sunos man page for mprotect

mprotect(2)							   System Calls 						       mprotect(2)

NAME
       mprotect - set protection of memory mapping

SYNOPSIS
       #include <sys/mman.h>

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

DESCRIPTION
       The   mprotect()  function changes the access protections on the mappings specified by the range [addr, addr + len), rounding len up to the
       next multiple of the page size as returned by sysconf(3C), to be that specified by prot. Legitimate values for prot are the same  as  those
       permitted for mmap(2) and are defined in <sys/mman.h> as:

       PROT_READ       /* page can be read */

       PROT_WRITE      /* page can be written */

       PROT_EXEC       /* page can be executed */

       PROT_NONE       /* page can not be accessed */

       When  mprotect()  fails	for  reasons other than EINVAL, the protections on some of the pages in the range [addr, addr + len) may have been
       changed. If the error occurs on some page at addr2, then the protections of all whole pages in the range [addr, addr2] will have been modi-
       fied.

RETURN VALUES
       Upon successful completion, mprotect() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.

ERRORS
       The mprotect() function will fail if:

       EACCES	       The  prot  argument  specifies  a  protection  that violates the access permission the process has to the underlying memory
		       object.

       EINVAL	       The len argument has a value equal to 0, or addr is not a multiple of the page size as returned by sysconf(3C).

       ENOMEM	       Addresses in the range [addr, addr + len) are invalid for the address space of a process, or  specify  one  or  more  pages
		       which are not mapped.

       The mprotect() function may fail if:

       EAGAIN	       The  address  range  [addr,  addr  +  len)  includes one or more pages that have been locked in memory and that were mapped
		       MAP_PRIVATE; prot includes PROT_WRITE; and the system has insufficient resources to reserve memory for  the  private  pages
		       that may be created. These private pages may be created by store operations in the now-writable address range.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       mmap(2), plock(3C), mlock(3C), mlockall(3C), sysconf(3C), attributes(5), standards(5)

SunOS 5.10							    12 Jan 1998 						       mprotect(2)