ioperm — set port input/output permissions
#include <unistd.h> /* for libc5 */ #include <sys/io.h> /* for glibc */
int
ioperm( |
unsigned long | from, |
| unsigned long | num, | |
| int | turn_on); |
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 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.
On success, zero is returned. On error, −1 is
returned, and errno is set
appropriately.
Invalid values for from or num.
(on PowerPC) This call is not supported.
Out of memory.
The calling process has insufficient privilege.
ioperm() is Linux-specific
and should not be used in programs intended to be
portable.
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.