Function appendPsqlMetaConnect

src/fe_utils/string_utils.c:763–826

* Append a psql meta-command that connects to the given database with the * then-current connection's user, host and port. */

 * then-current connection's user, host and port.
 */
void
appendPsqlMetaConnect(PQExpBuffer buf, const char *dbname)
{
	const char *s;
	bool complex;

	/*
	 * If the name is plain ASCII characters, emit a trivial "\connect "foo"".
	 * For other names, even many not technically requiring it, skip to the
	 * general case.  No database has a zero-length name.
	 */
	complex = false;

	for (s = dbname; *s; s++)
	{
		if (*s == '\n' || *s == '\r')
		{
			fprintf(stderr,
					_("database name contains a newline or carriage return: \"%s\"\n"),
					dbname);
			exit(EXIT_FAILURE);
		}

		if (!((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
			  (*s >= '0' && *s <= '9') || *s == '_' || *s == '.'))
		{
			complex = true;
		}
	}

	if (complex)
	{
		PQExpBufferData connstr;

		initPQExpBuffer(&connstr);

		/*
		 * Force the target psql's encoding to SQL_ASCII.  We don't really
		 * know the encoding of the database name, and it doesn't matter as
		 * long as psql will forward it to the server unchanged.
		 */
		appendPQExpBufferStr(buf, "\\encoding SQL_ASCII\n");
		appendPQExpBufferStr(buf, "\\connect -reuse-previous=on ");

		appendPQExpBufferStr(&connstr, "dbname=");
		appendConnStrVal(&connstr, dbname);

		/*
		 * As long as the name does not contain a newline, SQL identifier
		 * quoting satisfies the psql meta-command parser.  Prefer not to
		 * involve psql-interpreted single quotes, which behaved differently
		 * before PostgreSQL 9.2.
		 */
		appendPQExpBufferStr(buf, fmtIdEnc(connstr.data, PG_SQL_ASCII));

		termPQExpBuffer(&connstr);
	}
	else