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Fix unaligned reads in utf8-checker

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This commit is contained in:
Vinnie Falco
2017-06-14 17:50:48 -07:00
parent 1cb4601005
commit 1002502068
2 changed files with 58 additions and 32 deletions
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6
CHANGELOG.md
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@@ -1,3 +1,9 @@
Version 58:
* Fix unaligned reads in utf8-checker
--------------------------------------------------------------------------------
Version 57:
* Fix message.hpp javadocs

84
include/beast/websocket/detail/utf8_checker.hpp
View File

@@ -245,39 +245,59 @@ write(std::uint8_t const* in, std::size_t size)
p_ = have_;
}
auto last = in + size - 7;
while(in < last)
{
#if BEAST_WEBSOCKET_NO_UNALIGNED_READ
auto constexpr align = sizeof(std::size_t) - 1;
auto constexpr mask = static_cast<
std::size_t>(0x8080808080808080 &
~std::size_t{0});
if(
((reinterpret_cast<
std::uintptr_t>(in) & align) == 0) &&
(*reinterpret_cast<
std::size_t const*>(in) & mask) == 0)
in += sizeof(std::size_t);
else if(! valid(in))
return false;
#else
auto constexpr mask = static_cast<
std::size_t>(0x8080808080808080 &
~std::size_t{0});
if(
(*reinterpret_cast<
std::size_t const*>(in) & mask) == 0)
in += sizeof(std::size_t);
else if(! valid(in))
return false;
#endif
}
last += 4;
while(in < last)
if(! valid(in))
return false;
if(size <= sizeof(std::size_t))
goto slow;
// align in to sizeof(std::size_t) boundary
{
auto const in0 = in;
auto last = reinterpret_cast<std::uint8_t const*>(
((reinterpret_cast<std::uintptr_t>(in) + sizeof(std::size_t) - 1) /
sizeof(std::size_t)) * sizeof(std::size_t));
while(in < last)
{
if(*in & 0x80)
{
size = size - (in - in0);
goto slow;
}
++in;
}
size = size - (in - in0);
}
// fast loop
{
auto const in0 = in;
auto last = in + size - 7;
auto constexpr mask = static_cast<
std::size_t>(0x8080808080808080 & ~std::size_t{0});
while(in < last)
{
if((*reinterpret_cast<std::size_t const*>(in) & mask) != 0)
{
size = size - (in - in0);
goto slow;
}
in += sizeof(std::size_t);
}
last += 4;
while(in < last)
if(! valid(in))
return false;
goto tail;
}
// slow loop: one code point at a time
slow:
{
auto last = in + size - 3;
while(in < last)
if(! valid(in))
return false;
}
tail:
for(;;)
{
auto n = end - in;