |long|.
r'operator new\(unsigned',
# Matches |operator new[](unsigned T)|, where |T| is |int| or |long|.
r'operator new\[\]\(unsigned',
r'memalign',
# These three aren't available on all Linux configurations.
#r'posix_memalign',
#r'aligned_alloc',
#r'valloc',
]
if args.aggressive:
alloc_fns += [
r'malloc',
r'calloc',
r'realloc',
r'free',
r'strdup'
]
# This is like alloc_fns, but regexp chars are not escaped.
alloc_fns_unescaped = [fn.translate(None, r'\\') for fn in alloc_fns]
# This regexp matches the relevant lines in the output of |nm|, which look
# like the following.
#
# js/src/libjs_static.a:jsutil.o: U malloc
#
alloc_fns_re = r'([^:/ ]+):\s+U (' + r'|'.join(alloc_fns) + r')'
# This tracks which allocation/free functions have been seen in jsutil.cpp.
jsutil_cpp = set([])
# Would it be helpful to emit detailed line number information after a failure?
emit_line_info = False
for line in lines:
m = re.search(alloc_fns_re, line)
if m is None:
continue
filename = m.group(1)
fn = m.group(2)
if filename == 'jsutil.o':
jsutil_cpp.add(fn)
else:
# An allocation is present in a non-special file. Fail!
fail("'" + fn + "' present in " + filename)
# Try to give more precise information about the offending code.
emit_line_info = True
# Check that all functions we expect are used in jsutil.cpp. (This will
# fail if the function-detection code breaks at any point.)
for fn in alloc_fns_unescaped:
if fn not in jsutil_cpp:
fail("'" + fn + "' isn't used as expected in jsutil.cpp")
else:
jsutil_cpp.remove(fn)
# This should never happen, but check just in case.
if jsutil_cpp:
fail('unexpected allocation fns used in jsutil.cpp: ' +
', '.join(jsutil_cpp))
# If we found any improper references to allocation functions, try to use
# DWARF debug info to get more accurate line number information about the
# bad calls. This is a lot slower than 'nm -A', and it is not always
# precise when building with --enable-optimized.
if emit_line_info:
print('check_vanilla_allocations.py: Source lines with allocation calls:')
print('check_vanilla_allocations.py: Accurate in unoptimized builds; jsutil.cpp expected.')
# Run |nm|. Options:
# -u: show only undefined symbols
# -C: demangle symbol names
# -l: show line number information for each undefined symbol
cmd = ['nm', '-u', '-C', '-l', args.file]
lines = subprocess.check_output(cmd, universal_newlines=True,
stderr=subprocess.PIPE).split('\n')
# This regexp matches the relevant lines in the output of |nm -l|,
# which look like the following.
#
# U malloc jsutil.cpp:117
#
alloc_lines_re = r'U ((' + r'|'.join(alloc_fns) + r').*)\s+(\S+:\d+)$'
for line in lines:
m = re.search(alloc_lines_re, line)
if m:
print('check_vanilla_allocations.py:', m.group(1), 'called at', m.group(3))
if has_failed:
sys.exit(1)
print('TEST-PASS | check_vanilla_allocations.py | ok')
sys.exit(0)
if __name__ == '__main__':
main()
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