/**
* 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 "mds-respawn.h"
#include <libmdsserver/macros.h>
#include <libmdsserver/util.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
/**
* This variable should declared by the actual server implementation.
* It must be configured before `main` is invoked.
*
* This tells the server-base how to behave
*/
server_characteristics_t server_characteristics =
{
.require_privileges = 0,
.require_display = 0,
.require_respawn_info = 1,
.sanity_check_argc = 0
};
/**
* Do not respawn crashed servers that did not live this many seconds
*/
static int interval = 5;
/**
* The number of servers managed by this process
*/
static size_t servers = 0;
/**
* Command line arguments, for each server — concatenated, with NULL termination
*/
static const char** commands_args = NULL;
/**
* Mapping elements in `commands_args` that are the first
* argument for each server to run
*/
static const char*** commands = NULL;
/**
* States of managed servers
*/
static server_state_t* states = NULL;
/**
* Parse command line arguments
*
* @return Non-zero on error
*/
int parse_cmdline(void)
{
int i;
size_t j, args = 0, stack = 0;
for (i = 1; i < argc; i++)
{
char* arg = argv[i];
if (startswith(arg, "--alarm=")) /* Schedule an alarm signal for forced abort. */
alarm((unsigned)min(atoi(arg + strlen("--alarm=")), 60)); /* At most 1 minute. */
else if (startswith(arg, "--interval="))
interval = min(atoi(arg + strlen("--interval=")), 60); /* At most 1 minute. */
else if (strequals(arg, "--re-exec")) /* Re-exec state-marshal. */
is_reexec = 1;
else if (strequals(arg, "{"))
servers += stack++ == 0 ? 1 : 0;
else if (strequals(arg, "}"))
{
exit_if (stack-- == 0, eprint("Terminating non-started command, aborting"););
exit_if (stack == 0 && strequals(argv[i - 1], "{"),
eprint("Zero argument command specified, aborting"););
}
else if (stack == 0)
eprintf("Unrecognised option: %s, did you forget `='?", arg);
else
args++;
}
if (is_reexec)
{
is_respawn = 1;
eprint("re-exec performed.");
}
exit_if (stack > 0, eprint("Non-terminated command specified, aborting"););
exit_if (servers == 0, eprint("No programs to spawn, aborting"););
fail_if (xmalloc(commands_args, args + servers, char*));
fail_if (xmalloc(commands, servers, char**));
fail_if (xmalloc(states, servers, server_state_t));
for (i = 1, args = j = 0; i < argc; i++)
{
char* arg = argv[i];
if (strequals(arg, "}")) commands_args[args++] = --stack == 0 ? NULL : arg;
else if (stack > 0) commands_args[args++] = arg;
else if (strequals(arg, "{") && (stack++ == 0))
commands[j++] = commands_args + args;
}
return 0;
pfail:
perror(*argv);
return 1;
}
/**
* This function is called when a signal that
* signals the program to respawn all
* `DEAD_AND_BURIED` server is received
*
* @param signo The signal that has been received
*/
static void received_revive(int signo)
{
/* TODO */
(void) signo;
eprint("revive signal received.");
}
/**
* This function will be invoked before `initialise_server` (if not re-exec:ing)
* or before `unmarshal_server` (if re-exec:ing)
*
* @return Non-zero on error
*/
int preinitialise_server(void)
{
/* Make the server revive all `DEAD_AND_BURIED` servers on SIGUSR2. */
fail_if (xsigaction(SIGUSR2, received_revive) < 0);
return 0;
pfail:
perror(*argv);
return 1;
}
/**
* This function should initialise the server,
* and it not invoked after a re-exec.
*
* @return Non-zero on error
*/
int initialise_server(void)
{
size_t i;
for (i = 0; i < servers; i++)
{
states[i].pid = 0;
states[i].state = UNBORN;
}
return 0;
}
/**
* This function will be invoked after `initialise_server` (if not re-exec:ing)
* or after `unmarshal_server` (if re-exec:ing)
*
* @return Non-zero on error
*/
int postinitialise_server(void)
{
size_t i, j;
/* TODO Spawn `UNBORN` servers. */
for (i = j = 0; j < servers; i++)
if (commands_args[i] == NULL)
j++;
else if (strequals(commands_args[i], "--initial-spawn"))
commands_args[i] = "--respawn";
/* TODO Spawn `DEAD` and `DEAD_AND_BURIED` servers. */
return 0;
}
/**
* 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)
{
/* TODO */
return 0;
}
/**
* 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)
{
/* TODO */
(void) state_buf;
return 0;
}
/**
* 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)
{
/* TODO */
(void) state_buf;
return 0;
}
/**
* 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)
{
/* TODO */
return 0;
}
/**
* Perform the server's mission
*
* @return Non-zero on error
*/
int master_loop(void)
{
/* TODO */
return 0;
}
