pl_funcs.c

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/*-------------------------------------------------------------------------
 *
 * pl_funcs.c		- Misc functions for the PL/pgSQL
 *			  procedural language
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_funcs.c,v 1.67 2008/01/01 19:46:00 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "plpgsql.h"
#include "pl.tab.h"

#include <ctype.h>

#include "parser/scansup.h"


/* ----------
 * Local variables for the namestack handling
 * ----------
 */
static PLpgSQL_ns *ns_current = NULL;
static bool ns_localmode = false;


/* ----------
 * plpgsql_dstring_init			Dynamic string initialization
 * ----------
 */
void
plpgsql_dstring_init(PLpgSQL_dstring *ds)
{
	ds->value = palloc(ds->alloc = 512);
	ds->used = 1;
	ds->value[0] = '\0';
}


/* ----------
 * plpgsql_dstring_free			Dynamic string destruction
 * ----------
 */
void
plpgsql_dstring_free(PLpgSQL_dstring *ds)
{
	pfree(ds->value);
}

static void
plpgsql_dstring_expand(PLpgSQL_dstring *ds, int needed)
{
	/* Don't allow truncating the string */
	Assert(needed > ds->alloc);
	Assert(ds->used <= ds->alloc);

	/* Might have to double more than once, if needed is large */
	do
	{
		ds->alloc *= 2;
	} while (needed > ds->alloc);
	ds->value = repalloc(ds->value, ds->alloc);
}

/* ----------
 * plpgsql_dstring_append		Dynamic string extending
 * ----------
 */
void
plpgsql_dstring_append(PLpgSQL_dstring *ds, const char *str)
{
	int			len = strlen(str);
	int			needed = ds->used + len;

	if (needed > ds->alloc)
		plpgsql_dstring_expand(ds, needed);

	memcpy(&(ds->value[ds->used - 1]), str, len);
	ds->used += len;
	ds->value[ds->used - 1] = '\0';
}

/* ----------
 * plpgsql_dstring_append_char	Append a single character
 *								to a dynamic string
 * ----------
 */
void
plpgsql_dstring_append_char(PLpgSQL_dstring *ds, char c)
{
	if (ds->used == ds->alloc)
		plpgsql_dstring_expand(ds, ds->used + 1);

	ds->value[ds->used - 1] = c;
	ds->value[ds->used] = '\0';
	ds->used++;
}


/* ----------
 * plpgsql_dstring_get			Dynamic string get value
 * ----------
 */
char *
plpgsql_dstring_get(PLpgSQL_dstring *ds)
{
	return ds->value;
}


/* ----------
 * plpgsql_ns_init			Initialize the namestack
 * ----------
 */
void
plpgsql_ns_init(void)
{
	ns_current = NULL;
	ns_localmode = false;
}


/* ----------
 * plpgsql_ns_setlocal			Tell plpgsql_ns_lookup whether to
 *					look into the current level only.
 *
 * This is a crock, but in the current design we need it because scan.l
 * initiates name lookup, and the scanner does not know whether we are
 * examining a name being declared in a DECLARE section.  For that case
 * we only want to know if there is a conflicting name earlier in the
 * same DECLARE section.  So the grammar must temporarily set local mode
 * before scanning decl_varnames.
 * ----------
 */
bool
plpgsql_ns_setlocal(bool flag)
{
	bool		oldstate;

	oldstate = ns_localmode;
	ns_localmode = flag;
	return oldstate;
}


/* ----------
 * plpgsql_ns_push			Enter a new namestack level
 * ----------
 */
void
plpgsql_ns_push(const char *label)
{
	PLpgSQL_ns *new;

	if (label == NULL)
		label = "";

	new = palloc0(sizeof(PLpgSQL_ns));
	new->upper = ns_current;
	ns_current = new;

	plpgsql_ns_additem(PLPGSQL_NSTYPE_LABEL, 0, label);
}


/* ----------
 * plpgsql_ns_pop			Return to the previous level
 * ----------
 */
void
plpgsql_ns_pop(void)
{
	int			i;
	PLpgSQL_ns *old;

	old = ns_current;
	ns_current = old->upper;

	for (i = 0; i < old->items_used; i++)
		pfree(old->items[i]);
	pfree(old->items);
	pfree(old);
}


/* ----------
 * plpgsql_ns_additem			Add an item to the current
 *					namestack level
 * ----------
 */
void
plpgsql_ns_additem(int itemtype, int itemno, const char *name)
{
	PLpgSQL_ns *ns = ns_current;
	PLpgSQL_nsitem *nse;

	Assert(name != NULL);

	if (ns->items_used == ns->items_alloc)
	{
		if (ns->items_alloc == 0)
		{
			ns->items_alloc = 32;
			ns->items = palloc(sizeof(PLpgSQL_nsitem *) * ns->items_alloc);
		}
		else
		{
			ns->items_alloc *= 2;
			ns->items = repalloc(ns->items,
								 sizeof(PLpgSQL_nsitem *) * ns->items_alloc);
		}
	}

	nse = palloc(sizeof(PLpgSQL_nsitem) + strlen(name));
	nse->itemtype = itemtype;
	nse->itemno = itemno;
	strcpy(nse->name, name);
	ns->items[ns->items_used++] = nse;
}


/* ----------
 * plpgsql_ns_lookup			Lookup an identifier in the namestack
 *
 * Note that this only searches for variables, not labels.
 *
 * name1 must be non-NULL.  Pass NULL for name2 and/or name3 if parsing a name
 * with fewer than three components.
 *
 * If names_used isn't NULL, *names_used receives the number of names
 * matched: 0 if no match, 1 if name1 matched an unqualified variable name,
 * 2 if name1 and name2 matched a block label + variable name.
 *
 * Note that name3 is never directly matched to anything.  However, if it
 * isn't NULL, we will disregard qualified matches to scalar variables.
 * Similarly, if name2 isn't NULL, we disregard unqualified matches to
 * scalar variables.
 * ----------
 */
PLpgSQL_nsitem *
plpgsql_ns_lookup(const char *name1, const char *name2, const char *name3,
				  int *names_used)
{
	PLpgSQL_ns *ns;
	int			i;

	/* Scan each level of the namestack */
	for (ns = ns_current; ns != NULL; ns = ns->upper)
	{
		/* Check for unqualified match to variable name */
		for (i = 1; i < ns->items_used; i++)
		{
			PLpgSQL_nsitem *nsitem = ns->items[i];

			if (strcmp(nsitem->name, name1) == 0)
			{
				if (name2 == NULL ||
					nsitem->itemtype != PLPGSQL_NSTYPE_VAR)
				{
					if (names_used)
						*names_used = 1;
					return nsitem;
				}
			}
		}

		/* Check for qualified match to variable name */
		if (name2 != NULL &&
			strcmp(ns->items[0]->name, name1) == 0)
		{
			for (i = 1; i < ns->items_used; i++)
			{
				PLpgSQL_nsitem *nsitem = ns->items[i];

				if (strcmp(nsitem->name, name2) == 0)
				{
					if (name3 == NULL ||
						nsitem->itemtype != PLPGSQL_NSTYPE_VAR)
					{
						if (names_used)
							*names_used = 2;
						return nsitem;
					}
				}
			}
		}

		if (ns_localmode)
			break;				/* do not look into upper levels */
	}

	/* This is just to suppress possibly-uninitialized-variable warnings */
	if (names_used)
		*names_used = 0;
	return NULL;				/* No match found */
}


/* ----------
 * plpgsql_ns_lookup_label		Lookup a label in the namestack
 * ----------
 */
PLpgSQL_nsitem *
plpgsql_ns_lookup_label(const char *name)
{
	PLpgSQL_ns *ns;

	for (ns = ns_current; ns != NULL; ns = ns->upper)
	{
		if (strcmp(ns->items[0]->name, name) == 0)
			return ns->items[0];
	}

	return NULL;				/* label not found */
}


/* ----------
 * plpgsql_ns_rename			Rename a namespace entry
 * ----------
 */
void
plpgsql_ns_rename(char *oldname, char *newname)
{
	PLpgSQL_ns *ns;
	PLpgSQL_nsitem *newitem;
	int			i;

	/*
	 * Lookup name in the namestack
	 */
	for (ns = ns_current; ns != NULL; ns = ns->upper)
	{
		for (i = 1; i < ns->items_used; i++)
		{
			if (strcmp(ns->items[i]->name, oldname) == 0)
			{
				newitem = palloc(sizeof(PLpgSQL_nsitem) + strlen(newname));
				newitem->itemtype = ns->items[i]->itemtype;
				newitem->itemno = ns->items[i]->itemno;
				strcpy(newitem->name, newname);

				pfree(oldname);
				pfree(newname);

				pfree(ns->items[i]);
				ns->items[i] = newitem;
				return;
			}
		}
	}

	ereport(ERROR,
			(errcode(ERRCODE_UNDEFINED_OBJECT),
			 errmsg("there is no variable \"%s\" in the current block",
					oldname)));
}


/* ----------
 * plpgsql_convert_ident
 *
 * Convert a possibly-qualified identifier to internal form: handle
 * double quotes, translate to lower case where not inside quotes,
 * truncate to NAMEDATALEN.
 *
 * There may be several identifiers separated by dots and optional
 * whitespace.	Each one is converted to a separate palloc'd string.
 * The caller passes the expected number of identifiers, as well as
 * a char* array to hold them.	It is an error if we find the wrong
 * number of identifiers (cf grammar processing of fori_varname).
 *
 * NOTE: the input string has already been accepted by the flex lexer,
 * so we don't need a heckuva lot of error checking here.
 * ----------
 */
void
plpgsql_convert_ident(const char *s, char **output, int numidents)
{
	const char *sstart = s;
	int			identctr = 0;

	/* Outer loop over identifiers */
	while (*s)
	{
		char	   *curident;
		char	   *cp;

		/* Process current identifier */

		if (*s == '"')
		{
			/* Quoted identifier: copy, collapsing out doubled quotes */

			curident = palloc(strlen(s) + 1);	/* surely enough room */
			cp = curident;
			s++;
			while (*s)
			{
				if (*s == '"')
				{
					if (s[1] != '"')
						break;
					s++;
				}
				*cp++ = *s++;
			}
			if (*s != '"')		/* should not happen if lexer checked */
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("unterminated \" in name: %s", sstart)));
			s++;
			*cp = '\0';
			/* Truncate to NAMEDATALEN */
			truncate_identifier(curident, cp - curident, false);
		}
		else
		{
			/* Normal identifier: extends till dot or whitespace */
			const char *thisstart = s;

			while (*s && *s != '.' && !scanner_isspace(*s))
				s++;
			/* Downcase and truncate to NAMEDATALEN */
			curident = downcase_truncate_identifier(thisstart, s - thisstart,
													false);
		}

		/* Pass ident to caller */
		if (identctr < numidents)
			output[identctr++] = curident;
		else
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("qualified identifier cannot be used here: %s",
							sstart)));

		/* If not done, skip whitespace, dot, whitespace */
		if (*s)
		{
			while (*s && scanner_isspace(*s))
				s++;
			if (*s++ != '.')
				elog(ERROR, "expected dot between identifiers: %s", sstart);
			while (*s && scanner_isspace(*s))
				s++;
			if (*s == '\0')
				elog(ERROR, "expected another identifier: %s", sstart);
		}
	}

	if (identctr != numidents)
		elog(ERROR, "improperly qualified identifier: %s",
			 sstart);
}


/*
 * Statement type as a string, for use in error messages etc.
 */
const char *
plpgsql_stmt_typename(PLpgSQL_stmt *stmt)
{
	switch (stmt->cmd_type)
	{
		case PLPGSQL_STMT_BLOCK:
			return _("statement block");
		case PLPGSQL_STMT_ASSIGN:
			return _("assignment");
		case PLPGSQL_STMT_IF:
			return "IF";
		case PLPGSQL_STMT_LOOP:
			return "LOOP";
		case PLPGSQL_STMT_WHILE:
			return "WHILE";
		case PLPGSQL_STMT_FORI:
			return _("FOR with integer loop variable");
		case PLPGSQL_STMT_FORS:
			return _("FOR over SELECT rows");
		case PLPGSQL_STMT_EXIT:
			return "EXIT";
		case PLPGSQL_STMT_RETURN:
			return "RETURN";
		case PLPGSQL_STMT_RETURN_NEXT:
			return "RETURN NEXT";
		case PLPGSQL_STMT_RETURN_QUERY:
			return "RETURN QUERY";
		case PLPGSQL_STMT_RAISE:
			return "RAISE";
		case PLPGSQL_STMT_EXECSQL:
			return _("SQL statement");
		case PLPGSQL_STMT_DYNEXECUTE:
			return _("EXECUTE statement");
		case PLPGSQL_STMT_DYNFORS:
			return _("FOR over EXECUTE statement");
		case PLPGSQL_STMT_GETDIAG:
			return "GET DIAGNOSTICS";
		case PLPGSQL_STMT_OPEN:
			return "OPEN";
		case PLPGSQL_STMT_FETCH:
			return "FETCH";
		case PLPGSQL_STMT_CLOSE:
			return "CLOSE";
		case PLPGSQL_STMT_PERFORM:
			return "PERFORM";
	}

	return "unknown";
}


/**********************************************************************
 * Debug functions for analyzing the compiled code
 **********************************************************************/
static int	dump_indent;

static void dump_ind(void);
static void dump_stmt(PLpgSQL_stmt *stmt);
static void dump_block(PLpgSQL_stmt_block *block);
static void dump_assign(PLpgSQL_stmt_assign *stmt);
static void dump_if(PLpgSQL_stmt_if *stmt);
static void dump_loop(PLpgSQL_stmt_loop *stmt);
static void dump_while(PLpgSQL_stmt_while *stmt);
static void dump_fori(PLpgSQL_stmt_fori *stmt);
static void dump_fors(PLpgSQL_stmt_fors *stmt);
static void dump_exit(PLpgSQL_stmt_exit *stmt);
static void dump_return(PLpgSQL_stmt_return *stmt);
static void dump_return_next(PLpgSQL_stmt_return_next *stmt);
static void dump_return_query(PLpgSQL_stmt_return_query *stmt);
static void dump_raise(PLpgSQL_stmt_raise *stmt);
static void dump_execsql(PLpgSQL_stmt_execsql *stmt);
static void dump_dynexecute(PLpgSQL_stmt_dynexecute *stmt);
static void dump_dynfors(PLpgSQL_stmt_dynfors *stmt);
static void dump_getdiag(PLpgSQL_stmt_getdiag *stmt);
static void dump_open(PLpgSQL_stmt_open *stmt);
static void dump_fetch(PLpgSQL_stmt_fetch *stmt);
static void dump_cursor_direction(PLpgSQL_stmt_fetch *stmt);
static void dump_close(PLpgSQL_stmt_close *stmt);
static void dump_perform(PLpgSQL_stmt_perform *stmt);
static void dump_expr(PLpgSQL_expr *expr);


static void
dump_ind(void)
{
	int			i;

	for (i = 0; i < dump_indent; i++)
		printf(" ");
}

static void
dump_stmt(PLpgSQL_stmt *stmt)
{
	printf("%3d:", stmt->lineno);
	switch (stmt->cmd_type)
	{
		case PLPGSQL_STMT_BLOCK:
			dump_block((PLpgSQL_stmt_block *) stmt);
			break;
		case PLPGSQL_STMT_ASSIGN:
			dump_assign((PLpgSQL_stmt_assign *) stmt);
			break;
		case PLPGSQL_STMT_IF:
			dump_if((PLpgSQL_stmt_if *) stmt);
			break;
		case PLPGSQL_STMT_LOOP:
			dump_loop((PLpgSQL_stmt_loop *) stmt);
			break;
		case PLPGSQL_STMT_WHILE:
			dump_while((PLpgSQL_stmt_while *) stmt);
			break;
		case PLPGSQL_STMT_FORI:
			dump_fori((PLpgSQL_stmt_fori *) stmt);
			break;
		case PLPGSQL_STMT_FORS:
			dump_fors((PLpgSQL_stmt_fors *) stmt);
			break;
		case PLPGSQL_STMT_EXIT:
			dump_exit((PLpgSQL_stmt_exit *) stmt);
			break;
		case PLPGSQL_STMT_RETURN: