postgresql/src/backend/catalog/catalog.c

/*-------------------------------------------------------------------------
 *
 * catalog.c--
 *    
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/catalog/catalog.c,v 1.5 1996/11/10 02:59:21 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include <postgres.h>

#include <miscadmin.h>  /* for DataDir */
#include <utils/syscache.h>
#include <catalog/catname.h>	/* NameIs{,Shared}SystemRelationName */
#include <catalog/pg_type.h>
#include <catalog/catalog.h>
#include <access/transam.h>

/*
 * relpath		- path to the relation
 *	Perhaps this should be in-line code in relopen().
 */
char *
relpath(char relname[])
{
    char    *path;
    
    if (IsSharedSystemRelationName(relname)) {
	path = (char *) palloc(strlen(DataDir) + sizeof(NameData) + 2);
	sprintf(path, "%s/%.*s", DataDir, NAMEDATALEN, relname);
	return (path);
    }
    return(relname);
}

#ifdef NOT_USED
/*
 * issystem	- returns non-zero iff relname is a system catalog
 *
 *	We now make a new requirement where system catalog relns must begin
 *	with pg_ while user relns are forbidden to do so.  Make the test
 * 	trivial and instantaneous.
 *
 *	XXX this is way bogus. -- pma
 */
bool
issystem(char relname[])
{
    if (relname[0] && relname[1] && relname[2])
	return (relname[0] == 'p' && 
		relname[1] == 'g' && 
		relname[2] == '_');
    else
	return FALSE;
}
#endif

/*
 * IsSystemRelationName --
 *	True iff name is the name of a system catalog relation.
 *
 *	We now make a new requirement where system catalog relns must begin
 *	with pg_ while user relns are forbidden to do so.  Make the test
 * 	trivial and instantaneous.
 *
 *	XXX this is way bogus. -- pma
 */
bool
IsSystemRelationName(char *relname)
{
    if (relname[0] && relname[1] && relname[2])
	return (relname[0] == 'p' && 
		relname[1] == 'g' && 
		relname[2] == '_');
    else
	return FALSE;
}

/*
 * IsSharedSystemRelationName --
 *	True iff name is the name of a shared system catalog relation.
 */
bool
IsSharedSystemRelationName(char *relname)
{
    int i;
    
    /*
     * Quick out: if it's not a system relation, it can't be a shared
     * system relation.
     */
    if (!IsSystemRelationName(relname))
	return FALSE;
    
    i = 0;
    while ( SharedSystemRelationNames[i] != NULL) {
         if (strcmp(SharedSystemRelationNames[i],relname) == 0)
	     return TRUE;
	 i++;
    }
    return FALSE;
}

/*
 *	newoid		- returns a unique identifier across all catalogs.
 *
 *	Object Id allocation is now done by GetNewObjectID in
 *	access/transam/varsup.c.  oids are now allocated correctly.
 *
 * old comments:
 *	This needs to change soon, it fails if there are too many more
 *	than one call per second when postgres restarts after it dies.
 *
 *	The distribution of OID's should be done by the POSTMASTER.
 *	Also there needs to be a facility to preallocate OID's.  Ie.,
 *	for a block of OID's to be declared as invalid ones to allow
 *	user programs to use them for temporary object identifiers.
 */
Oid newoid()
{
    Oid	 lastoid;
    
    GetNewObjectId(&lastoid);
    if (! OidIsValid(lastoid))
	elog(WARN, "newoid: GetNewObjectId returns invalid oid");
    return lastoid;
}

/*
 *	fillatt		- fills the ATTRIBUTE relation fields from the TYP
 *
 *	Expects that the atttypid domain is set for each att[].
 *	Returns with the attnum, and attlen domains set.
 *	attnum, attproc, atttyparg, ... should be set by the user.
 *
 *	In the future, attnum may not be set?!? or may be passed as an arg?!?
 *
 *	Current implementation is very inefficient--should cashe the
 *	information if this is at all possible.
 *
 *	Check to see if this is really needed, and especially in the case
 *	of index tuples.
 */
void
fillatt(TupleDesc tupleDesc)
{
    AttributeTupleForm	*attributeP;
    register TypeTupleForm	typp;
    HeapTuple		tuple;
    int			i;
    int natts = tupleDesc->natts;
    AttributeTupleForm *att = tupleDesc->attrs;

    if (natts < 0 || natts > MaxHeapAttributeNumber)
	elog(WARN, "fillatt: %d attributes is too large", natts);
    if (natts == 0) {
	elog(DEBUG, "fillatt: called with natts == 0");
	return;
    }
    
    attributeP = &att[0];
    
    for (i = 0; i < natts;) {
	tuple = SearchSysCacheTuple(TYPOID,
				    Int32GetDatum((*attributeP)->atttypid),
				    0,0,0);
	if (!HeapTupleIsValid(tuple)) {
	    elog(WARN, "fillatt: unknown atttypid %ld",
		 (*attributeP)->atttypid);
	} else {
	    (*attributeP)->attnum = (int16) ++i;
	    /* Check if the attr is a set before messing with the length
	       and byval, since those were already set in 
	       TupleDescInitEntry.  In fact, this seems redundant 
	       here, but who knows what I'll break if I take it out...

	       same for char() and varchar() stuff. I share the same
	       sentiments. This function is poorly written anyway. -ay 6/95
	       */
	    if (!(*attributeP)->attisset &&
		(*attributeP)->atttypid!=BPCHAROID &&
		(*attributeP)->atttypid!=VARCHAROID) {
		
		typp = (TypeTupleForm) GETSTRUCT(tuple);  /* XXX */
		(*attributeP)->attlen = typp->typlen;
		(*attributeP)->attbyval = typp->typbyval;
	    }
	}
	attributeP += 1;
    }
}