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pthread_mutexattr_setpshared(3)

NAME

pthread_mutexattr_setpshared - Sets the process-shared attribute of a mutex attributes object

SYNOPSIS

#include <pthread.h> int pthread_mutexattr_setpshared( pthread_mutexattr_t *attr, int pshared );

LIBRARY

DECthreads POSIX 1003.1c Library (libpthread.so)

PARAMETERS

attr Address of the mutex attributes object whose process-shared attribute is to be set. pshared Value to set in the process-shared attribute of attr. Must be the value PTHREAD_PROCESS_SHARED, to permit access to the mutex in by any thread in any process that can access the memory where the mutex object is allocated, or PTHREAD_PROCESS_PRIVATE, to permit access to the mutex only by threads in the same process as the thread that initialized the mutex object.

DESCRIPTION

This routine uses the value in pshared to set the process-shared attribute in the mutex attributes object referenced by attr. The object referenced by attr must be initialized before this routine is called. The value of pshared must be either PTHREAD_PROCESS_SHARED or PTHREAD_PROCESS_PRIVATE, as defined in the pthread.h include file. Setting the process-shared attribute to PTHREAD_PROCESS_PRIVATE permits a mutex to be operated upon by threads created within the same process as the thread that initialized the mutex. If threads of differing processes attempt to operate on such a mutex, the behavior is undefined. The default value of the process-shared attribute of a mutex attributes object is PTHREAD_PROCESS_PRIVATE. Setting the process-shared attribute to PTHREAD_PROCESS_SHARED permits a mutex to be operated upon by any thread that has access to the memory where the mutex is allocated, even if the mutex is allocated in memory that is shared by multiple processes.

RETURN VALUES

If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: 0 Successful completion. [EINVAL] The value specified by attr is not a valid mutex attributes object, or the new value specified for the attribute is outside the range of legal values for that attribute.

ERRORS

None

SEE ALSO

Functions: pthread_mutexattr_getpshared(3), pthread_mutexattr_init(3) Manuals: Guide to DECthreads and Programmer's Guide

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