1.\" Copyright (c) 1998 Alex Nash
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25.\" $FreeBSD: src/share/man/man3/pthread_rwlock_init.3,v 1.11 2007/10/22 10:08:00 ru Exp $
26.\" $DragonFly: src/lib/libc_r/man/pthread_rwlock_init.3,v 1.3 2006/02/17 19:35:07 swildner Exp $
27.\"
28.Dd July 10, 2009
29.Dt PTHREAD_RWLOCK_INIT 3
30.Os
31.Sh NAME
32.Nm pthread_rwlock_init
33.Nd initialize a read/write lock
34.Sh LIBRARY
35.Lb libpthread
36.Sh SYNOPSIS
37.In pthread.h
38.Ft int
39.Fn pthread_rwlock_init "pthread_rwlock_t *lock" "const pthread_rwlockattr_t *attr"
40.Sh DESCRIPTION
41The
42.Fn pthread_rwlock_init
43function is used to initialize a read/write lock, with attributes
44specified by
45.Fa attr .
46If
47.Fa attr
48is NULL, the default read/write lock attributes are used.
49.Pp
50The results of calling
51.Fn pthread_rwlock_init
52with an already initialized lock are undefined.
53.Sh RETURN VALUES
54If successful, the
55.Fn pthread_rwlock_init
56function will return zero.
57Otherwise an error number will be returned
58to indicate the error.
59.Sh ERRORS
60The
61.Fn pthread_rwlock_init
62function will fail if:
63.Bl -tag -width Er
64.It Bq Er EAGAIN
65The system lacked the necessary resources (other than memory) to
66initialize the lock.
67.It Bq Er ENOMEM
68Insufficient memory exists to initialize the lock.
69.It Bq Er EPERM
70The caller does not have sufficient privilege to perform the
71operation.
72.El
73.Pp
74The
75.Fn pthread_rwlock_init
76function may fail if:
77.Bl -tag -width Er
78.It Bq Er EBUSY
79The system has detected an attempt to re-initialize the object
80referenced by
81.Fa lock ,
82a previously initialized but not yet destroyed read/write lock.
83.It Bq Er EINVAL
84The value specified by
85.Fa attr
86is invalid.
87.El
88.Sh SEE ALSO
89.Xr pthread_rwlockattr_init 3 ,
90.Xr pthread_rwlockattr_setpshared 3 ,
91.Xr pthread_rwlock_destroy 3
92.Sh STANDARDS
93The
94.Fn pthread_rwlock_init
95function is expected to conform to
96.St -susv2 .
97.Sh HISTORY
98The
99.Fn pthread_rwlock_init
100function first appeared in
101.Fx 3.0 .
102.Sh BUGS
103The PTHREAD_PROCESS_SHARED attribute is not supported.
104