pthread_rwlockattr_getpshared(3T) pthread_rwlockattr_getpshared(3T)
NAME
pthread_rwlockattr_getpshared(), pthread_rwlockattr_setpshared() - get or set the process-shared attribute
SYNOPSIS
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 function) or points to the memory loca-
tion 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 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:
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.
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
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.
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, and return zero. Otherwise, an error number is returned to indicate the error (the variable is not set).
ERRORS
If any of the following occur, the and functions return the corresponding error number:
is not defined and these functions are not supported.
For each of the following conditions, if the condition is detected, the and functions return the corresponding error number:
The value specified by
attr is invalid.
The value specified by
pshared is not a legal value.
The value pshared points to an illegal address.
WARNINGS
If a read-write lock is created with the process-shared attribute defined as the cooperating processes should have access to the memory in
which the read-write lock is allocated.
AUTHOR
and were developed by X/Open.
SEE ALSO
pthread_create(3T), pthread_rwlockattr_init(3T), pthread_rwlock_init(3T).
STANDARDS CONFORMANCE
Pthread Library pthread_rwlockattr_getpshared(3T)