# 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 # from within SpiderMonkey itself (e.g. malloc(), free()) is a bug. Calls from # within mozglue and non-SpiderMonkey locations are fine; there is a list of # exceptions that can be added to as the need arises. # # 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. # ---------------------------------------------------------------------------- import argparse import re import subprocess import sys from collections import defaultdict import buildconfig # 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 util/Utility.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 # util/Utility.cpp, *or* (b) fails to find them in util/Utility.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: # -C: demangle symbol names # -A: show an object filename for each undefined symbol nm = buildconfig.substs.get("NM") or "nm" cmd = [nm, "-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. operator_news = [ # 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", ] # operator new may end up inlined and replaced with moz_xmalloc. inlined_operator_news = [ r"moz_xmalloc", ] alloc_fns = ( operator_news + inlined_operator_news + [ 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_escaped = [re.escape(fn) 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:Utility.o: U malloc # js/src/libjs_static.a:Utility.o: 00000000000007e0 T js::SetSourceOptions(...) # # It may also, in LTO builds, look like # js/src/libjs_static.a:Utility.o: ---------------- T js::SetSourceOptions(...) # nm_line_re = re.compile(r"([^:/ ]+):\s*(?:[0-9a-fA-F]*|-*)\s+([TUw]) (.*)") alloc_fns_re = re.compile(r"|".join(alloc_fns_escaped)) # This tracks which allocation/free functions have been seen. functions = defaultdict(set) files = defaultdict(int) # Files to ignore allocation/free functions from. ignored_files = [ # Ignore implicit call to operator new in std::condition_variable_any. # # From intl/icu/source/common/umutex.h: # On Linux, the default constructor of std::condition_variable_any # produces an in-line reference to global operator new(), [...]. "umutex.o", # Ignore allocations from decimal conversion functions inside mozglue. "Decimal.o", # Ignore use of std::string in regexp AST debug output. "regexp-ast.o", # mozglue/misc/Debug.cpp contains a call to `printf_stderr("%s", aStr.str().c_str())` # where `aStr` is a `std::stringstream`. In inlined opt builds, this calls # `operator new()` and `operator delete` for a temporary. "Debug.o", ] all_ignored_files = set((f, 1) for f in ignored_files) # Would it be helpful to emit detailed line number information after a failure? emit_line_info = False prev_filename = None for line in lines: m = nm_line_re.search(line) if m is None: continue filename, symtype, fn = m.groups() if prev_filename != filename: # When the same filename appears multiple times, separated by other # file names, this denotes a different file. Thankfully, we can more # or less safely assume that dir1/Foo.o and dir2/Foo.o are not going # to be next to each other. files[filename] += 1 prev_filename = filename # The stdc++compat library has an implicit call to operator new in # thread::_M_start_thread. if "stdc++compat" in filename: continue # The memory allocator code contains calls to memalign. These are ok, so # we whitelist them. if "_memory_" in filename: continue # {fmt} can do transient allocations when formatting strings if "third_party_fmt" in filename: continue # Ignore the fuzzing code imported from m-c if "Fuzzer" in filename: continue # Ignore the profiling pseudo-stack, since it needs to run even when # SpiderMonkey's allocator isn't initialized. if "ProfilingStack" in filename: continue if symtype == "T": # We can't match intl/components files by file name because in # non-unified builds they overlap with files in js/src. # So we check symbols they define, and consider files with symbols # in the mozilla::intl namespace to be those. if fn.startswith("mozilla::intl::"): all_ignored_files.add((filename, files[filename])) else: m = alloc_fns_re.match(fn) if m: functions[(filename, files[filename])].add(m.group(0)) util_Utility_cpp = functions.pop(("Utility.o", 1)) if ("Utility.o", 2) in functions: fail("There should be only one Utility.o file") for f, n in all_ignored_files: functions.pop((f, n), None) if f in ignored_files and (f, 2) in functions: fail(f"There should be only one {f} file") for filename, n in sorted(functions): for fn in functions[(filename, n)]: # 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 util/Utility.cpp. (This # will fail if the function-detection code breaks at any point.) # operator new and its inlined equivalent are mutually exclusive. has_operator_news = any(fn in operator_news for fn in util_Utility_cpp) has_inlined_operator_news = any( fn in inlined_operator_news for fn in util_Utility_cpp ) if has_operator_news and has_inlined_operator_news: fail( "Both operator new and moz_xmalloc aren't expected in util/Utility.cpp at the same time" ) for fn in alloc_fns: if fn not in util_Utility_cpp: if ( (fn in operator_news and not has_inlined_operator_news) or (fn in inlined_operator_news and not has_operator_news) or (fn not in operator_news and fn not in inlined_operator_news) ): fail("'" + fn + "' isn't used as expected in util/Utility.cpp") else: util_Utility_cpp.remove(fn) # This should never happen, but check just in case. if util_Utility_cpp: fail( "unexpected allocation fns used in util/Utility.cpp: " + ", ".join(util_Utility_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; " "util/Utility.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 util/Utility.cpp:117 # alloc_lines_re = ( r"[Uw] ((" + r"|".join(alloc_fns_escaped) + 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()