Remember to reset yy_start state when firing up repl_scanner.l.

tglsfdc · tglsfdc · commit 3c06ec6d1412 · 2022-01-24T12:09:46.000-05:00
Without this, we get odd behavior when the previous cycle of lexing exited in a non-default exclusive state. Every other copy of this code is aware that it has to do BEGIN(INITIAL), but repl_scanner.l did not get that memo. The real-world impact of this is probably limited, since most replication clients would abandon their connection after getting a syntax error. Still, it's a bug. This mistake is old, so back-patch to all supported branches. Discussion: https://postgr.es/m/1874781.1643035952@sss.pgh.pa.us
diff --git a/src/backend/replication/repl_scanner.l b/src/backend/replication/repl_scanner.l
@@ -247,6 +247,9 @@ replication_scanner_init(const char *str)
 	memcpy(scanbuf, str, slen);
 	scanbuf[slen] = scanbuf[slen + 1] = YY_END_OF_BUFFER_CHAR;
 	scanbufhandle = yy_scan_buffer(scanbuf, slen + 2);
+
+	/* Make sure we start in proper state */
+	BEGIN(INITIAL);
 }
 
 void

Original file line number	Diff line number	Diff line change
`@@ -247,6 +247,9 @@ replication_scanner_init(const char *str)`
`247`	`247`	`memcpy(scanbuf, str, slen);`
`248`	`248`	`scanbuf[slen] = scanbuf[slen + 1] = YY_END_OF_BUFFER_CHAR;`
`249`	`249`	`scanbufhandle = yy_scan_buffer(scanbuf, slen + 2);`
	`250`	`+`
	`251`	`+ /* Make sure we start in proper state */`
	`252`	`+ BEGIN(INITIAL);`
`250`	`253`	`}`
`251`	`254`
`252`	`255`	`void`