deps: cherry-pick eb306f463e from nghttp2 upstream

Original commit message:

  lib: add nghttp2_rcbuf_is_static()

  Add a `nghttp2_rcbuf_is_static()` method to tell whether a rcbuf
  is statically allocated.

  This can be useful for language bindings that wish to avoid
  creating duplicate strings for these buffers; concretely, I am
  planning to use this in the Node HTTP/2 module that is being
  introduced.

Ref: https://github.com/nghttp2/nghttp2/commit/eb306f463efea645de611de2bff0a8f823deb048
PR-URL: https://github.com/nodejs/node/pull/14808
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>

2 files changed, 13 insertions, 0 deletions

diff --git a/deps/nghttp2/lib/includes/nghttp2/nghttp2.h b/deps/nghttp2/lib/includes/nghttp2/nghttp2.h
index 159010040c..848ef066be 100644
--- a/deps/nghttp2/lib/includes/nghttp2/nghttp2.h
+++ b/deps/nghttp2/lib/includes/nghttp2/nghttp2.h
@@ -470,6 +470,15 @@ NGHTTP2_EXTERN void nghttp2_rcbuf_decref(nghttp2_rcbuf *rcbuf);
 NGHTTP2_EXTERN nghttp2_vec nghttp2_rcbuf_get_buf(nghttp2_rcbuf *rcbuf);
 
 /**
+ * @function
+ *
+ * Returns 1 if the underlying buffer is statically allocated,
+ * and 0 otherwise. This can be useful for language bindings that wish to avoid
+ * creating duplicate strings for these buffers.
+ */
+NGHTTP2_EXTERN int nghttp2_rcbuf_is_static(const nghttp2_rcbuf *rcbuf);
+
+/**
  * @enum
  *
  * The flags for header field name/value pair.
diff --git a/deps/nghttp2/lib/nghttp2_rcbuf.c b/deps/nghttp2/lib/nghttp2_rcbuf.c
index 24f561af97..7e7814d2d3 100644
--- a/deps/nghttp2/lib/nghttp2_rcbuf.c
+++ b/deps/nghttp2/lib/nghttp2_rcbuf.c
@@ -96,3 +96,7 @@ nghttp2_vec nghttp2_rcbuf_get_buf(nghttp2_rcbuf *rcbuf) {
   nghttp2_vec res = {rcbuf->base, rcbuf->len};
   return res;
 }
+
+int nghttp2_rcbuf_is_static(const nghttp2_rcbuf *rcbuf) {
+  return rcbuf->ref == -1;
+}