Minix/minix
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

pthread yet again

Browse Source
This commit is contained in:
Lionel Sambuc
2017-05-12 17:53:28 +00:00
parent d5e4fc0151
commit aa2076a2eb
83 changed files with 14283 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

175
lib/libpthread/pthread_attr_getstack.3 Normal file
View File

@@ -0,0 +1,175 @@
.\" $NetBSD: pthread_attr_getstack.3,v 1.5 2010/07/09 17:15:59 jruoho Exp $
.\"
.\" Copyright (c) 2010 Jukka Ruohonen <jruohonen@iki.fi>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd July 9, 2010
.Dt PTHREAD_ATTR_GETSTACK 3
.Os
.Sh NAME
.Nm pthread_attr_getstack
.Nd get and set thread stack attributes
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_attr_getstack \
"const pthread_attr_t * restrict attr" \
"void ** restrict stackaddr, size_t * restrict stacksize"
.Ft int
.Fn pthread_attr_setstack \
"pthread_attr_t * restrict attr" "void *stackaddr, size_t stacksize"
.Ft int
.Fn pthread_attr_getstacksize \
"const pthread_attr_t * restrict attr" "size_t * restrict stacksize"
.Ft int
.Fn pthread_attr_setstacksize \
"pthread_attr_t *attr" "size_t stacksize"
.Ft int
.Fn pthread_attr_getstackaddr \
"const pthread_attr_t * restrict attr" "void ** restrict stackaddr"
.Ft int
.Fn pthread_attr_setstackaddr \
"pthread_attr_t *attr" "void *stackaddr"
.Sh DESCRIPTION
The
.Fn pthread_attr_getstack
and
.Fn pthread_attr_setstack
functions get and set, respectively, the thread stack attributes
.Fa stackaddr
and
.Fa stacksize
in the
.Fa attr
object.
The remaining four functions behave similarly,
but instead of getting or setting both
.Fa stackaddr
and
.Fa stacksize ,
these get and set the values individually.
.Pp
The
.Fa stacksize
parameter is defined to be the minimum stack size (in bytes)
allocated for the thread's stack during the creation of the thread.
The
.Fa stackaddr
attribute specifies the location of storage to be used for the thread's stack.
All pages within the stack described by
.Fa stackaddr
and
.Fa stacksize
should be both readable and writable by the thread.
.Pp
The behavior is undefined in all functions if the
.Fa attr
parameter does not refer to an attribute object initialized by using
.Xr pthread_attr_init 3
prior to the call.
In addition, undefined behavior may follow if the
.Fn pthread_attr_getstack
function is called before the
.Fa stackaddr
attribute has been set.
.Ss Rationale
The rationale behind these functions is to address cases where an application
may be used in an environment where the stack of a thread must be placed to
some particular region of memory.
For the majority of applications, this is seldom necessary,
and the use of these functions should be generally avoided.
At least few potential caveats can be mentioned.
.Bl -bullet -offset 2n
.It
There is a certain degree of ambiguity in the
.Tn POSIX
standard with respect to thread stack.
.It
The exact behavior of the functions may vary
both across machines and operating systems.
In particular, the address specified by
.Fa stackaddr
should be suitably aligned.
The system page size, as specified by
.Xr sysconf 3 ,
and the use of
.Xr posix_memalign 3
may guarantee some degree of portability.
Also
.Xr mmap 2
provides means for alignment.
.It
If the application modifies the stack address, it claims also
the responsibility of allocating the stack area and guarding it against
possible stack overflow.
No default guard area will be allocated (see
.Xr pthread_attr_getguardsize 3 ) .
It may be necessary to manually use
.Xr mprotect 2
in order to define a guard area at the end of the allocated stack.
.It
Moreover, if
.Fa attr
is used to create multiple threads, the stack address must be changed
by the application between successive calls to
.Xr pthread_create 3 .
.El
.Sh RETURN VALUES
If successful, these functions return 0.
Otherwise, an error number is returned to indicate the error.
.Sh ERRORS
No errors are defined for the three functions that obtain the stack values.
The three functions that set the stack values may fail if:
.Bl -tag -width Er
.It Bq Er ENOMEM
There was insufficient memory to complete the operation.
.El
.Pp
The
.Fn pthread_attr_setstacksize
function may additionally fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The specified
.Fa stacksize
is less than
.Dv PTHREAD_STACK_MIN
or exceeds some system-imposed limit.
.El
.Sh SEE ALSO
.Xr pthread_attr 3 ,
.Xr pthread_attr_setguardsize 3
.Sh STANDARDS
All described functions conform to
.St -p1003.1-2001 .
Note that
.Fn pthread_attr_getstackaddr
and
.Fn pthread_attr_setstackaddr
were however removed from the specification in the
.St -p1003.1-2008
revision.