src/integer.h

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7 #ifndef INCLUDE_integer_h__
   8 #define INCLUDE_integer_h__
   9
  10 /** @return true if p fits into the range of a size_t */
  11 GIT_INLINE(int) git__is_sizet(int64_t p)
  12 {
  13         size_t r = (size_t)p;
  14         return p == (int64_t)r;
  15 }
  16
  17 /** @return true if p fits into the range of an ssize_t */
  18 GIT_INLINE(int) git__is_ssizet(size_t p)
  19 {
  20         ssize_t r = (ssize_t)p;
  21         return p == (size_t)r;
  22 }
  23
  24 /** @return true if p fits into the range of a uint16_t */
  25 GIT_INLINE(int) git__is_uint16(size_t p)
  26 {
  27         uint16_t r = (uint16_t)p;
  28         return p == (size_t)r;
  29 }
  30
  31 /** @return true if p fits into the range of a uint32_t */
  32 GIT_INLINE(int) git__is_uint32(size_t p)
  33 {
  34         uint32_t r = (uint32_t)p;
  35         return p == (size_t)r;
  36 }
  37
  38 /** @return true if p fits into the range of an unsigned long */
  39 GIT_INLINE(int) git__is_ulong(int64_t p)
  40 {
  41         unsigned long r = (unsigned long)p;
  42         return p == (int64_t)r;
  43 }
  44
  45 /** @return true if p fits into the range of an int */
  46 GIT_INLINE(int) git__is_int(long long p)
  47 {
  48         int r = (int)p;
  49         return p == (long long)r;
  50 }
  51
  52 /* Use clang/gcc compiler intrinsics whenever possible */
  53 #if (__has_builtin(__builtin_add_overflow) || \
  54      (defined(__GNUC__) && (__GNUC__ >= 5)))
  55
  56 # if (SIZE_MAX == UINT_MAX)
  57 #  define git__add_sizet_overflow(out, one, two) \
  58      __builtin_uadd_overflow(one, two, out)
  59 #  define git__multiply_sizet_overflow(out, one, two) \
  60      __builtin_umul_overflow(one, two, out)
  61 # elif (SIZE_MAX == ULONG_MAX)
  62 #  define git__add_sizet_overflow(out, one, two) \
  63      __builtin_uaddl_overflow(one, two, out)
  64 #  define git__multiply_sizet_overflow(out, one, two) \
  65      __builtin_umull_overflow(one, two, out)
  66 # elif (SIZE_MAX == ULLONG_MAX)
  67 #  define git__add_sizet_overflow(out, one, two) \
  68      __builtin_uaddll_overflow(one, two, out)
  69 #  define git__multiply_sizet_overflow(out, one, two) \
  70      __builtin_umulll_overflow(one, two, out)
  71 # else
  72 #  error compiler has add with overflow intrinsics but SIZE_MAX is unknown
  73 # endif
  74
  75 # define git__add_int_overflow(out, one, two) \
  76     __builtin_sadd_overflow(one, two, out)
  77 # define git__sub_int_overflow(out, one, two) \
  78     __builtin_ssub_overflow(one, two, out)
  79
  80 /* Use Microsoft's safe integer handling functions where available */
  81 #elif defined(_MSC_VER)
  82
  83 # define ENABLE_INTSAFE_SIGNED_FUNCTIONS
  84 # include <intsafe.h>
  85
  86 # define git__add_sizet_overflow(out, one, two) \
  87     (SizeTAdd(one, two, out) != S_OK)
  88 # define git__multiply_sizet_overflow(out, one, two) \
  89     (SizeTMult(one, two, out) != S_OK)
  90 #define git__add_int_overflow(out, one, two) \
  91     (IntAdd(one, two, out) != S_OK)
  92 #define git__sub_int_overflow(out, one, two) \
  93     (IntSub(one, two, out) != S_OK)
  94
  95 #else
  96
  97 /**
  98  * Sets `one + two` into `out`, unless the arithmetic would overflow.
  99  * @return false if the result fits in a `size_t`, true on overflow.
 100  */
 101 GIT_INLINE(bool) git__add_sizet_overflow(size_t *out, size_t one, size_t two)
 102 {
 103         if (SIZE_MAX - one < two)
 104                 return true;
 105         *out = one + two;
 106         return false;
 107 }
 108
 109 /**
 110  * Sets `one * two` into `out`, unless the arithmetic would overflow.
 111  * @return false if the result fits in a `size_t`, true on overflow.
 112  */
 113 GIT_INLINE(bool) git__multiply_sizet_overflow(size_t *out, size_t one, size_t two)
 114 {
 115         if (one && SIZE_MAX / one < two)
 116                 return true;
 117         *out = one * two;
 118         return false;
 119 }
 120
 121 GIT_INLINE(bool) git__add_int_overflow(int *out, int one, int two)
 122 {
 123         if ((two > 0 && one > (INT_MAX - two)) ||
 124             (two < 0 && one < (INT_MIN - two)))
 125                 return true;
 126         *out = one + two;
 127         return false;
 128 }
 129
 130 GIT_INLINE(bool) git__sub_int_overflow(int *out, int one, int two)
 131 {
 132         if ((two > 0 && one < (INT_MIN + two)) ||
 133             (two < 0 && one > (INT_MAX + two)))
 134                 return true;
 135         *out = one - two;
 136         return false;
 137 }
 138
 139 #endif
 140
 141 #endif