In psql, avoid leaking a PGresult after a query is cancelled.

tglsfdc · tglsfdc · commit f463de59d90c · 2024-04-08T17:00:07.000-04:00
After a query cancel, the tail end of ExecQueryAndProcessResults took care to clear any not-yet-read PGresults; but it forgot about the one it has already read. There would only be such a result when handling a multi-command string made with "\;", so that you'd have to cancel an earlier command in such a string to reach the bug at all. Even then, there would only be leakage of a single PGresult per cancel, so it's not surprising nobody noticed this. But a leak is a leak. Noted while re-reviewing 90f5178, but this is independent of that: it dates to 7844c99. Back-patch to v15 where that came in.
diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
@@ -1812,6 +1812,8 @@ ExecQueryAndProcessResults(const char *query,
 
 		if (cancel_pressed)
 		{
+			/* drop this next result, as well as any others not yet read */
+			ClearOrSaveResult(result);
 			ClearOrSaveAllResults();
 			break;
 		}

Original file line number	Diff line number	Diff line change
`@@ -1812,6 +1812,8 @@ ExecQueryAndProcessResults(const char *query,`
`1812`	`1812`
`1813`	`1813`	`if (cancel_pressed)`
`1814`	`1814`	`{`
	`1815`	`+ /* drop this next result, as well as any others not yet read */`
	`1816`	`+ ClearOrSaveResult(result);`
`1815`	`1817`	`ClearOrSaveAllResults();`
`1816`	`1818`	`break;`
`1817`	`1819`	`}`