pthread_rwlockattr_getpshared(3T)pthread_rwlockattr_getpshared(3T)NAMEpthread_rwlockattr_getpshared(), pthread_rwlockattr_setpshared() - get
or set the process-shared attribute
SYNOPSISPARAMETERS
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 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 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 allo‐
cating the read-write lock in memory that multiple pro‐
cesses 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 unde‐
fined.
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 correspond‐
ing 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 ALSOpthread_create(3T), pthread_rwlockattr_init(3T),
pthread_rwlock_init(3T).
STANDARDS CONFORMANCE
Pthread Librapthread_rwlockattr_getpshared(3T)