The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> pthread.h - threads

#### SYNOPSIS

> `#include <pthread.h>`

#### DESCRIPTION

> The <pthread.h> header shall define the following symbolic constants:

> PTHREAD_BARRIER_SERIAL_THREAD
> PTHREAD_CANCEL_ASYNCHRONOUS
> PTHREAD_CANCEL_ENABLE
> PTHREAD_CANCEL_DEFERRED
> PTHREAD_CANCEL_DISABLE
> PTHREAD_CANCELED
> PTHREAD_CREATE_DETACHED
> PTHREAD_CREATE_JOINABLE
> [TPS]
> PTHREAD_EXPLICIT_SCHED
> PTHREAD_INHERIT_SCHED
> PTHREAD_MUTEX_DEFAULT
> PTHREAD_MUTEX_ERRORCHECK
> PTHREAD_MUTEX_NORMAL
> PTHREAD_MUTEX_RECURSIVE
> PTHREAD_MUTEX_ROBUST
> PTHREAD_MUTEX_STALLED
> PTHREAD_ONCE_INIT
> [RPI|TPI]
> PTHREAD_PRIO_INHERIT
> [MC1]
> PTHREAD_PRIO_NONE
> [RPP|TPP]
> PTHREAD_PRIO_PROTECT
> PTHREAD_PROCESS_SHARED
> PTHREAD_PROCESS_PRIVATE
> [TPS]
> PTHREAD_SCOPE_PROCESS
> PTHREAD_SCOPE_SYSTEM

> The <pthread.h> header shall define the following compile-time constant expressions valid as initializers for the following types:

> Name | Initializer for Type
> --- | ---
> PTHREAD_COND_INITIALIZER | pthread_cond_t
> PTHREAD_MUTEX_INITIALIZER | pthread_mutex_t
> PTHREAD_RWLOCK_INITIALIZER | pthread_rwlock_t

> The <pthread.h> header shall define the pthread_attr_t, pthread_barrier_t, pthread_barrierattr_t, pthread_cond_t, pthread_condattr_t, pthread_key_t, pthread_mutex_t, pthread_mutexattr_t, pthread_once_t, pthread_rwlock_t, pthread_rwlockattr_t, pthread_spinlock_t, and pthread_t types as described in <sys/types.h>.

> The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

>     int   pthread_atfork(void (*)(void), void (*)(void),
>               void(*)(void));
>     int   pthread_attr_destroy(pthread_attr_t *);
>     int   pthread_attr_getdetachstate(const pthread_attr_t *, int *);
>     int   pthread_attr_getguardsize(const pthread_attr_t *restrict,
>               size_t *restrict);
>     [TPS]
>     int   pthread_attr_getinheritsched(const pthread_attr_t *restrict,
>               int *restrict);

>     int   pthread_attr_getschedparam(const pthread_attr_t *restrict,
>               struct sched_param *restrict);
>     [TPS]
>     int   pthread_attr_getschedpolicy(const pthread_attr_t *restrict,
>               int *restrict);
>     int   pthread_attr_getscope(const pthread_attr_t *restrict,
>               int *restrict);

>     [TSA TSS]
>     int   pthread_attr_getstack(const pthread_attr_t *restrict,
>               void **restrict, size_t *restrict);

>     [TSS]
>     int   pthread_attr_getstacksize(const pthread_attr_t *restrict,
>               size_t *restrict);

>     int   pthread_attr_init(pthread_attr_t *);
>     int   pthread_attr_setdetachstate(pthread_attr_t *, int);
>     int   pthread_attr_setguardsize(pthread_attr_t *, size_t);
>     [TPS]
>     int   pthread_attr_setinheritsched(pthread_attr_t *, int);

>     int   pthread_attr_setschedparam(pthread_attr_t *restrict,
>               const struct sched_param *restrict);
>     [TPS]
>     int   pthread_attr_setschedpolicy(pthread_attr_t *, int);
>     int   pthread_attr_setscope(pthread_attr_t *, int);

>     [TSA TSS]
>     int   pthread_attr_setstack(pthread_attr_t *, void *, size_t);

>     [TSS]
>     int   pthread_attr_setstacksize(pthread_attr_t *, size_t);

>     int   pthread_barrier_destroy(pthread_barrier_t *);
>     int   pthread_barrier_init(pthread_barrier_t *restrict,
>               const pthread_barrierattr_t *restrict, unsigned);
>     int   pthread_barrier_wait(pthread_barrier_t *);
>     int   pthread_barrierattr_destroy(pthread_barrierattr_t *);
>     [TSH]
>     int   pthread_barrierattr_getpshared(
>               const pthread_barrierattr_t *restrict, int *restrict);

>     int   pthread_barrierattr_init(pthread_barrierattr_t *);
>     [TSH]
>     int   pthread_barrierattr_setpshared(pthread_barrierattr_t *, int);

>     int   pthread_cancel(pthread_t);
>     int   pthread_cond_broadcast(pthread_cond_t *);
>     int   pthread_cond_destroy(pthread_cond_t *);
>     int   pthread_cond_init(pthread_cond_t *restrict,
>               const pthread_condattr_t *restrict);
>     int   pthread_cond_signal(pthread_cond_t *);
>     int   pthread_cond_timedwait(pthread_cond_t *restrict,
>               pthread_mutex_t *restrict, const struct timespec *restrict);
>     int   pthread_cond_wait(pthread_cond_t *restrict,
>               pthread_mutex_t *restrict);
>     int   pthread_condattr_destroy(pthread_condattr_t *);
>     int   pthread_condattr_getclock(const pthread_condattr_t *restrict,
>               clockid_t *restrict);
>     [TSH]
>     int   pthread_condattr_getpshared(const pthread_condattr_t *restrict,
>               int *restrict);

>     int   pthread_condattr_init(pthread_condattr_t *);
>     int   pthread_condattr_setclock(pthread_condattr_t *, clockid_t);
>     [TSH]
>     int   pthread_condattr_setpshared(pthread_condattr_t *, int);

>     int   pthread_create(pthread_t *restrict, const pthread_attr_t *restrict,
>               void *(*)(void*), void *restrict);
>     int   pthread_detach(pthread_t);
>     int   pthread_equal(pthread_t, pthread_t);
>     void  pthread_exit(void *);
>     [OB XSI]
>     int   pthread_getconcurrency(void);

>     [TCT]
>     int   pthread_getcpuclockid(pthread_t, clockid_t *);

>     [TPS]
>     int   pthread_getschedparam(pthread_t, int *restrict,
>               struct sched_param *restrict);

>     void *pthread_getspecific(pthread_key_t);
>     int   pthread_join(pthread_t, void **);
>     int   pthread_key_create(pthread_key_t *, void (*)(void*));
>     int   pthread_key_delete(pthread_key_t);
>     int   pthread_mutex_consistent(pthread_mutex_t *);
>     int   pthread_mutex_destroy(pthread_mutex_t *);
>     [RPP|TPP]
>     int   pthread_mutex_getprioceiling(const pthread_mutex_t *restrict,
>               int *restrict);

>     int   pthread_mutex_init(pthread_mutex_t *restrict,
>               const pthread_mutexattr_t *restrict);
>     int   pthread_mutex_lock(pthread_mutex_t *);
>     [RPP|TPP]
>     int   pthread_mutex_setprioceiling(pthread_mutex_t *restrict, int,
>               int *restrict);

>     int   pthread_mutex_timedlock(pthread_mutex_t *restrict,
>               const struct timespec *restrict);
>     int   pthread_mutex_trylock(pthread_mutex_t *);
>     int   pthread_mutex_unlock(pthread_mutex_t *);
>     int   pthread_mutexattr_destroy(pthread_mutexattr_t *);
>     [RPP|TPP]
>     int   pthread_mutexattr_getprioceiling(
>               const pthread_mutexattr_t *restrict, int *restrict);

>     [MC1]
>     int   pthread_mutexattr_getprotocol(const pthread_mutexattr_t *restrict,
>               int *restrict);

>     [TSH]
>     int   pthread_mutexattr_getpshared(const pthread_mutexattr_t *restrict,
>               int *restrict);

>     int   pthread_mutexattr_getrobust(const pthread_mutexattr_t *restrict,
>               int *restrict);
>     int   pthread_mutexattr_gettype(const pthread_mutexattr_t *restrict,
>               int *restrict);
>     int   pthread_mutexattr_init(pthread_mutexattr_t *);
>     [RPP|TPP]
>     int   pthread_mutexattr_setprioceiling(pthread_mutexattr_t *, int);

>     [MC1]
>     int   pthread_mutexattr_setprotocol(pthread_mutexattr_t *, int);

>     [TSH]
>     int   pthread_mutexattr_setpshared(pthread_mutexattr_t *, int);

>     int   pthread_mutexattr_setrobust(pthread_mutexattr_t *, int);
>     int   pthread_mutexattr_settype(pthread_mutexattr_t *, int);
>     int   pthread_once(pthread_once_t *, void (*)(void));
>     int   pthread_rwlock_destroy(pthread_rwlock_t *);
>     int   pthread_rwlock_init(pthread_rwlock_t *restrict,
>               const pthread_rwlockattr_t *restrict);
>     int   pthread_rwlock_rdlock(pthread_rwlock_t *);
>     int   pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict,
>               const struct timespec *restrict);
>     int   pthread_rwlock_timedwrlock(pthread_rwlock_t *restrict,
>               const struct timespec *restrict);
>     int   pthread_rwlock_tryrdlock(pthread_rwlock_t *);
>     int   pthread_rwlock_trywrlock(pthread_rwlock_t *);
>     int   pthread_rwlock_unlock(pthread_rwlock_t *);
>     int   pthread_rwlock_wrlock(pthread_rwlock_t *);
>     int   pthread_rwlockattr_destroy(pthread_rwlockattr_t *);
>     [TSH]
>     int   pthread_rwlockattr_getpshared(
>               const pthread_rwlockattr_t *restrict, int *restrict);

>     int   pthread_rwlockattr_init(pthread_rwlockattr_t *);
>     [TSH]
>     int   pthread_rwlockattr_setpshared(pthread_rwlockattr_t *, int);

>     pthread_t
>           pthread_self(void);
>     int   pthread_setcancelstate(int, int *);
>     int   pthread_setcanceltype(int, int *);
>     [OB XSI]
>     int   pthread_setconcurrency(int);

>     [TPS]
>     int   pthread_setschedparam(pthread_t, int,
>               const struct sched_param *);
>     int   pthread_setschedprio(pthread_t, int);

>     int   pthread_setspecific(pthread_key_t, const void *);
>     int   pthread_spin_destroy(pthread_spinlock_t *);
>     int   pthread_spin_init(pthread_spinlock_t *, int);
>     int   pthread_spin_lock(pthread_spinlock_t *);
>     int   pthread_spin_trylock(pthread_spinlock_t *);
>     int   pthread_spin_unlock(pthread_spinlock_t *);
>     void  pthread_testcancel(void);

> The following may be declared as functions, or defined as macros, or both. If functions are declared, function prototypes shall be provided.

> >     pthread_cleanup_pop()
> >     pthread_cleanup_push()

> Inclusion of the <pthread.h> header shall make symbols defined in the headers <sched.h> and <time.h> visible.

The following sections are informative.

#### APPLICATION USAGE

> None.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> <sched.h>, <sys/types.h>, <time.h>

> XSH pthread_atfork, pthread_attr_destroy, pthread_attr_getdetachstate, pthread_attr_getguardsize, pthread_attr_getinheritsched, pthread_attr_getschedparam, pthread_attr_getschedpolicy, pthread_attr_getscope, pthread_attr_getstack, pthread_attr_getstacksize, pthread_barrier_destroy, pthread_barrier_wait, pthread_barrierattr_destroy, pthread_barrierattr_getpshared, pthread_cancel, pthread_cleanup_pop, pthread_cond_broadcast, pthread_cond_destroy, pthread_cond_timedwait, pthread_condattr_destroy, pthread_condattr_getclock, pthread_condattr_getpshared, pthread_create, pthread_detach, pthread_equal , pthread_exit, pthread_getconcurrency, pthread_getcpuclockid, pthread_getschedparam, pthread_getspecific, pthread_join, pthread_key_create, pthread_key_delete, pthread_mutex_consistent, pthread_mutex_destroy, pthread_mutex_getprioceiling, pthread_mutex_lock, pthread_mutex_timedlock, pthread_mutexattr_destroy, pthread_mutexattr_getprioceiling, pthread_mutexattr_getprotocol, pthread_mutexattr_getpshared, pthread_mutexattr_getrobust, pthread_mutexattr_gettype, pthread_once, pthread_rwlock_destroy, pthread_rwlock_rdlock, pthread_rwlock_timedrdlock, pthread_rwlock_timedwrlock, pthread_rwlock_trywrlock, pthread_rwlock_unlock, pthread_rwlockattr_destroy, pthread_rwlockattr_getpshared, pthread_self, pthread_setcancelstate, pthread_setschedprio, pthread_spin_destroy, pthread_spin_lock, pthread_spin_unlock

#### CHANGE HISTORY

> First released in Issue 5. Included for alignment with the POSIX Threads Extension.

#### Issue 6

> The RTT margin markers are broken out into their POSIX options.

> The Open Group Corrigendum U021/9 is applied, correcting the prototype for the pthread_cond_wait() function.

> The Open Group Corrigendum U026/2 is applied, correcting the prototype for the pthread_setschedparam() function so that its second argument is of type int.

> The pthread_getcpuclockid() and pthread_mutex_timedlock() functions are added for alignment with IEEE Std 1003.1d-1999.

> The following functions are added for alignment with IEEE Std 1003.1j-2000: pthread_barrier_destroy(), pthread_barrier_init(), pthread_barrier_wait(), pthread_barrierattr_destroy(), pthread_barrierattr_getpshared(), pthread_barrierattr_init(), pthread_barrierattr_setpshared(), pthread_condattr_getclock(), pthread_condattr_setclock(), pthread_rwlock_timedrdlock(), pthread_rwlock_timedwrlock(), pthread_spin_destroy(), pthread_spin_init(), pthread_spin_lock(), pthread_spin_trylock(), and pthread_spin_unlock().

> PTHREAD_RWLOCK_INITIALIZER is removed for alignment with IEEE Std 1003.1j-2000.

> Functions previously marked as part of the Read-Write Locks option are now moved to the Threads option.

> The restrict keyword is added to the prototypes for pthread_attr_getguardsize(), pthread_attr_getinheritsched(), pthread_attr_getschedparam(), pthread_attr_getschedpolicy(), pthread_attr_getscope(), pthread_attr_getstackaddr,() pthread_attr_getstacksize(), pthread_attr_setschedparam(), pthread_barrier_init(), pthread_barrierattr_getpshared(), pthread_cond_init(), pthread_cond_signal(), pthread_cond_timedwait(), pthread_cond_wait(), pthread_condattr_getclock(), pthread_condattr_getpshared(), pthread_create(), pthread_getschedparam(), pthread_mutex_getprioceiling(), pthread_mutex_init(), pthread_mutex_setprioceiling(), pthread_mutexattr_getprioceiling(), pthread_mutexattr_getprotocol(), pthread_mutexattr_getpshared(), pthread_mutexattr_gettype(), pthread_rwlock_init(), pthread_rwlock_timedrdlock(), pthread_rwlock_timedwrlock(), pthread_rwlockattr_getpshared(), and pthread_sigmask().

> IEEE PASC Interpretation 1003.1 #86 is applied, allowing the symbols from <sched.h> and <time.h> to be made visible when <pthread.h> is included. Previously this was an XSI option.

> IEEE PASC Interpretation 1003.1c #42 is applied, removing the requirement for prototypes for the pthread_kill() and pthread_sigmask() functions. These are required to be in the <signal.h> header. They are allowed here through the name space rules.

> IEEE PASC Interpretation 1003.1 #96 is applied, adding the pthread_setschedprio() function.

> IEEE Std 1003.1-2001/Cor 1-2002, item XBD/TC1/D6/13 is applied, correcting shading errors that were in contradiction with the System Interfaces volume of POSIX.1-2008.

#### Issue 7

> SD5-XBD-ERN-55 is applied, adding the restrict keyword to the pthread_mutex_timedlock() function prototype.

> SD5-XBD-ERN-62 is applied.

> Austin Group Interpretation 1003.1-2001 #048 is applied, reinstating the PTHREAD_RWLOCK_INITIALIZER symbol.

> The <pthread.h> header is moved from the Threads option to the Base.

> The following extended mutex types are moved from the XSI option to the Base:

> >     PTHREAD_MUTEX_NORMAL
> >     PTHREAD_MUTEX_ERRORCHECK
> >     PTHREAD_MUTEX_RECURSIVE
> >     PTHREAD_MUTEX_DEFAULT

> The PTHREAD_MUTEX_ROBUST and PTHREAD_MUTEX_STALLED symbols and the pthread_mutex_consistent(), pthread_mutexattr_getrobust(), and pthread_mutexattr_setrobust() functions are added from The Open Group Technical Standard, 2006, Extended API Set Part 2.

> Functionality relating to the Thread Priority Protection and Thread Priority Inheritance options is changed to be Non-Robust Mutex or Robust Mutex Priority Protection and Non-Robust Mutex or Robust Mutex Priority Inheritance, respectively.

> This reference page is clarified with respect to macros and symbolic constants.

> POSIX.1-2008, Technical Corrigendum 2, XBD/TC2-2008/0069 [624] is applied.

End of informative text.

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