/**
* mds — A micro-display server
* Copyright © 2014, 2015, 2016, 2017 Mattias Andrée (maandree@kth.se)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "globals.h"
#include "client.h"
#include "slavery.h"
#include <libmdsserver/linked-list.h>
#include <libmdsserver/hash-table.h>
#include <libmdsserver/fd-table.h>
#include <libmdsserver/macros.h>
#include <libmdsserver/util.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <errno.h>
#include <signal.h>
#include <limits.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <dirent.h>
#include <string.h>
/**
* Calculate the number of bytes that will be stored by `marshal_server`
*
* On failure the program should `abort()` or exit by other means.
* However it should not be possible for this function to fail.
*
* @return The number of bytes that will be stored by `marshal_server`
*/
size_t
marshal_server_size(void)
{
size_t list_size = linked_list_marshal_size(&client_list);
size_t map_size = fd_table_marshal_size(&client_map);
size_t list_elements = 0;
size_t state_n = 0;
ssize_t node;
/* Calculate the grand size of all client information. */
foreach_linked_list_node (client_list, node) {
state_n += client_marshal_size((void *)(client_list.values[node]));
list_elements++;
}
/* Add the size of the rest of the program's state. */
state_n += sizeof(int) + sizeof(sig_atomic_t) + 2 * sizeof(uint64_t) + 2 * sizeof(size_t);
state_n += list_elements * sizeof(size_t) + list_size + map_size;
return state_n;
}
/**
* Marshal server implementation specific data into a buffer
*
* @param state_buf The buffer for the marshalled data
* @return Non-zero on error
*/
int
marshal_server(char *state_buf)
{
size_t list_size = linked_list_marshal_size(&client_list);
size_t list_elements = 0;
ssize_t node;
size_t value_address;
client_t *value, *client;
/* Release resources. */
pthread_mutex_destroy(&slave_mutex);
pthread_cond_destroy(&slave_cond);
pthread_mutex_destroy(&modify_mutex);
pthread_cond_destroy(&modify_cond);
hash_table_destroy(&modify_map, NULL, NULL);
/* Count the number of clients that online. */
foreach_linked_list_node (client_list, node)
list_elements++;
/* Tell the new version of the program what version of the program it is marshalling. */
buf_set_next(state_buf, int, MDS_SERVER_VARS_VERSION);
/* Marshal the miscellaneous state data. */
buf_set_next(state_buf, sig_atomic_t, running);
buf_set_next(state_buf, uint64_t, next_client_id);
buf_set_next(state_buf, uint64_t, next_modify_id);
/* Tell the program how large the marshalled client list is and how any clients are marshalled. */
buf_set_next(state_buf, size_t, list_size);
buf_set_next(state_buf, size_t, list_elements);
/* Marshal the clients. */
foreach_linked_list_node (client_list, node) {
/* Get the memory address of the client. */
value_address = client_list.values[node];
/* Get the client's information. */
value = (void *)value_address;
/* Marshal the address, it is used the the client list and the client map, that will be marshalled. */
buf_set_next(state_buf, size_t, value_address);
/* Marshal the client informationation. */
state_buf += client_marshal(value, state_buf) / sizeof(char);
}
/* Marshal the client list. */
linked_list_marshal(&client_list, state_buf);
state_buf += list_size / sizeof(char);
/* Marshal the client map. */
fd_table_marshal(&client_map, state_buf);
/* Release resources. */
foreach_linked_list_node (client_list, node) {
client = (void *)(client_list.values[node]);
client_destroy(client);
}
fd_table_destroy(&client_map, NULL, NULL);
linked_list_destroy(&client_list);
return 0;
}
/**
* Address translation table used by `unmarshal_server` and `remapper`
*/
static hash_table_t unmarshal_remap_map;
/**
* Address translator for `unmarshal_server`
*
* @param old The old address
* @return The new address
*/
static size_t
unmarshal_remapper(size_t old)
{
return hash_table_get(&unmarshal_remap_map, old);
}
/**
* Unmarshal server implementation specific data and update the servers state accordingly
*
* On critical failure the program should `abort()` or exit by other means.
* That is, do not let `reexec_failure_recover` run successfully, if it unrecoverable
* error has occurred or one severe enough that it is better to simply respawn.
*
* @param state_buf The marshalled data that as not been read already
* @return Non-zero on error
*/
int
unmarshal_server(char *state_buf)
{
int with_error = 0;
size_t list_size;
size_t list_elements;
size_t i;
ssize_t node;
pthread_t slave_thread;
size_t n, value_address, new_address;
client_t *value, *client;
int slave_fd;
#define fail soft_fail
/* Create memory address remapping table. */
fail_if (hash_table_create(&unmarshal_remap_map));
#undef fail
#define fail clients_fail
/* Get the marshal protocal version. Not needed, there is only the one version right now. */
/* buf_get(state_buf, int, 0, MDS_SERVER_VARS_VERSION); */
buf_next(state_buf, int, 1);
/* Unmarshal the miscellaneous state data. */
buf_get_next(state_buf, sig_atomic_t, running);
buf_get_next(state_buf, uint64_t, next_client_id);
buf_get_next(state_buf, uint64_t, next_modify_id);
/* Get the marshalled size of the client list and how any clients that are marshalled. */
buf_get_next(state_buf, size_t, list_size);
buf_get_next(state_buf, size_t, list_elements);
/* Unmarshal the clients. */
for (i = 0; i < list_elements; i++) {
/* Allocate the client's information. */
fail_if (xmalloc(value, 1, client_t));
/* Unmarshal the address, it is used the the client list and the client map, that are also marshalled. */
buf_get_next(state_buf, size_t, value_address);
/* Unmarshal the client information. */
fail_if (n = client_unmarshal(value, state_buf), n == 0);
/* Populate the remapping table. */
if (!hash_table_put(&unmarshal_remap_map, value_address, (size_t)(void *)value))
fail_if (errno);
/* Delayed seeking. */
state_buf += n / sizeof(char);
/* On error, seek past all clients. */
continue;
clients_fail:
xperror(*argv);
with_error = 1;
if (value) {
buf_prev(state_buf, size_t, 1);
free(value);
}
for (; i < list_elements; i++)
/* There is not need to close the sockets, it is done by
the caller because there are conditions where we cannot
get here anyway. */
state_buf += client_unmarshal_skip(state_buf) / sizeof(char);
break;
}
#undef fail
#define fail critical_fail
/* Unmarshal the client list. */
fail_if (linked_list_unmarshal(&client_list, state_buf));
state_buf += list_size / sizeof(char);
/* Unmarshal the client map. */
fail_if (fd_table_unmarshal(&client_map, state_buf, unmarshal_remapper));
/* Remove non-found elements from the fd table. */
#define __bit(I, _OP_) (client_map.used[I / 64] _OP_ ((uint64_t)1 << (I % 64)))
if (with_error)
for (i = 0; i < client_map.capacity; i++)
if (__bit(i, &) && !client_map.values[i])
/* Lets not presume that fd-table actually initialise its allocations. */
__bit(i, &= ~);
#undef __bit
/* Remap the linked list and remove non-found elements, and start the clients. */
foreach_linked_list_node (client_list, node) {
/* Remap the linked list and remove non-found elements. */
new_address = unmarshal_remapper(client_list.values[node]);
client_list.values[node] = new_address;
if (new_address == 0) { /* Returned if missing (or if the address is the invalid NULL.) */
linked_list_remove(&client_list, node);
} else {
/* Start the clients. (Errors do not need to be reported.) */
client = (client_t*)(void*)new_address;
slave_fd = client->socket_fd;
/* Increase number of running slaves. */
with_mutex (slave_mutex, running_slaves++;);
/* Start slave thread. */
create_slave(&slave_thread, slave_fd);
}
}
/* Release the remapping table's resources. */
hash_table_destroy(&unmarshal_remap_map, NULL, NULL);
return with_error;
#undef fail
soft_fail:
xperror(*argv);
hash_table_destroy(&unmarshal_remap_map, NULL, NULL);
return -1;
critical_fail:
xperror(*argv);
abort();
}
/**
* Attempt to recover from a re-exec failure that has been
* detected after the server successfully updated it execution image
*
* @return Non-zero on error
*/
int
reexec_failure_recover(void)
{
/* Close all files (hopefully sockets) we do not know what they are. */
close_files(fd > 2 && fd != socket_fd && !fd_table_contains_key(&client_map, fd));
return 0;
}
