1.\" $OpenBSD: pthread_setspecific.3,v 1.13 2017/01/27 15:47:47 schwarze Exp $
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3.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
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33.\" $FreeBSD: pthread_setspecific.3,v 1.5 1999/08/28 00:03:11 peter Exp $
34.\"
35.Dd $Mdocdate: January 27 2017 $
36.Dt PTHREAD_SETSPECIFIC 3
37.Os
38.Sh NAME
39.Nm pthread_setspecific
40.Nd set a thread-specific data value
41.Sh SYNOPSIS
42.In pthread.h
43.Ft int
44.Fn pthread_setspecific "pthread_key_t key" "const void *value"
45.Sh DESCRIPTION
46The
47.Fn pthread_setspecific
48function associates a thread-specific value with a
49.Fa key
50obtained via a previous call to
51.Fn pthread_key_create .
52Different threads may bind different values to the same key.
53These values are
54typically pointers to blocks of dynamically allocated memory that have been
55reserved for use by the calling thread.
56.Pp
57The effect of calling
58.Fn pthread_setspecific
59with a key value not obtained from
60.Fn pthread_key_create
61or after
62.Fa key
63has been deleted with
64.Fn pthread_key_delete
65is undefined.
66.Pp
67.Fn pthread_setspecific
68may be called from a thread-specific data destructor function; however, this
69may result in lost storage or infinite loops.
70.Sh RETURN VALUES
71If successful, the
72.Fn pthread_setspecific
73function will return zero.
74Otherwise an error number will be returned to indicate the error.
75.Sh ERRORS
76.Fn pthread_setspecific
77will fail if:
78.Bl -tag -width Er
79.It Bq Er ENOMEM
80Insufficient memory exists to associate the value with the
81.Fa key .
82.It Bq Er EINVAL
83The
84.Fa key
85value is invalid.
86.El
87.Sh SEE ALSO
88.Xr pthread_getspecific 3 ,
89.Xr pthread_key_create 3 ,
90.Xr pthread_key_delete 3
91.Sh STANDARDS
92.Fn pthread_setspecific
93conforms to
94.St -p1003.1-96 .
95