Fix recently-introduced breakage in psql's \connect command.

tglsfdc · tglsfdc · commit 7e5e1bba034e · 2020-11-29T15:22:04.000-05:00
Through my misreading of what the existing code actually did, commits 85c5428 et al. broke psql's behavior for the case where "\c connstring" provides a password in the connstring. We should use that password in such a case, but as of 85c5428 we ignored it (and instead, prompted for a password). Commit 94929f1 fixed that in HEAD, but since I thought it was cleaning up a longstanding misbehavior and not one I'd just created, I didn't back-patch it. Hence, back-patch the portions of 94929f1 having to do with password management. In addition to fixing the introduced bug, this means that "\c -reuse-previous=on connstring" will allow re-use of an existing connection's password if the connstring doesn't change user/host/port. That didn't happen before, but it seems like a bug fix, and anyway I'm loath to have significant differences in this code across versions. Also fix an error with the same root cause about whether or not to override a connstring's setting of client_encoding. As of 85c5428 we always did so; restore the previous behavior of overriding only when stdin/stdout are a terminal and there's no environment setting of PGCLIENTENCODING. (I find that definition a bit surprising, but right now doesn't seem like the time to revisit it.) Per bug #16746 from Krzysztof Gradek. As with the previous patch, back-patch to all supported branches. Discussion: https://postgr.es/m/16746-44b30e2edf4335d4@postgresql.org
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
@@ -3030,6 +3030,7 @@ do_connect(enum trivalue reuse_previous_specification,
 	int			nconnopts = 0;
 	bool		same_host = false;
 	char	   *password = NULL;
+	char	   *client_encoding;
 	bool		success = true;
 	bool		keep_password = true;
 	bool		has_connection_string;
@@ -3239,6 +3240,16 @@ do_connect(enum trivalue reuse_previous_specification,
 		password = prompt_for_password(has_connection_string ? NULL : user);
 	}
 
+	/*
+	 * Consider whether to force client_encoding to "auto" (overriding
+	 * anything in the connection string).  We do so if we have a terminal
+	 * connection and there is no PGCLIENTENCODING environment setting.
+	 */
+	if (pset.notty || getenv("PGCLIENTENCODING"))
+		client_encoding = NULL;
+	else
+		client_encoding = "auto";
+
 	/* Loop till we have a connection or fail, which we might've already */
 	while (success)
 	{
@@ -3279,8 +3290,9 @@ do_connect(enum trivalue reuse_previous_specification,
 				values[paramnum++] = password;
 			else if (strcmp(ci->keyword, "fallback_application_name") == 0)
 				values[paramnum++] = pset.progname;
-			else if (strcmp(ci->keyword, "client_encoding") == 0)
-				values[paramnum++] = (pset.notty || getenv("PGCLIENTENCODING")) ? NULL : "auto";
+			else if (client_encoding &&
+					 strcmp(ci->keyword, "client_encoding") == 0)
+				values[paramnum++] = client_encoding;
 			else if (ci->val)
 				values[paramnum++] = ci->val;
 			/* else, don't bother making libpq parse this keyword */
