mprotect(3p) — Linux manual page


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

       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

       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

              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



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

RATIONALE         top




SEE ALSO         top

       mmap(3p), sysconf(3p)

       The Base Definitions volume of POSIX.1‐2017, sys_mman.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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 .

       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 .

IEEE/The Open Group               2017                      MPROTECT(3P)

Pages that refer to this page: sys_mman.h(0p)mmap(3p)