On 28/05/2010 2:42 PM, Ralph Versteegen wrote:
On 29 May 2010 06:20, Mike Caron<[email protected]> wrote:
On 28/05/2010 2:17 PM, Ralph Versteegen wrote:
On 29 May 2010 06:02, James Paige<[email protected]> wrote:
How do zstrings work?
Back in the days of the one C/C++ class I took, I remember learning that
zstrings were a zero-terminated string buffer.
They were no good for storing arbitrary binary data, because the first 0
would terminate the string, causing any data from the 0 to the end of
the buffer to be ignored.
Am I correct to assume that the zstring ptr's used in Reload are not
like that?
I would hate to be losing saved tag data beccause 8 or more
low-numbered tags in a row happened to all be off.
Please put my probably-unfounded fears to rest :)
---
James
Right. They are actually just byte ptrs. I don't understand why Mike
used zstring instead of byte ptr, since there's a separate GetString
if you want a string instead of a binary lump.
Mike wrote in r3540:
- Also, nodes now keep track of the size of their internal ZStrings,
in case they have embedded nulls.
I used ZString ptr so that I would only need one pointer to do all of the
following:
- Cast to String if requested
- Store arbitrary binary daya
- Cache strings if needed (although, this doesn't happen currently with
data)
(No idea what you mean)
- etc.
--
Mike
I don't see the point of having a "GetZString" function. Surely if you
wanted a string, you would use GetString instead, whereas if you
wanted binary data, you would expect a "GetBinary" function which
returns a byte ptr instead. Plus a SetContent overload.
So, all binary blobs should be terminated in-memory by an extra null?
Suppose that you want to store x bytes of binary, so you call
ResizeZString(node, x). Then you retrieve the Zstring and write to it.
Shouldn't you also write an extra null? That's a bit of a nuisance.
Just look at SaveBitsetArray: not only does it not write the null, but
it writes off the end of allocated memory (which may be causing
crashes for James this very moment :P).
Take a closer look at ResizeZString: It adds a null for you. The buffer
is actually size + 1.
--
Mike
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