/*
* read_one_buf
*
* Read one buffer from the tape
*/
static int
read_one_buf(ndmpd_module_params_t *mod_params, tlm_buffers_t *bufs,
tlm_buffer_t *buf)
{
int rv;
if ((rv = MOD_READ(mod_params, buf->tb_buffer_data,
bufs->tbs_data_transfer_size)) == 0) {
buf->tb_eof = buf->tb_eot = FALSE;
buf->tb_errno = 0;
buf->tb_buffer_size = bufs->tbs_data_transfer_size;
buf->tb_buffer_spot = 0;
buf->tb_full = TRUE;
(void) tlm_buffer_advance_in_idx(bufs);
}
return (rv);
}
/*ARGSUSED*/
char *
tlm_get_write_buffer(long want, long *actual_size,
tlm_buffers_t *buffers, int zero)
{
int buf = buffers->tbs_buffer_in;
tlm_buffer_t *buffer = &buffers->tbs_buffer[buf];
int align_size = RECORDSIZE - 1;
char *rec;
/*
* make sure the allocation is in chunks of 512 bytes
*/
want += align_size;
want &= ~align_size;
*actual_size = buffer->tb_buffer_size - buffer->tb_buffer_spot;
if (*actual_size <= 0) {
/*
* no room, send this one
* and wait for a free one
*/
if (!buffer->tb_full) {
/*
* we are now ready to send a full buffer
* instead of trying to get a new buffer
*
* do not send if we failed to get a buffer
* on the previous call
*/
buffer->tb_full = TRUE;
/*
* tell the writer that a buffer is available
*/
tlm_buffer_release_in_buf(buffers);
buffer = tlm_buffer_advance_in_idx(buffers);
}
buffer = tlm_buffer_in_buf(buffers, NULL);
if (buffer->tb_full) {
/*
* wait for the writer to free up a buffer
*/
tlm_buffer_out_buf_timed_wait(buffers, 500);
}
buffer = tlm_buffer_in_buf(buffers, NULL);
if (buffer->tb_full) {
/*
* the next buffer is still full
* of data from previous activity
*
* nothing has changed.
*/
return (0);
}
buffer->tb_buffer_spot = 0;
*actual_size = buffer->tb_buffer_size - buffer->tb_buffer_spot;
}
*actual_size = min(want, *actual_size);
rec = &buffer->tb_buffer_data[buffer->tb_buffer_spot];
buffer->tb_buffer_spot += *actual_size;
buffers->tbs_offset += *actual_size;
if (zero) {
(void) memset(rec, 0, *actual_size);
}
return (rec);
}