vacuumdb: don't prompt for passwords over and over

Having the script prompt for passwords over and over was a preexisting
problem when it processed multiple databases or when it processed
multiple analyze stages, but the parallel mode introduced in commit
a179232047 made it worse.

Fix the annoyance by keeping a copy of the password used by the first
connection that requires one.  Since users can (currently) only have a
single password, there's no need for more complex arrangements (such as
remembering one password per database).

Per bug #13741 reported by Eric Brown.  Patch authored and
cross-reviewed by Haribabu Kommi and Michael Paquier, slightly tweaked
by Álvaro Herrera.

Discussion: http://www.postgresql.org/message-id/20151027193919.931.54948@wrigleys.postgresql.org
Backpatch to 9.5, where parallel vacuumdb was introduced.

src/bin/scripts/clusterdb.c

@@ -203,7 +203,7 @@ cluster_one_database(const char *dbname, bool verbose, const char *table,
 		appendPQExpBuffer(&sql, " %s", table);
 	appendPQExpBufferChar(&sql, ';');
 
-	conn = connectDatabase(dbname, host, port, username, prompt_password,
+	conn = connectDatabase(dbname, host, port, username, NULL, prompt_password,
 						   progname, false);
 	if (!executeMaintenanceCommand(conn, sql.data, echo))
 	{

src/bin/scripts/common.c

@@ -52,19 +52,24 @@ handle_help_version_opts(int argc, char *argv[],
 
 
 /*
- * Make a database connection with the given parameters.  An
- * interactive password prompt is automatically issued if required.
+ * Make a database connection with the given parameters.
+ *
+ * A password can be given, but if not (or if user forces us to) we prompt
+ * interactively for one, unless caller prohibited us from doing so.
  */
 PGconn *
 connectDatabase(const char *dbname, const char *pghost, const char *pgport,
-				const char *pguser, enum trivalue prompt_password,
-				const char *progname, bool fail_ok)
+				const char *pguser, const char *pgpassword,
+				enum trivalue prompt_password, const char *progname,
+				bool fail_ok)
 {
 	PGconn	   *conn;
-	char	   *password = NULL;
+	char	   *password;
 	bool		new_pass;
 
-	if (prompt_password == TRI_YES)
+	password = pgpassword ? strdup(pgpassword) : NULL;
+
+	if (prompt_password == TRI_YES && !pgpassword)
 		password = simple_prompt("Password: ", 100, false);
 
 	/*
@@ -95,22 +100,26 @@ connectDatabase(const char *dbname, const char *pghost, const char *pgport,
 		new_pass = false;
 		conn = PQconnectdbParams(keywords, values, true);
 
-		free(keywords);
-		free(values);
-
 		if (!conn)
 		{
-			fprintf(stderr, _("%s: could not connect to database %s\n"),
+			fprintf(stderr, _("%s: could not connect to database %s: out of memory\n"),
 					progname, dbname);
 			exit(1);
 		}
 
+		pg_free(keywords);
+		pg_free(values);
+
+		/*
+		 * No luck?  Trying asking (again) for a password.
+		 */
 		if (PQstatus(conn) == CONNECTION_BAD &&
 			PQconnectionNeedsPassword(conn) &&
-			password == NULL &&
 			prompt_password != TRI_NO)
 		{
 			PQfinish(conn);
+			if (password)
+				free(password);
 			password = simple_prompt("Password: ", 100, false);
 			new_pass = true;
 		}
@@ -148,14 +157,14 @@ connectMaintenanceDatabase(const char *maintenance_db, const char *pghost,
 
 	/* If a maintenance database name was specified, just connect to it. */
 	if (maintenance_db)
-		return connectDatabase(maintenance_db, pghost, pgport, pguser,
+		return connectDatabase(maintenance_db, pghost, pgport, pguser, NULL,
 							   prompt_password, progname, false);
 
 	/* Otherwise, try postgres first and then template1. */
-	conn = connectDatabase("postgres", pghost, pgport, pguser, prompt_password,
-						   progname, true);
+	conn = connectDatabase("postgres", pghost, pgport, pguser, NULL,
+						   prompt_password, progname, true);
 	if (!conn)
-		conn = connectDatabase("template1", pghost, pgport, pguser,
+		conn = connectDatabase("template1", pghost, pgport, pguser, NULL,
 							   prompt_password, progname, false);
 
 	return conn;

src/bin/scripts/common.h

@@ -31,8 +31,8 @@ extern void handle_help_version_opts(int argc, char *argv[],
 
 extern PGconn *connectDatabase(const char *dbname, const char *pghost,
 				const char *pgport, const char *pguser,
-				enum trivalue prompt_password, const char *progname,
-				bool fail_ok);
+				const char *pgpassword, enum trivalue prompt_password,
+				const char *progname, bool fail_ok);
 
 extern PGconn *connectMaintenanceDatabase(const char *maintenance_db,
 				  const char *pghost, const char *pgport, const char *pguser,

src/bin/scripts/createlang.c

@@ -140,8 +140,8 @@ main(int argc, char *argv[])
 		printQueryOpt popt;
 		static const bool translate_columns[] = {false, true};
 
-		conn = connectDatabase(dbname, host, port, username, prompt_password,
-							   progname, false);
+		conn = connectDatabase(dbname, host, port, username, NULL,
+							   prompt_password, progname, false);
 
 		printfPQExpBuffer(&sql, "SELECT lanname as \"%s\", "
 				"(CASE WHEN lanpltrusted THEN '%s' ELSE '%s' END) as \"%s\" "
@@ -180,8 +180,8 @@ main(int argc, char *argv[])
 		if (*p >= 'A' && *p <= 'Z')
 			*p += ('a' - 'A');
 
-	conn = connectDatabase(dbname, host, port, username, prompt_password,
-						   progname, false);
+	conn = connectDatabase(dbname, host, port, username, NULL,
+						   prompt_password, progname, false);
 
 	/*
 	 * Make sure the language isn't already installed

src/bin/scripts/createuser.c

@@ -250,8 +250,8 @@ main(int argc, char *argv[])
 	if (login == 0)
 		login = TRI_YES;
 
-	conn = connectDatabase("postgres", host, port, username, prompt_password,
-						   progname, false);
+	conn = connectDatabase("postgres", host, port, username, NULL,
+						   prompt_password, progname, false);
 
 	initPQExpBuffer(&sql);
 

src/bin/scripts/droplang.c

@@ -139,8 +139,8 @@ main(int argc, char *argv[])
 		printQueryOpt popt;
 		static const bool translate_columns[] = {false, true};
 
-		conn = connectDatabase(dbname, host, port, username, prompt_password,
-							   progname, false);
+		conn = connectDatabase(dbname, host, port, username, NULL,
+							   prompt_password, progname, false);
 
 		printfPQExpBuffer(&sql, "SELECT lanname as \"%s\", "
 				"(CASE WHEN lanpltrusted THEN '%s' ELSE '%s' END) as \"%s\" "
@@ -181,8 +181,8 @@ main(int argc, char *argv[])
 		if (*p >= 'A' && *p <= 'Z')
 			*p += ('a' - 'A');
 
-	conn = connectDatabase(dbname, host, port, username, prompt_password,
-						   progname, false);
+	conn = connectDatabase(dbname, host, port, username, NULL,
+						   prompt_password, progname, false);
 
 	/*
 	 * Force schema search path to be just pg_catalog, so that we don't have

src/bin/scripts/dropuser.c

@@ -128,8 +128,8 @@ main(int argc, char *argv[])
 	appendPQExpBuffer(&sql, "DROP ROLE %s%s;",
 					  (if_exists ? "IF EXISTS " : ""), fmtId(dropuser));
 
-	conn = connectDatabase("postgres", host, port, username, prompt_password,
-						   progname, false);
+	conn = connectDatabase("postgres", host, port, username, NULL,
+						   prompt_password, progname, false);
 
 	if (echo)
 		printf("%s\n", sql.data);

src/bin/scripts/reindexdb.c

@@ -297,8 +297,8 @@ reindex_one_database(const char *name, const char *dbname, const char *type,
 		appendPQExpBuffer(&sql, " DATABASE %s", fmtId(name));
 	appendPQExpBufferChar(&sql, ';');
 
-	conn = connectDatabase(dbname, host, port, username, prompt_password,
-						   progname, false);
+	conn = connectDatabase(dbname, host, port, username, NULL,
+						   prompt_password, progname, false);
 
 	if (!executeMaintenanceCommand(conn, sql.data, echo))
 	{
@@ -372,8 +372,8 @@ reindex_system_catalogs(const char *dbname, const char *host, const char *port,
 
 	appendPQExpBuffer(&sql, " SYSTEM %s;", dbname);
 
-	conn = connectDatabase(dbname, host, port, username, prompt_password,
-						   progname, false);
+	conn = connectDatabase(dbname, host, port, username, NULL,
+						   prompt_password, progname, false);
 	if (!executeMaintenanceCommand(conn, sql.data, echo))
 	{
 		fprintf(stderr, _("%s: reindexing of system catalogs failed: %s"),

src/bin/scripts/vacuumdb.c

@@ -43,7 +43,8 @@ static void vacuum_one_database(const char *dbname, vacuumingOptions *vacopts,
 					const char *host, const char *port,
 					const char *username, enum trivalue prompt_password,
 					int concurrentCons,
-					const char *progname, bool echo, bool quiet);
+					const char *progname, bool echo, bool quiet,
+					char **password);
 
 static void vacuum_all_databases(vacuumingOptions *vacopts,
 					 bool analyze_in_stages,
@@ -275,6 +276,8 @@ main(int argc, char *argv[])
 	}
 	else
 	{
+		char *password = NULL;
+
 		if (dbname == NULL)
 		{
 			if (getenv("PGDATABASE"))
@@ -296,7 +299,8 @@ main(int argc, char *argv[])
 									&tables,
 									host, port, username, prompt_password,
 									concurrentCons,
-									progname, echo, quiet);
+									progname, echo, quiet,
+									&password);
 			}
 		}
 		else
@@ -305,7 +309,10 @@ main(int argc, char *argv[])
 								&tables,
 								host, port, username, prompt_password,
 								concurrentCons,
-								progname, echo, quiet);
+								progname, echo, quiet,
+								&password);
+
+		pg_free(password);
 	}
 
 	exit(0);
@@ -323,15 +330,21 @@ main(int argc, char *argv[])
  * If concurrentCons is > 1, multiple connections are used to vacuum tables
  * in parallel.  In this case and if the table list is empty, we first obtain
  * a list of tables from the database.
+ *
+ * 'password' is both an input and output parameter.  If one is not passed,
+ * then whatever is used in a connection is returned so that caller can
+ * reuse it in future connections.
  */
 static void
 vacuum_one_database(const char *dbname, vacuumingOptions *vacopts,
 					int stage,
 					SimpleStringList *tables,
 					const char *host, const char *port,
-					const char *username, enum trivalue prompt_password,
+					const char *username,
+					enum trivalue prompt_password,
 					int concurrentCons,
-					const char *progname, bool echo, bool quiet)
+					const char *progname, bool echo, bool quiet,
+					char **password)
 {
 	PQExpBufferData sql;
 	PGconn	   *conn;
@@ -365,8 +378,15 @@ vacuum_one_database(const char *dbname, vacuumingOptions *vacopts,
 		fflush(stdout);
 	}
 
-	conn = connectDatabase(dbname, host, port, username, prompt_password,
-						   progname, false);
+	conn = connectDatabase(dbname, host, port, username, *password,
+						   prompt_password, progname, false);
+
+	/*
+	 * If no password was not specified by caller and the connection required
+	 * one, remember it; this suppresses further password prompts.
+	 */
+	if (PQconnectionUsedPassword(conn) && *password == NULL)
+		*password = pg_strdup(PQpass(conn));
 
 	initPQExpBuffer(&sql);
 
@@ -424,10 +444,20 @@ vacuum_one_database(const char *dbname, vacuumingOptions *vacopts,
 	init_slot(slots, conn);
 	if (parallel)
 	{
+		const char *pqpass;
+
+		/*
+		 * If a password was supplied for the initial connection, use it for
+		 * subsequent ones too.  (Note that since we're connecting to the same
+		 * database with the same user, there's no need to update the stored
+		 * password any further.)
+		 */
+		pqpass = PQpass(conn);
+
 		for (i = 1; i < concurrentCons; i++)
 		{
-			conn = connectDatabase(dbname, host, port, username, prompt_password,
-								   progname, false);
+			conn = connectDatabase(dbname, host, port, username, pqpass,
+								   prompt_password, progname, false);
 			init_slot(slots + i, conn);
 		}
 	}
@@ -542,12 +572,23 @@ vacuum_all_databases(vacuumingOptions *vacopts,
 	PGresult   *result;
 	int			stage;
 	int			i;
+	char	   *password = NULL;
 
 	conn = connectMaintenanceDatabase(maintenance_db, host, port,
 									  username, prompt_password, progname);
+
 	result = executeQuery(conn,
 			"SELECT datname FROM pg_database WHERE datallowconn ORDER BY 1;",
 						  progname, echo);
+
+	/*
+	 * Remember the password for further connections.  If no password was
+	 * required for the maintenance db connection, this gets updated for the
+	 * first connection that does.
+	 */
+	if (PQconnectionUsedPassword(conn))
+		password = pg_strdup(PQpass(conn));
+
 	PQfinish(conn);
 
 	if (analyze_in_stages)
@@ -572,7 +613,8 @@ vacuum_all_databases(vacuumingOptions *vacopts,
 									NULL,
 									host, port, username, prompt_password,
 									concurrentCons,
-									progname, echo, quiet);
+									progname, echo, quiet,
+									&password);
 			}
 		}
 	}
@@ -588,11 +630,13 @@ vacuum_all_databases(vacuumingOptions *vacopts,
 								NULL,
 								host, port, username, prompt_password,
 								concurrentCons,
-								progname, echo, quiet);
+								progname, echo, quiet,
+								&password);
 		}
 	}
 
 	PQclear(result);
+	pg_free(password);
 }
 
 /*