Add missing bad-PGconn guards in libpq entry points.

tglsfdc · tglsfdc · commit c19024d74e98 · 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
@@ -3268,6 +3268,8 @@ PQsetnonblocking(PGconn *conn, int arg)
 int
 PQisnonblocking(const PGconn *conn)
 {
+	if (!conn || conn->status == CONNECTION_BAD)
+		return false;
 	return pqIsnonblocking(conn);
 }
 
@@ -3287,6 +3289,8 @@ 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
`@@ -3268,6 +3268,8 @@ PQsetnonblocking(PGconn *conn, int arg)`
`3268`	`3268`	`int`
`3269`	`3269`	`PQisnonblocking(const PGconn *conn)`
`3270`	`3270`	`{`
	`3271`	`+ if (!conn \|\| conn->status == CONNECTION_BAD)`
	`3272`	`+ return false;`
`3271`	`3273`	`return pqIsnonblocking(conn);`
`3272`	`3274`	`}`
`3273`	`3275`
`@@ -3287,6 +3289,8 @@ PQisthreadsafe(void)`
`3287`	`3289`	`int`
`3288`	`3290`	`PQflush(PGconn *conn)`
`3289`	`3291`	`{`
	`3292`	`+ if (!conn \|\| conn->status == CONNECTION_BAD)`
	`3293`	`+ return -1;`
`3290`	`3294`	`return pqFlush(conn);`
`3291`	`3295`	`}`
`3292`	`3296`