.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
.\" <mtk.manpages@gmail.com>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
-.TH PTHREAD_GETATTR_NP 3 2010-09-10 "Linux" "Linux Programmer's Manual"
+.TH PTHREAD_GETATTR_NP 3 2019-03-06 "Linux" "Linux Programmer's Manual"
.SH NAME
pthread_getattr_np \- get attributes of created thread
.SH SYNOPSIS
.nf
.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
.B #include <pthread.h>
-
+.PP
.BI "int pthread_getattr_np(pthread_t " thread ", pthread_attr_t *" attr );
-.sp
+.PP
Compile and link with \fI\-pthread\fP.
.fi
.SH DESCRIPTION
.I attr
so that it contains actual attribute values describing the running thread
.IR thread .
-
+.PP
The returned attribute values may differ from
the corresponding attribute values passed in the
.I attr
in the thread attributes object used to create the thread,
then the returned thread attributes object will report the actual
stack address that the implementation selected for the thread.
-
+.PP
When the thread attributes object returned by
.BR pthread_getattr_np ()
is no longer required, it should be destroyed using
resource limit is not supported.
.SH VERSIONS
This function is available in glibc since version 2.2.3.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.ad l
+.TS
+allbox;
+lbw20 lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR pthread_getattr_np ()
+T} Thread safety MT-Safe
+.TE
+.ad
.SH CONFORMING TO
This function is a nonstandard GNU extension;
hence the suffix "_np" (nonportable) in the name.
Command-line arguments can be used to set these attributes
to values other than the default when creating the thread.
The shell sessions below demonstrate the use of the program.
-
+.PP
In the first run, on an x86-32 system,
a thread is created using default attributes:
-
+.PP
.in +4n
-.nf
-.RB "$" " ulimit \-s" " # No stack limit ==> default stack size is 2MB"
+.EX
+.RB "$" " ulimit \-s" " # No stack limit ==> default stack size is 2 MB"
unlimited
.RB "$" " ./a.out"
Attributes of created thread:
Guard size = 4096 bytes
Stack address = 0x40196000 (EOS = 0x40397000)
Stack size = 0x201000 (2101248) bytes
-.fi
+.EE
.in
-
+.PP
In the following run, we see that if a guard size is specified,
it is rounded up to the next multiple of the system page size
(4096 bytes on x86-32):
-
+.PP
.in +4n
-.nf
+.EX
.RB "$" " ./a.out \-g 4097"
Thread attributes object after initializations:
Guard size = 4097 bytes
Guard size = 8192 bytes
Stack address = 0x40196000 (EOS = 0x40397000)
Stack size = 0x201000 (2101248) bytes
-.fi
+.EE
.in
.\".in +4n
.\".nf
.\" Stack size = 0x8000 (32768) bytes
.\".fi
.\".in
-
+.PP
In the last run, the program manually allocates a stack for the thread.
In this case, the guard size attribute is ignored.
-
+.PP
.in +4n
-.nf
+.EX
.RB "$" " ./a.out \-g 4096 \-s 0x8000 \-a"
Allocated thread stack at 0x804d000
Guard size = 0 bytes
Stack address = 0x804d000 (EOS = 0x8055000)
Stack size = 0x8000 (32768) bytes
-.fi
+.EE
.in
.SS Program source
\&
-.nf
+.EX
#define _GNU_SOURCE /* To get pthread_getattr_np() declaration */
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
-#define handle_error_en(en, msg) \\
+#define handle_error_en(en, msg) \e
do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
static void
s = pthread_attr_getguardsize(attr, &guard_size);
if (s != 0)
handle_error_en(s, "pthread_attr_getguardsize");
- printf("%sGuard size = %d bytes\\n", prefix, guard_size);
+ printf("%sGuard size = %d bytes\en", prefix, guard_size);
s = pthread_attr_getstack(attr, &stack_addr, &stack_size);
if (s != 0)
printf("%sStack address = %p", prefix, stack_addr);
if (stack_size > 0)
printf(" (EOS = %p)", (char *) stack_addr + stack_size);
- printf("\\n");
- printf("%sStack size = 0x%x (%d) bytes\\n",
+ printf("\en");
+ printf("%sStack size = 0x%x (%d) bytes\en",
prefix, stack_size, stack_size);
}
static void * /* Start function for thread we create */
thread_start(void *arg)
{
- printf("Attributes of created thread:\\n");
- display_thread_attributes(pthread_self(), "\\t");
+ printf("Attributes of created thread:\en");
+ display_thread_attributes(pthread_self(), "\et");
exit(EXIT_SUCCESS); /* Terminate all threads */
}
if (msg != NULL)
fputs(msg, stderr);
fprintf(stderr, "Usage: %s [\-s stack\-size [\-a]]"
- " [\-g guard\-size]\\n", pname);
- fprintf(stderr, "\\t\\t\-a means program should allocate stack\\n");
+ " [\-g guard\-size]\en", pname);
+ fprintf(stderr, "\et\et\-a means program should allocate stack\en");
exit(EXIT_FAILURE);
}
}
if (allocate_stack && stack_size == \-1)
- usage(argv[0], "Specifying \-a without \-s makes no sense\\n");
+ usage(argv[0], "Specifying \-a without \-s makes no sense\en");
if (argc > optind)
- usage(argv[0], "Extraneous command\-line arguments\\n");
+ usage(argv[0], "Extraneous command\-line arguments\en");
if (stack_size >= 0 || guard_size > 0) {
ret_attrp = attrp;
stack_size);
if (s != 0)
handle_error_en(s, "posix_memalign");
- printf("Allocated thread stack at %p\\n\\n", stack_addr);
+ printf("Allocated thread stack at %p\en\en", stack_addr);
s = pthread_attr_setstack(attrp, stack_addr, stack_size);
if (s != 0)
attrp = get_thread_attributes_from_cl(argc, argv, &attr);
if (attrp != NULL) {
- printf("Thread attributes object after initializations:\\n");
- display_stack_related_attributes(attrp, "\\t");
- printf("\\n");
+ printf("Thread attributes object after initializations:\en");
+ display_stack_related_attributes(attrp, "\et");
+ printf("\en");
}
s = pthread_create(&thr, attrp, &thread_start, NULL);
pause(); /* Terminates when other thread calls exit() */
}
-.fi
+.EE
.SH SEE ALSO
.ad l
.nh
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