PTHREAD...TPSHARED(3POSIX)

💖 PROLOG 💖

hiii bestie, welcome to the POSIX Programmer's Manual, page PTHREAD...TPSHARED(3POSIX) 🎀 — yes that's the whole vibe, we're in the POSIX house tonight.

Real talk before we start: this page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so go check the matching Linux manual page for the tea on Linux behavior, fr), or the interface might just not be implemented on Linux at all. 💀 iykyk.

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✨ NAME ✨

pthread_rwlockattr_getpshared, pthread_rwlockattr_setpshared — get and set the process-shared attribute of the read-write lock attributes object 🦋

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🌸 SYNOPSIS 🌸

#include <pthread.h>

int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t
    *restrict attr, int *restrict pshared);
int pthread_rwlockattr_setpshared(pthread_rwlockattr_t *attr,
    int pshared);

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💅 DESCRIPTION 💅

okay so here's the situation, two little functions, one big job:

• pthread_rwlockattr_getpshared() shall obtain the value of the process-shared attribute from the initialized attributes object referenced by attr. reading the room, basically. 👀
• pthread_rwlockattr_setpshared() shall set the process-shared attribute in an initialized attributes object referenced by attr. making the change, periodt.

So, the process-shared attribute shall be set to PTHREAD_PROCESS_SHARED to permit a read-write lock to be operated upon by any thread that has access to the memory where the read-write lock is allocated — even if the read-write lock is allocated in memory that is shared by multiple processes. the way that works?? iconic. 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 process-shared attribute shall be PTHREAD_PROCESS_PRIVATE.

Additional attributes, their default values, and the names of the associated functions to get and set those attribute values are implementation-defined. so like, not our problem, that's your implementation's business. 🙈

⚠️ The behavior is undefined if the value specified by the attr argument to pthread_rwlockattr_getpshared() or pthread_rwlockattr_setpshared() does not refer to an initialized read-write lock attributes object. no cap, don't do that, that's chaos behavior. 💀

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⭐ RETURN VALUE ⭐

Upon successful completion, the pthread_rwlockattr_getpshared() function 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. 🫶

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

so like... zero = slay, anything else = something went wrong. simple as that. ✨

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🔥 ERRORS 🔥

The pthread_rwlockattr_setpshared() function may fail if:

• EINVAL — The new value specified for the attribute is outside the range of legal values for that attribute. ma'am that is not a legal value, please try again. 😭

These functions shall not return an error code of [EINTR]. nope. not a thing here. 💅

The following sections are informative. (translation: the required stuff is done, everything below is bonus content 🍓)

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🌈 EXAMPLES 🌈

None.

🧚 APPLICATION USAGE 🧚

None.

👑 RATIONALE 👑

None.

💜 FUTURE DIRECTIONS 💜

None.

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🦋 SEE ALSO 🦋

• pthread_rwlock_destroy()
• pthread_rwlockattr_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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and that's the whole page bestie 🫶 courtesy of IEEE/The Open Group, 2017, filed under PTHREAD...TPSHARED(3POSIX). go forth and sync responsibly, mwah 💋✨