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 # (e.g. malloc(), free()) is a bug.
  14 #
  15 # This script checks for the presence of such disallowed vanilla
  16 # allocation/free function in SpiderMonkey when it's built as a library.  It
  17 # relies on |nm| from the GNU binutils, and so only works on Linux, but one
  18 # platform is good enough to catch almost all violations.
  19 #
  20 # This checking is only 100% reliable in a JS_USE_CUSTOM_ALLOCATOR build in
  21 # which the default definitions of js_malloc et al (in Utility.h) -- which call
  22 # malloc et al -- are replaced with empty definitions.  This is because the
  23 # presence and possible inlining of the default js_malloc et al can cause
  24 # malloc/calloc/realloc/free calls show up in unpredictable places.
  25 #
  26 # Unfortunately, that configuration cannot be tested on Mozilla's standard
  27 # testing infrastructure.  Instead, by default this script only tests that none
  28 # of the other vanilla allocation/free functions (operator new, memalign, etc)
  29 # are present.  If given the --aggressive flag, it will also check for
  30 # malloc/calloc/realloc/free.
  31 #
  32 # Note:  We don't check for |operator delete| and |operator delete[]|.  These
  33 # can be present somehow due to virtual destructors, but this is not too
  34 # because vanilla delete/delete[] calls don't make sense without corresponding
  35 # vanilla new/new[] calls, and any explicit calls will be caught by Valgrind's
  36 # mismatched alloc/free checking.
  37 # ----------------------------------------------------------------------------
  38
  39 from __future__ import print_function
  40
  41 import argparse
  42 import re
  43 import subprocess
  44 import sys
  45 import buildconfig
  46
  47 # The obvious way to implement this script is to search for occurrences of
  48 # malloc et al, succeed if none are found, and fail is some are found.
  49 # However, "none are found" does not necessarily mean "none are present" --
  50 # this script could be buggy.  (Or the output format of |nm| might change in
  51 # the future.)
  52 #
  53 # So jsutil.cpp deliberately contains a (never-called) function that contains a
  54 # single use of all the vanilla allocation/free functions.  And this script
  55 # fails if it (a) finds uses of those functions in files other than jsutil.cpp,
  56 # *or* (b) fails to find them in jsutil.cpp.
  57
  58 # Tracks overall success of the test.
  59 has_failed = False
  60
  61
  62 def fail(msg):
  63     print('TEST-UNEXPECTED-FAIL | check_vanilla_allocations.py |', msg)
  64     global has_failed
  65     has_failed = True
  66
  67
  68 def main():
  69     parser = argparse.ArgumentParser()
  70     parser.add_argument('--aggressive', action='store_true',
  71                         help='also check for malloc, calloc, realloc and free')
  72     parser.add_argument('file', type=str,
  73                         help='name of the file to check')
  74     args = parser.parse_args()
  75
  76     # Run |nm|.  Options:
  77     # -u: show only undefined symbols
  78     # -C: demangle symbol names
  79     # -A: show an object filename for each undefined symbol
  80     nm = buildconfig.substs.get('NM') or 'nm'
  81     cmd = [nm, '-u', '-C', '-A', args.file]
  82     lines = subprocess.check_output(cmd, universal_newlines=True,
  83                                     stderr=subprocess.PIPE).split('\n')
  84
  85     # alloc_fns contains all the vanilla allocation/free functions that we look
  86     # for. Regexp chars are escaped appropriately.
  87
  88     alloc_fns = [
  89         # Matches |operator new(unsigned T)|, where |T| is |int| or |long|.
  90         r'operator new\(unsigned',
  91
  92         # Matches |operator new[](unsigned T)|, where |T| is |int| or |long|.
  93         r'operator new\[\]\(unsigned',
  94
  95         r'memalign',
  96         # These three aren't available on all Linux configurations.
  97         # r'posix_memalign',
  98         # r'aligned_alloc',
  99         # r'valloc',
 100     ]
 101
 102     if args.aggressive:
 103         alloc_fns += [
 104             r'malloc',
 105             r'calloc',
 106             r'realloc',
 107             r'free',
 108             r'strdup'
 109         ]
 110
 111     # This is like alloc_fns, but regexp chars are not escaped.
 112     alloc_fns_unescaped = [fn.translate(None, r'\\') for fn in alloc_fns]
 113
 114     # This regexp matches the relevant lines in the output of |nm|, which look
 115     # like the following.
 116     #
 117     #   js/src/libjs_static.a:jsutil.o:              U malloc
 118     #
 119     alloc_fns_re = r'([^:/ ]+):\s+U (' + r'|'.join(alloc_fns) + r')'
 120
 121     # This tracks which allocation/free functions have been seen in jsutil.cpp.
 122     jsutil_cpp = set([])
 123
 124     # Would it be helpful to emit detailed line number information after a failure?
 125     emit_line_info = False
 126
 127     for line in lines:
 128         m = re.search(alloc_fns_re, line)
 129         if m is None:
 130             continue
 131
 132         filename = m.group(1)
 133
 134         # The stdc++compat library has an implicit call to operator new in
 135         # thread::_M_start_thread.
 136         if 'stdc++compat' in filename:
 137             continue
 138
 139         # The memory allocator code contains calls to memalign. These are ok, so
 140         # we whitelist them.
 141         if "_memory_" in filename:
 142             continue
 143
 144         # Ignore the fuzzing code imported from m-c
 145         if "Fuzzer" in filename:
 146             continue
 147
 148         # Ignore the profiling pseudo-stack, since it needs to run even when
 149         # SpiderMonkey's allocator isn't initialized.
 150         if "ProfilingStack" in filename:
 151             continue
 152
 153         fn = m.group(2)
 154         if filename == 'jsutil.o':
 155             jsutil_cpp.add(fn)
 156         else:
 157             # An allocation is present in a non-special file.  Fail!
 158             fail("'" + fn + "' present in " + filename)
 159             # Try to give more precise information about the offending code.
 160             emit_line_info = True
 161
 162     # Check that all functions we expect are used in jsutil.cpp.  (This will
 163     # fail if the function-detection code breaks at any point.)
 164     for fn in alloc_fns_unescaped:
 165         if fn not in jsutil_cpp:
 166             fail("'" + fn + "' isn't used as expected in jsutil.cpp")
 167         else:
 168             jsutil_cpp.remove(fn)
 169
 170     # This should never happen, but check just in case.
 171     if jsutil_cpp:
 172         fail('unexpected allocation fns used in jsutil.cpp: ' +
 173              ', '.join(jsutil_cpp))
 174
 175     # If we found any improper references to allocation functions, try to use
 176     # DWARF debug info to get more accurate line number information about the
 177     # bad calls. This is a lot slower than 'nm -A', and it is not always
 178     # precise when building with --enable-optimized.
 179     if emit_line_info:
 180         print('check_vanilla_allocations.py: Source lines with allocation calls:')
 181         print('check_vanilla_allocations.py: Accurate in unoptimized builds; jsutil.cpp expected.')
 182
 183         # Run |nm|.  Options:
 184         # -u: show only undefined symbols
 185         # -C: demangle symbol names
 186         # -l: show line number information for each undefined symbol
 187         cmd = ['nm', '-u', '-C', '-l', args.file]
 188         lines = subprocess.check_output(cmd, universal_newlines=True,
 189                                         stderr=subprocess.PIPE).split('\n')
 190
 191         # This regexp matches the relevant lines in the output of |nm -l|,
 192         # which look like the following.
 193         #
 194         #       U malloc jsutil.cpp:117
 195         #
 196         alloc_lines_re = r'U ((' + r'|'.join(alloc_fns) + r').*)\s+(\S+:\d+)$'
 197
 198         for line in lines:
 199             m = re.search(alloc_lines_re, line)
 200             if m:
 201                 print('check_vanilla_allocations.py:',
 202                       m.group(1), 'called at', m.group(3))
 203
 204     if has_failed:
 205         sys.exit(1)
 206
 207     print('TEST-PASS | check_vanilla_allocations.py | ok')
 208     sys.exit(0)
 209
 210
 211 if __name__ == '__main__':
 212     main()