reapi: add grow function to C API

resource/reapi/bindings/c/reapi_cli.cpp

@@ -186,6 +186,16 @@ extern "C" int reapi_cli_update_allocate (reapi_cli_ctx_t *ctx,
     return rc;
 }
 
+extern "C" int reapi_cli_grow (reapi_cli_ctx_t *ctx,
+                               const char *R_subgraph)
+{
+    if (!ctx || !ctx->rqt || !R_subgraph) {
+        errno = EINVAL;
+        return -1;
+    }
+    return reapi_cli_t::grow (ctx->rqt, R_subgraph)
+}
+
 extern "C" int reapi_cli_cancel (reapi_cli_ctx_t *ctx, const uint64_t jobid, bool noent_ok)
 {
     if (!ctx || !ctx->rqt) {
@@ -259,11 +269,13 @@ extern "C" const char *reapi_cli_get_err_msg (reapi_cli_ctx_t *ctx)
 {
     std::string err_buf = "";
 
-    if (ctx->rqt)
-        err_buf = ctx->rqt->get_resource_query_err_msg () + reapi_cli_t::get_err_message ()
-                  + ctx->err_msg;
-    else
-        err_buf = reapi_cli_t::get_err_message () + ctx->err_msg;
+    if (!ctx || !ctx->rqt) {
+        errno = EINVAL;
+        return "ERROR: REAPI context and/or rqt null \n";
+    }
+
+    err_buf = ctx->rqt->get_resource_query_err_msg () + reapi_cli_t::get_err_message ()
+                + ctx->err_msg;
 
     return strdup (err_buf.c_str ());
 }

resource/reapi/bindings/c/reapi_cli.h

@@ -140,6 +140,18 @@ int reapi_cli_update_allocate (reapi_cli_ctx_t *ctx,
                                double *ov,
                                const char **R_out);
 
+/*! Update the resource state with R.
+    *
+    *  \param h         Opaque handle. How it is used is an implementation
+    *                   detail. However, when it is used within a Flux's
+    *                   service module, it is expected to be a pointer
+    *                   to a flux_t object.
+    *  \param R_subgraph R string
+    *  \return          0 on success; -1 on error.
+    */
+int reapi_cli_grow (reapi_cli_ctx_t *ctx,
+                    const char *R_subgraph);
+
 /*! Cancel the allocation or reservation corresponding to jobid.
  *
  *  \param ctx       reapi_cli_ctx_t context object