IOPERMSection: Linux Programmer's Manual (2)
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NAMEioperm - set port input/output permissions
SYNOPSIS#include <unistd.h> /* for libc5 */
#include <sys/io.h> /* for glibc */
DESCRIPTIONioperm() sets the port access permission bits for the 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 on fork(2), but on execve(2) they are. This is useful for giving port access permissions to non-privileged tasks.
RETURN VALUEOn success, zero is returned. On error, -1 is returned, and errno is set appropriately.
- Invalid values for from or num.
- (on ppc) This call is not supported.
- Out of memory.
- The calling process has insufficient privilege.
CONFORMING TOioperm() is Linux specific and should not be used in programs intended to be portable.
NOTESLibc5 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 ALSOiopl(2), capabilities(7)