PostgreSQL/src/backend/nodes/readfuncs.c

/*-------------------------------------------------------------------------
 *
 * readfuncs.c
 *	  Reader functions for Postgres tree nodes.
 *
 * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/nodes/readfuncs.c
 *
 * NOTES
 *	  Parse location fields are written out by outfuncs.c, but only for
 *	  debugging use.  When reading a location field, we normally discard
 *	  the stored value and set the location field to -1 (ie, "unknown").
 *	  This is because nodes coming from a stored rule should not be thought
 *	  to have a known location in the current query's text.
 *
 *	  However, if restore_location_fields is true, we do restore location
 *	  fields from the string.  This is currently intended only for use by the
 *	  WRITE_READ_PARSE_PLAN_TREES test code, which doesn't want to cause
 *	  any change in the node contents.
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <math.h>

#include "miscadmin.h"
#include "nodes/bitmapset.h"
#include "nodes/readfuncs.h"


/*
 * Macros to simplify reading of different kinds of fields.  Use these
 * wherever possible to reduce the chance for silly typos.  Note that these
 * hard-wire conventions about the names of the local variables in a Read
 * routine.
 */

/* Macros for declaring appropriate local variables */

/* A few guys need only local_node */
#define READ_LOCALS_NO_FIELDS(nodeTypeName) \
	nodeTypeName *local_node = makeNode(nodeTypeName)

/* And a few guys need only the pg_strtok support fields */
#define READ_TEMP_LOCALS()	\
	const char *token;		\
	int			length

/* ... but most need both */
#define READ_LOCALS(nodeTypeName)			\
	READ_LOCALS_NO_FIELDS(nodeTypeName);	\
	READ_TEMP_LOCALS()

/* Read an integer field (anything written as ":fldname %d") */
#define READ_INT_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = atoi(token)

/* Read an unsigned integer field (anything written as ":fldname %u") */
#define READ_UINT_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = atoui(token)

/* Read an unsigned integer field (anything written using UINT64_FORMAT) */
#define READ_UINT64_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = strtou64(token, NULL, 10)

/* Read a long integer field (anything written as ":fldname %ld") */
#define READ_LONG_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = atol(token)

/* Read an OID field (don't hard-wire assumption that OID is same as uint) */
#define READ_OID_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = atooid(token)

/* Read a char field (ie, one ascii character) */
#define READ_CHAR_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	/* avoid overhead of calling debackslash() for one char */ \
	local_node->fldname = (length == 0) ? '\0' : (token[0] == '\\' ? token[1] : token[0])

/* Read an enumerated-type field that was written as an integer code */
#define READ_ENUM_FIELD(fldname, enumtype) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = (enumtype) atoi(token)

/* Read a float field */
#define READ_FLOAT_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = atof(token)

/* Read a boolean field */
#define READ_BOOL_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = strtobool(token)

/* Read a character-string field */
#define READ_STRING_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = nullable_string(token, length)

/* Read a parse location field (and possibly throw away the value) */
#ifdef WRITE_READ_PARSE_PLAN_TREES
#define READ_LOCATION_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	local_node->fldname = restore_location_fields ? atoi(token) : -1
#else
#define READ_LOCATION_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	token = pg_strtok(&length);		/* get field value */ \
	(void) token;				/* in case not used elsewhere */ \
	local_node->fldname = -1	/* set field to "unknown" */
#endif

/* Read a Node field */
#define READ_NODE_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	(void) token;				/* in case not used elsewhere */ \
	local_node->fldname = nodeRead(NULL, 0)

/* Read a bitmapset field */
#define READ_BITMAPSET_FIELD(fldname) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	(void) token;				/* in case not used elsewhere */ \
	local_node->fldname = _readBitmapset()

/* Read an attribute number array */
#define READ_ATTRNUMBER_ARRAY(fldname, len) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	local_node->fldname = readAttrNumberCols(len)

/* Read an oid array */
#define READ_OID_ARRAY(fldname, len) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	local_node->fldname = readOidCols(len)

/* Read an int array */
#define READ_INT_ARRAY(fldname, len) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	local_node->fldname = readIntCols(len)

/* Read a bool array */
#define READ_BOOL_ARRAY(fldname, len) \
	token = pg_strtok(&length);		/* skip :fldname */ \
	local_node->fldname = readBoolCols(len)

/* Routine exit */
#define READ_DONE() \
	return local_node


/*
 * NOTE: use atoi() to read values written with %d, or atoui() to read
 * values written with %u in outfuncs.c.  An exception is OID values,
 * for which use atooid().  (As of 7.1, outfuncs.c writes OIDs as %u,
 * but this will probably change in the future.)
 */
#define atoui(x)  ((unsigned int) strtoul((x), NULL, 10))

#define strtobool(x)  ((*(x) == 't') ? true : false)

#define nullable_string(token,length)  \
	((length) == 0 ? NULL : debackslash(token, length))


/*
 * _readBitmapset
 */
static Bitmapset *
_readBitmapset(void)
{
	Bitmapset  *result = NULL;

	READ_TEMP_LOCALS();

	token = pg_strtok(&length);
	if (token == NULL)
		elog(ERROR, "incomplete Bitmapset structure");
	if (length != 1 || token[0] != '(')
		elog(ERROR, "unrecognized token: \"%.*s\"", length, token);

	token = pg_strtok(&length);
	if (token == NULL)
		elog(ERROR, "incomplete Bitmapset structure");
	if (length != 1 || token[0] != 'b')
		elog(ERROR, "unrecognized token: \"%.*s\"", length, token);

	for (;;)
	{
		int			val;
		char	   *endptr;

		token = pg_strtok(&length);
		if (token == NULL)
			elog(ERROR, "unterminated Bitmapset structure");
		if (length == 1 && token[0] == ')')
			break;
		val = (int) strtol(token, &endptr, 10);
		if (endptr != token + length)
			elog(ERROR, "unrecognized integer: \"%.*s\"", length, token);
		result = bms_add_member(result, val);
	}

	return result;
}

/*
 * for use by extensions which define extensible nodes
 */
Bitmapset *
readBitmapset(void)
{
	return _readBitmapset();
}

#include "readfuncs.funcs.c"


/*
 * Support functions for nodes with custom_read_write attribute or
 * special_read_write attribute
 */

static Const *
_readConst(void)
{
	READ_LOCALS(Const);

	READ_OID_FIELD(consttype);
	READ_INT_FIELD(consttypmod);
	READ_OID_FIELD(constcollid);
	READ_INT_FIELD(constlen);
	READ_BOOL_FIELD(constbyval);
	READ_BOOL_FIELD(constisnull);
	READ_LOCATION_FIELD(location);

	token = pg_strtok(&length); /* skip :constvalue */
	if (local_node->constisnull)
		token = pg_strtok(&length); /* skip "<>" */
	else
		local_node->constvalue = readDatum(local_node->constbyval);

	READ_DONE();
}

static BoolExpr *
_readBoolExpr(void)
{
	READ_LOCALS(BoolExpr);

	/* do-it-yourself enum representation */
	token = pg_strtok(&length); /* skip :boolop */
	token = pg_strtok(&length); /* get field value */
	if (strncmp(token, "and", 3) == 0)
		local_node->boolop = AND_EXPR;
	else if (strncmp(token, "or", 2) == 0)
		local_node->boolop = OR_EXPR;
	else if (strncmp(token, "not", 3) == 0)
		local_node->boolop = NOT_EXPR;
	else
		elog(ERROR, "unrecognized boolop \"%.*s\"", length, token);

	READ_NODE_FIELD(args);
	READ_LOCATION_FIELD(location);

	READ_DONE();
}

static RangeTblEntry *
_readRangeTblEntry(void)
{
	READ_LOCALS(RangeTblEntry);

	/* put alias + eref first to make dump more legible */
	READ_NODE_FIELD(alias);
	READ_NODE_FIELD(eref);
	READ_ENUM_FIELD(rtekind, RTEKind);

	switch (local_node->rtekind)
	{
		case RTE_RELATION:
			READ_OID_FIELD(relid);
			READ_CHAR_FIELD(relkind);
			READ_INT_FIELD(rellockmode);
			READ_NODE_FIELD(tablesample);
			break;
		case RTE_SUBQUERY:
			READ_NODE_FIELD(subquery);
			READ_BOOL_FIELD(security_barrier);
			break;
		case RTE_JOIN:
			READ_ENUM_FIELD(jointype, JoinType);
			READ_INT_FIELD(joinmergedcols);
			READ_NODE_FIELD(joinaliasvars);
			READ_NODE_FIELD(joinleftcols);
			READ_NODE_FIELD(joinrightcols);
			READ_NODE_FIELD(join_using_alias);
			break;
		case RTE_FUNCTION:
			READ_NODE_FIELD(functions);
			READ_BOOL_FIELD(funcordinality);
			break;
		case RTE_TABLEFUNC:
			READ_NODE_FIELD(tablefunc);
			/* The RTE must have a copy of the column type info, if any */
			if (local_node->tablefunc)
			{
				TableFunc  *tf = local_node->tablefunc;

				local_node->coltypes = tf->coltypes;
				local_node->coltypmods = tf->coltypmods;
				local_node->colcollations = tf->colcollations;
			}
			break;
		case RTE_VALUES:
			READ_NODE_FIELD(values_lists);
			READ_NODE_FIELD(coltypes);
			READ_NODE_FIELD(coltypmods);
			READ_NODE_FIELD(colcollations);
			break;
		case RTE_CTE:
			READ_STRING_FIELD(ctename);
			READ_UINT_FIELD(ctelevelsup);
			READ_BOOL_FIELD(self_reference);
			READ_NODE_FIELD(coltypes);
			READ_NODE_FIELD(coltypmods);
			READ_NODE_FIELD(colcollations);
			break;
		case RTE_NAMEDTUPLESTORE:
			READ_STRING_FIELD(enrname);
			READ_FLOAT_FIELD(enrtuples);
			READ_OID_FIELD(relid);
			READ_NODE_FIELD(coltypes);
			READ_NODE_FIELD(coltypmods);
			READ_NODE_FIELD(colcollations);
			break;
		case RTE_RESULT:
			/* no extra fields */
			break;
		default:
			elog(ERROR, "unrecognized RTE kind: %d",
				 (int) local_node->rtekind);
			break;
	}

	READ_BOOL_FIELD(lateral);
	READ_BOOL_FIELD(inh);
	READ_BOOL_FIELD(inFromCl);
	READ_UINT_FIELD(requiredPerms);
	READ_OID_FIELD(checkAsUser);
	READ_BITMAPSET_FIELD(selectedCols);
	READ_BITMAPSET_FIELD(insertedCols);
	READ_BITMAPSET_FIELD(updatedCols);
	READ_BITMAPSET_FIELD(extraUpdatedCols);
	READ_NODE_FIELD(securityQuals);

	READ_DONE();
}

static ExtensibleNode *
_readExtensibleNode(void)
{
	const ExtensibleNodeMethods *methods;
	ExtensibleNode *local_node;
	const char *extnodename;

	READ_TEMP_LOCALS();

	token = pg_strtok(&length); /* skip :extnodename */
	token = pg_strtok(&length); /* get extnodename */

	extnodename = nullable_string(token, length);
	if (!extnodename)
		elog(ERROR, "extnodename has to be supplied");
	methods = GetExtensibleNodeMethods(extnodename, false);

	local_node = (ExtensibleNode *) newNode(methods->node_size,
											T_ExtensibleNode);
	local_node->extnodename = extnodename;

	/* deserialize the private fields */
	methods->nodeRead(local_node);

	READ_DONE();
}


/*
 * parseNodeString
 *
 * Given a character string representing a node tree, parseNodeString creates
 * the internal node structure.
 *
 * The string to be read must already have been loaded into pg_strtok().
 */
Node *
parseNodeString(void)
{
	void	   *return_value;

	READ_TEMP_LOCALS();

	/* Guard against stack overflow due to overly complex expressions */
	check_stack_depth();

	token = pg_strtok(&length);

#define MATCH(tokname, namelen) \
	(length == namelen && memcmp(token, tokname, namelen) == 0)

	if (false)
		;
#include "readfuncs.switch.c"
	else
	{
		elog(ERROR, "badly formatted node string \"%.32s\"...", token);
		return_value = NULL;	/* keep compiler quiet */
	}

	return (Node *) return_value;
}


/*
 * readDatum
 *
 * Given a string representation of a constant, recreate the appropriate
 * Datum.  The string representation embeds length info, but not byValue,
 * so we must be told that.
 */
Datum
readDatum(bool typbyval)
{
	Size		length,
				i;
	int			tokenLength;
	const char *token;
	Datum		res;
	char	   *s;

	/*
	 * read the actual length of the value
	 */
	token = pg_strtok(&tokenLength);
	length = atoui(token);

	token = pg_strtok(&tokenLength);	/* read the '[' */
	if (token == NULL || token[0] != '[')
		elog(ERROR, "expected \"[\" to start datum, but got \"%s\"; length = %zu",
			 token ? token : "[NULL]", length);

	if (typbyval)
	{
		if (length > (Size) sizeof(Datum))
			elog(ERROR, "byval datum but length = %zu", length);
		res = (Datum) 0;
		s = (char *) (&res);
		for (i = 0; i < (Size) sizeof(Datum); i++)
		{
			token = pg_strtok(&tokenLength);
			s[i] = (char) atoi(token);
		}
	}
	else if (length <= 0)
		res = (Datum) NULL;
	else
	{
		s = (char *) palloc(length);
		for (i = 0; i < length; i++)
		{
			token = pg_strtok(&tokenLength);
			s[i] = (char) atoi(token);
		}
		res = PointerGetDatum(s);
	}

	token = pg_strtok(&tokenLength);	/* read the ']' */
	if (token == NULL || token[0] != ']')
		elog(ERROR, "expected \"]\" to end datum, but got \"%s\"; length = %zu",
			 token ? token : "[NULL]", length);

	return res;
}

/*
 * readAttrNumberCols
 */
AttrNumber *
readAttrNumberCols(int numCols)
{
	int			tokenLength,
				i;
	const char *token;
	AttrNumber *attr_vals;

	if (numCols <= 0)
		return NULL;

	attr_vals = (AttrNumber *) palloc(numCols * sizeof(AttrNumber));
	for (i = 0; i < numCols; i++)
	{
		token = pg_strtok(&tokenLength);
		attr_vals[i] = atoi(token);
	}

	return attr_vals;
}

/*
 * readOidCols
 */
Oid *
readOidCols(int numCols)
{
	int			tokenLength,
				i;
	const char *token;
	Oid		   *oid_vals;

	if (numCols <= 0)
		return NULL;

	oid_vals = (Oid *) palloc(numCols * sizeof(Oid));
	for (i = 0; i < numCols; i++)
	{
		token = pg_strtok(&tokenLength);
		oid_vals[i] = atooid(token);
	}

	return oid_vals;
}

/*
 * readIntCols
 */
int *
readIntCols(int numCols)
{
	int			tokenLength,
				i;
	const char *token;
	int		   *int_vals;

	if (numCols <= 0)
		return NULL;

	int_vals = (int *) palloc(numCols * sizeof(int));
	for (i = 0; i < numCols; i++)
	{
		token = pg_strtok(&tokenLength);
		int_vals[i] = atoi(token);
	}

	return int_vals;
}

/*
 * readBoolCols
 */
bool *
readBoolCols(int numCols)
{
	int			tokenLength,
				i;
	const char *token;
	bool	   *bool_vals;

	if (numCols <= 0)
		return NULL;

	bool_vals = (bool *) palloc(numCols * sizeof(bool));
	for (i = 0; i < numCols; i++)
	{
		token = pg_strtok(&tokenLength);
		bool_vals[i] = strtobool(token);
	}

	return bool_vals;
}