ioperm - phpMan

IOPERM(2)                  Linux Programmer's Manual                 IOPERM(2)



NAME
       ioperm - set port input/output permissions

SYNOPSIS
       #include <unistd.h> /* for libc5 */
       #include <sys/io.h> /* for glibc */

       int ioperm(unsigned long from, unsigned long num, int turn_on);

DESCRIPTION
       Ioperm  sets the port access permission bits for the process for num bytes starting
       from port address from to the value turn_on.  The use  of  ioperm()  requires  root
       privileges.

       Only  the  first  0x3ff I/O ports can be specified in this manner.  For more ports,
       the iopl() function must be used.  Permissions are not inherited on fork(), but  on
       exec()  they  are.  This is useful for giving port access permissions to non-privi-
       leged tasks.

       This call is mostly for the i386 architecture.  On many other architectures it does
       not exist or will always return an error.

RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and errno is set appropri-
       ately.

ERRORS
       EINVAL Invalid values for from or num.

       EIO    (on ppc) This call is not supported.

       EPERM  The calling  process  has  insufficient  privilege  to  call  ioperm();  the
              CAP_SYS_RAWIO capability is required.

CONFORMING TO
       ioperm()  is  Linux  specific  and  should  not  be used in programs intended to be
       portable.

NOTES
       Libc5 treats it as a system call and has a prototype in  <unistd.h>.   Glibc1  does
       not   have  a  prototype.  Glibc2  has  a  prototype  both  in  <sys/io.h>  and  in
       <sys/perm.h>.  Avoid the latter, it is available on i386 only.

SEE ALSO
       iopl(2), capabilities(7)



Linux 2.6.6                       2004-05-27                         IOPERM(2)

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