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