[Libguestfs] [libnbd PATCH v4 06/25] generator: Support Extent64 arg in Go code

[Richard W.M. Jones]

On Wed, Aug 02, 2023 at 08:50:26PM -0500, Eric Blake wrote:
> See the earlier commit "Add Extent64 arg type" for rationale in
> supporting a new generator arg type.  This patch adds the Go bindings
> for use of Extent64, which required adding a counterpart Go type and
> introducing a helper function for copying from the C array to an
> actual Go object, very similar to the existing copy_uint32_array
> helper for 32-bit extents.
> 
> Signed-off-by: Eric Blake <eblake at redhat.com>
> ---
> 
> v4: split out of larger patch [Laszlo], avoid awkward slice since we
> can't use copy() anyway [Laszlo]
> ---
>  generator/GoLang.ml | 23 +++++++++++++++++++++++
>  golang/handle.go    |  6 ++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/generator/GoLang.ml b/generator/GoLang.ml
> index cc7d78b6..7a516366 100644
> --- a/generator/GoLang.ml
> +++ b/generator/GoLang.ml
> @@ -528,6 +528,21 @@ let
>      }
>      return ret
>  }
> +
> +func copy_extent_array(entries *C.nbd_extent, count C.size_t) []LibnbdExtent {
> +    if (uint64(count) > 64*1024*1024) {
> +        panic(\"violation of state machine guarantee\")
> +    }

Same comment about the internal error as for previous commit.

> +    ret := make([]LibnbdExtent, count)
> +    addr := uintptr(unsafe.Pointer(entries))
> +    for i := 0; i < int(count); i++ {
> +        ptr := (*C.nbd_extent)(unsafe.Pointer(addr))
> +        ret[i].Length = uint64((*ptr).length)
> +        ret[i].Flags = uint64((*ptr).flags)
> +        addr += unsafe.Sizeof(*ptr)
> +    }
> +    return ret
> +}
>  ";
> 
>    List.iter (
> @@ -542,6 +557,8 @@ let
>            match cbarg with
>            | CBArrayAndLen (UInt32 n, _) ->
>               pr "%s []uint32" n;
> +          | CBArrayAndLen (Extent64 n, _) ->
> +             pr "%s []LibnbdExtent" n;
>            | CBBytesIn (n, len) ->
>               pr "%s []byte" n;
>            | CBInt n ->
> @@ -568,6 +585,8 @@ let
>            match cbarg with
>            | CBArrayAndLen (UInt32 n, count) ->
>               pr "%s *C.uint32_t, %s C.size_t" n count
> +          | CBArrayAndLen (Extent64 n, count) ->
> +             pr "%s *C.nbd_extent, %s C.size_t" n count
>            | CBBytesIn (n, len) ->
>               pr "%s unsafe.Pointer, %s C.size_t" n len
>            | CBInt n ->
> @@ -610,6 +629,8 @@ let
>            match cbarg with
>            | CBArrayAndLen (UInt32 n, count) ->
>               pr "copy_uint32_array(%s, %s)" n count
> +          | CBArrayAndLen (Extent64 n, count) ->
> +             pr "copy_extent_array(%s, %s)" n count
>            | CBBytesIn (n, len) ->
>               pr "C.GoBytes(%s, C.int(%s))" n len
>            | CBInt n ->
> @@ -760,6 +781,8 @@ let
>             match cbarg with
>             | CBArrayAndLen (UInt32 n, count) ->
>                pr "uint32_t *%s, size_t %s" n count
> +           | CBArrayAndLen (Extent64 n, count) ->
> +              pr "nbd_extent *%s, size_t %s" n count
>             | CBBytesIn (n, len) ->
>                pr "void *%s, size_t %s" n len
>             | CBInt n ->
> diff --git a/golang/handle.go b/golang/handle.go
> index 5fe4ed4f..2b0ee6d5 100644
> --- a/golang/handle.go
> +++ b/golang/handle.go
> @@ -58,6 +58,12 @@ func (h *Libnbd) String() string {
>  	return "&Libnbd{}"
>  }
> 
> +/* Used for block status callback. */
> +type LibnbdExtent struct {
> +	Length uint64 // length of the extent
> +	Flags  uint64 // flags describing properties of the extent
> +}
> +
>  /* All functions (except Close) return ([result,] LibnbdError). */
>  type LibnbdError struct {
>  	Op     string        // operation which failed
> -- 

Reviewed-by: Richard W.M. Jones <rjones at redhat.com>

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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