[haiku-commits] Re: haiku: hrev46860 - in src/kits: shared package/hpkg package/hpkg/v1
- From: Stephan Aßmus <superstippi@xxxxxx>
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Tue, 18 Feb 2014 14:57:23 +0100
Hi guys, mostly Adrien,
I completely fail to see what the problem is.
As far as I understand, you want to use a class which implements BDataOutput in
a context where you need a BDataIO. As Ingo pointed out, instead of changing
all the places where BDataOutput was previously used, you could have simply
written a BDataIO which wraps a BDataOutput. The fact that BDataIO can in
theory return less bytes from Read() then requested, is completely irrelevant
in this context, since when the underlying BDataOutput (the deflate output)
only returns all or nothing, then that's what happens in your wrapper. It
simply has the behavior of always returning the requested number of bytes. Why
would that be any sort of problem?
This is how the BDataOutputAdapterIO could look like:
ssize_t
BDataOutputAdapterIO::Read(const void* buffer, size_t size)
{
status_t error = fWrappedDataOutput->Read(buffer, size);
if (error == B_OK)
return size;
else
return (ssize_t)error;
}
The other direction would include the loop: Your BDataIOAdapterOutput:
status_t
BDataIOAdapterOutput::Read(const void* buffer, size_t size)
{
while (size > 0) {
ssize_t bytesRead = fWrappedDataIO->Read(buffer, size);
if (bytesRead < 0)
return (status_t) bytesRead;
ASSERT(size >= bytesRead);
size -= bytesRead;
buffer += bytesRead;
}
return B_OK;
}
With both adapters, you can build mixed chains that contain classes of both
types.
Best regards,
-Stephan
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