-/*
- * Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
/** \file server.c Paraslash's main server. */
/* Command line options (no config file options). Used in handle_sighup(). */
static struct lls_parse_result *cmdline_lpr;
-/** A random value used in child context for authentication. */
+/**
+ * A random number used to "authenticate" the afs connection.
+ *
+ * para_server picks this number by random before it forks the afs process. The
+ * command handlers know this number as well and write it to the afs socket,
+ * together with the id of the shared memory area which contains the payload of
+ * the afs command. A local process has to know this number to abuse the afs
+ * service provided by the local socket.
+ */
uint32_t afs_socket_cookie;
/** The mutex protecting the shared memory area containing the mmd struct. */
static struct sched sched;
static struct signal_task *signal_task;
+/** The process id of the audio file selector process. */
+pid_t afs_pid = 0;
+
+/* The the main server process (parent of afs and the command handlers). */
+static pid_t server_pid;
+
+/**
+ * Tell whether the executing process is a command handler.
+ *
+ * Cleanup on exit must be performed differently for command handlers.
+ *
+ * \return True if the pid of the executing process is neither the server pid
+ * nor the afs pid.
+ */
+bool process_is_command_handler(void)
+{
+ pid_t pid = getpid();
+
+ return pid != afs_pid && pid != server_pid;
+}
+
/** The task responsible for server command handling. */
struct server_command_task {
/** TCP port on which para_server listens for connections. */
int listen_fd;
+ /* File descriptor for the accepted socket. */
+ int child_fd;
/** Copied from para_server's main function. */
int argc;
/** Argument vector passed to para_server's main function. */
struct lls_parse_result *cf_lpr, *merged_lpr;
char *home = para_homedir();
- daemon_close_log();
if (OPT_GIVEN(CONFIG_FILE))
cf = para_strdup(OPT_STRING_VAL(CONFIG_FILE));
else
cf = make_message("%s/.paraslash/server.conf", home);
- if (!mmd || getpid() != mmd->afs_pid) {
+ if (!mmd || getpid() != afs_pid) {
if (OPT_GIVEN(USER_LIST))
user_list_file = para_strdup(OPT_STRING_VAL(USER_LIST));
else
goto free_cf;
if (ret == -ERRNO_TO_PARA_ERROR(ENOENT) && OPT_GIVEN(CONFIG_FILE))
goto free_cf;
- ret = 0;
server_lpr = cmdline_lpr;
goto success;
}
if (reload) /* config file overrides command line */
ret = lls(lls_merge(cf_lpr, cmdline_lpr, CMD_PTR, &merged_lpr,
&errctx));
- else /* command line options overrride config file options */
+ else /* command line options override config file options */
ret = lls(lls_merge(cmdline_lpr, cf_lpr, CMD_PTR, &merged_lpr,
&errctx));
lls_free_parse_result(cf_lpr, CMD_PTR);
PARA_NOTICE_LOG("SIGHUP\n");
parse_config_or_die(true);
- if (mmd->afs_pid)
- kill(mmd->afs_pid, SIGHUP);
+ if (afs_pid != 0)
+ kill(afs_pid, SIGHUP);
}
static int signal_post_select(struct sched *s, __a_unused void *context)
{
- int signum = para_next_signal(&s->rfds);
+ int ret, signum;
+ ret = task_get_notification(signal_task->task);
+ if (ret < 0)
+ return ret;
+ signum = para_next_signal(&s->rfds);
switch (signum) {
case 0:
return 0;
case SIGCHLD:
for (;;) {
pid_t pid;
- int ret = para_reap_child(&pid);
+ ret = para_reap_child(&pid);
if (ret <= 0)
break;
- if (pid != mmd->afs_pid)
+ if (pid != afs_pid)
continue;
PARA_EMERG_LOG("fatal: afs died\n");
kill(0, SIGTERM);
PARA_EMERG_LOG("terminating on signal %d\n", signum);
kill(0, SIGTERM);
/*
- * We must wait for afs because afs catches SIGINT/SIGTERM.
- * Before reacting to the signal, afs might want to use the
+ * We must wait for all of our children to die. For the afs
+ * process or a command handler might want to use the
* shared memory area and the mmd mutex. If we destroy this
* mutex too early and afs tries to lock the shared memory
* area, the call to mutex_lock() will fail and terminate the
* afs process. This leads to dirty osl tables.
- *
- * There's no such problem with the other children of the
- * server process (the command handlers) as these reset their
- * SIGINT/SIGTERM handlers to the default action, i.e. these
- * processes get killed immediately by the above kill().
*/
- PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
- (int)mmd->afs_pid);
- waitpid(mmd->afs_pid, NULL, 0);
+ PARA_INFO_LOG("waiting for child processes to die\n");
+ mutex_unlock(mmd_mutex);
+ while (wait(NULL) != -1 || errno != ECHILD)
+ ; /* still at least one child alive */
+ mutex_lock(mmd_mutex);
cleanup:
free(mmd->afd.afhi.chunk_table);
- close_listed_fds();
- mutex_destroy(mmd_mutex);
- shm_detach(mmd);
- exit(EXIT_FAILURE);
+ task_notify_all(s, E_DEADLY_SIGNAL);
+ return -E_DEADLY_SIGNAL;
}
return 0;
}
static int command_post_select(struct sched *s, void *context)
{
struct server_command_task *sct = context;
-
int new_fd, ret, i;
char *peer_name;
pid_t child_pid;
uint32_t *chunk_table;
+ ret = task_get_notification(sct->task);
+ if (ret < 0)
+ return ret;
ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
if (ret <= 0)
goto out;
- peer_name = remote_name(new_fd);
- PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
mmd->num_connects++;
mmd->active_connections++;
/*
/* parent keeps accepting connections */
return 0;
}
+ peer_name = remote_name(new_fd);
+ PARA_INFO_LOG("accepted connection from %s\n", peer_name);
/* mmd might already have changed at this point */
free(chunk_table);
- alarm(ALARM_TIMEOUT);
- close_listed_fds();
- signal_shutdown(signal_task);
+ sct->child_fd = new_fd;
/*
* put info on who we are serving into argv[0] to make
* client ip visible in top/ps
memset(sct->argv[i], 0, strlen(sct->argv[i]));
i = sct->argc - 1 - lls_num_inputs(cmdline_lpr);
sprintf(sct->argv[i], "para_server (serving %s)", peer_name);
- handle_connect(new_fd, peer_name);
- /* never reached*/
+ /* ask other tasks to terminate */
+ task_notify_all(s, E_CHILD_CONTEXT);
+ /*
+ * After we return, the scheduler calls server_select() with a minimal
+ * timeout value, because the remaining tasks have a notification
+ * pending. Next it calls the ->post_select method of these tasks,
+ * which will return negative in view of the notification. This causes
+ * schedule() to return as there are no more runnable tasks.
+ *
+ * Note that semaphores are not inherited across a fork(), so we don't
+ * hold the lock at this point. Since server_select() drops the lock
+ * prior to calling para_select(), we need to acquire it here.
+ */
+ mutex_lock(mmd_mutex);
+ return -E_CHILD_CONTEXT;
out:
if (ret < 0)
PARA_CRIT_LOG("%s\n", para_strerror(-ret));
return 0;
}
-static void init_server_command_task(int argc, char **argv)
+static void init_server_command_task(struct server_command_task *sct,
+ int argc, char **argv)
{
int ret;
- static struct server_command_task server_command_task_struct,
- *sct = &server_command_task_struct;
PARA_NOTICE_LOG("initializing tcp command socket\n");
+ sct->child_fd = -1;
sct->argc = argc;
sct->argv = argv;
ret = para_listen_simple(IPPROTO_TCP, OPT_UINT32_VAL(PORT));
static int init_afs(int argc, char **argv)
{
int ret, afs_server_socket[2];
- pid_t afs_pid;
char c;
ret = socketpair(PF_UNIX, SOCK_STREAM, 0, afs_server_socket);
if (afs_pid == 0) { /* child (afs) */
int i;
+ afs_pid = getpid();
for (i = argc - 1; i >= 0; i--)
memset(argv[i], 0, strlen(argv[i]));
i = argc - lls_num_inputs(cmdline_lpr) - 1;
sprintf(argv[i], "para_server (afs)");
close(afs_server_socket[0]);
- afs_init(afs_socket_cookie, afs_server_socket[1]);
+ afs_init(afs_server_socket[1]);
}
- mmd->afs_pid = afs_pid;
close(afs_server_socket[1]);
if (read(afs_server_socket[0], &c, 1) <= 0) {
PARA_EMERG_LOG("early afs exit\n");
exit(EXIT_SUCCESS);
}
-static void server_init(int argc, char **argv)
+static void server_init(int argc, char **argv, struct server_command_task *sct)
{
int ret, afs_socket, daemon_pipe = -1;
char *errctx;
/* become daemon */
if (OPT_GIVEN(DAEMON))
daemon_pipe = daemonize(true /* parent waits for SIGTERM */);
+ server_pid = getpid();
init_random_seed_or_die();
daemon_log_welcome("server");
init_ipc_or_die(); /* init mmd struct and mmd->lock */
init_signal_task();
para_unblock_signal(SIGCHLD);
PARA_NOTICE_LOG("initializing virtual streaming system\n");
- init_vss_task(afs_socket, &sched);
- init_server_command_task(argc, argv);
+ vss_init(afs_socket, &sched);
+ init_server_command_task(sct, argc, argv);
if (daemon_pipe >= 0) {
if (write(daemon_pipe, "\0", 1) < 0) {
PARA_EMERG_LOG("daemon_pipe: %s", strerror(errno));
int main(int argc, char *argv[])
{
int ret;
+ struct server_command_task server_command_task_struct,
+ *sct = &server_command_task_struct;
sched.default_timeout.tv_sec = 1;
sched.select_function = server_select;
- server_init(argc, argv);
+ server_init(argc, argv, sct);
mutex_lock(mmd_mutex);
ret = schedule(&sched);
+ /*
+ * We hold the mmd lock: it was re-acquired in server_select()
+ * after the select call.
+ */
+ mutex_unlock(mmd_mutex);
sched_shutdown(&sched);
+ signal_shutdown(signal_task);
+ if (!process_is_command_handler()) { /* parent (server) */
+ mutex_destroy(mmd_mutex);
+ shm_detach(mmd);
+ if (ret < 0)
+ PARA_EMERG_LOG("%s\n", para_strerror(-ret));
+ } else {
+ alarm(ALARM_TIMEOUT);
+ close_listed_fds();
+ ret = handle_connect(sct->child_fd);
+ }
+ vss_shutdown();
+ shm_detach(mmd);
lls_free_parse_result(server_lpr, CMD_PTR);
if (server_lpr != cmdline_lpr)
lls_free_parse_result(cmdline_lpr, CMD_PTR);
- if (ret < 0)
- PARA_EMERG_LOG("%s\n", para_strerror(-ret));
exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
}
projects / paraslash.git / blobdiff