Function v4l2_ioctl

rustcv-camera/src/backend/linux/sys.rs:75–82

Call a V4L2 ioctl and convert errors to `io::Result`. 调用 V4L2 ioctl 并将错误转换为 `io::Result`。 # Safety The caller must ensure `arg` points to a valid, correctly-typed struct for the given `request` code. 调用者必须确保 `arg` 指向与 `request` 对应的有效且类型正确的结构体。

(fd: RawFd, request: u32, arg: *mut libc::c_void)

/// for the given `request` code.
/// 调用者必须确保 `arg` 指向与 `request` 对应的有效且类型正确的结构体。
unsafe fn v4l2_ioctl(fd: RawFd, request: u32, arg: *mut libc::c_void) -> io::Result<()> {
    let ret = libc::ioctl(fd, request as libc::c_ulong, arg);
    if ret == -1 {
        Err(io::Error::last_os_error())
    } else {
        Ok(())
    }
}

// ─── Device capability ──────────────────────────────────────────────────────