Function PrepareTempTablespaces

src/backend/commands/tablespace.c:1888–1974

* PrepareTempTablespaces -- prepare to use temp tablespaces * * If we have not already done so in the current transaction, parse the * temp_tablespaces GUC variable and tell fd.c which tablespace(s) to use * for temp files. */

 * for temp files.
 */
void
PrepareTempTablespaces(void)
{
	char	   *rawname;
	List	   *namelist;
	Oid		   *tblSpcs;
	int			numSpcs;
	ListCell   *l;

	/* No work if already done in current transaction */
	if (TempTablespacesAreSet())
		return;

	/*
	 * Can't do catalog access unless within a transaction.  This is just a
	 * safety check in case this function is called by low-level code that
	 * could conceivably execute outside a transaction.  Note that in such a
	 * scenario, fd.c will fall back to using the current database's default
	 * tablespace, which should always be OK.
	 */
	if (!IsTransactionState())
		return;

	/* Need a modifiable copy of string */
	rawname = pstrdup(temp_tablespaces);

	/* Parse string into list of identifiers */
	if (!SplitIdentifierString(rawname, ',', &namelist))
	{
		/* syntax error in name list */
		SetTempTablespaces(NULL, 0);
		pfree(rawname);
		list_free(namelist);
		return;
	}

	/* Store tablespace OIDs in an array in TopTransactionContext */
	tblSpcs = (Oid *) MemoryContextAlloc(TopTransactionContext,
										 list_length(namelist) * sizeof(Oid));
	numSpcs = 0;
	foreach(l, namelist)
	{
		char	   *curname = (char *) lfirst(l);
		Oid			curoid;
		AclResult	aclresult;

		/* Allow an empty string (signifying database default) */
		if (curname[0] == '\0')
		{
			/* InvalidOid signifies database's default tablespace */
			tblSpcs[numSpcs++] = InvalidOid;
			continue;
		}

		/* Else verify that name is a valid tablespace name */
		curoid = get_tablespace_oid(curname, true);
		if (curoid == InvalidOid)
		{