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

NAME
     mprotect -- control the protection of pages

SYNOPSIS
     #include <sys/mman.h>

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

DESCRIPTION
     The mprotect() system call changes the specified pages to have protection
     prot.  Not all implementations will guarantee protection on a page basis
     but Mac OS X's current implementation does.

     When a program violates the protections of a page, it gets a SIGBUS or
     SIGSEGV signal.

     Currently prot can be one or more of the following:

     PROT_NONE   No permissions at all.
     PROT_READ   The pages can be read.
     PROT_WRITE  The pages can be written.
     PROT_EXEC   The pages can be executed.

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

ERRORS
     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 (i.e.  addr is
                        not page-aligned).

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

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

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

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

     The type of addr has changed.

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

HISTORY
     The mprotect() function first appeared in 4.4BSD.

BSD                            October 16, 2008                            BSD