Improve handling of password reuse in src/bin/scripts programs.

This reverts most of commit 83dec5a71 in favor of having connectDatabase()
store the possibly-reusable password in a static variable, similar to the
coding we've had for a long time in pg_dump's version of that function.
To avoid possible problems with unwanted password reuse, make callers
specify whether it's reasonable to attempt to re-use the password.
This is a wash for cases where re-use isn't needed, but it is far simpler
for callers that do want that.  Functionally there should be no difference.

Even though we're past RC1, it seems like a good idea to back-patch this
into 9.5, like the prior commit.  Otherwise, if there are any third-party
users of connectDatabase(), they'll have to deal with an API change in
9.5 and then another one in 9.6.

Michael Paquier

src/bin/scripts/clusterdb.c

@@ -203,8 +203,8 @@ cluster_one_database(const char *dbname, bool verbose, const char *table,
 		appendPQExpBuffer(&sql, " %s", table);
 	appendPQExpBufferChar(&sql, ';');
 
-	conn = connectDatabase(dbname, host, port, username, NULL, prompt_password,
-						   progname, false);
+	conn = connectDatabase(dbname, host, port, username, prompt_password,
+						   progname, false, false);
 	if (!executeMaintenanceCommand(conn, sql.data, echo))
 	{
 		if (table)

src/bin/scripts/common.c

@@ -54,22 +54,31 @@ handle_help_version_opts(int argc, char *argv[],
 /*
  * 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.
+ * An interactive password prompt is automatically issued if needed and
+ * allowed by prompt_password.
+ *
+ * If allow_password_reuse is true, we will try to re-use any password
+ * given during previous calls to this routine.  (Callers should not pass
+ * allow_password_reuse=true unless reconnecting to the same database+user
+ * as before, else we might create password exposure hazards.)
  */
 PGconn *
 connectDatabase(const char *dbname, const char *pghost, const char *pgport,
-				const char *pguser, const char *pgpassword,
-				enum trivalue prompt_password, const char *progname,
-				bool fail_ok)
+				const char *pguser, enum trivalue prompt_password,
+				const char *progname, bool fail_ok, bool allow_password_reuse)
 {
 	PGconn	   *conn;
-	char	   *password;
+	static char *password = NULL;
 	bool		new_pass;
 
-	password = pgpassword ? strdup(pgpassword) : NULL;
+	if (!allow_password_reuse)
+	{
+		if (password)
+			free(password);
+		password = NULL;
+	}
 
-	if (prompt_password == TRI_YES && !pgpassword)
+	if (password == NULL && prompt_password == TRI_YES)
 		password = simple_prompt("Password: ", 100, false);
 
 	/*
@@ -78,9 +87,8 @@ connectDatabase(const char *dbname, const char *pghost, const char *pgport,
 	 */
 	do
 	{
-#define PARAMS_ARRAY_SIZE	7
-		const char **keywords = pg_malloc(PARAMS_ARRAY_SIZE * sizeof(*keywords));
-		const char **values = pg_malloc(PARAMS_ARRAY_SIZE * sizeof(*values));
+		const char *keywords[7];
+		const char *values[7];
 
 		keywords[0] = "host";
 		values[0] = pghost;
@@ -107,9 +115,6 @@ connectDatabase(const char *dbname, const char *pghost, const char *pgport,
 			exit(1);
 		}
 
-		pg_free(keywords);
-		pg_free(values);
-
 		/*
 		 * No luck?  Trying asking (again) for a password.
 		 */
@@ -125,9 +130,6 @@ connectDatabase(const char *dbname, const char *pghost, const char *pgport,
 		}
 	} while (new_pass);
 
-	if (password)
-		free(password);
-
 	/* check to see that the backend connection was successfully made */
 	if (PQstatus(conn) == CONNECTION_BAD)
 	{
@@ -157,15 +159,15 @@ 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, NULL,
-							   prompt_password, progname, false);
+		return connectDatabase(maintenance_db, pghost, pgport, pguser,
+							   prompt_password, progname, false, false);
 
 	/* Otherwise, try postgres first and then template1. */
-	conn = connectDatabase("postgres", pghost, pgport, pguser, NULL,
-						   prompt_password, progname, true);
+	conn = connectDatabase("postgres", pghost, pgport, pguser, prompt_password,
+						   progname, true, false);
 	if (!conn)
-		conn = connectDatabase("template1", pghost, pgport, pguser, NULL,
-							   prompt_password, progname, false);
+		conn = connectDatabase("template1", pghost, pgport, pguser,
+							   prompt_password, progname, false, 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,
-				const char *pgpassword, enum trivalue prompt_password,
-				const char *progname, bool fail_ok);
+				enum trivalue prompt_password, const char *progname,
+				bool fail_ok, bool allow_password_reuse);
 
 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, NULL,
-							   prompt_password, progname, false);
+		conn = connectDatabase(dbname, host, port, username, prompt_password,
+							   progname, false, 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, NULL,
-						   prompt_password, progname, false);
+	conn = connectDatabase(dbname, host, port, username, prompt_password,
+						   progname, false, 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, NULL,
-						   prompt_password, progname, false);
+	conn = connectDatabase("postgres", host, port, username, prompt_password,
+						   progname, false, 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, NULL,
-							   prompt_password, progname, false);
+		conn = connectDatabase(dbname, host, port, username, prompt_password,
+							   progname, false, 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, NULL,
-						   prompt_password, progname, false);
+	conn = connectDatabase(dbname, host, port, username, prompt_password,
+						   progname, false, 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, NULL,
-						   prompt_password, progname, false);
+	conn = connectDatabase("postgres", host, port, username, prompt_password,
+						   progname, false, 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, NULL,
-						   prompt_password, progname, false);
+	conn = connectDatabase(dbname, host, port, username, prompt_password,
+						   progname, false, 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, NULL,
-						   prompt_password, progname, false);
+	conn = connectDatabase(dbname, host, port, username, prompt_password,
+						   progname, false, false);
 	if (!executeMaintenanceCommand(conn, sql.data, echo))
 	{
 		fprintf(stderr, _("%s: reindexing of system catalogs failed: %s"),

src/bin/scripts/vacuumdb.c

@@ -43,8 +43,7 @@ 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,
-					char **password);
+					const char *progname, bool echo, bool quiet);
 
 static void vacuum_all_databases(vacuumingOptions *vacopts,
 					 bool analyze_in_stages,
@@ -276,8 +275,6 @@ main(int argc, char *argv[])
 	}
 	else
 	{
-		char *password = NULL;
-
 		if (dbname == NULL)
 		{
 			if (getenv("PGDATABASE"))
@@ -299,8 +296,7 @@ main(int argc, char *argv[])
 									&tables,
 									host, port, username, prompt_password,
 									concurrentCons,
-									progname, echo, quiet,
-									&password);
+									progname, echo, quiet);
 			}
 		}
 		else
@@ -309,10 +305,7 @@ main(int argc, char *argv[])
 								&tables,
 								host, port, username, prompt_password,
 								concurrentCons,
-								progname, echo, quiet,
-								&password);
-
-		pg_free(password);
+								progname, echo, quiet);
 	}
 
 	exit(0);
@@ -330,21 +323,15 @@ 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,
-					char **password)
+					const char *progname, bool echo, bool quiet)
 {
 	PQExpBufferData sql;
 	PGconn	   *conn;
@@ -378,15 +365,8 @@ vacuum_one_database(const char *dbname, vacuumingOptions *vacopts,
 		fflush(stdout);
 	}
 
-	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));
+	conn = connectDatabase(dbname, host, port, username, prompt_password,
+						   progname, false, true);
 
 	initPQExpBuffer(&sql);
 
@@ -444,20 +424,10 @@ 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, pqpass,
-								   prompt_password, progname, false);
+			conn = connectDatabase(dbname, host, port, username, prompt_password,
+								   progname, false, true);
 			init_slot(slots + i, conn);
 		}
 	}
@@ -572,23 +542,12 @@ 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)
@@ -613,8 +572,7 @@ vacuum_all_databases(vacuumingOptions *vacopts,
 									NULL,
 									host, port, username, prompt_password,
 									concurrentCons,
-									progname, echo, quiet,
-									&password);
+									progname, echo, quiet);
 			}
 		}
 	}
@@ -630,13 +588,11 @@ vacuum_all_databases(vacuumingOptions *vacopts,
 								NULL,
 								host, port, username, prompt_password,
 								concurrentCons,
-								progname, echo, quiet,
-								&password);
+								progname, echo, quiet);
 		}
 	}
 
 	PQclear(result);
-	pg_free(password);
 }
 
 /*