posix_typed_mem_get_info()

Get information about a typed memory object

Synopsis:

#include <sys/mman.h>

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

Arguments:

fildes

The file descriptor for the typed memory object that you want to query, returned by a call to posix_typed_mem_open().

info

A pointer to a posix_typed_mem_info structure where the function can store the information.

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 to obtain the amount of memory currently available. This is particularly important for typed memory objects that may in some cases be scarce resources.

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

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The posix_typed_mem_get_info() function stores, 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.

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If the typed memory pool is a shared resource, some form of mutual-exclusion or synchronization may be required while querying and allocating it, to prevent race conditions.

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The maximum length is dynamic; it's valid only while the current mapping of the corresponding typed memory pool remains unchanged. It takes into account the POSIX_TYPED_MEM_ALLOCATE or POSIX_TYPED_MEM_ALLOCATE_CONTIG flag specified when the typed memory object was opened.

As a Neutrino extension, if fildes represents a typed memory object opened with neither POSIX_TYPED_MEM_ALLOCATE nor POSIX_TYPED_MEM_ALLOCATE_CONTIG, the function sets info->posix_tmi_length to 0.

Returns:

0

Success.

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:

See also:

posix_mem_offset(), posix_typed_mem_open()

"Typed memory" in the Interprocess Communication (IPC) chapter of the System Architecture guide