[Libguestfs] [PATCH 6/9] Rust bindings: Add generator of function signatures

[Richard W.M. Jones]

On Thu, Jun 27, 2019 at 05:06:07PM +0900, Hiroyuki Katsura wrote:
> From: Hiroyuki_Katsura <hiroyuki.katsura.0513 at gmail.com>
> 
> ---
>  generator/rust.ml | 137 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 137 insertions(+)
> 
> diff --git a/generator/rust.ml b/generator/rust.ml
> index a229d5eac..aa8b249ff 100644
> --- a/generator/rust.ml
> +++ b/generator/rust.ml
> @@ -59,8 +59,10 @@ let generate_rust () =
>    generate_header CStyle LGPLv2plus;
>  
>    pr "
> +use std::collections;
>  use std::ffi;
>  use std::slice;
> +use std::ptr;
>  use std::os::raw::c_char;
>  
>  
> @@ -130,6 +132,18 @@ impl CreateFlags {
>      }
>  }
>  
> +fn arg_string_list (v: &Vec<String>) -> Vec<*const i8> {
> +    let length = v.len();
> +    let mut w = Vec::new();
> +    for x in v.iter() {
> +        let y: &str = x;
> +        let s = ffi::CString::new(y).unwrap();
> +        w.push(s.as_ptr());
> +    }
> +    w.push(ptr::null());
> +    w
> +}
> +
>  impl Handle {
>      pub fn create() -> Result<Handle, &'static str> {
>          let g = unsafe { guestfs_create() };
> @@ -151,6 +165,10 @@ impl Handle {
>      }
>  }\
>  
> +pub struct Error {
> +    // TODO
> +}
> +
>  pub struct UUID {
>      uuid: [u8; 32]
>  }
> @@ -226,6 +244,8 @@ impl UUID {
>        pr "    }\n";
>        pr "}\n"
>    ) external_structs;
> +
> +  (* generate structs for optional arguments *)
>    List.iter (
>      fun ({ name = name; shortdesc = shortdesc;
>            style = (ret, args, optargs) }) ->
> @@ -275,3 +295,120 @@ impl UUID {
>          pr "}\n\n";
>        );
>    ) (actions |> external_functions |> sort);
> +
> +  pr "impl Handle {\n";
> +  List.iter (
> +    fun ({ name = name; shortdesc = shortdesc;
> +          style = (ret, args, optargs) } as f) ->
> +      let cname = snake2caml name in
> +      pr "    /// %s \n" shortdesc;
> +      pr "    pub fn %s" name;
> +
> +      (* generate arguments *)
> +      pr "(&self, ";
> +      let comma = ref false in
> +      List.iter (
> +        fun arg ->
> +          if !comma then pr ", ";
> +          comma := true;
> +          match arg with
> +          | Bool n -> pr "%s: bool" n
> +          | Int n -> pr "%s: i32" n
> +          | Int64 n -> pr "%s: i64" n
> +          | String (_, n) -> pr "%s: String" n
> +          | OptString n -> pr "%s: Option<String>" n
> +          | StringList (_, n) -> pr "%s: Vec<String>" n
> +          | BufferIn n -> pr "%s: Vec<u8>" n
> +          | Pointer (_, n) -> pr "%s: usize" n
> +      ) args;
> +      if optargs <> [] then (
> +        if !comma then pr ", ";
> +        comma := true;
> +        pr "optargs: OptArgs%s" cname
> +      );
> +      pr ")";
> +
> +      (* generate return type *)
> +      pr " -> Result<";
> +      (match ret with
> +      | RErr -> pr "()"
> +      | RInt _ -> pr "i32"
> +      | RInt64 _ -> pr "i64"
> +      | RBool _ -> pr "bool"
> +      | RConstString _
> +      | RString _ -> pr "String"
> +      | RConstOptString _ -> pr "Option<String>"
> +      | RStringList _ -> pr "Vec<String>"
> +      | RStruct (_, sn) ->
> +        let sn = camel_name_of_struct sn in
> +        pr "%s" sn
> +      | RStructList (_, sn) ->
> +        let sn = camel_name_of_struct sn in
> +        pr "Vec<%s>" sn
> +      | RHashtable _ -> pr "collections::HashMap<String, String>"
> +      | RBufferOut _ -> pr "Vec<u8>");
> +      pr ", Error> {\n";
> +
> +      let _pr = pr in
> +      let pr fs = indent 2; pr fs in
> +      List.iter (
> +        function
> +        | Bool n ->
> +          pr "let c_%s = if %s { 1 } else { 0 };\n" n n
> +        | String (_, n) ->
> +          (* TODO: handle errors *)
> +          pr "let c_%s = \n" n;
> +          pr "    ffi::CString::new(%s).expect(\"CString::new failed\").as_ptr();\n" n;
> +        | OptString n ->
> +          pr "let c_%s = match %s {" n n;
> +          pr "    Some(s) => \n";
> +          pr "        ffi::CString::new(s)\n";
> +          pr "            .expect(\"CString::new failed\")\n";
> +          pr "            .as_ptr(),\n";
> +          pr "    None => ptr::null(),\n";
> +          pr "};\n";
> +        | StringList (_, n) ->
> +          pr "let c_%s_v = arg_string_list(%s);\n" n n;
> +        | BufferIn n ->
> +          pr "let c_%s = ffi::CString::new(%s)\n" n n;
> +          pr "            .expect(\"CString::new failed\")\n";
> +          pr "            .as_ptr();\n";
> +          pr "let c_%s_len = %s.len();\n" n n;
> +        | Int _ | Int64 _ | Pointer _ -> ()
> +      ) args;
> +
> +      (* TODO: handle optargs *)
> +      if optargs <> [] then (
> +      );
> +
> +      (match ret with
> +       | RBufferOut _ ->
> +         pr "let mut size = 0;\n"
> +       | _ -> ()
> +      );
> +
> +      pr "\n";
> +
> +      pr "let r = unsafe { %s(self.g" f.c_function;
> +      List.iter (
> +        fun arg ->
> +          pr ", ";
> +          match arg with
> +          | Bool n | String (_, n) | OptString n -> pr "c_%s" n
> +          | Int n | Int64 n -> pr "%s" n
> +          | Pointer _ -> pr "ptr::null()" (* XXX: what is pointer? *)

It's used only by one libguestfs function (guestfs_add_domain), and it
requires you to look at the rust libvirt bindings to find out how to
implement it.  It's safe to ignore it for now.

> +          | StringList (_, n) -> pr "&c_%s as *const *const c_char" n
> +          | BufferIn n -> pr "c_%s, c_%s_len" n n
> +      ) args;
> +      (match ret with
> +       | RBufferOut _ -> pr ", &size as *const usize"
> +       | _ -> ()
> +      );
> +      pr ") };\n";
> +
> +      pr "unimplemented!()\n";
> +      let pr = _pr in
> +
> +      pr "    }\n\n"
> +  ) (actions |> external_functions |> sort);
> +  pr "}\n"
> -- 
> 2.20.1 (Apple Git-117)

This patch looks OK.

Rich.

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