Add missing bad-PGconn guards in libpq entry points.

tglsfdc · tglsfdc · commit 2a280832e1d0 · 2022-08-15T15:40:07.000-04:00
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
@@ -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);
 }
 

Original file line number	Diff line number	Diff line change
`@@ -3221,6 +3221,8 @@ PQsetnonblocking(PGconn *conn, int arg)`
`3221`	`3221`	`int`
`3222`	`3222`	`PQisnonblocking(const PGconn *conn)`
`3223`	`3223`	`{`
	`3224`	`+ if (!conn \|\| conn->status == CONNECTION_BAD)`
	`3225`	`+ return false;`
`3224`	`3226`	`return pqIsnonblocking(conn);`
`3225`	`3227`	`}`
`3226`	`3228`
`@@ -3240,6 +3242,8 @@ PQisthreadsafe(void)`
`3240`	`3242`	`int`
`3241`	`3243`	`PQflush(PGconn *conn)`
`3242`	`3244`	`{`
	`3245`	`+ if (!conn \|\| conn->status == CONNECTION_BAD)`
	`3246`	`+ return -1;`
`3243`	`3247`	`return pqFlush(conn);`
`3244`	`3248`	`}`
`3245`	`3249`