pthread_rwlockattr_getpshared.3t (2010 09)

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pthread_rwlockattr_getpshared(3T) pthread_rwlockattr_getpshared(3T)

(Pthread Library)

NAME

pthread_rwlockattr_getpshared(), pthread_rwlockattr_setpshared() - get or set the process-shared attri-

bute

SYNOPSIS

#include <pthread.h>

int pthread_rwlockattr_setpshared(pthread_rwlockattr_t *attr,

int pshared);

int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t

*__restrict attr, int *__restrict pshared);

PARAMETERS

attr Pointer to the read-write lock attributes object whose attributes are to be set/retrieved.

pshared This parameter either speciﬁes the new value of the process-shared attribute (set func-

tion) or points to the memory location where the process-shared attribute of attr is to be

returned (get function).

DESCRIPTION

The attributes object attr must have been previously initialized with the function

pthread_rwlockattr_init()

before these functions are called.

Read-Write locks can be used only by threads within the process or shared by threads in multiple

processes. The process-shared attribute in a read-write lock attributes object describes who may use the

read-write lock. The legal values for the process-shared attribute are:

PTHREAD_PROCESS_SHARED

This option permits a read-write lock to be operated upon by any thread that has access to the

memory where the read-write lock is allocated. The application is responsible for allocating

the read-write lock in memory that multiple processes can access.

PTHREAD_PROCESS_PRIVATE

The read-write lock can only be operated upon by threads created within the same process as

the thread that initialized the read-write lock. If threads of differing processes attempt to

operate on such read-write lock, the behavior is undeﬁned.

The default value of process-shared is

PTHREAD_PROCESS_PRIVATE.

pthread_rwlockattr_setpshared()

is used to set the process-shared attribute in the initialized

attributes object attr . The new value of the process-shared attribute of attr is set to the value speciﬁed in

the pshared parameter.

pthread_rwlockattr_getpshared()

retrieves the value of the process-shared attribute from the

read-write lock attributes object attr . The value of the process-shared attribute of attr is returned in the

pshared parameter.

RETURN VALUE

Upon successful completion,

pthread_rwlockattr_getpshared()

and

pthread_rwlockattr_setpshared() return zero. Otherwise, an error number is returned to indi-

cate the error (the

errno variable is not set).

ERRORS

If any of the following occur, the

pthread_rwlockattr_getpshared()

and

pthread_rwlockattr_setpshared() functions return the corresponding error number:

[ENOSYS]

_POSIX_THREAD_PROCESS_SHARED is not deﬁned and these functions are not

supported.

For each of the following conditions, if the condition is detected, the

pthread_rwlockattr_getpshared() and pthread_rwlockattr_setpshared() functions

return the corresponding error number:

[EINVAL] The value speciﬁed by attr is invalid.

[EINVAL] The value speciﬁed by pshared is not a legal value.

[EINVAL] The value pshared points to an illegal address.

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (2 pages)

PAGE 1
pthread_rwlockattr_getpshared(3T) pthread_rwlockattr_getpshared(3T) (Pthread Library) NAME pthread_rwlockattr_getpshared(), pthread_rwlockattr_setpshared() - get or set the process-shared attribute SYNOPSIS #include
PAGE 2
pthread_rwlockattr_getpshared(3T) pthread_rwlockattr_getpshared(3T) (Pthread Library) WARNINGS If a read-write lock is created with the process-shared attribute defined as PTHREAD_PROCESS_SHARED, the cooperating processes should have access to the memory in which the read-write lock is allocated. AUTHOR pthread_rwlockattr_setpshared() and pthread_rwlockattr_getpshared() were developed by X/Open. SEE ALSO pthread_create(3T), pthread_rwlockattr_init(3T), pthread_rwlock_init(3T).