config/check_vanilla_allocations.py

   1 # vim: set ts=8 sts=4 et sw=4 tw=79:
   2 # This Source Code Form is subject to the terms of the Mozilla Public
   3 # License, v. 2.0. If a copy of the MPL was not distributed with this
   4 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
   5
   6 # ----------------------------------------------------------------------------
   7 # All heap allocations in SpiderMonkey must go through js_malloc, js_calloc,
   8 # js_realloc, and js_free.  This is so that any embedder who uses a custom
   9 # allocator (by defining JS_USE_CUSTOM_ALLOCATOR) will see all heap allocation
  10 # go through that custom allocator.
  11 #
  12 # Therefore, the presence of any calls to "vanilla" allocation/free functions
  13 # from within SpiderMonkey itself (e.g. malloc(), free()) is a bug.  Calls from
  14 # within mozglue and non-SpiderMonkey locations are fine; there is a list of
  15 # exceptions that can be added to as the need arises.
  16 #
  17 # This script checks for the presence of such disallowed vanilla
  18 # allocation/free function in SpiderMonkey when it's built as a library.  It
  19 # relies on |nm| from the GNU binutils, and so only works on Linux, but one
  20 # platform is good enough to catch almost all violations.
  21 #
  22 # This checking is only 100% reliable in a JS_USE_CUSTOM_ALLOCATOR build in
  23 # which the default definitions of js_malloc et al (in Utility.h) -- which call
  24 # malloc et al -- are replaced with empty definitions.  This is because the
  25 # presence and possible inlining of the default js_malloc et al can cause
  26 # malloc/calloc/realloc/free calls show up in unpredictable places.
  27 #
  28 # Unfortunately, that configuration cannot be tested on Mozilla's standard
  29 # testing infrastructure.  Instead, by default this script only tests that none
  30 # of the other vanilla allocation/free functions (operator new, memalign, etc)
  31 # are present.  If given the --aggressive flag, it will also check for
  32 # malloc/calloc/realloc/free.
  33 #
  34 # Note:  We don't check for |operator delete| and |operator delete[]|.  These
  35 # can be present somehow due to virtual destructors, but this is not too
  36 # because vanilla delete/delete[] calls don't make sense without corresponding
  37 # vanilla new/new[] calls, and any explicit calls will be caught by Valgrind's
  38 # mismatched alloc/free checking.
  39 # ----------------------------------------------------------------------------
  40
  41 import argparse
  42 import re
  43 import subprocess
  44 import sys
  45 from collections import defaultdict
  46
  47 import buildconfig
  48
  49 # The obvious way to implement this script is to search for occurrences of
  50 # malloc et al, succeed if none are found, and fail is some are found.
  51 # However, "none are found" does not necessarily mean "none are present" --
  52 # this script could be buggy.  (Or the output format of |nm| might change in
  53 # the future.)
  54 #
  55 # So util/Utility.cpp deliberately contains a (never-called) function that
  56 # contains a single use of all the vanilla allocation/free functions.  And this
  57 # script fails if it (a) finds uses of those functions in files other than
  58 # util/Utility.cpp, *or* (b) fails to find them in util/Utility.cpp.
  59
  60 # Tracks overall success of the test.
  61 has_failed = False
  62
  63
  64 def fail(msg):
  65     print("TEST-UNEXPECTED-FAIL | check_vanilla_allocations.py |", msg)
  66     global has_failed
  67     has_failed = True
  68
  69
  70 def main():
  71     parser = argparse.ArgumentParser()
  72     parser.add_argument(
  73         "--aggressive",
  74         action="store_true",
  75         help="also check for malloc, calloc, realloc and free",
  76     )
  77     parser.add_argument("file", type=str, help="name of the file to check")
  78     args = parser.parse_args()
  79
  80     # Run |nm|.  Options:
  81     # -C: demangle symbol names
  82     # -A: show an object filename for each undefined symbol
  83     nm = buildconfig.substs.get("NM") or "nm"
  84     cmd = [nm, "-C", "-A", args.file]
  85     lines = subprocess.check_output(
  86         cmd, universal_newlines=True, stderr=subprocess.PIPE
  87     ).split("\n")
  88
  89     # alloc_fns contains all the vanilla allocation/free functions that we look
  90     # for. Regexp chars are escaped appropriately.
  91
  92     operator_news = [
  93         # Matches |operator new(unsigned T)|, where |T| is |int| or |long|.
  94         r"operator new(unsigned",
  95         # Matches |operator new[](unsigned T)|, where |T| is |int| or |long|.
  96         r"operator new[](unsigned",
  97     ]
  98
  99     # operator new may end up inlined and replaced with moz_xmalloc.
 100     inlined_operator_news = [
 101         r"moz_xmalloc",
 102     ]
 103
 104     alloc_fns = (
 105         operator_news
 106         + inlined_operator_news
 107         + [
 108             r"memalign",
 109             # These three aren't available on all Linux configurations.
 110             # r'posix_memalign',
 111             # r'aligned_alloc',
 112             # r'valloc',
 113         ]
 114     )
 115
 116     if args.aggressive:
 117         alloc_fns += [r"malloc", r"calloc", r"realloc", r"free", r"strdup"]
 118
 119     # This is like alloc_fns, but regexp chars are not escaped.
 120     alloc_fns_escaped = [re.escape(fn) for fn in alloc_fns]
 121
 122     # This regexp matches the relevant lines in the output of |nm|, which look
 123     # like the following.
 124     #
 125     #   js/src/libjs_static.a:Utility.o:                  U malloc
 126     #   js/src/libjs_static.a:Utility.o: 00000000000007e0 T js::SetSourceOptions(...)
 127     #
 128     # It may also, in LTO builds, look like
 129     #   js/src/libjs_static.a:Utility.o: ---------------- T js::SetSourceOptions(...)
 130     #
 131     nm_line_re = re.compile(r"([^:/ ]+):\s*(?:[0-9a-fA-F]*|-*)\s+([TUw]) (.*)")
 132     alloc_fns_re = re.compile(r"|".join(alloc_fns_escaped))
 133
 134     # This tracks which allocation/free functions have been seen.
 135     functions = defaultdict(set)
 136     files = defaultdict(int)
 137
 138     # Files to ignore allocation/free functions from.
 139     ignored_files = [
 140         # Ignore implicit call to operator new in std::condition_variable_any.
 141         #
 142         # From intl/icu/source/common/umutex.h:
 143         # On Linux, the default constructor of std::condition_variable_any
 144         # produces an in-line reference to global operator new(), [...].
 145         "umutex.o",
 146         # Ignore allocations from decimal conversion functions inside mozglue.
 147         "Decimal.o",
 148         # Ignore use of std::string in regexp AST debug output.
 149         "regexp-ast.o",
 150         # mozglue/misc/Debug.cpp contains a call to `printf_stderr("%s", aStr.str().c_str())`
 151         # where `aStr` is a `std::stringstream`. In inlined opt builds, this calls
 152         # `operator new()` and `operator delete` for a temporary.
 153         "Debug.o",
 154     ]
 155     all_ignored_files = set((f, 1) for f in ignored_files)
 156
 157     # Would it be helpful to emit detailed line number information after a failure?
 158     emit_line_info = False
 159
 160     prev_filename = None
 161     for line in lines:
 162         m = nm_line_re.search(line)
 163         if m is None:
 164             continue
 165
 166         filename, symtype, fn = m.groups()
 167         if prev_filename != filename:
 168             # When the same filename appears multiple times, separated by other
 169             # file names, this denotes a different file. Thankfully, we can more
 170             # or less safely assume that dir1/Foo.o and dir2/Foo.o are not going
 171             # to be next to each other.
 172             files[filename] += 1
 173             prev_filename = filename
 174
 175         # The stdc++compat library has an implicit call to operator new in
 176         # thread::_M_start_thread.
 177         if "stdc++compat" in filename:
 178             continue
 179
 180         # The memory allocator code contains calls to memalign. These are ok, so
 181         # we whitelist them.
 182         if "_memory_" in filename:
 183             continue
 184
 185         # Ignore the fuzzing code imported from m-c
 186         if "Fuzzer" in filename:
 187             continue
 188
 189         # Ignore the profiling pseudo-stack, since it needs to run even when
 190         # SpiderMonkey's allocator isn't initialized.
 191         if "ProfilingStack" in filename:
 192             continue
 193
 194         if symtype == "T":
 195             # We can't match intl/components files by file name because in
 196             # non-unified builds they overlap with files in js/src.
 197             # So we check symbols they define, and consider files with symbols
 198             # in the mozilla::intl namespace to be those.
 199             if fn.startswith("mozilla::intl::"):
 200                 all_ignored_files.add((filename, files[filename]))
 201         else:
 202             m = alloc_fns_re.match(fn)
 203             if m:
 204                 functions[(filename, files[filename])].add(m.group(0))
 205
 206     util_Utility_cpp = functions.pop(("Utility.o", 1))
 207     if ("Utility.o", 2) in functions:
 208         fail("There should be only one Utility.o file")
 209
 210     for f, n in all_ignored_files:
 211         functions.pop((f, n), None)
 212         if f in ignored_files and (f, 2) in functions:
 213             fail(f"There should be only one {f} file")
 214
 215     for filename, n in sorted(functions):
 216         for fn in functions[(filename, n)]:
 217             # An allocation is present in a non-special file.  Fail!
 218             fail("'" + fn + "' present in " + filename)
 219             # Try to give more precise information about the offending code.
 220             emit_line_info = True
 221
 222     # Check that all functions we expect are used in util/Utility.cpp.  (This
 223     # will fail if the function-detection code breaks at any point.)
 224     # operator new and its inlined equivalent are mutually exclusive.
 225     has_operator_news = any(fn in operator_news for fn in util_Utility_cpp)
 226     has_inlined_operator_news = any(
 227         fn in inlined_operator_news for fn in util_Utility_cpp
 228     )
 229     if has_operator_news and has_inlined_operator_news:
 230         fail(
 231             "Both operator new and moz_xmalloc aren't expected in util/Utility.cpp at the same time"
 232         )
 233
 234     for fn in alloc_fns:
 235         if fn not in util_Utility_cpp:
 236             if (
 237                 (fn in operator_news and not has_inlined_operator_news)
 238                 or (fn in inlined_operator_news and not has_operator_news)
 239                 or (fn not in operator_news and fn not in inlined_operator_news)
 240             ):
 241                 fail("'" + fn + "' isn't used as expected in util/Utility.cpp")
 242         else:
 243             util_Utility_cpp.remove(fn)
 244
 245     # This should never happen, but check just in case.
 246     if util_Utility_cpp:
 247         fail(
 248             "unexpected allocation fns used in util/Utility.cpp: "
 249             + ", ".join(util_Utility_cpp)
 250         )
 251
 252     # If we found any improper references to allocation functions, try to use
 253     # DWARF debug info to get more accurate line number information about the
 254     # bad calls. This is a lot slower than 'nm -A', and it is not always
 255     # precise when building with --enable-optimized.
 256     if emit_line_info:
 257         print("check_vanilla_allocations.py: Source lines with allocation calls:")
 258         print(
 259             "check_vanilla_allocations.py: Accurate in unoptimized builds; "
 260             "util/Utility.cpp expected."
 261         )
 262
 263         # Run |nm|.  Options:
 264         # -u: show only undefined symbols
 265         # -C: demangle symbol names
 266         # -l: show line number information for each undefined symbol
 267         cmd = ["nm", "-u", "-C", "-l", args.file]
 268         lines = subprocess.check_output(
 269             cmd, universal_newlines=True, stderr=subprocess.PIPE
 270         ).split("\n")
 271
 272         # This regexp matches the relevant lines in the output of |nm -l|,
 273         # which look like the following.
 274         #
 275         #       U malloc util/Utility.cpp:117
 276         #
 277         alloc_lines_re = (
 278             r"[Uw] ((" + r"|".join(alloc_fns_escaped) + r").*)\s+(\S+:\d+)$"
 279         )
 280
 281         for line in lines:
 282             m = re.search(alloc_lines_re, line)
 283             if m:
 284                 print(
 285                     "check_vanilla_allocations.py:", m.group(1), "called at", m.group(3)
 286                 )
 287
 288     if has_failed:
 289         sys.exit(1)
 290
 291     print("TEST-PASS | check_vanilla_allocations.py | ok")
 292     sys.exit(0)
 293
 294
 295 if __name__ == "__main__":
 296     main()