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/* nbd client library in userspace: state machine
* Copyright Red Hat
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* This isn't "real" C code. It is read by the generator, parsed, and
* put into generated files. Also it won't make much sense unless you
* read the generator state machine and documentation in
* generator/README.state-machine.md first.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include "minmax.h"
#include "internal.h"
/* Uncomment this to dump received protocol packets to stderr. */
/*#define DUMP_PACKETS 1*/
static int
recv_into_rbuf (struct nbd_handle *h)
{
ssize_t r;
void *rbuf;
size_t rlen;
/* As a special case h->rbuf is allowed to be NULL, meaning
* throw away the data.
*
* When building with DUMP_PACKETS, it's worth debugging even
* discarded packets; this makes our stack frame larger, but
* DUMP_PACKETS is already for developers. Otherwise, we share a
* single static sink buffer across all nbd handles; we don't care
* about thread-safety issues with two clients discarding data at
* the same time, because we never read the sink.
*/
#ifdef DUMP_PACKETS
char sink[1024];
#else
static char sink[BUFSIZ];
#endif
if (h->rlen == 0)
return 0; /* move to next state */
if (h->rbuf) {
rbuf = h->rbuf;
rlen = h->rlen;
}
else {
rbuf = sink;
rlen = MIN (h->rlen, sizeof sink);
}
r = h->sock->ops->recv (h, h->sock, rbuf, rlen);
if (r == -1) {
if (errno == EAGAIN || errno == EWOULDBLOCK)
return 1; /* more data */
/* sock->ops->recv called set_error already. */
return -1;
}
if (r == 0) {
set_error (0, "recv: server disconnected unexpectedly");
return -1;
}
#ifdef DUMP_PACKETS
nbd_internal_hexdump (rbuf, r, stderr);
#endif
h->bytes_received += r;
if (h->rbuf)
h->rbuf = (char *)h->rbuf + r;
h->rlen -= r;
if (h->rlen == 0)
return 0; /* move to next state */
else
return 1; /* more data */
}
static int
send_from_wbuf (struct nbd_handle *h)
{
ssize_t r;
if (h->wlen == 0)
goto next_state;
r = h->sock->ops->send (h, h->sock, h->wbuf, h->wlen, h->wflags);
if (r == -1) {
if (errno == EAGAIN || errno == EWOULDBLOCK)
return 1; /* more data */
/* sock->ops->send called set_error already. */
return -1;
}
h->bytes_sent += r;
h->wbuf = (char *)h->wbuf + r;
h->wlen -= r;
if (h->wlen == 0)
goto next_state;
else
return 1; /* more data */
next_state:
h->wflags = 0; /* reset this when moving to next state */
return 0; /* move to next state */
}
/* Forcefully fail any in-flight option */
static void
abort_option (struct nbd_handle *h)
{
int err = nbd_get_errno () ? : ENOTCONN;
CALL_CALLBACK (h->opt_cb.completion, &err);
nbd_internal_free_option (h);
}
/* Forcefully fail any remaining in-flight commands in list */
void
nbd_internal_abort_commands (struct nbd_handle *h, struct command **list)
{
struct command *next, *cmd;
for (cmd = *list, *list = NULL; cmd != NULL; cmd = next) {
bool retire = cmd->type == NBD_CMD_DISC;
next = cmd->next;
if (CALLBACK_IS_NOT_NULL (cmd->cb.completion)) {
int error = cmd->error ? cmd->error : ENOTCONN;
int r;
assert (cmd->type != NBD_CMD_DISC);
r = CALL_CALLBACK (cmd->cb.completion, &error);
switch (r) {
case -1:
if (error)
cmd->error = error;
break;
case 1:
retire = true;
break;
}
}
if (cmd->error == 0)
cmd->error = ENOTCONN;
if (retire)
nbd_internal_retire_and_free_command (cmd);
else {
cmd->next = NULL;
if (h->cmds_done_tail)
h->cmds_done_tail->next = cmd;
else {
assert (h->cmds_done == NULL);
h->cmds_done = cmd;
}
h->cmds_done_tail = cmd;
}
}
}
STATE_MACHINE {
READY:
if (h->cmds_to_issue)
SET_NEXT_STATE (%ISSUE_COMMAND.START);
else {
assert (h->sock);
if (h->sock->ops->pending && h->sock->ops->pending (h->sock))
SET_NEXT_STATE (%REPLY.START);
}
return 0;
DEAD:
const char *err = nbd_get_error ();
/* The caller should have used set_error() before reaching here */
assert (err != NULL);
debug (h, "handle dead: %s", err);
abort_option (h);
nbd_internal_abort_commands (h, &h->cmds_to_issue);
nbd_internal_abort_commands (h, &h->cmds_in_flight);
h->in_flight = 0;
if (h->sock) {
h->sock->ops->close (h->sock);
h->sock = NULL;
}
return -1;
CLOSED:
abort_option (h);
nbd_internal_abort_commands (h, &h->cmds_to_issue);
nbd_internal_abort_commands (h, &h->cmds_in_flight);
h->in_flight = 0;
if (h->sock) {
h->sock->ops->close (h->sock);
h->sock = NULL;
}
return 0;
} /* END STATE MACHINE */
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