oauth: Report cleanup errors as warnings on stderr

Using conn->errorMessage for these "shouldn't-happen" cases will only
work if the connection itself fails. Our SSL and password callbacks
print WARNINGs when they find themselves in similar situations, so
follow their lead.

Reviewed-by: Zsolt Parragi <zsolt.parragi@percona.com>
Discussion: https://postgr.es/m/CAOYmi%2BmEU_q9sr1PMmE-4rLwFN%3DOjyndDwFZvpsMU3RNJLrM9g%40mail.gmail.com

diff --git a/src/interfaces/libpq-oauth/oauth-curl.c b/src/interfaces/libpq-oauth/oauth-curl.c
index 691e7ec1d9faa0909264d2768b98e9a72f2b70e5..2c147f98d0d2b283c50b74d8da749eadc3f303a0 100644 (file)
--- a/src/interfaces/libpq-oauth/oauth-curl.c
+++ b/src/interfaces/libpq-oauth/oauth-curl.c
@@ -286,17 +286,15 @@ struct async_ctx
  * Tears down the Curl handles and frees the async_ctx.
  */
 static void
-free_async_ctx(PGconn *conn, struct async_ctx *actx)
+free_async_ctx(struct async_ctx *actx)
 {
        /*
         * In general, none of the error cases below should ever happen if we have
         * no bugs above. But if we do hit them, surfacing those errors somehow
         * might be the only way to have a chance to debug them.
         *
-        * TODO: At some point it'd be nice to have a standard way to warn about
-        * teardown failures. Appending to the connection's error message only
-        * helps if the bug caused a connection failure; otherwise it'll be
-        * buried...
+        * Print them as warnings to stderr, following the example of similar
+        * situations in fe-secure-openssl.c and fe-connect.c.
         */
 
        if (actx->curlm && actx->curl)
@@ -304,9 +302,9 @@ free_async_ctx(PGconn *conn, struct async_ctx *actx)
                CURLMcode       err = curl_multi_remove_handle(actx->curlm, actx->curl);
 
                if (err)
-                       libpq_append_conn_error(conn,
-                                                                       "libcurl easy handle removal failed: %s",
-                                                                       curl_multi_strerror(err));
+                       fprintf(stderr,
+                                       libpq_gettext("WARNING: libcurl easy handle removal failed: %s\n"),
+                                       curl_multi_strerror(err));
        }
 
        if (actx->curl)
@@ -324,9 +322,9 @@ free_async_ctx(PGconn *conn, struct async_ctx *actx)
                CURLMcode       err = curl_multi_cleanup(actx->curlm);
 
                if (err)
-                       libpq_append_conn_error(conn,
-                                                                       "libcurl multi handle cleanup failed: %s",
-                                                                       curl_multi_strerror(err));
+                       fprintf(stderr,
+                                       libpq_gettext("WARNING: libcurl multi handle cleanup failed: %s\n"),
+                                       curl_multi_strerror(err));
        }
 
        free_provider(&actx->provider);
@@ -359,7 +357,7 @@ pg_fe_cleanup_oauth_flow(PGconn *conn)
 
        if (state->async_ctx)
        {
-               free_async_ctx(conn, state->async_ctx);
+               free_async_ctx(state->async_ctx);
                state->async_ctx = NULL;
        }