ioperm
NAME
ioperm - set port input/output permissions
SYNOPSIS
#include <unistd.h>
/* for libc5 */
#include <sys/io.h> /* for glibc */ I int ioperm(unsigned long from , unsigned long num , int turn_on );
#include <sys/io.h> /* for glibc */ I int ioperm(unsigned long from , unsigned long num , int turn_on );
DESCRIPTION
R ioperm ()
sets the port access permission bits for the calling process for
num bytes starting from port address from to the value
turn_on.
If turn_on is non-zero, the calling process must be privileged
(CAP_SYS_RAWIO).
Only the first 0x3ff I/O ports can be specified in this manner.
For more ports, the
iopl(2)
system call must be used.
Permissions are not inherited by the child created by
fork(2).
Permissions are preserved across
execve(2);
this is useful for giving port access permissions to non-privileged
programs.
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 appropriately.
ERRORS
EINVAL
Invalid values for
from
or
R num .
EIO
(on PowerPC) This call is not supported.
ENOMEM
Out of memory.
EPERM
The calling process has insufficient privilege.
CONFORMING TO
R 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
R <unistd.h> .
Glibc1 does not have a prototype.
Glibc2 has a prototype both in
<sys/io.h>
and in
R <sys/perm.h> .
Avoid the latter, it is available on i386 only.
SEE ALSO
iopl(2),
capabilities(7)
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