man2/set_thread_area.2

   1 .\" Copyright (C) 2003 Free Software Foundation, Inc.
   2 .\" This file is distributed according to the GNU General Public License.
   3 .\" See the file COPYING in the top level source directory for details.
   4 .\"
   5 .\" Author: Kent Yoder
   6 .\"
   7 .TH SET_THREAD_AREA 2 2012-07-13 "Linux" "Linux Programmer's Manual"
   8 .SH NAME
   9 set_thread_area \- set a thread local storage (TLS) area
  10 .SH SYNOPSIS
  11 .B #include <linux/unistd.h>
  12 .br
  13 .B #include <asm/ldt.h>
  14 .sp
  15 .BI "int set_thread_area(struct user_desc *" u_info );
  16
  17 .IR Note :
  18 There is no glibc wrapper for this system call; see NOTES.
  19 .SH DESCRIPTION
  20 .BR set_thread_area ()
  21 sets an entry in the current thread's thread-local storage (TLS) array.
  22 The TLS array entry set by
  23 .BR set_thread_area ()
  24 corresponds to the value of
  25 .I u_info\->entry_number
  26 passed in by the user.
  27 If this value is in bounds,
  28 .BR set_thread_area ()
  29 copies the TLS descriptor pointed to by
  30 .I u_info
  31 into the thread's TLS array.
  32 .PP
  33 When
  34 .BR set_thread_area ()
  35 is passed an
  36 .I entry_number
  37 of \-1, it uses a free TLS entry.
  38 If
  39 .BR set_thread_area ()
  40 finds a free TLS entry, the value of
  41 .I u_info\->entry_number
  42 is set upon return to show which entry was changed.
  43 .SH RETURN VALUE
  44 .BR set_thread_area ()
  45 returns 0 on success, and \-1 on failure, with
  46 .I errno
  47 set appropriately.
  48 .SH ERRORS
  49 .TP
  50 .B EINVAL
  51 \fIu_info\->entry_number\fP is out of bounds.
  52 .TP
  53 .B EFAULT
  54 \fIu_info\fP is an invalid pointer.
  55 .TP
  56 .B ESRCH
  57 A free TLS entry could not be located.
  58 .SH VERSIONS
  59 A version of
  60 .BR set_thread_area ()
  61 first appeared in Linux 2.5.29.
  62 .SH CONFORMING TO
  63 .BR set_thread_area ()
  64 is Linux-specific and should not be used in programs that are intended
  65 to be portable.
  66 .SH NOTES
  67 Glibc does not provide a wrapper for this system call,
  68 since it is generally intended only for use by threading libraries.
  69 In the unlikely event that you want to call it directly, use
  70 .BR syscall (2).
  71 .SH SEE ALSO
  72 .BR get_thread_area (2)