man2/ioperm.2

   1 .\" Copyright (c) 1993 Michael Haardt
   2 .\" (michael@moria.de)
   3 .\" Fri Apr  2 11:32:09 MET DST 1993
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  26 .\" Modified Sat Jul 24 15:12:05 1993 by Rik Faith <faith@cs.unc.edu>
  27 .\" Modified Tue Aug  1 16:27    1995 by Jochen Karrer
  28 .\"                              <cip307@cip.physik.uni-wuerzburg.de>
  29 .\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
  30 .\" Modified Mon Feb 15 17:28:41 CET 1999 by Andries E. Brouwer <aeb@cwi.nl>
  31 .\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
  32 .\"     Added notes on capability requirements
  33 .\"
  34 .TH IOPERM 2 2007-06-15 "Linux" "Linux Programmer's Manual"
  35 .SH NAME
  36 ioperm \- set port input/output permissions
  37 .SH SYNOPSIS
  38 .B #include <unistd.h>
  39 /* for libc5 */
  40 .br
  41 .B #include <sys/io.h>
  42 /* for glibc */
  43 .sp
  44 .BI "int ioperm(unsigned long " from ", unsigned long " num ", int " turn_on );
  45 .SH DESCRIPTION
  46 .BR ioperm ()
  47 sets the port access permission bits for the calling process for
  48 \fInum\fP bytes starting from port address \fIfrom\fP to the value
  49 \fIturn_on\fP.
  50 If \fIturn_on\fP is nonzero, the calling process must be privileged
  51 .RB ( CAP_SYS_RAWIO ).
  52
  53 .\" FIXME is the following ("Only the first 0x3ff I/O ports can be
  54 .\" specified in this manner") still true?  Looking at changes in
  55 .\" include/asm-i386/processor.h between 2.4 and 2.6 suggests
  56 .\" that the limit is different in 2.6.
  57 Only the first 0x3ff I/O ports can be specified in this manner.
  58 For more ports, the
  59 .BR iopl (2)
  60 system call must be used.
  61
  62 Permissions are not inherited by the child created by
  63 .BR fork (2).
  64 Permissions are preserved across
  65 .BR execve (2);
  66 this is useful for giving port access permissions to unprivileged
  67 programs.
  68
  69 This call is mostly for the i386 architecture.
  70 On many other architectures it does not exist or will always
  71 return an error.
  72 .SH RETURN VALUE
  73 On success, zero is returned.
  74 On error, \-1 is returned, and
  75 .I errno
  76 is set appropriately.
  77 .SH ERRORS
  78 .TP
  79 .B EINVAL
  80 Invalid values for
  81 .I from
  82 or
  83 .IR num .
  84 .TP
  85 .B EIO
  86 (on PowerPC) This call is not supported.
  87 .TP
  88 .B ENOMEM
  89 .\" Could not allocate I/O bitmap.
  90 Out of memory.
  91 .TP
  92 .B EPERM
  93 The calling process has insufficient privilege.
  94 .SH CONFORMING TO
  95 .BR ioperm ()
  96 is Linux-specific and should not be used in programs
  97 intended to be portable.
  98 .SH NOTES
  99 Libc5 treats it as a system call and has a prototype in
 100 .IR <unistd.h> .
 101 Glibc1 does not have a prototype.
 102 Glibc2 has a prototype both in
 103 .I <sys/io.h>
 104 and in
 105 .IR <sys/perm.h> .
 106 Avoid the latter, it is available on i386 only.
 107 .SH SEE ALSO
 108 .BR iopl (2),
 109 .BR capabilities (7)