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(git_off_t p)
  12 {
  13         size_t r = (size_t)p;
  14         return p == (git_off_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 uint32_t */
  25 GIT_INLINE(int) git__is_uint32(size_t p)
  26 {
  27         uint32_t r = (uint32_t)p;
  28         return p == (size_t)r;
  29 }
  30
  31 /** @return true if p fits into the range of an unsigned long */
  32 GIT_INLINE(int) git__is_ulong(git_off_t p)
  33 {
  34         unsigned long r = (unsigned long)p;
  35         return p == (git_off_t)r;
  36 }
  37
  38 /** @return true if p fits into the range of an int */
  39 GIT_INLINE(int) git__is_int(long long p)
  40 {
  41         int r = (int)p;
  42         return p == (long long)r;
  43 }
  44
  45 /**
  46  * Sets `one + two` into `out`, unless the arithmetic would overflow.
  47  * @return true if the result fits in a `uint64_t`, false on overflow.
  48  */
  49 GIT_INLINE(bool) git__add_uint64_overflow(uint64_t *out, uint64_t one, uint64_t two)
  50 {
  51         if (UINT64_MAX - one < two)
  52                 return true;
  53         *out = one + two;
  54         return false;
  55 }
  56
  57 /* Use clang/gcc compiler intrinsics whenever possible */
  58 #if (SIZE_MAX == UINT_MAX) && __has_builtin(__builtin_uadd_overflow)
  59 # define git__add_sizet_overflow(out, one, two) \
  60         __builtin_uadd_overflow(one, two, out)
  61 # define git__multiply_sizet_overflow(out, one, two) \
  62         __builtin_umul_overflow(one, two, out)
  63 #elif (SIZE_MAX == ULONG_MAX) && __has_builtin(__builtin_uaddl_overflow)
  64 # define git__add_sizet_overflow(out, one, two) \
  65         __builtin_uaddl_overflow(one, two, out)
  66 # define git__multiply_sizet_overflow(out, one, two) \
  67         __builtin_umull_overflow(one, two, out)
  68 #else
  69
  70 /**
  71  * Sets `one + two` into `out`, unless the arithmetic would overflow.
  72  * @return true if the result fits in a `size_t`, false on overflow.
  73  */
  74 GIT_INLINE(bool) git__add_sizet_overflow(size_t *out, size_t one, size_t two)
  75 {
  76         if (SIZE_MAX - one < two)
  77                 return true;
  78         *out = one + two;
  79         return false;
  80 }
  81
  82 /**
  83  * Sets `one * two` into `out`, unless the arithmetic would overflow.
  84  * @return true if the result fits in a `size_t`, false on overflow.
  85  */
  86 GIT_INLINE(bool) git__multiply_sizet_overflow(size_t *out, size_t one, size_t two)
  87 {
  88         if (one && SIZE_MAX / one < two)
  89                 return true;
  90         *out = one * two;
  91         return false;
  92 }
  93
  94 #endif
  95
  96 #endif /* INCLUDE_integer_h__ */