PTHREAD...PSHARED(3POSIX)

✨ PROLOG ✨

okay so bestie, real talk before we even start: this page is part of the POSIX Programmer's Manual — like, the official one, not a Linux-specific glow-up. The Linux implementation of this interface may differ (so if you're on Linux, go peek at the corresponding Linux manual page for the actual tea 🍵), or honestly the interface might not be implemented on Linux at all. No cap.

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💖 NAME 💖

pthread_barrierattr_getpshared, pthread_barrierattr_setpshared — get and set the process-shared attribute of the barrier attributes object

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🌸 SYNOPSIS 🌸

#include <pthread.h>

int pthread_barrierattr_getpshared(const pthread_barrierattr_t
    *restrict attr, int *restrict pshared);
int pthread_barrierattr_setpshared(pthread_barrierattr_t *attr,
    int pshared);

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🦋 DESCRIPTION 🦋

So pthread_barrierattr_getpshared() shall obtain the value of the process-shared attribute from the attributes object referenced by attr. And pthread_barrierattr_setpshared() shall set the process-shared attribute in an initialized attributes object referenced by attr. One gets, one sets, they're a duo, they ate 💅

The process-shared attribute is set to PTHREAD_PROCESS_SHARED to permit a barrier to be operated upon by any thread that has access to the memory where the barrier is allocated. See Section 2.9.9, Synchronization Object Copies and Alternative Mappings for further requirements, bestie, don't skip that part.

The default value of the attribute shall be PTHREAD_PROCESS_PRIVATE. Both constants PTHREAD_PROCESS_SHARED and PTHREAD_PROCESS_PRIVATE are defined in <pthread.h>.

Additional attributes, their default values, and the names of the associated functions to get and set those attribute values are implementation-defined. So like, ask your implementation, not me.

🚨 okay this is the important one: the behavior is undefined if the value specified by the attr argument to pthread_barrierattr_getpshared() or pthread_barrierattr_setpshared() does not refer to an initialized barrier attributes object. Undefined. Behavior. Not a vibe. Do not do it.

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💜 RETURN VALUE 💜

If successful, pthread_barrierattr_getpshared() shall return zero and store the value of the process-shared attribute of attr into the object referenced by the pshared parameter. Otherwise, an error number shall be returned to indicate the error. So zero = slay, nonzero = 😭

If successful, pthread_barrierattr_setpshared() shall return zero; otherwise, an error number shall be returned to indicate the error.

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🔥 ERRORS 🔥

pthread_barrierattr_setpshared() may fail if:

• EINVAL — the new value specified for the process-shared attribute is not one of the legal values PTHREAD_PROCESS_SHARED or PTHREAD_PROCESS_PRIVATE. Like, pick one of the two actual options please 🙈

These functions shall not return an error code of [EINTR]. Not ever. Periodt.

The following sections are informative. (iykyk — that means they're the fun bonus content, not the binding rules 📖✨)

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🎀 EXAMPLES 🎀

None. 💀 Yeah. Nothing here. Move along, gorgeous.

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🌈 APPLICATION USAGE 🌈

The pthread_barrierattr_getpshared() and pthread_barrierattr_setpshared() functions are part of the Thread Process-Shared Synchronization option and need not be provided on all implementations. So if your platform's like "who?", that's technically allowed, ngl.

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🧚 RATIONALE 🧚

If an implementation detects that the value specified by the attr argument to pthread_barrierattr_getpshared() or pthread_barrierattr_setpshared() does not refer to an initialized barrier attributes object, it is recommended that the function should fail and report an [EINVAL] error. Recommended, not mandated — the spec is being polite about it 🫶

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⭐ FUTURE DIRECTIONS ⭐

None. The future is empty, bestie. Enjoy the present 🌸

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👑 SEE ALSO 👑

• pthread_barrier_destroy()
• pthread_barrierattr_destroy()
• The Base Definitions volume of POSIX.1‐2017, <pthread.h>

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📜 COPYRIGHT 📜

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group.

In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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