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 calling process for
num bytes starting from port address
from to the value
turn_on. If
turn_on is nonzero, 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 unprivileged 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 num.
- EIO
- (on PowerPC) This call is not supported.
- ENOMEM
- Out of memory.
- EPERM
- The calling process has insufficient privilege.
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)
COLOPHON¶
This page is part of release 3.44 of the Linux
man-pages project. A
description of the project, and information about reporting bugs, can be found
at
http://www.kernel.org/doc/man-pages/.