1/*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkSafe_math_DEFINED
9#define SkSafe_math_DEFINED
10
11// This file protects against known bugs in ucrt\math.h.
12// Namely, that header defines inline methods without marking them static,
13// which makes it very easy to cause ODR violations and ensuing chaos.
14//
15// TODO: other headers?  Here are some potential problem headers:
16// $ grep -R __inline * | grep -v static | cut -f 1 -d: | sort | uniq
17//   corecrt.h
18//   corecrt_stdio_config.h
19//   ctype.h
20//   fenv.h
21//   locale.h
22//   malloc.h
23//   math.h
24//   tchar.h
25//   wchar.h
26// I took a quick look through other headers outside math.h.
27// Nothing looks anywhere near as likely to be used by Skia as math.h.
28
29#if defined(_MSC_VER) && !defined(_INC_MATH)
30    // Our strategy here is to simply inject "static" into the headers
31    // where it should have been written, just before __inline.
32    //
33    // Most inline-but-not-static methods in math.h are 32-bit only,
34    // but not all of them (see frexpf, hypothf, ldexpf...).  So to
35    // be safe, 32- and 64-bit builds both get this treatment.
36
37    #define __inline static __inline
38    #include <math.h>
39    #undef __inline
40
41    #if !defined(_INC_MATH)
42        #error Hmm.  Looks like math.h has changed its header guards.
43    #endif
44
45    #define INC_MATH_IS_SAFE_NOW
46
47#else
48    #include <math.h>
49
50#endif
51
52#endif//SkSafe_math_DEFINED
53