/share/man/man3/pthread_setspecific.3

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31.\" $FreeBSD$
32.\"
33.Dd April 4, 1996
34.Dt PTHREAD_SETSPECIFIC 3
35.Os
36.Sh NAME
37.Nm pthread_setspecific
38.Nd set a thread-specific data value
39.Sh LIBRARY
40.Lb libpthread
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 can 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
67The
68.Fn pthread_setspecific
69function may be called from a thread-specific data destructor function,
70however this may result in lost storage or infinite loops.
71.Sh RETURN VALUES
72If successful, the
73.Fn pthread_setspecific
74function will return zero.
75Otherwise an error number will be returned to
76indicate the error.
77.Sh ERRORS
78The
79.Fn pthread_setspecific
80function will fail if:
81.Bl -tag -width Er
82.It Bq Er ENOMEM
83Insufficient memory exists to associate the value with the
84.Fa key .
85.It Bq Er EINVAL
86The
87.Fa key
88value is invalid.
89.El
90.Sh SEE ALSO
91.Xr pthread_getspecific 3 ,
92.Xr pthread_key_create 3 ,
93.Xr pthread_key_delete 3
94.Sh STANDARDS
95The
96.Fn pthread_setspecific
97function conforms to
98.St -p1003.1-96 .