config/check_vanilla_allocations.py
author Narcis Beleuzu <nbeleuzu@mozilla.com>
Fri, 15 Dec 2017 02:16:50 +0200
changeset 396515 d0d709880f192e88d1601b657cd562a6fe56d4aa
parent 382473 05ad53f12a1bc0128d58fbfa1c61da44774c6a5e
child 397319 0052f68e4f792b2da308909387c6f12f14a59b9c
permissions -rw-r--r--
Backed out 7 changesets (bug 1377007) for web platform reftests failures on CSS2/borders. r=backout Backed out changeset c30bc5d5adbc (bug 1377007) Backed out changeset 33fdf9e531e2 (bug 1377007) Backed out changeset 267abdb38036 (bug 1377007) Backed out changeset 4a452c3ac115 (bug 1377007) Backed out changeset e9310960c9e6 (bug 1377007) Backed out changeset 8e5e61dfbbaf (bug 1377007) Backed out changeset 9ac83e79e656 (bug 1377007)

# 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)

        # The memory allocator code contains calls to memalign. These are ok, so
        # we whitelist them.
        if "_memory_" in filename:
            continue

        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()