mprotect(2)                      UNIX System V                      mprotect(2)


NAME
      mprotect - set protection of memory mapping

SYNOPSIS
      #include <sys/types.h>
      #include <sys/mman.h>
      int mprotect(caddrt addr, sizet len, int prot);

DESCRIPTION
      The function mprotect changes the access protections on the mappings
      specified by the range [addr, addr + len) to be that specified by prot.
      Legitimate values for prot are the same as those permitted for mmap and
      are defined in <sys/mman.h> as:
            PROTREAD                /* page can be read */
            PROTWRITE               /* page can be written */
            PROTEXEC                /* page can be executed */
            PROTNONE                /* page can not be accessed */

RETURN VALUE
      Upon successful completion, the function mprotect returns a value of 0;
      otherwise, it returns a value of -1 and sets errno to indicate an error.

ERRORS
      Under the following conditions, the function mprotect fails and sets
      errno to:

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

     EAGAIN if prot specifies PROTWRITE over a MAPPRIVATE mapping and there
             are insufficient memory resources to reserve for locking the
             private page.

     EINVAL if addr is not a multiple of the page size as returned by sysconf.

     EINVAL The argument len has a value less than or equal to 0.

     ENOMEM if 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.

      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 modified.

SEE ALSO
      memcntl(2), mmap(2), plock(2), mlock(3C), mlockall(3C), sysconf(3C).






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