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Re: Proposed addition of strcodecs(3) library - review requested

>> Though for that to not suck, there'd need to be some way to
>> mux/demux, so things like hash values or crc32 could come back "on
>> the side" of the main data stream.
> I wonder if we could have multiple parents in a layer, or,
> alternatively, think of it as a tee-style FILE on the side.

Certainly.  First API that comes to mind:

FILE *fopen_crc32_r(FILE *sub, FILE *crc, unsigned int flags)
FILE *fopen_crc32_w(FILE *sub, FILE *crc, unsigned int flags)

The returned FILE is just like sub for read (_r) or write (_w), but, at
EOF, writes the generated CRC to crc.  If FSTACK_CASCADE_CLOSE is set
in flags, closing the returned stream also closes sub, othewise not; if

I've done a lot of stdio stacking in various programs (funopen() makes
this sort of thing relatively easy), and it is a very pleasant kind of
API to use.

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