size_t vrb_read_min(vrb_p vrb, int fd, size_t maxsize, size_t minsize);
reads a minimum amount of data from a specified open file descriptor
into the specified
virtual ring buffer until the specified maximum length has been read,
the buffer is full, or end-of-file, or an error is returned
(including EAGAIN or EWOULDBLOCK for a non-blocking descriptor).
If there is insufficient space in the buffer to read the minimum amount,
will not be called.
specifies which virtual ring buffer.
specifies the open file descriptor to read from
specifies the maximum length to read, or
specifies the minimum length to read.
If successful, the actual length of data read into the buffer is returned.
If the minimum amount of space was not available to read into,
0 is returned.
If end-of-file occurs, the return value is ~0 and errno is 0.
If an error occurs from
the return value is ~0 and
errno is set by
If an error is returned, then
will have one of the following values:
An end-of-file has occurred.
Note that this is a different way of returning an end-of-file
An invalid virtual ring buffer pointer was specified.