ADC Home > Reference Library > Reference > Mac OS X > Mac OS X Man Pages


This document is a Mac OS X manual page. Manual pages are a command-line technology for providing documentation. You can view these manual pages locally using the man(1) command. These manual pages come from many different sources, and thus, have a variety of writing styles.

This manual page is associated with the Mac OS X developer tools. The software or headers described may not be present on your Mac OS X installation until you install the developer tools package. This package is available on your Mac OS X installation DVD, and the latest versions can be downloaded from

For more information about the manual page format, see the manual page for manpages(5).

MPROTECT(2)                 BSD System Calls Manual                MPROTECT(2)

     mprotect -- control the protection of pages

     #include <sys/mman.h>

     mprotect(void *addr, size_t len, int prot);

     The mprotect() system call changes the specified pages to have protection prot.  Not all implementa-tions implementations
     tions will guarantee protection on a page basis; the granularity of protection changes may be as large
     as an entire region.

     Upon successful completion, a value of 0 is returned.  Otherwise, a value of -1 is returned and errno
     is set to indicate the error.

     mprotect() will fail if:

     [EACCES]           The requested protection conflicts with the access permissions of the process on the
                        specified address range.

     [EINVAL]           addr is not a multiple of the page size.

     [ENOTSUP]          The combination of accesses requested in prot is not supported.

     #include <sys/types.h>
     #include <sys/mman.h>

     The include file <sys/types.h> is necessary.

     mprotect(caddr_t addr, size_t len, int prot);

     The type of addr has changed.

     madvise(2), mincore(2), msync(2), munmap(2), compat(5)

     The mprotect() function first appeared in 4.4BSD.

BSD                              June 9, 1993                              BSD

Did this document help you?
Yes: Tell us what works for you.
It’s good, but: Report typos, inaccuracies, and so forth.
It wasn’t helpful: Tell us what would have helped.