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ioperm() - Unix, Linux System Call
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 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
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-privileged tasks.
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
(on ppc) This call is not supported.
The calling process has insufficient privilege to call
CAP_SYS_RAWIO capability is required.
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.