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



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

NNAAMMEE
       mprotect -- set protection of memory mapping

SSYYNNOOPPSSIISS
       #include <sys/mman.h>

       int mprotect(void *_a_d_d_r, size_t _l_e_n, int _p_r_o_t);

DDEESSCCRRIIPPTTIIOONN
       The _m_p_r_o_t_e_c_t() function shall change the access protections to be that
       specified by _p_r_o_t for those whole pages containing any part of the
       address space of the process starting at address _a_d_d_r and continuing
       for _l_e_n bytes. The parameter _p_r_o_t determines whether read, write,
       execute, or some combination of accesses are permitted to the data
       being mapped. The _p_r_o_t 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 _p_r_o_t, the call to _m_p_r_o_t_e_c_t() shall fail.

       An implementation may permit accesses other than those specified by
       _p_r_o_t; 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 _p_r_o_t: 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 _a_d_d_r be a multiple of the page size
       as returned by _s_y_s_c_o_n_f().

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

       When _m_p_r_o_t_e_c_t() fails for reasons other than [[EEIINNVVAALL]], the protections
       on some of the pages in the range [_a_d_d_r,_a_d_d_r+_l_e_n) may have been
       changed.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, _m_p_r_o_t_e_c_t() shall return 0; otherwise, it
       shall return -1 and set _e_r_r_n_o to indicate the error.

EERRRROORRSS
       The _m_p_r_o_t_e_c_t() function shall fail if:

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

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

       EENNOOMMEEMM Addresses in the range [_a_d_d_r,_a_d_d_r+_l_e_n) are invalid for the
              address space of a process, or specify one or more pages which
              are not mapped.

       EENNOOMMEEMM The _p_r_o_t 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.

       EENNOOTTSSUUPP
              The implementation does not support the combination of accesses
              requested in the _p_r_o_t argument.

       The _m_p_r_o_t_e_c_t() function may fail if:

       EEIINNVVAALL The _a_d_d_r argument is not a multiple of the page size as returned
              by _s_y_s_c_o_n_f().

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       Most implementations require that _a_d_d_r is a multiple of the page size
       as returned by _s_y_s_c_o_n_f().

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _m_m_a_p(), _s_y_s_c_o_n_f()

       The Base Definitions volume of POSIX.1-2017, <<ssyyss__mmmmaann..hh>>

CCOOPPYYRRIIGGHHTT
       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 http://www.opengroup.org/unix/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                  2017                          MPROTECT(3)
