/**
* mds — A micro-display server
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* 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 "reexec.h"
#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>
/**
* Marshal the server's state into a file
*
* @param fd The file descriptor
* @return Negative on error
*/
int marshal_server(int fd)
{
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;
char* state_buf = NULL;
char* state_buf_;
ssize_t node;
/* Calculate the grand size of all client information. */
for (node = client_list.edge;; list_elements++)
{
if ((node = client_list.next[node]) == client_list.edge)
break;
state_n += client_marshal_size((client_t*)(void*)(client_list.values[node]));
}
/* 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;
/* Allocate a buffer for all data except the client list and the client map. */
state_buf = state_buf_ = malloc(state_n);
if (state_buf == NULL)
goto fail;
/* 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. */
size_t value_address = client_list.values[node];
/* Get the client's information. */
client_t* value = (client_t*)(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_);
/* Send the marshalled data into the file. */
if (full_write(fd, state_buf, state_n) < 0)
goto fail;
free(state_buf);
return 0;
fail:
perror(*argv);
free(state_buf);
return -1;
}
/**
* 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 the server's state from a file
*
* @param fd The file descriptor
* @return Negative on error
*/
int unmarshal_server(int fd)
{
int with_error = 0;
char* state_buf;
char* state_buf_;
size_t list_size;
size_t list_elements;
size_t i;
ssize_t node;
pthread_t slave_thread;
/* Read the file. */
if ((state_buf = state_buf_ = full_read(fd)) == NULL)
{
perror(*argv);
return -1;
}
/* Create memory address remapping table. */
if (hash_table_create(&unmarshal_remap_map))
{
perror(*argv);
free(state_buf);
hash_table_destroy(&unmarshal_remap_map, NULL, NULL);
return -1;
}
/* 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++)
{
size_t n;
size_t value_address;
client_t* value;
/* Allocate the client's information. */
if (xmalloc(value, 1, client_t))
goto clients_fail;
/* 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. */
n = client_unmarshal(value, state_buf_);
if (n == 0)
goto clients_fail;
/* Populate the remapping table. */
if (hash_table_put(&unmarshal_remap_map, value_address, (size_t)(void*)value) == 0)
if (errno)
goto clients_fail;
/* Delayed seeking. */
state_buf_ += n / sizeof(char);
/* On error, seek past all clients. */
continue;
clients_fail:
perror(*argv);
with_error = 1;
if (value != NULL)
{
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;
}
/* Unmarshal the client list. */
if (linked_list_unmarshal(&client_list, state_buf_))
goto critical_fail;
state_buf_ += list_size / sizeof(char);
/* Unmarshal the client map. */
if (fd_table_unmarshal(&client_map, state_buf_, unmarshal_remapper))
goto critical_fail;
/* Release the raw data. */
free(state_buf);
/* 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] == 0))
/* 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. */
size_t 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_t* client = (client_t*)(void*)new_address;
int socket_fd = client->socket_fd;
/* Increase number of running slaves. */
with_mutex (slave_mutex, running_slaves++;);
/* Start slave thread. */
create_slave(&slave_thread, socket_fd);
}
}
/* Release the remapping table's resources. */
hash_table_destroy(&unmarshal_remap_map, NULL, NULL);
return -with_error;
critical_fail:
perror(*argv);
abort();
}
/**
* Marshal and re-execute the server
*
* @param reexec Whether the server was previously re-executed
*/
void perform_reexec(int reexec)
{
pid_t pid = getpid();
int reexec_fd;
char shm_path[NAME_MAX + 1];
ssize_t node;
/* Join with all slaves threads. */
with_mutex (slave_mutex,
while (running_slaves > 0)
pthread_cond_wait(&slave_cond, &slave_mutex););
/* 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);
/* Marshal the state of the server. */
xsnprintf(shm_path, SHM_PATH_PATTERN, (unsigned long int)pid);
reexec_fd = shm_open(shm_path, O_RDWR | O_CREAT | O_EXCL, S_IRWXU);
fail_if (reexec_fd < 0);
fail_if (marshal_server(reexec_fd) < 0);
close(reexec_fd);
reexec_fd = -1;
/* Release resources. */
foreach_linked_list_node (client_list, node)
{
client_t* client = (client_t*)(void*)(client_list.values[node]);
client_destroy(client);
}
fd_table_destroy(&client_map, NULL, NULL);
linked_list_destroy(&client_list);
/* Re-exec the server. */
reexec_server(argc, argv, reexec);
pfail:
perror(*argv);
if (reexec_fd >= 0)
{
close(reexec_fd);
shm_unlink(shm_path);
}
}
/**
* Attempt to reload the server after a re-execution
*
* @param socket_fd The file descriptor of the server socket
*/
void complete_reexec(int socket_fd)
{
pid_t pid = getpid();
int reexec_fd, r;
char shm_path[NAME_MAX + 1];
/* Acquire access to marshalled data. */
xsnprintf(shm_path, SHM_PATH_PATTERN, (unsigned long int)pid);
reexec_fd = shm_open(shm_path, O_RDONLY, S_IRWXU);
fail_if (reexec_fd < 0); /* Critical. */
/* Unmarshal state. */
r = unmarshal_server(reexec_fd);
close(reexec_fd);
shm_unlink(shm_path);
if (r < 0)
{
/* 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) == 0));
}
return;
pfail:
perror(*argv);
abort();
}
