/**
* Does a non-blocking read and either reads in the amount you requested
* with "need" or less so you can try again. It sets out_len to what is
* available (<= need) so you can decide after that. You can keep attempting
* to read more and more (up to buf->len) and you'll get the same start point
* each time.
*
* Once you're done with the data you've been trying to read, you use IOBuf_read_commit
* to commit the "need" amount and then start doing new reads.
*
* Internally this works like a "half open ring buffer" and it tries to greedily
* read as much as possible without blocking or copying.
*
* To just get as much as possible, use the IOBuf_read_some macro.
*/
char *IOBuf_read(IOBuf *buf, int need, int *out_len)
{
int rc = 0;
assert(buf->cur + buf->avail <= buf->len &&
"Buffer math off, cur+avail can't be more than > len.");
assert(buf->cur >= 0 && "Buffer cur can't be < 0");
assert(buf->avail >= 0 && "Buffer avail can't be < 0");
assert(need <= buf->len && "Request for more than possible in the buffer.");
if(IOBuf_closed(buf)) {
if(buf->avail > 0) {
*out_len = buf->avail;
} else {
*out_len = 0;
return NULL;
}
} else if(buf->avail < need) {
if(buf->cur > 0 && IOBuf_compact_needed(buf, need)) {
IOBuf_compact(buf);
}
rc = buf->recv(buf, IOBuf_read_point(buf), IOBuf_remaining(buf));
if(rc <= 0) {
debug("Socket was closed, will return only what's available: %d", buf->avail);
buf->closed = 1;
} else {
buf->avail = buf->avail + rc;
}
if(buf->avail < need) {
// less than expected
*out_len = buf->avail;
} else {
// more than expected
*out_len = need;
}
} else if(buf->avail >= need) {
*out_len = need;
} else {
sentinel("Invalid branch processing buffer, Tell Zed.");
}
return IOBuf_start(buf);
error:
return NULL;
}
char *test_IOBuf_read_operations()
{
char *data = NULL;
int avail = 0;
Connection *conn = fake_conn("/dev/zero", O_RDONLY);
mu_assert(conn != NULL, "Failed to make fake /dev/zero connection.");
IOBuf *buf = conn->iob;
IOBuf_resize(buf, 31);
mu_assert(buf->len == 31, "Wrong size after resize.");
data = IOBuf_start(buf);
avail = IOBuf_avail(buf);
mu_assert(data != NULL, "Didn't get a data response on begin.");
mu_assert(data == buf->buf, "Begin on fresh iobuf should be at the beginning.");
mu_assert(avail == 0, "Should not have anything available yet.");
data = IOBuf_read(buf, 10, &avail);
mu_assert(data != NULL, "Should get something always.");
mu_assert(data == IOBuf_start(buf), "First read should work from start.");
mu_assert(data == buf->buf, "First read should be at start of internal buf.");
mu_assert(avail == 10, "Should get 10 bytes.");
// check compacting
mu_assert(!IOBuf_compact_needed(buf, 10), "Should not need compacting for 10.");
mu_assert(IOBuf_compact_needed(buf, 100), "SHOULD need compacting for 100.");
mu_assert(IOBuf_read_commit(buf, 10) != -1, "Failed to commit.");
data = IOBuf_start(buf);
avail = IOBuf_avail(buf);
mu_assert(data != NULL, "Didn't get a data response on begin.");
mu_assert(data != buf->buf, "Later reads should not be at the start.");
mu_assert(avail == 21, "Should have 21 bytes available in the buf already.");
data = IOBuf_read(buf, 10, &avail);
mu_assert(data != NULL, "Should get something always.");
mu_assert(avail == 10, "Should get 10 bytes.");
mu_assert(IOBuf_read_commit(buf, 10) != -1, "Finaly commit failed.");
data = IOBuf_start(buf);
avail = IOBuf_avail(buf);
mu_assert(data != NULL, "Didn't get a data response on begin.");
mu_assert(data != buf->buf, "Later reads should not be at the start.");
mu_assert(avail == 11, "Should have 11 bytes available in the buf already.");
// now test two reads, one that fits one that doesn't then commit
// remember this doesn't *return* anything, just a pointer to the start
data = IOBuf_read(buf, 5, &avail);
mu_assert(data != NULL, "Should get something always.");
mu_assert(avail == 5, "Should get 10 bytes.");
// ok we didn't want 5 we want 20, so this will cause a compact
data = IOBuf_read(buf, 20, &avail);
mu_assert(data != NULL, "Should get something always.");
mu_assert(avail == 20, "Should get 10 bytes.");
mu_assert(IOBuf_read_commit(buf, 21) != -1, "Final commit failed.");
debug("We've got %d avail after the last read.", buf->avail);
mu_assert(buf->avail == 10, "Should have 11 still in the queue.");
data = IOBuf_read_all(buf, 30, 1);
mu_assert(data != NULL, "Failed to read all.");
mu_assert(buf->avail == 1, "Should have 1 in the queue.");
data = IOBuf_read_some(buf, &avail);
mu_assert(data != NULL, "Failed to read some.");
mu_assert(buf->avail == 31, "Should be full.");
mu_assert(avail == 31, "And we should get the full amount.");
fake_conn_close(conn);
return NULL;
}
