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25.\" $FreeBSD: src/share/man/man3/pthread_attr_get_np.3,v 1.14 2007/10/22 10:08:00 ru Exp $
26.\"
27.Dd December 12, 2020
28.Dt PTHREAD_ATTR_GET_NP 3
29.Os
30.Sh NAME
31.Nm pthread_attr_get_np ,
32.Nm pthread_getattr_np
33.Nd get attributes of existing thread
34.Sh LIBRARY
35.Lb libpthread
36.Sh SYNOPSIS
37.In pthread.h
38.In pthread_np.h
39.Ft int
40.Fn pthread_attr_get_np "pthread_t thread" "pthread_attr_t *attr"
41.Ft int
42.Fn pthread_getattr_np "pthread_t thread" "pthread_attr_t *attr"
43.Sh DESCRIPTION
44The
45.Fn pthread_attr_get_np
46and
47.Fn pthread_getattr_np
48functions can be used to retrieve attributes of a running
49.Fa thread .
50Most fields of
51.Vt pthread_attr_t
52structure are exact values of attributes provided at thread creation
53time (as parameter to
54.Xr pthread_create 3
55function), except for the stack address.
56.Pp
57Value returned as
58.Fa attr
59is supposed to be used in conjunction with
60.Fn pthread_attr_get*
61functions to retrieve individual values from
62.Vt pthread_attr_t
63structure.
64Parameter
65.Fa attr
66should point to allocated memory area big enough to fit this structure.
67.Pp
68It is HIGHLY RECOMMENDED to use
69.Xr pthread_attr_init 3
70function to allocate attribute storage.
71.Fn pthread_getattr_np
72does this automatically.
73.Sh IMPLEMENTATION NOTES
74The
75.Fn pthread_attr_get_np
76function will always return a pointer to the thread's real stack address,
77regardless of its value in the original attributes structure.
78.Sh RETURN VALUES
79If successful,
80.Fn pthread_attr_get_np
81and
82.Fn pthread_getattr_np
83return 0.
84Otherwise, an error number is returned to indicate the error.
85.Sh EXAMPLES
86.Bd -literal
87size_t
88my_thread_stack_size(pthread_t pid)
89{
90    pthread_attr_t attr;
91    size_t size;
92
93    pthread_attr_init(&attr);
94    pthread_attr_get_np(pid, &attr);
95    pthread_attr_getstacksize(&attr, &size);
96    pthread_attr_destroy(&attr);
97    return(size);
98}
99.Ed
100.Sh ERRORS
101The
102.Fn pthread_attr_get_np
103function will fail if:
104.Bl -tag -width Er
105.It Bq Er EINVAL
106Invalid value for one of given parameters.
107.It Bq Er ESRC
108No thread could be found corresponding to that specified by the given
109thread ID.
110.El
111.Sh SEE ALSO
112.Xr pthread_attr_destroy 3 ,
113.Xr pthread_attr_getdetachstate 3 ,
114.Xr pthread_attr_getinheritsched 3 ,
115.Xr pthread_attr_getschedparam 3 ,
116.Xr pthread_attr_getschedpolicy 3 ,
117.Xr pthread_attr_getscope 3 ,
118.Xr pthread_attr_getstack 3 ,
119.Xr pthread_attr_getstackaddr 3 ,
120.Xr pthread_attr_getstacksize 3 ,
121.Xr pthread_attr_init 3
122.Sh AUTHORS
123The
124.Fn pthread_attr_get_np
125function and this manual page were written by
126.An Alexey Zelkin Aq Mt phantom@FreeBSD.org .
127