MPROTECT(2)                     Domain/OS BSD                      MPROTECT(2)



NAME
     mprotect - assign protection to region mapped in virtual memory

SYNOPSIS
     #include <sys/mman.h>

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

DESCRIPTION
     mprotect ignores len.  It sets the protection for the entire region
     mapped beginning at addr.  <sys/mman.h> defines the possible settings for
     prot:

     /* protections are chosen from these bits, ORed together */

     #define  PROT_READ        0x04    /* pages can be read */
     #define  PROT_WRITE       0x02    /* pages can be written */
     #define  PROT_EXEC        0x01    /* pages can be executed */

NOTES
     This implementation is based upon a proposal by McKusick and Karels, and
     upon other sources.  Its details may change in a future release.

SEE ALSO
     McKusick, M.K. and Karels, M.J.  A New Virtual Memory Implementation for
          Berkeley UNIX.  Berkeley, California:  Department of Electrical
          Engineering and Computer Science, University of California, 1986.
     madvise(2), mmap(2), mset(2).

DIAGNOSTICS
     A successful call returns 0.  An unsuccessful call returns -1 and sets
     errno as indicated below.

ERRORS
     mprotect will fail if any of the following is true:

     [EINVAL]   An invalid protection mode was specified.

     [ENOENT]   No region is mapped at the specified address.

     [EACCESS]  Attempt to change the protection to a mode precluded by file
                access proctections.

     [ETXTBSY]  The file is a pure-procedure (shared text) file that is being
                executed and the protections request write access.

     [EROFS]    The mapped file resides on a read-only file system and the
                protections request write access.