MPROTECT(2-SVR4)    RISC/os Reference Manual     MPROTECT(2-SVR4)



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:
          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 */

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 PROT_WRITE over a MAP_PRIVATE map-
            ping 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 pro-
     tections 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.




                        Printed 11/19/92                   Page 1

MPROTECT(2-SVR4)    RISC/os Reference Manual     MPROTECT(2-SVR4)



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




















































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