pthread_mutexattr_settype(3P)

NAME
     pthread_mutexattr_settype, pthread_mutexattr_gettype - set/get a mutex
     attribute object's type

C SYNOPSIS
     #include <pthread.h>

     int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);

     int pthread_mutexattr_gettype(pthread_mutexattr_t *attr, int *type);

DESCRIPTION
     These functions manipulate a mutex attribute object referenced by attr
     which has been previously created by pthread_mutexattr_init().

     The function pthread_mutexattr_settype() defines the type of mutex.  The
     type value may be one of PTHREAD_MUTEX_NORMAL, PTHREAD_MUTEX_ERRORCHECK,
     PTHREAD_MUTEX_RECURSIVE, or PTHREAD_MUTEX_DEFAULT.

     The function pthread_mutexattr_gettype() stores into the memory
     referenced by type the mutex type associated with the named mutex
     attribute object.  The default type is PTHREAD_MUTEX_DEFAULT.

     A mutex with a type attribute of PTHREAD_MUTEX_DEFAULT or
     PTHREAD_MUTEX_NORMAL works as a simple mutual exclusion lock with no
     error checking.  A thread attempting to relock a mutex of this type will
     deadlock.

     A mutex with a type attribute of PTHREAD_MUTEX_ERRORCHECK is a simple
     mutual exclusion lock with error checking.  A thread attempting to relock
     a mutex of this type will return an error.  A thread attempting to unlock
     a mutex that another thread has locked will return an error.  A thread
     attempting to unlock a mutex that has not been locked will return an
     error.

     A mutex with a type attribute of PTHREAD_MUTEX_RECURSIVE is a simple
     mutual exclusion lock with error checking that also allows a single
     thread to recursively lock the mutex.  In this case there must be a
     matching number of unlocks by the thread before the mutex can be
     released.  A thread attempting to unlock a mutex that another thread has
     locked will return an error.  A thread attempting to unlock a mutex that
     has not been locked will return an error.

DIAGNOSTICS
     The mutex attribute type functions return zero on success; otherwise, an
     error number is returned:

     [EINVAL]       The value specified by type is invalid.
SEE ALSO
     pthread_mutex_lock(3P), pthread_mutexattr_init(3P).