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Enable same buffer for in and out on ARM A-32 (GH #683)

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Jeffrey Walton 2018-10-13 22:16:59 -04:00
parent 1acbedd4f8
commit 49d852ee8c
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GPG Key ID: B36AB348921B1838
1 changed files with 14 additions and 13 deletions
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27
strciphr.cpp
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@ -203,12 +203,18 @@ void CFB_CipherTemplate<BASE>::ProcessData(byte *outString, const byte *inString
//
// Also see https://github.com/weidai11/cryptopp/issues/683.
//
#if !defined(__arm__)
unsigned int alignment = policy.GetAlignment();
if (policy.CanIterate() && length >= bytesPerIteration && IsAlignedOn(outString, alignment))
// UPDATE: It appears the issue is related to alignment checks. When we made
// the alignment check result volatile GCC and Clang stopped
// short-circuiting the transform, which is what we wanted. I suspect
// there's a little more to the issue, but we can enable the block again.
const unsigned int alignment = policy.GetAlignment();
volatile bool isAligned = IsAlignedOn(outString, alignment);
if (policy.CanIterate() && length >= bytesPerIteration && isAligned)
{
isAligned &= IsAlignedOn(inString, alignment);
const CipherDir cipherDir = GetCipherDir(*this);
if (IsAlignedOn(inString, alignment))
if (isAligned)
policy.Iterate(outString, inString, cipherDir, length / bytesPerIteration);
else
{
@ -226,11 +232,6 @@ void CFB_CipherTemplate<BASE>::ProcessData(byte *outString, const byte *inString
// to use ptrdiff_t when subtracting pointers. We believe the relevant code paths
// are clean.
//
// There are two remaining open questions. The first is aliasing rules. Char-types
// are not bound by aliasing rules so we are OK. The second is array const-ness.
// The arrays are created in datatest.cpp and they are non-const. Since the original
// objects are non-const we are OK casting const-ness away as buffers are twiddled.
//
// One workaround is a distinct and aligned temporary buffer. It [mostly] works
// as expected but requires an extra allocation (casts not shown):
//
@ -241,11 +242,11 @@ void CFB_CipherTemplate<BASE>::ProcessData(byte *outString, const byte *inString
memcpy(outString, inString, length);
policy.Iterate(outString, outString, cipherDir, length / bytesPerIteration);
}
inString = PtrAdd(inString, length - length % bytesPerIteration);
outString = PtrAdd(outString, length - length % bytesPerIteration);
length %= bytesPerIteration;
const size_t remainder = length % bytesPerIteration;
inString = PtrAdd(inString, length - remainder);
outString = PtrAdd(outString, length - remainder);
length = remainder;
}
#endif
while (length >= bytesPerIteration)
{