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_ANON

Synonym for MAP_ANONYMOUS. MAP_ANON shall have the same value as MAP_ANONYMOUS.

MAP_ANONYMOUS

Map anonymous memory.

MAP_FIXED

Interpret addr exactly.

MAP_PRIVATE

Changes are private.

MAP_SHARED

Share changes.

^[XSI|SIO] 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.

^[ML] 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 .

^[ADV] 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.

^[TYM] 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>.

^[TYM] 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 <sys/mman.h> header shall define the following symbolic constants as described in <fcntl.h>:

^[SHM|TYM]
O_RDONLY
O_RDWR

^[TYM]
O_WRONLY
O_CLOEXEC
O_CLOFORK

^[SHM]
O_CREAT
O_EXCL
O_TRUNC

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

[MLR]
int    mlock(const void *, size_t);

[ML]
int    mlockall(int);

void  *mmap(void *, size_t, int, int, int, off_t);
int    mprotect(void *, size_t, int);
[XSI|SIO]
int    msync(void *, size_t, int);

[MLR]
int    munlock(const void *, size_t);

[ML]
int    munlockall(void);

int    munmap(void *, size_t);
[ADV]
int    posix_madvise(void *, size_t, int);

[TYM]
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);

[SHM]
int    shm_open(const char *, int, mode_t);
int    shm_unlink(const char *);

Inclusion of the <sys/mman.h> header may make visible all symbols from the <fcntl.h> header.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

<sys/types.h>

XSH mlock, mlockall, mmap, mprotect, msync, munmap, posix_madvise, posix_mem_offset, posix_typed_mem_get_info, posix_typed_mem_open, shm_open, shm_unlink

CHANGE HISTORY

First released in Issue 4, Version 2.

Issue 5

Updated for alignment with the POSIX Realtime Extension.

Issue 6

The <sys/mman.h> header is marked as dependent on support for either the Memory Mapped Files, Process Memory Locking, or Shared Memory Objects options.

The following changes are made for alignment with IEEE Std 1003.1j-2000:

• The TYM margin code is added to the list of margin codes for the <sys/mman.h> header line, as well as for other lines.

• The POSIX_TYPED_MEM_ALLOCATE, POSIX_TYPED_MEM_ALLOCATE_CONTIG, and POSIX_TYPED_MEM_MAP_ALLOCATABLE flags are added.

• The posix_tmi_length structure is added.

• The posix_mem_offset(), posix_typed_mem_get_info(), and posix_typed_mem_open() functions are added.

The restrict keyword is added to the prototype for posix_mem_offset().

IEEE PASC Interpretation 1003.1 #102 is applied, adding the prototype for posix_madvise().

IEEE Std 1003.1-2001/Cor 1-2002, item XBD/TC1/D6/16 is applied, correcting margin code and shading errors for the mlock() and munlock() functions.

IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/34 is applied, changing the margin code for the mmap() function from MF|SHM to MC3 (notation for MF|SHM|TYM).

IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/36 is applied, changing the margin code for the munmap() function from MF|SHM to MC3 (notation for MF|SHM|TYM).

Issue 7

SD5-XBD-ERN-5 is applied, rewriting the DESCRIPTION.

Functionality relating to the Memory Protection and Memory Mapped Files options is moved to the Base.

This reference page is clarified with respect to macros and symbolic constants.

Issue 8

Austin Group Defect 593 is applied, adding O_RDONLY, O_RDWR, O_WRONLY, O_CLOEXEC, O_CLOFORK, O_CREAT, O_EXCL, and O_TRUNC, and allowing <sys/mman.h> to make visible all symbols from <fcntl.h>.

Austin Group Defect 850 is applied, adding MAP_ANON and MAP_ANONYMOUS.