NAME
buffer_rpeek, buffer_rseek - peek/seek into a reading I/O buffer
SYNOPSIS
#include <limb/buffer.h>
void buffer_rpeek(buffer *buf, struct iovec v[2]) size_t buffer_rseek(buffer *buf, size_t len)
DESCRIPTION
The buffer_rpeek() macro allows to peek into a reading buffer's used space.
The array of vectors pointed by v will be set to the in-use space inside
the memory of the buffer pointed by buf, i.e. the data to be copied next
by a call to buffer_get(3) or similar.
The buffer_rseek() macro will update the internals of the buffer pointed by
buf to move past the next len bytes of data from its internal memory space,
as if they had been read/consumed.
Because a buffer's internal memory is kept as a circular buffer (see
cbuffer.h(0) for more), the data might not be stored as a continuous block
and requires a couple of vectors to possibly get the full space. Note than it
is possible the second vector will be set to zero if not needed, however v
should always point to an array of 2 elements.
Typically, one would use buffer_rpeek() to get the locations where to read
from the buffer, and after all went well use buffer_rseek() to have said data
"removed" from the buffer.
RETURN VALUE
The buffer_rseek() function returns the amount of bytes in use by which its
internal buffer shrunk, which may be less than len (even 0 if the buffer was
empty).