/*

 * mt_support.c - multi-thread resource locking support 

 */

/*

 * Author: Markku Laukkanen

 * Created: 6-Sep-1999

 * History:

 *  8-Sep-1999 M. Slifcak method names changed;

 *                        use array of resource locking structures.

 */

#include <net-snmp/net-snmp-config.h>

#include <errno.h>

#include <net-snmp/library/mt_support.h>

#ifdef __cplusplus

extern          "C" {

#endif

#ifdef NETSNMP_REENTRANT

static mutex_type s_res[MT_MAX_IDS][MT_LIB_MAXIMUM];  /* locking structures */

static mutex_type *

_mt_res(int groupID, int resourceID)

{

    if (groupID < 0) {

	return 0;

    }

    if (groupID >= MT_MAX_IDS) {

	return 0;

    }

    if (resourceID < 0) {

	return 0;

    }

    if (resourceID >= MT_LIB_MAXIMUM) {

	return 0;

    }

    return (&s_res[groupID][resourceID]);

}

static int

snmp_res_init_mutex(mutex_type *mutex)

{

    int rc = 0;

#if HAVE_PTHREAD_H

    pthread_mutexattr_t attr;

    pthread_mutexattr_init(&attr);

    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);

    rc = pthread_mutex_init(mutex, &attr);

    pthread_mutexattr_destroy(&attr);

#elif defined(WIN32)

    InitializeCriticalSection(mutex);

#endif

    return rc;

}

int

snmp_res_init(void)

{

    int ii, jj, rc = 0;

    mutex_type *mutex;

    for (jj = 0; (0 == rc) && (jj < MT_MAX_IDS); jj++) {

	for (ii = 0; (0 == rc) && (ii < MT_LIB_MAXIMUM); ii++) {

	    mutex = _mt_res(jj, ii);

	    if (!mutex) {

		continue;

	    }

	    rc = snmp_res_init_mutex(mutex);

	}

    }

    return rc;

}

int

snmp_res_destroy_mutex(int groupID, int resourceID)

{

    int rc = 0;

    mutex_type *mutex = _mt_res(groupID, resourceID);

    if (!mutex) {

	return EFAULT;

    }

#if HAVE_PTHREAD_H

    rc = pthread_mutex_destroy(mutex);

#elif defined(WIN32)

    DeleteCriticalSection(mutex);

#endif

    return rc;

}

int

snmp_res_lock(int groupID, int resourceID)

{

    int rc = 0;

    mutex_type *mutex = _mt_res(groupID, resourceID);

    if (!mutex) {

	return EFAULT;

    }

#if HAVE_PTHREAD_H

    rc = pthread_mutex_lock(mutex);

#elif defined(WIN32)

    EnterCriticalSection(mutex);

#endif

    return rc;

}

int

snmp_res_unlock(int groupID, int resourceID)

{

    int rc = 0;

    mutex_type *mutex = _mt_res(groupID, resourceID);

    if (!mutex) {

	return EFAULT;

    }

#if HAVE_PTHREAD_H

    rc = pthread_mutex_unlock(mutex);

#elif defined(WIN32)

    LeaveCriticalSection(mutex);

#endif

    return rc;

}

#else  /*  NETSNMP_REENTRANT  */

#ifdef WIN32

/*

 * Provide "do nothing" targets for Release (.DLL) builds. 

 */

int

snmp_res_init(void)

{

    return 0;

}

int

snmp_res_lock(int groupID, int resourceID)

{

    return 0;

}

int

snmp_res_unlock(int groupID, int resourceID)

{

    return 0;

}

int

snmp_res_destroy_mutex(int groupID, int resourceID)

{

    return 0;

}

#endif /*  WIN32  */

#endif /*  NETSNMP_REENTRANT  */

#ifdef __cplusplus

}

#endif