man3/pthread_attr_setstack.3

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   2 .\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
   3 .\"     <mtk.manpages@gmail.com>
   4 .\"
   5 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
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   7 .TH pthread_attr_setstack 3 (date) "Linux man-pages (unreleased)"
   8 .SH NAME
   9 pthread_attr_setstack, pthread_attr_getstack \- set/get stack
  10 attributes in thread attributes object
  11 .SH LIBRARY
  12 POSIX threads library
  13 .RI ( libpthread ", " \-lpthread )
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <pthread.h>
  17 .PP
  18 .BI "int pthread_attr_setstack(pthread_attr_t *" attr ,
  19 .BI "                          void " stackaddr [. stacksize ],
  20 .BI "                          size_t " stacksize );
  21 .BI "int pthread_attr_getstack(const pthread_attr_t *restrict " attr ,
  22 .BI "                          void **restrict " stackaddr ,
  23 .BI "                          size_t *restrict " stacksize );
  24 .fi
  25 .PP
  26 .RS -4
  27 Feature Test Macro Requirements for glibc (see
  28 .BR feature_test_macros (7)):
  29 .RE
  30 .PP
  31 .BR pthread_attr_getstack (),
  32 .BR pthread_attr_setstack ():
  33 .nf
  34     _POSIX_C_SOURCE >= 200112L
  35 .fi
  36 .SH DESCRIPTION
  37 The
  38 .BR pthread_attr_setstack ()
  39 function sets the stack address and stack size attributes of the
  40 thread attributes object referred to by
  41 .I attr
  42 to the values specified in
  43 .I stackaddr
  44 and
  45 .IR stacksize ,
  46 respectively.
  47 These attributes specify the location and size of the stack that should
  48 be used by a thread that is created using the thread attributes object
  49 .IR attr .
  50 .PP
  51 .I stackaddr
  52 should point to the lowest addressable byte of a buffer of
  53 .I stacksize
  54 bytes that was allocated by the caller.
  55 The pages of the allocated buffer should be both readable and writable.
  56 .PP
  57 The
  58 .BR pthread_attr_getstack ()
  59 function returns the stack address and stack size attributes of the
  60 thread attributes object referred to by
  61 .I attr
  62 in the buffers pointed to by
  63 .I stackaddr
  64 and
  65 .IR stacksize ,
  66 respectively.
  67 .SH RETURN VALUE
  68 On success, these functions return 0;
  69 on error, they return a nonzero error number.
  70 .SH ERRORS
  71 .BR pthread_attr_setstack ()
  72 can fail with the following error:
  73 .TP
  74 .B EINVAL
  75 .I stacksize
  76 is less than
  77 .B PTHREAD_STACK_MIN
  78 (16384) bytes.
  79 On some systems, this error may also occur if
  80 .I stackaddr
  81 or
  82 .I stackaddr\~+\~stacksize
  83 is not suitably aligned.
  84 .PP
  85 POSIX.1 also documents an
  86 .B EACCES
  87 error if the stack area described by
  88 .I stackaddr
  89 and
  90 .I stacksize
  91 is not both readable and writable by the caller.
  92 .SH ATTRIBUTES
  93 For an explanation of the terms used in this section, see
  94 .BR attributes (7).
  95 .ad l
  96 .nh
  97 .TS
  98 allbox;
  99 lbx lb lb
 100 l l l.
 101 Interface       Attribute       Value
 102 T{
 103 .BR pthread_attr_setstack (),
 104 .BR pthread_attr_getstack ()
 105 T}      Thread safety   MT-Safe
 106 .TE
 107 .hy
 108 .ad
 109 .sp 1
 110 .SH STANDARDS
 111 POSIX.1-2008.
 112 .SH HISTORY
 113 glibc 2.2.
 114 POSIX.1-2001.
 115 .SH NOTES
 116 These functions are provided for applications that must ensure that
 117 a thread's stack is placed in a particular location.
 118 For most applications, this is not necessary,
 119 and the use of these functions should be avoided.
 120 (Use
 121 .BR pthread_attr_setstacksize (3)
 122 if an application simply requires a stack size other than the default.)
 123 .PP
 124 When an application employs
 125 .BR pthread_attr_setstack (),
 126 it takes over the responsibility of allocating the stack.
 127 Any guard size value that was set using
 128 .BR pthread_attr_setguardsize (3)
 129 is ignored.
 130 If deemed necessary,
 131 it is the application's responsibility to allocate a guard area
 132 (one or more pages protected against reading and writing)
 133 to handle the possibility of stack overflow.
 134 .PP
 135 The address specified in
 136 .I stackaddr
 137 should be suitably aligned:
 138 for full portability, align it on a page boundary
 139 .RI ( sysconf(_SC_PAGESIZE) ).
 140 .BR posix_memalign (3)
 141 may be useful for allocation.
 142 Probably,
 143 .I stacksize
 144 should also be a multiple of the system page size.
 145 .PP
 146 If
 147 .I attr
 148 is used to create multiple threads, then the caller must change the
 149 stack address attribute between calls to
 150 .BR pthread_create (3);
 151 otherwise, the threads will attempt to use the same memory area
 152 for their stacks, and chaos will ensue.
 153 .SH EXAMPLES
 154 See
 155 .BR pthread_attr_init (3).
 156 .SH SEE ALSO
 157 .ad l
 158 .nh
 159 .BR mmap (2),
 160 .BR mprotect (2),
 161 .BR posix_memalign (3),
 162 .BR pthread_attr_init (3),
 163 .BR pthread_attr_setguardsize (3),
 164 .BR pthread_attr_setstackaddr (3),
 165 .BR pthread_attr_setstacksize (3),
 166 .BR pthread_create (3),
 167 .BR pthreads (7)