Re: Two interesting and difficult problems with descriptors

euroq — Thu, 26 Jul 2007 21:52:39 +0200

Yep, you're absolutely correct... but unfortunately, like I mentioned in the post, it wasn't introduced in earlier version of the SDK, and this program has to be compatible with Series 80 devices.

Another "gotcha" I failed to mention on the above post:

	iBuffer = HBufC8::NewL(iRequiredLength);
	iBufPtr.Set((TUint8*)iBuffer->Ptr(), 0, iRequiredLength);
	iSocket->Read(iBufPtr, iStatus);

The problem with this is that the RSocket will adjust the TPtr8's iBufPtr's new length, but not the HBufC8 iBuffer's descriptor (although the iBuffer correctly has the data). Guess this would be Problem 3 .

I ended up giving up on the idea of using the HBufC8... it just wasn't worth it. Now I have an array and only use one descriptor, the TPtr8. The HBufC8 was actually just extra unnecessary overhead to a byte buffer. As it turns out, I know the maximum size of any data coming from the server, so I simply have:

	// member variable
	unsigned char iBuffer[8192];

	// In the class method...
	iBufPtr.Set(iBuffer, 0, iRequiredLength);
	iSocket.Read(iBufPtr, iStatus);

This way is a little easier to read, always guarantees I won't run out of memory for the buffer, and doesn't require the overhead of an HBufC8. (By the way, note that you could also have iBuffer as an unsigned char* pointer, and allocate the memory, and still be able to use the exact same code)

-euroq

Re: Two interesting and difficult problems with descriptors

Mr. Buttington F. Phucque Lewis — Thu, 26 Jul 2007 19:33:19 +0200

Both your problems would be solved if you switched to using an RBuf - its max length doesn't get rounded up to the size of the heap cell like a HBufC and as RBuf derives from TDes you can pass it into a function taking that as a parameter.

Two interesting and difficult problems with descriptors

euroq — Thu, 26 Jul 2007 19:14:16 +0200

Descriptors seem to be the bane of all newcomers to Symbian programming. I thought I had them down, but just came across two problem that took me a while to solve, and might send newbies running around for days.

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Re: Two interesting and difficult problems with descriptors

Re: Two interesting and difficult problems with descriptors

Two interesting and difficult problems with descriptors