# vkGetFenceFdKHR(3) Manual Page

## Name

vkGetFenceFdKHR - Get a POSIX file descriptor handle for a fence

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## C Specification

To export a POSIX file descriptor representing the payload of a fence, call:

    // Provided by VK_KHR_external_fence_fd
    VkResult vkGetFenceFdKHR(
        VkDevice                                    device,
        const VkFenceGetFdInfoKHR*                  pGetFdInfo,
        int*                                        pFd);

## Parameters

- `device` is the logical device that created the fence being exported.

- `pGetFdInfo` is a pointer to a VkFenceGetFdInfoKHR structure containing parameters of the export operation.

- `pFd` will return the file descriptor representing the fence payload.

## Description

Each call to `vkGetFenceFdKHR` must create a new file descriptor and transfer ownership of it to the application. To avoid leaking resources, the application must release ownership of the file descriptor when it is no longer needed.

Note | Ownership can be released in many ways. For example, the application can call `close`() on the file descriptor, or transfer ownership back to Vulkan by using the file descriptor to import a fence payload.

If `pGetFdInfo->handleType` is `VK_EXTERNAL_FENCE_HANDLE_TYPE_SYNC_FD_BIT` and the fence is signaled at the time `vkGetFenceFdKHR` is called, `pFd` may return the value `-1` instead of a valid file descriptor.

Where supported by the operating system, the implementation must set the file descriptor to be closed automatically when an `execve` system call is made.

Exporting a file descriptor from a fence may have side effects depending on the transference of the specified handle type, as described in Importing Fence State.

Valid Usage (Implicit)

- VUID-vkGetFenceFdKHR-device-parameter
  `device` must be a valid VkDevice handle

- VUID-vkGetFenceFdKHR-pGetFdInfo-parameter
  `pGetFdInfo` must be a valid pointer to a valid VkFenceGetFdInfoKHR structure

- VUID-vkGetFenceFdKHR-pFd-parameter
  `pFd` must be a valid pointer to an `int` value

Return Codes

On success, this command returns

  - `VK_SUCCESS`

On failure, this command returns

  - `VK_ERROR_TOO_MANY_OBJECTS`

  - `VK_ERROR_OUT_OF_HOST_MEMORY`

## See Also

VK_KHR_external_fence_fd, VkDevice, VkFenceGetFdInfoKHR

## Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

## Copyright

Copyright 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0