Function copy_plpgsql_datums

src/pl/plpgsql/src/pl_exec.c:1271–1338

---------- * Support function for initializing local execution variables * ---------- */

 * ----------
 */
static void
copy_plpgsql_datums(PLpgSQL_execstate *estate,
					PLpgSQL_function *func)
{
	int			ndatums = estate->ndatums;
	PLpgSQL_datum **indatums;
	PLpgSQL_datum **outdatums;
	char	   *workspace;
	char	   *ws_next;
	int			i;

	/* Allocate local datum-pointer array */
	estate->datums = (PLpgSQL_datum **)
		palloc(sizeof(PLpgSQL_datum *) * ndatums);

	/*
	 * To reduce palloc overhead, we make a single palloc request for all the
	 * space needed for locally-instantiated datums.
	 */
	workspace = palloc(func->copiable_size);
	ws_next = workspace;

	/* Fill datum-pointer array, copying datums into workspace as needed */
	indatums = func->datums;
	outdatums = estate->datums;
	for (i = 0; i < ndatums; i++)
	{
		PLpgSQL_datum *indatum = indatums[i];
		PLpgSQL_datum *outdatum;

		/* This must agree with plpgsql_finish_datums on what is copiable */
		switch (indatum->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
			case PLPGSQL_DTYPE_PROMISE:
				outdatum = (PLpgSQL_datum *) ws_next;
				memcpy(outdatum, indatum, sizeof(PLpgSQL_var));
				ws_next += MAXALIGN(sizeof(PLpgSQL_var));
				break;

			case PLPGSQL_DTYPE_REC:
				outdatum = (PLpgSQL_datum *) ws_next;
				memcpy(outdatum, indatum, sizeof(PLpgSQL_rec));
				ws_next += MAXALIGN(sizeof(PLpgSQL_rec));
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_RECFIELD:

				/*
				 * These datum records are read-only at runtime, so no need to
				 * copy them (well, RECFIELD contains cached data, but we'd
				 * just as soon centralize the caching anyway).
				 */
				outdatum = indatum;
				break;

			default: