bionic (3) mprotect.3posix.gz

Provided by: manpages-posix-dev_2013a-2_all bug

PROLOG
       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.


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 shall change the access protections to be that specified by prot for those whole
       pages containing any part of the address space of the process starting at address addr and continuing for
       len  bytes.  The  parameter prot determines whether read, write, execute, or some combination of accesses
       are permitted to the data being mapped. The prot argument should be  either  PROT_NONE  or  the  bitwise-
       inclusive OR of one or more of PROT_READ, PROT_WRITE, and PROT_EXEC.

       If  an  implementation  cannot  support  the  combination  of access types specified by prot, the call to
       mprotect() shall fail.

       An implementation may permit accesses other than those specified  by  prot;  however,  no  implementation
       shall  permit  a  write  to  succeed  where  PROT_WRITE has not been set or shall permit any access where
       PROT_NONE alone has been set. Implementations shall support  at  least  the  following  values  of  prot:
       PROT_NONE, PROT_READ, PROT_WRITE, and the bitwise-inclusive OR of PROT_READ and PROT_WRITE. If PROT_WRITE
       is specified, the application shall ensure that it has opened the mapped objects in the specified address
       range  with  write  permission,  unless  MAP_PRIVATE was specified in the original mapping, regardless of
       whether the file descriptors used to map the objects have since been closed.

       The implementation may require that addr be a multiple of the page size as returned by sysconf().

       The behavior of this function is unspecified if the mapping was not established by a call to mmap().

       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.


RETURN VALUE
       Upon  successful  completion,  mprotect()  shall return 0; otherwise, it shall return −1 and set errno to
       indicate the error.


ERRORS
       The mprotect() function shall fail if:

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

       EAGAIN The  prot  argument  specifies  PROT_WRITE  over  a MAP_PRIVATE mapping and there are insufficient
              memory resources to reserve for locking the private page.

       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.

       ENOMEM The  prot  argument specifies PROT_WRITE on a MAP_PRIVATE mapping, and it would require more space
              than the system is able to supply for locking the private pages, if required.

       ENOTSUP
              The implementation does not support the combination of accesses requested in the prot argument.

       The mprotect() function may fail if:

       EINVAL The addr argument is not a multiple of the page size as returned by sysconf().

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       Most implementations require that addr is a multiple of the page size as returned by sysconf().


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       mmap(), sysconf()

       The Base Definitions volume of POSIX.1‐2008, <sys_mman.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event
       of any discrepancy between this version and the original IEEE and The Open Group Standard,  the  original
       IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at
       http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .