ioperm - set port input/output permissions
#include <unistd.h> /* for libc5 / #include <sys/io.h> / for glibc */
Only the first 0x3ff I/O ports can be specified in this manner. For more ports, the iopl(2) 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.
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ioperm(2) 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.