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¶

sys/mman.h — memory management declarations

SYNOPSIS¶

#include <sys/mman.h>

DESCRIPTION¶

The <sys/mman.h> header shall define the following symbolic constants for use as protection options:

PROT_EXEC

Page can be executed.

PROT_NONE

Page cannot be accessed.

PROT_READ

Page can be read.

PROT_WRITE

Page can be written.

The <sys/mman.h> header shall define the following symbolic constants for use as flag options:

MAP_FIXED

Interpret addr exactly.

MAP_PRIVATE

Changes are private.

MAP_SHARED

Share changes.

The <sys/mman.h> header shall define the following symbolic constants for the msync() function:

MS_ASYNC

Perform asynchronous writes.

MS_INVALIDATE

Invalidate mappings.

MS_SYNC

Perform synchronous writes.

The <sys/mman.h> header shall define the following symbolic constants for the mlockall() function:

MCL_CURRENT

Lock currently mapped pages.

MCL_FUTURE

Lock pages that become mapped.

The <sys/mman.h> header shall define the symbolic constant MAP_FAILED which shall have type void * and shall be used to indicate a failure from the mmap() function .

If the Advisory Information option is supported, the <sys/mman.h> header shall define symbolic constants for the advice argument to the posix_madvise() function as follows:

POSIX_MADV_DONTNEED

The application expects that it will not access the specified range in the near future.

POSIX_MADV_NORMAL

The application has no advice to give on its behavior with respect to the specified range. It is the default characteristic if no advice is given for a range of memory.

POSIX_MADV_RANDOM

The application expects to access the specified range in a random order.

POSIX_MADV_SEQUENTIAL

The application expects to access the specified range sequentially from lower addresses to higher addresses.

POSIX_MADV_WILLNEED

The application expects to access the specified range in the near future.

The <sys/mman.h> header shall define the following symbolic constants for use as flags for the posix_typed_mem_open() function:

POSIX_TYPED_MEM_ALLOCATE

Allocate on mmap().

POSIX_TYPED_MEM_ALLOCATE_CONTIG

Allocate contiguously on mmap().

POSIX_TYPED_MEM_MAP_ALLOCATABLE

Map on mmap(), without affecting allocatability.

The <sys/mman.h> header shall define the mode_t, off_t, and size_t types as described in <sys_types.h>.

The <sys/mman.h> header shall define the posix_typed_mem_info structure, which shall include at least the following member:

size_t  posix_tmi_length  Maximum length which may be allocated


                          from a typed memory object.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

int    mlock(const void *, size_t);
int    mlockall(int);
void  *mmap(void *, size_t, int, int, int, off_t);
int    mprotect(void *, size_t, int);
int    msync(void *, size_t, int);
int    munlock(const void *, size_t);
int    munlockall(void);
int    munmap(void *, size_t);
int    posix_madvise(void *, size_t, int);
int    posix_mem_offset(const void *restrict, size_t, off_t *restrict,


           size_t *restrict, int *restrict);
int    posix_typed_mem_get_info(int, struct posix_typed_mem_info *);
int    posix_typed_mem_open(const char *, int, int);
int    shm_open(const char *, int, mode_t);
int    shm_unlink(const char *);

The following sections are informative.

APPLICATION USAGE¶

None.

RATIONALE¶

None.

FUTURE DIRECTIONS¶

None.

SEE ALSO¶

<sys_types.h>

The System Interfaces volume of POSIX.1‐2017, mlock(), mlockall(), mmap(), mprotect(), msync(), munmap(), posix_madvise(), posix_mem_offset(), posix_typed_mem_get_info(), posix_typed_mem_open(), shm_open(), shm_unlink()

COPYRIGHT¶

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 .