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posix_typed_mem_get_info()

Query typed memory object to obtain the memory amount available

Synopsis:

#include <sys/mman.h>

int posix_typed_mem_get_info(int fildes,
                             struct posix_typed_mem_info *info);

Arguments:

fildes

Represent a typed memory object.

info

Pointer to posix_typed_mem_info structure that contain posix_tmi_length field.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The posix_typed_mem_get_info() function queries the typed memory object for obtaining the amount of memory currently available.

The posix_typed_mem_get_info() function allows an application to immediately determine available memory. This is particularly important for typed memory objects that may in some cases be scarce resources. The posix_typed_mem_get_info() function shall return, in the posix_tmi_length field of the posix_typed_mem_info structure pointed to by info, the maximum length that may be successfully allocated by the typed memory object designated by fildes. Note that when a typed memory pool is a shared resource, some form of mutual-exclusion or synchronization may be required while typed memory is being queried and allocated to prevent race conditions.

The posix_typed_mem_get_info() function returns the maximum length which may be successfully allocated by the typed memory object designated by fildes.

The maximum length is dynamic; it's available in the posix_tmi_length field, pointed to by info, of the posix_typed_mem_info structure. The maximum length is valid only while the current mapping of the corresponding typed memory pool remains unchanged.

This maximum length takes into account the flag POSIX_TYPED_MEM_ALLOCATE or POSIX_TYPED_MEM_ALLOCATE_CONTIG specified when the typed memory object represented by fildes is opened.

If fildes represents a typed memory object opened with neither the POSIX_TYPED_MEM_ALLOCATE flag nor the POSIX_TYPED_MEM_ALLOCATE_CONTIG flag specified, the returned value of info->posix_tmi_length is unspecified.

This function was added in the QNX Neutrino Core OS 6.3.2.

Returns:

0

Success.

Errors as mentioned below

An error has occurred.

Errors:

EBADF

The fildes argument isn't a valid open file descriptor.

ENODEV

The fildes isn't connected to a memory object supported by this function.

Classification:

posix_typed_mem_get_info() is POSIX 1003.1-2001

See also:

posix_mem_offset(), posix_typed_mem_open()