Manual Pages for UNIX Operating System command usage for man mprotect

System Calls                                          mprotect(2)



NAME
     mprotect - set protection of memory mapping

SYNOPSIS
     #include 

     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. Legi-
     timate values for prot are the same as those  permitted  for
     mmap(2) and are defined in  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 modified.

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).




SunOS 5.11          Last change: 12 Jan 1998                    1






System Calls                                          mprotect(2)



     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  attri-
     butes:



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Standard                    |
    |_____________________________|_____________________________|


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





















SunOS 5.11          Last change: 12 Jan 1998                    2