config/check_vanilla_allocations.py
author Ryan VanderMeulen <ryanvm@gmail.com>
Tue, 07 Oct 2014 13:16:11 -0400
changeset 209203 47a1219c63246bd760e74c88ed67a722c0230367
parent 206553 e76c7a8df029f0d4ddd0a840cae94d3089fd110a
child 220666 a5e74ea5a1594dab03f3d06e28e065f6de65abdd
permissions -rw-r--r--
Backed out 7 changesets (bug 1047483, bug 1079301, bug 1079335) for webplatform test failures. Backed out changeset 7d06b68c44d0 (bug 1079335) Backed out changeset 92030169528e (bug 1079301) Backed out changeset c09d7f95554a (bug 1047483) Backed out changeset c199f1057d7e (bug 1047483) Backed out changeset 18830d07884c (bug 1047483) Backed out changeset e087289ccfbb (bug 1047483) Backed out changeset 6238ff5d3ed0 (bug 1047483) CLOSED TREE

# 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
    # -l: show a filename and line number for each undefined symbol
    cmd = ['nm', '-u', '-C', '-l', 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 two 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.
    #
    #   U malloc  /path/to/objdir/dist/include/js/Utility.h:142
    #
    alloc_fns_re = r'U (' + r'|'.join(alloc_fns) + r').*\/([\w\.]+):(\d+)$'

    # This tracks which allocation/free functions have been seen in jsutil.cpp.
    jsutil_cpp = set([])

    for line in lines:
        m = re.search(alloc_fns_re, line)
        if m is None:
            continue

        fn = m.group(1)
        filename = m.group(2)
        linenum = m.group(3)
        if filename == 'jsutil.cpp':
            jsutil_cpp.add(fn)
        else:
            # An allocation is present in a non-special file.  Fail!
            fail("'" + fn + "' present at " + filename + ':' + linenum)


    # 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 has_failed:
        sys.exit(1)

    print('TEST-PASS | check_vanilla_allocations.py | ok')
    sys.exit(0)


if __name__ == '__main__':
    main()