# pthread_mutexattr_gettype

## PROLOG



           This manual page is part of the POSIX Programmer's Manual.  The
           Linux implementation of this interface may differ (consult the
           corresponding Linux manual page for details of Linux behavior), or
           the interface may not be implemented on Linux.
    


## NAME



           pthread_mutexattr_gettype, pthread_mutexattr_settype — get and set
           the mutex type attribute
    


## SYNOPSIS



           #include <pthread.h>
    
           int pthread_mutexattr_gettype(const pthread_mutexattr_t *restrict _attr_ ,
               int *restrict _type_);
           int pthread_mutexattr_settype(pthread_mutexattr_t *_attr_ , int _type_);
    


## DESCRIPTION



           The _pthread_mutexattr_gettype_() and _pthread_mutexattr_settype_()
           functions, respectively, shall get and set the mutex _type_
           attribute. This attribute is set in the _type_ parameter to these
           functions. The default value of the _type_ attribute is
           PTHREAD_MUTEX_DEFAULT.
    
           The type of mutex is contained in the _type_ attribute of the mutex
           attributes. Valid mutex types include:
    
                  PTHREAD_MUTEX_NORMAL PTHREAD_MUTEX_ERRORCHECK
                  PTHREAD_MUTEX_RECURSIVE PTHREAD_MUTEX_DEFAULT
    
           The mutex type affects the behavior of calls which lock and unlock
           the mutex. See pthread_mutex_lock(3p) for details. An
           implementation may map PTHREAD_MUTEX_DEFAULT to one of the other
           mutex types.
    
           The behavior is undefined if the value specified by the _attr_
           argument to _pthread_mutexattr_gettype_() or
           _pthread_mutexattr_settype_() does not refer to an initialized mutex
           attributes object.
    


## RETURN VALUE



           Upon successful completion, the _pthread_mutexattr_gettype_()
           function shall return zero and store the value of the _type_
           attribute of _attr_ into the object referenced by the _type_
           parameter. Otherwise, an error shall be returned to indicate the
           error.
    
           If successful, the _pthread_mutexattr_settype_() function shall
           return zero; otherwise, an error number shall be returned to
           indicate the error.
    


## ERRORS



           The _pthread_mutexattr_settype_() function shall fail if:
    
           **EINVAL** The value _type_ is invalid.
    
           These functions shall not return an error code of **[EINTR]**.
    
           _The following sections are informative._
    


## EXAMPLES



           None.
    


## APPLICATION USAGE



           It is advised that an application should not use a
           PTHREAD_MUTEX_RECURSIVE mutex with condition variables because the
           implicit unlock performed for a _pthread_cond_timedwait_() or
           _pthread_cond_wait_() may not actually release the mutex (if it had
           been locked multiple times). If this happens, no other thread can
           satisfy the condition of the predicate.
    


## RATIONALE



           If an implementation detects that the value specified by the _attr_
           argument to _pthread_mutexattr_gettype_() or
           _pthread_mutexattr_settype_() does not refer to an initialized mutex
           attributes object, it is recommended that the function should fail
           and report an **[EINVAL]** error.
    


## FUTURE DIRECTIONS



           None.
    


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