libunit-wasm: Add a luw_get_http_total_content_sent() function

This function returns the total amount of content that the Wasm module
has received so far.

This will be used in the rusty API's uwr_get_http_content_str() function
which returns the body content as a string. Due to the body content not
being null-terminated we need to know how much data to use for the
string, for which we are currently using uwr_get_http_content_len(),
which could in some cases return too much if a request is being split
over multiple calls the module.

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

Author: ac000

API-C.md

@@ -38,6 +38,7 @@ C Library for creating WebAssembly modules for use with NGINX Unit.
   * [luw_get_http_content](#luw_get_http_content)
   * [luw_get_http_content_len](#luw_get_http_content_len)
   * [luw_get_http_content_sent](#luw_get_http_content_sent)
+  * [luw_get_http_total_content_sent](#luw_get_http_total_content_sent)
   * [luw_http_is_tls](#luw_http_is_tls)
   * [luw_http_hdr_iter](#luw_http_hdr_iter)
   * [luw_http_hdr_get_value](#luw_http_hdr_get_value)
@@ -657,6 +658,16 @@ This function returns the length of the content that was sent to the
 WebAssembly module in _this_ request. Remember, a single HTTP request may be
 split over several calls to luw_request_handler().
 
+### luw_get_http_total_content_sent
+
+```C
+size_t luw_get_http_total_content_sent(const luw_ctx_t *ctx);
+```
+
+This function returns the total length of the content that was sent to the
+WebAssembly module so far. Remember, a single HTTP request may be split over
+several calls to luw_request_handler().
+
 ### luw_http_is_tls
 
 ```C

src/c/include/unit/unit-wasm.h

@@ -176,6 +176,7 @@ extern const char *luw_get_http_server_name(const luw_ctx_t *ctx);
 extern const u8 *luw_get_http_content(const luw_ctx_t *ctx);
 extern size_t luw_get_http_content_len(const luw_ctx_t *ctx);
 extern size_t luw_get_http_content_sent(const luw_ctx_t *ctx);
+extern size_t luw_get_http_total_content_sent(const luw_ctx_t *ctx);
 extern bool luw_http_is_tls(const luw_ctx_t *ctx);
 extern void luw_http_hdr_iter(luw_ctx_t *ctx,
 			      bool (*luw_http_hdr_iter_func)(luw_ctx_t *ctx,

src/c/libunit-wasm.c

@@ -207,6 +207,12 @@ size_t luw_get_http_content_sent(const luw_ctx_t *ctx)
 	return ctx->req->content_sent;
 }
 
+/* Returns the size of the overall content sent so far */
+size_t luw_get_http_total_content_sent(const luw_ctx_t *ctx)
+{
+	return ctx->req->total_content_sent;
+}
+
 bool luw_http_is_tls(const luw_ctx_t *ctx)
 {
 	return ctx->req->tls;