Rust/rusty: Add a couple of convenience functions

This adds the following convenience functions for adding HTTP response
headers, Content-Type & Content-length

  uwr_http_add_header_content_type(ctx: *mut luw_ctx_t, ctype: &str);
  uwr_http_add_header_content_len(ctx: *mut luw_ctx_t);

These are perhaps the two most common headers so it makes sense to
reduce the effort to adding them.

E.g before

  uwr_http_add_header(&ctx, "Content-Type", "text/plain");
  uwr_http_add_header(
      ctx,
      "Content-Length",
      &format!("{}", uwr_get_response_data_size(ctx)),
  );

after

  uwr_http_add_header_content_type(ctx, "text/plain");
  uwr_http_add_header_content_len(ctx);

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Author: ac000

API-Rust.md

@@ -78,6 +78,8 @@ and there isn't a real need to create wrappers specifically for them.
   * [uwr_http_send_response](#uwr_http_send_response)
   * [uwr_http_init_headers](#uwr_http_init_headers)
   * [uwr_http_add_header](#uwr_http_add_header)
+  * [uwr_http_add_header_content_type](#uwr_http_add_header_content_type)
+  * [uwr_http_add_header_content_len](#uwr_http_add_header_content_len)
   * [uwr_http_send_headers](#uwr_http_send_headers)
   * [uwr_http_response_end](#uwr_http_response_end)
   * [uwr_mem_get_init_size](#uwr_mem_get_init_size)
@@ -859,6 +861,37 @@ uwr_http_add_header(
 );
 ```
 
+### uwr_http_add_header_content_type
+
+```Rust
+pub fn uwr_http_add_header_content_type(ctx: *mut luw_ctx_t, ctype: &str);
+```
+
+A convenience function for setting the 'Content-Type' response header.
+E.g the above example that adds the _Content-Type_ header could be
+written as
+
+```Rust
+uwr_http_add_header_content_type(ctx, "text/plain");
+```
+
+### uwr_http_add_header_content_len
+
+```Rust
+pub fn uwr_http_add_header_content_len(ctx: *mut luw_ctx_t);
+```
+
+A convenience function for setting the 'Content-Length' response header.
+E.g the above example that adds the _Content-Length_ header could be
+written as
+
+```Rust
+uwr_http_add_header_content_len(ctx);
+```
+
+This function uses [uwr_get_response_data_size](#uwr_get_response_data_size)
+internally to get the size of the response data.
+
 ### uwr_http_send_headers
 
 ```Rust

src/rust/unit-wasm-sys/rusty.rs

@@ -197,6 +197,18 @@ pub fn uwr_http_add_header(ctx: *mut luw_ctx_t, name: &str, value: &str) {
     }
 }
 
+pub fn uwr_http_add_header_content_type(ctx: *mut luw_ctx_t, ctype: &str) {
+    uwr_http_add_header(ctx, "Content-Type", ctype);
+}
+
+pub fn uwr_http_add_header_content_len(ctx: *mut luw_ctx_t) {
+    uwr_http_add_header(
+        ctx,
+        "Content-Length",
+        &format!("{}", uwr_get_response_data_size(ctx)),
+    );
+}
+
 pub fn uwr_http_send_headers(ctx: *const luw_ctx_t) {
     unsafe {
         luw_http_send_headers(ctx);