PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

MPROTECT(3P)              POSIX Programmer's Manual             MPROTECT(3P)

PROLOG         top

       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         top

       mprotect — set protection of memory mapping

SYNOPSIS         top

       #include <sys/mman.h>

       int mprotect(void *addr, size_t len, int prot);

DESCRIPTION         top

       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         top

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

ERRORS         top

       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         top

       None.

APPLICATION USAGE         top

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

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       mmap(3p), sysconf(3p)

       The Base Definitions volume of POSIX.1‐2008, sys_mman.h(0p)

COPYRIGHT         top

       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 .

IEEE/The Open Group                 2013                        MPROTECT(3P)