jcs.org
jcs's openbsd hax
openbsd
1.\" $OpenBSD: pthread_attr_setguardsize.3,v 1.4 2025/06/07 00:16:52 schwarze Exp $
2.\" Manual page derived from TOG's XPG6 documentation.
3.\"
4.\" David Leonard, 2000. Public Domain.
5.\"
6.Dd $Mdocdate: June 7 2025 $
7.Dt PTHREAD_ATTR_SETGUARDSIZE 3
8.Os
9.Sh NAME
10.Nm pthread_attr_setguardsize ,
11.Nm pthread_attr_getguardsize
12.Nd set and get guardsize attribute
13.Sh SYNOPSIS
14.Lb libpthread
15.In pthread.h
16.Ft int
17.Fn pthread_attr_setguardsize "pthread_attr_t *attr" "size_t guardsize"
18.Ft int
19.Fn pthread_attr_getguardsize "const pthread_attr_t *attr" "size_t *guardsize"
20.Sh DESCRIPTION
21The functions
22.Fn pthread_attr_setguardsize
23and
24.Fn pthread_attr_getguardsize ,
25respectively, set and get the thread
26creation
27.Va guardsize
28attribute in the
29.Fa attr
30object.
31If
32.Va guardsize
33is zero,
34a guard area shall not be provided for threads created with
35.Fa attr .
36If
37.Va guardsize
38is greater than zero,
39a guard area of at least size
40.Va guardsize
41bytes shall be provided for each thread created with
42.Fa attr .
43.Pp
44The
45.Va guardsize
46attribute controls the size of the guard area for the created
47thread's stack.
48The
49.Va guardsize
50attribute provides protection against overflow of the stack pointer.
51If a thread's stack is created with guard protection,
52the implementation allocates extra memory at the overflow end of
53the stack as a buffer against stack overflow of the stack pointer.
54If an application overflows into this buffer, an error shall result
55(possibly in a SIGSEGV signal being delivered to the thread).
56.Sh RETURN VALUES
57Upon successful completion,
58.Fn pthread_attr_setguardsize
59and
60.Fn pthread_attr_getguardsize
61return a value of 0.
62Otherwise, an error number is returned to indicate the error.
63.Pp
64The
65.Fn pthread_attr_getguardsize
66function stores the
67.Va guardsize
68attribute value in
69.Fa guardsize
70if successful.
71.Sh ERRORS
72No errors are defined.
73.Pp
74These functions will not return an error code of
75.Bq Er EINTR .
76.Sh SEE ALSO
77.Xr pthread_attr_init 3 ,
78.Xr pthread_attr_setdetachstate 3 ,
79.Xr pthread_attr_setstack 3 ,
80.Xr pthread_attr_setstackaddr 3 ,
81.Xr pthread_attr_setstacksize 3 ,
82.Xr pthread_create 3 ,
83.Xr pthreads 3
84.Sh STANDARDS
85.Fn pthread_attr_setguardsize
86and
87.Fn pthread_attr_getguardsize
88conform to ISO/IEC 9945-1 ANSI/IEEE
89.Pq Dq Tn POSIX
90Std 1003.1, 2004 Edition.