Add missing bad-PGconn guards in libpq entry points.

There's a convention that externally-visible libpq functions should
check for a NULL PGconn pointer, and fail gracefully instead of
crashing.  PQflush() and PQisnonblocking() didn't get that memo
though.  Also add a similar check to PQdefaultSSLKeyPassHook_OpenSSL;
while it's not clear that ordinary usage could reach that with a
null conn pointer, it's cheap enough to check, so let's be consistent.

Daniele Varrazzo and Tom Lane

Discussion: https://postgr.es/m/CA+mi_8Zm_mVVyW1iNFgyMd9Oh0Nv8-F+7Y3-BqwMgTMHuo_h2Q@mail.gmail.com

diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index 93c334b380e0444ef003606b4a9cd2a63af0c7ab..2876b71a3696457e3c617eab560f3c63e6915cde 100644 (file)
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -3221,6 +3221,8 @@ PQsetnonblocking(PGconn *conn, int arg)
 int
 PQisnonblocking(const PGconn *conn)
 {
+   if (!conn || conn->status == CONNECTION_BAD)
+       return false;
    return pqIsnonblocking(conn);
 }
 
@@ -3240,6 +3242,8 @@ PQisthreadsafe(void)
 int
 PQflush(PGconn *conn)
 {
+   if (!conn || conn->status == CONNECTION_BAD)
+       return -1;
    return pqFlush(conn);
 }