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25.Dd October 12, 2021
26.Dt PTHREAD_ATTR_GET_NP 3
27.Os
28.Sh NAME
29.Nm pthread_attr_get_np
30.Nd get attributes of existent thread
31.Sh LIBRARY
32.Lb libpthread
33.Sh SYNOPSIS
34.In pthread_np.h
35.Ft int
36.Fn pthread_attr_get_np "pthread_t pid" "pthread_attr_t *dst"
37.Sh DESCRIPTION
38The
39.Fn pthread_attr_get_np
40function is used to get existent thread's attributes.
41Most fields of
42.Vt pthread_attr_t
43structure are exact values of attributes provided at thread creation
44time (as parameter to
45.Xr pthread_create 3
46function), except for the stack address.
47.Pp
48Value returned as
49.Fa dst
50is supposed to be used in conjunction with
51.Fn pthread_attr_get*
52functions to retrieve individual values from
53.Vt pthread_attr_t
54structure.
55Parameter
56.Fa dst
57should point to allocated memory area big enough to fit this structure.
58.Pp
59It is HIGHLY RECOMMENDED to use
60.Xr pthread_attr_init 3
61function to allocate attribute storage.
62.Sh IMPLEMENTATION NOTES
63The
64.Fn pthread_attr_get_np
65function will always return a pointer to the thread's real stack address,
66regardless of its value in the original attributes structure.
67.Sh RETURN VALUES
68If successful,
69.Fn pthread_attr_get_np
70function returns 0.
71Otherwise, an error number is returned to indicate the error.
72.Sh EXAMPLES
73.Bd -literal
74size_t
75my_thread_stack_size(pthread_t pid)
76{
77    pthread_attr_t attr;
78    size_t size;
79
80    pthread_attr_init(&attr);
81    pthread_attr_get_np(pid, &attr);
82    pthread_attr_getstacksize(&attr, &size);
83    pthread_attr_destroy(&attr);
84    return(size);
85}
86.Ed
87.Sh ERRORS
88The
89.Fn pthread_attr_get_np
90function will fail if:
91.Bl -tag -width Er
92.It Bq Er EINVAL
93Invalid value for one of given parameters.
94.It Bq Er ESRCH
95No thread could be found corresponding to that specified by the given
96thread ID.
97.El
98.Sh SEE ALSO
99.Xr pthread_attr_destroy 3 ,
100.Xr pthread_attr_getdetachstate 3 ,
101.Xr pthread_attr_getinheritsched 3 ,
102.Xr pthread_attr_getschedparam 3 ,
103.Xr pthread_attr_getschedpolicy 3 ,
104.Xr pthread_attr_getscope 3 ,
105.Xr pthread_attr_getstack 3 ,
106.Xr pthread_attr_getstackaddr 3 ,
107.Xr pthread_attr_getstacksize 3 ,
108.Xr pthread_attr_init 3 ,
109.Xr pthread_np 3
110.Sh AUTHORS
111The
112.Fn pthread_attr_get_np
113function and this manual page were written by
114.An Alexey Zelkin Aq Mt phantom@FreeBSD.org .
115