/* 
   Unix SMB/CIFS implementation.

   thread model: standard (1 thread per client connection)

   Copyright (C) Andrew Tridgell 2003-2005
   Copyright (C) James J Myers 2003 <myersjj@samba.org>
   Copyright (C) Stefan (metze) Metzmacher 2004
   
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"
#include "version.h"
#include <pthread.h>
#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#endif
#include "system/wait.h"
#include "system/filesys.h"
#include "lib/events/events.h"
#include "dlinklist.h"
#include "smb_server/smb_server.h"
#include "mutex.h"

/* For sepecifiying event context to GSSAPI below */
#include "heimdal/lib/gssapi/gssapi_locl.h"

struct new_conn_state {
	struct event_context *ev;
	struct socket_context *sock;
	void (*new_conn)(struct event_context *, struct socket_context *, uint32_t , void *);
	void *private;
};

static void *thread_connection_fn(void *thread_parm)
{
	struct new_conn_state *new_conn = talloc_get_type(thread_parm, struct new_conn_state);

	new_conn->new_conn(new_conn->ev, new_conn->sock, pthread_self(), new_conn->private);

	/* run this connection from here */
	event_loop_wait(new_conn->ev);

	talloc_free(new_conn);

	return NULL;
}

/*
  called when a listening socket becomes readable
*/
static void thread_accept_connection(struct event_context *ev, 
				     struct socket_context *sock,
				     void (*new_conn)(struct event_context *, struct socket_context *, 
						      uint32_t , void *), 
				     void *private)
{		
	NTSTATUS status;
	int rc;
	pthread_t thread_id;
	pthread_attr_t thread_attr;
	struct new_conn_state *state;
	struct event_context *ev2;

	ev2 = event_context_init(ev);
	if (ev2 == NULL) return;

	state = talloc(ev2, struct new_conn_state);
	if (state == NULL) {
		talloc_free(ev2);
		return;
	}

	state->new_conn = new_conn;
	state->private  = private;
	state->ev       = ev2;

	/* accept an incoming connection. */
	status = socket_accept(sock, &state->sock);
	if (!NT_STATUS_IS_OK(status)) {
		talloc_free(ev2);
		/* We need to throttle things until the system clears
		   enough resources to handle this new socket. If we
		   don't then we will spin filling the log and causing
		   more problems. We don't panic as this is probably a
		   temporary resource constraint */
		sleep(1);
		return;
	}

	talloc_steal(state, state->sock);

	pthread_attr_init(&thread_attr);
	pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
	rc = pthread_create(&thread_id, &thread_attr, thread_connection_fn, state);
	pthread_attr_destroy(&thread_attr);
	if (rc == 0) {
		DEBUG(4,("accept_connection_thread: created thread_id=%lu for fd=%d\n", 
			(unsigned long int)thread_id, socket_get_fd(sock)));
	} else {
		DEBUG(0,("accept_connection_thread: thread create failed for fd=%d, rc=%d\n", socket_get_fd(sock), rc));
		talloc_free(ev2);
	}
}


struct new_task_state {
	struct event_context *ev;
	void (*new_task)(struct event_context *, uint32_t , void *);
	void *private;
};

static void *thread_task_fn(void *thread_parm)
{
	struct new_task_state *new_task = talloc_get_type(thread_parm, struct new_task_state);

	new_task->new_task(new_task->ev, pthread_self(), new_task->private);

	/* run this connection from here */
	event_loop_wait(new_task->ev);

	talloc_free(new_task);

	return NULL;
}

/*
  called when a new task is needed
*/
static void thread_new_task(struct event_context *ev, 
			    void (*new_task)(struct event_context *, uint32_t , void *), 
			    void *private)
{		
	int rc;
	pthread_t thread_id;
	pthread_attr_t thread_attr;
	struct new_task_state *state;
	struct event_context *ev2;

	ev2 = event_context_init(ev);
	if (ev2 == NULL) return;

	state = talloc(ev2, struct new_task_state);
	if (state == NULL) {
		talloc_free(ev2);
		return;
	}

	state->new_task = new_task;
	state->private  = private;
	state->ev       = ev2;

	pthread_attr_init(&thread_attr);
	pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
	rc = pthread_create(&thread_id, &thread_attr, thread_task_fn, state);
	pthread_attr_destroy(&thread_attr);
	if (rc == 0) {
		DEBUG(4,("thread_new_task: created thread_id=%lu\n", 
			 (unsigned long int)thread_id));
	} else {
		DEBUG(0,("thread_new_task: thread create failed rc=%d\n", rc));
		talloc_free(ev2);
	}
}

/* called when a task goes down */
static void thread_terminate(struct event_context *event_ctx, const char *reason) 
{
	DEBUG(10,("thread_terminate: reason[%s]\n",reason));

	talloc_free(event_ctx);

	/* terminate this thread */
	pthread_exit(NULL);  /* thread cleanup routine will do actual cleanup */
}

/*
  mutex init function for thread model
*/
static int thread_mutex_init(smb_mutex_t *mutex, const char *name)
{
	pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
	mutex->mutex = memdup(&m, sizeof(m));
	if (! mutex->mutex) {
		errno = ENOMEM;
		return -1;
	}
	return pthread_mutex_init((pthread_mutex_t *)mutex->mutex, NULL);
}

/*
  mutex destroy function for thread model
*/
static int thread_mutex_destroy(smb_mutex_t *mutex, const char *name)
{
	return pthread_mutex_destroy((pthread_mutex_t *)mutex->mutex);
}

static void mutex_start_timer(struct timeval *tp1)
{
	gettimeofday(tp1,NULL);
}

static double mutex_end_timer(struct timeval tp1)
{
	struct timeval tp2;
	gettimeofday(&tp2,NULL);
	return((tp2.tv_sec - tp1.tv_sec) + 
	       (tp2.tv_usec - tp1.tv_usec)*1.0e-6);
}

/*
  mutex lock function for thread model
*/
static int thread_mutex_lock(smb_mutex_t *mutexP, const char *name)
{
	pthread_mutex_t *mutex = (pthread_mutex_t *)mutexP->mutex;
	int rc;
	double t;
	struct timeval tp1;
	/* Test below is ONLY for debugging */
	if ((rc = pthread_mutex_trylock(mutex))) {
		if (rc == EBUSY) {
			mutex_start_timer(&tp1);
			printf("mutex lock: thread %d, lock %s not available\n", 
				(uint32_t)pthread_self(), name);
			print_suspicious_usage("mutex_lock", name);
			pthread_mutex_lock(mutex);
			t = mutex_end_timer(tp1);
			printf("mutex lock: thread %d, lock %s now available, waited %g seconds\n", 
				(uint32_t)pthread_self(), name, t);
			return 0;
		}
		printf("mutex lock: thread %d, lock %s failed rc=%d\n", 
				(uint32_t)pthread_self(), name, rc);
		SMB_ASSERT(errno == 0); /* force error */
	}
	return 0;
}

/* 
   mutex unlock for thread model
*/
static int thread_mutex_unlock(smb_mutex_t *mutex, const char *name)
{
	return pthread_mutex_unlock((pthread_mutex_t *)mutex->mutex);
}

/*****************************************************************
 Read/write lock routines.
*****************************************************************/  
/*
  rwlock init function for thread model
*/
static int thread_rwlock_init(smb_rwlock_t *rwlock, const char *name)
{
	pthread_rwlock_t m = PTHREAD_RWLOCK_INITIALIZER;
	rwlock->rwlock = memdup(&m, sizeof(m));
	if (! rwlock->rwlock) {
		errno = ENOMEM;
		return -1;
	}
	return pthread_rwlock_init((pthread_rwlock_t *)rwlock->rwlock, NULL);
}

/*
  rwlock destroy function for thread model
*/
static int thread_rwlock_destroy(smb_rwlock_t *rwlock, const char *name)
{
	return pthread_rwlock_destroy((pthread_rwlock_t *)rwlock->rwlock);
}

/*
  rwlock lock for read function for thread model
*/
static int thread_rwlock_lock_read(smb_rwlock_t *rwlockP, const char *name)
{
	pthread_rwlock_t *rwlock = (pthread_rwlock_t *)rwlockP->rwlock;
	int rc;
	double t;
	struct timeval tp1;
	/* Test below is ONLY for debugging */
	if ((rc = pthread_rwlock_tryrdlock(rwlock))) {
		if (rc == EBUSY) {
			mutex_start_timer(&tp1);
			printf("rwlock lock_read: thread %d, lock %s not available\n", 
				(uint32_t)pthread_self(), name);
			print_suspicious_usage("rwlock_lock_read", name);
			pthread_rwlock_rdlock(rwlock);
			t = mutex_end_timer(tp1);
			printf("rwlock lock_read: thread %d, lock %s now available, waited %g seconds\n", 
				(uint32_t)pthread_self(), name, t);
			return 0;
		}
		printf("rwlock lock_read: thread %d, lock %s failed rc=%d\n", 
				(uint32_t)pthread_self(), name, rc);
		SMB_ASSERT(errno == 0); /* force error */
	}
	return 0;
}

/*
  rwlock lock for write function for thread model
*/
static int thread_rwlock_lock_write(smb_rwlock_t *rwlockP, const char *name)
{
	pthread_rwlock_t *rwlock = (pthread_rwlock_t *)rwlockP->rwlock;
	int rc;
	double t;
	struct timeval tp1;
	/* Test below is ONLY for debugging */
	if ((rc = pthread_rwlock_trywrlock(rwlock))) {
		if (rc == EBUSY) {
			mutex_start_timer(&tp1);
			printf("rwlock lock_write: thread %d, lock %s not available\n", 
				(uint32_t)pthread_self(), name);
			print_suspicious_usage("rwlock_lock_write", name);
			pthread_rwlock_wrlock(rwlock);
			t = mutex_end_timer(tp1);
			printf("rwlock lock_write: thread %d, lock %s now available, waited %g seconds\n", 
				(uint32_t)pthread_self(), name, t);
			return 0;
		}
		printf("rwlock lock_write: thread %d, lock %s failed rc=%d\n", 
				(uint32_t)pthread_self(), name, rc);
		SMB_ASSERT(errno == 0); /* force error */
	}
	return 0;
}


/* 
   rwlock unlock for thread model
*/
static int thread_rwlock_unlock(smb_rwlock_t *rwlock, const char *name)
{
	return pthread_rwlock_unlock((pthread_rwlock_t *)rwlock->rwlock);
}

/*****************************************************************
 Log suspicious usage (primarily for possible thread-unsafe behavior.
*****************************************************************/  
static void thread_log_suspicious_usage(const char* from, const char* info)
{
	DEBUG(1,("log_suspicious_usage: from %s info='%s'\n", from, info));
#ifdef HAVE_BACKTRACE
	{
		void *addresses[10];
		int num_addresses = backtrace(addresses, 8);
		char **bt_symbols = backtrace_symbols(addresses, num_addresses);
		int i;

		if (bt_symbols) {
			for (i=0; i<num_addresses; i++) {
				DEBUG(1,("log_suspicious_usage: %s%s\n", DEBUGTAB(1), bt_symbols[i]));
			}
			free(bt_symbols);
		}
	}
#endif
}

/*****************************************************************
 Log suspicious usage to stdout (primarily for possible thread-unsafe behavior.
 Used in mutex code where DEBUG calls would cause recursion.
*****************************************************************/  
static void thread_print_suspicious_usage(const char* from, const char* info)
{
	printf("log_suspicious_usage: from %s info='%s'\n", from, info);
#ifdef HAVE_BACKTRACE
	{
		void *addresses[10];
		int num_addresses = backtrace(addresses, 8);
		char **bt_symbols = backtrace_symbols(addresses, num_addresses);
		int i;

		if (bt_symbols) {
			for (i=0; i<num_addresses; i++) {
				printf("log_suspicious_usage: %s%s\n", DEBUGTAB(1), bt_symbols[i]);
			}
			free(bt_symbols);
		}
	}
#endif
}

static uint32_t thread_get_task_id(void)
{
	return (uint32_t)pthread_self();
}

static void thread_log_task_id(int fd)
{
	char *s;
	
	asprintf(&s, "thread %u: ", (uint32_t)pthread_self());
	write(fd, s, strlen(s));
	free(s);
}

/****************************************************************************
catch serious errors
****************************************************************************/
static void thread_sig_fault(int sig)
{
	DEBUG(0,("===============================================================\n"));
	DEBUG(0,("TERMINAL ERROR: Recursive signal %d in thread %lu (%s)\n",sig,(unsigned long int)pthread_self(),SAMBA_VERSION_STRING));
	DEBUG(0,("===============================================================\n"));
	exit(1); /* kill the whole server for now */
}

/*******************************************************************
setup our recursive fault handlers
********************************************************************/
static void thread_fault_setup(void)
{
#ifdef SIGSEGV
	CatchSignal(SIGSEGV,SIGNAL_CAST thread_sig_fault);
#endif
#ifdef SIGBUS
	CatchSignal(SIGBUS,SIGNAL_CAST thread_sig_fault);
#endif
#ifdef SIGABRT
	CatchSignal(SIGABRT,SIGNAL_CAST thread_sig_fault);
#endif
}

/*******************************************************************
report a fault in a thread
********************************************************************/
static void thread_fault_handler(int sig)
{
	static int counter;
	
	/* try to catch recursive faults */
	thread_fault_setup();
	
	counter++;	/* count number of faults that have occurred */

	DEBUG(0,("===============================================================\n"));
	DEBUG(0,("INTERNAL ERROR: Signal %d in thread %lu (%s)\n",sig,(unsigned long int)pthread_self(),SAMBA_VERSION_STRING));
	DEBUG(0,("Please read the file BUGS.txt in the distribution\n"));
	DEBUG(0,("===============================================================\n"));
#ifdef HAVE_BACKTRACE
	{
		void *addresses[10];
		int num_addresses = backtrace(addresses, 8);
		char **bt_symbols = backtrace_symbols(addresses, num_addresses);
		int i;

		if (bt_symbols) {
			for (i=0; i<num_addresses; i++) {
				DEBUG(1,("fault_report: %s%s\n", DEBUGTAB(1), bt_symbols[i]));
			}
			free(bt_symbols);
		}
	}
#endif
	pthread_exit(NULL); /* terminate failing thread only */
}

/*
  called when the process model is selected
*/
static void thread_model_init(struct event_context *event_context)
{
	struct mutex_ops m_ops;
	struct debug_ops d_ops;

	ZERO_STRUCT(m_ops);
	ZERO_STRUCT(d_ops);

	/* register mutex/rwlock handlers */
	m_ops.mutex_init = thread_mutex_init;
	m_ops.mutex_lock = thread_mutex_lock;
	m_ops.mutex_unlock = thread_mutex_unlock;
	m_ops.mutex_destroy = thread_mutex_destroy;
	
	m_ops.rwlock_init = thread_rwlock_init;
	m_ops.rwlock_lock_write = thread_rwlock_lock_write;
	m_ops.rwlock_lock_read = thread_rwlock_lock_read;
	m_ops.rwlock_unlock = thread_rwlock_unlock;
	m_ops.rwlock_destroy = thread_rwlock_destroy;

	register_mutex_handlers("thread", &m_ops);

	register_fault_handler("thread", thread_fault_handler);

	d_ops.log_suspicious_usage = thread_log_suspicious_usage;
	d_ops.print_suspicious_usage = thread_print_suspicious_usage;
	d_ops.get_task_id = thread_get_task_id;
	d_ops.log_task_id = thread_log_task_id;

	register_debug_handlers("thread", &d_ops);

	/* Hack to ensure that GSSAPI uses the right event context */
	gssapi_krb5_init_ev(event_context);
}


static const struct model_ops thread_ops = {
	.name			= "thread",
	.model_init		= thread_model_init,
	.accept_connection	= thread_accept_connection,
	.new_task               = thread_new_task,
	.terminate              = thread_terminate,
};

/*
  initialise the thread process model, registering ourselves with the model subsystem
 */
NTSTATUS process_model_thread_init(void)
{
	NTSTATUS ret;

	/* register ourselves with the PROCESS_MODEL subsystem. */
	ret = register_process_model(&thread_ops);
	if (!NT_STATUS_IS_OK(ret)) {
		DEBUG(0,("Failed to register process_model 'thread'!\n"));
		return ret;
	}

	return ret;
}