acl.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * acl.c
 *	  Basic access control list data structures manipulation routines.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/utils/adt/acl.c,v 1.37.2.1 1999/08/02 05:24:49 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */
#include <ctype.h>
#include "postgres.h"

#include "catalog/catalog.h"
#include "catalog/pg_shadow.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "utils/acl.h"
#include "utils/memutils.h"
#include "utils/syscache.h"

static char *getid(char *s, char *n);
static int32 aclitemeq(AclItem *a1, AclItem *a2);
static int32 aclitemgt(AclItem *a1, AclItem *a2);
static char *aclparse(char *s, AclItem *aip, unsigned *modechg);

#define ACL_IDTYPE_GID_KEYWORD	"group"
#define ACL_IDTYPE_UID_KEYWORD	"user"


/*
 * getid
 *		Consumes the first alphanumeric string (identifier) found in string
 *		's', ignoring any leading white space.	If it finds a double quote
 *		it returns the word inside the quotes.
 *
 * RETURNS:
 *		the string position in 's' that points to the next non-space character
 *		in 's', after any quotes.  Also:
 *		- loads the identifier into 'name'.  (If no identifier is found, 'name'
 *		  contains an empty string).
 */
static char *
getid(char *s, char *n)
{
	unsigned	len;
	char	   *id;
	int			in_quotes = 0;

	Assert(s && n);

	while (isspace(*s))
		++s;

	if (*s == '"')
	{
		in_quotes = 1;
		s++;
	}

	for (id = s, len = 0; isalnum(*s) || *s == '_' || in_quotes; ++len, ++s)
	{
		if (in_quotes && *s == '"')
		{
			len--;
			in_quotes = 0;
		}
	}
	if (len > sizeof(NameData))
		elog(ERROR, "getid: identifier cannot be >%d characters",
			 sizeof(NameData));
	if (len > 0)
		memmove(n, id, len);
	n[len] = '\0';
	while (isspace(*s))
		++s;
	return s;
}

/*
 * aclparse
 *		Consumes and parses an ACL specification of the form:
 *				[group|user] [A-Za-z0-9]*[+-=][rwaR]*
 *		from string 's', ignoring any leading white space or white space
 *		between the optional id type keyword (group|user) and the actual
 *		ACL specification.
 *
 *		This routine is called by the parser as well as aclitemin(), hence
 *		the added generality.
 *
 * RETURNS:
 *		the string position in 's' immediately following the ACL
 *		specification.	Also:
 *		- loads the structure pointed to by 'aip' with the appropriate
 *		  UID/GID, id type identifier and mode type values.
 *		- loads 'modechg' with the mode change flag.
 */
static char *
aclparse(char *s, AclItem *aip, unsigned *modechg)
{
	HeapTuple	htup;
	char		name[NAMEDATALEN];

	Assert(s && aip && modechg);

#ifdef ACLDEBUG_TRACE
	printf("aclparse: input = '%s'\n", s);
#endif
	aip->ai_idtype = ACL_IDTYPE_UID;
	s = getid(s, name);
	if (*s != ACL_MODECHG_ADD_CHR &&
		*s != ACL_MODECHG_DEL_CHR &&
		*s != ACL_MODECHG_EQL_CHR)
	{
		/* we just read a keyword, not a name */
		if (!strcmp(name, ACL_IDTYPE_GID_KEYWORD))
			aip->ai_idtype = ACL_IDTYPE_GID;
		else if (strcmp(name, ACL_IDTYPE_UID_KEYWORD))
			elog(ERROR, "aclparse: bad keyword, must be [group|user]");
		s = getid(s, name);		/* move s to the name beyond the keyword */
		if (name[0] == '\0')
			elog(ERROR, "aclparse: a name must follow the [group|user] keyword");
	}
	if (name[0] == '\0')
		aip->ai_idtype = ACL_IDTYPE_WORLD;

	switch (*s)
	{
		case ACL_MODECHG_ADD_CHR:
			*modechg = ACL_MODECHG_ADD;
			break;
		case ACL_MODECHG_DEL_CHR:
			*modechg = ACL_MODECHG_DEL;
			break;
		case ACL_MODECHG_EQL_CHR:
			*modechg = ACL_MODECHG_EQL;
			break;
		default:
			elog(ERROR, "aclparse: mode change flag must use \"%s\"",
				 ACL_MODECHG_STR);
	}

	aip->ai_mode = ACL_NO;
	while (isalpha(*++s))
	{
		switch (*s)
		{
			case ACL_MODE_AP_CHR:
				aip->ai_mode |= ACL_AP;
				break;
			case ACL_MODE_RD_CHR:
				aip->ai_mode |= ACL_RD;
				break;
			case ACL_MODE_WR_CHR:
				aip->ai_mode |= ACL_WR;
				break;
			case ACL_MODE_RU_CHR:
				aip->ai_mode |= ACL_RU;
				break;
			default:
				elog(ERROR, "aclparse: mode flags must use \"%s\"",
					 ACL_MODE_STR);
		}
	}

	switch (aip->ai_idtype)
	{
		case ACL_IDTYPE_UID:
			htup = SearchSysCacheTuple(USENAME,
									   PointerGetDatum(name),
									   0, 0, 0);
			if (!HeapTupleIsValid(htup))
				elog(ERROR, "aclparse: non-existent user \"%s\"", name);
			aip->ai_id = ((Form_pg_shadow) GETSTRUCT(htup))->usesysid;
			break;
		case ACL_IDTYPE_GID:
			aip->ai_id = get_grosysid(name);
			break;
		case ACL_IDTYPE_WORLD:
			aip->ai_id = ACL_ID_WORLD;
			break;
	}

#ifdef ACLDEBUG_TRACE
	elog(DEBUG, "aclparse: correctly read [%x %d %x], modechg=%x",
		 aip->ai_idtype, aip->ai_id, aip->ai_mode, *modechg);
#endif
	return s;
}

/*
 * makeacl
 *		Allocates storage for a new Acl with 'n' entries.
 *
 * RETURNS:
 *		the new Acl
 */
Acl *
makeacl(int n)
{
	Acl		   *new_acl;
	Size		size;

	if (n < 0)
		elog(ERROR, "makeacl: invalid size: %d\n", n);
	size = ACL_N_SIZE(n);
	if (!(new_acl = (Acl *) palloc(size)))
		elog(ERROR, "makeacl: palloc failed on %d\n", size);
	MemSet((char *) new_acl, 0, size);
	new_acl->size = size;
	new_acl->ndim = 1;
	new_acl->flags = 0;
	ARR_LBOUND(new_acl)[0] = 0;
	ARR_DIMS(new_acl)[0] = n;
	return new_acl;
}

/*
 * aclitemin
 *		Allocates storage for, and fills in, a new AclItem given a string
 *		's' that contains an ACL specification.  See aclparse for details.
 *
 * RETURNS:
 *		the new AclItem
 */
AclItem    *
aclitemin(char *s)
{
	unsigned	modechg;
	AclItem    *aip;

	if (!s)
		elog(ERROR, "aclitemin: null string");

	aip = (AclItem *) palloc(sizeof(AclItem));
	if (!aip)
		elog(ERROR, "aclitemin: palloc failed");
	s = aclparse(s, aip, &modechg);
	if (modechg != ACL_MODECHG_EQL)
		elog(ERROR, "aclitemin: cannot accept anything but = ACLs");
	while (isspace(*s))
		++s;
	if (*s)
		elog(ERROR, "aclitemin: extra garbage at end of specification");
	return aip;
}

/*
 * aclitemout
 *		Allocates storage for, and fills in, a new null-delimited string
 *		containing a formatted ACL specification.  See aclparse for details.
 *
 * RETURNS:
 *		the new string
 */
char *
aclitemout(AclItem *aip)
{
	char	   *p;
	char	   *out;
	HeapTuple	htup;
	unsigned	i;
	static AclItem default_aclitem = {ACL_ID_WORLD,
		ACL_IDTYPE_WORLD,
	ACL_WORLD_DEFAULT};
	extern char *int2out();
	char	   *tmpname;

	if (!aip)
		aip = &default_aclitem;

	p = out = palloc(strlen("group =arwR ") + 1 + NAMEDATALEN);
	if (!out)
		elog(ERROR, "aclitemout: palloc failed");
	*p = '\0';

	switch (aip->ai_idtype)
	{
		case ACL_IDTYPE_UID:
			htup = SearchSysCacheTuple(USESYSID,
									   ObjectIdGetDatum(aip->ai_id),
									   0, 0, 0);
			if (!HeapTupleIsValid(htup))
			{
				char	   *tmp = int2out(aip->ai_id);

#ifdef NOT_USED

				When this	elog(NOTICE) goes to the libpq client,
							it crashes the
							client because the NOTICE protocol is coming right in the middle
							of a request for a field value.We skip the NOTICE for now.

							elog(NOTICE, "aclitemout: usesysid %d not found",
											 aip->ai_id);

#endif

				strcat(p, tmp);
				pfree(tmp);
			}
			else
				strncat(p, (char *) &((Form_pg_shadow)
									  GETSTRUCT(htup))->usename,
						sizeof(NameData));
			break;
		case ACL_IDTYPE_GID:
			strcat(p, "group ");
			tmpname = get_groname(aip->ai_id);
			strncat(p, tmpname, NAMEDATALEN);
			break;
		case ACL_IDTYPE_WORLD:
			break;
		default:
			elog(ERROR, "aclitemout: bad ai_idtype: %d", aip->ai_idtype);
			break;
	}
	while (*p)
		++p;
	*p++ = '=';
	for (i = 0; i < N_ACL_MODES; ++i)
		if ((aip->ai_mode >> i) & 01)
			*p++ = ACL_MODE_STR[i];
	*p = '\0';

	return out;
}

/*
 * aclitemeq
 * aclitemgt
 *		AclItem equality and greater-than comparison routines.
 *		Two AclItems are equal iff they are both NULL or they have the
 *		same identifier (and identifier type).
 *
 * RETURNS:
 *		a boolean value indicating = or >
 */
static int32
aclitemeq(AclItem *a1, AclItem *a2)
{
	if (!a1 && !a2)
		return 1;
	if (!a1 || !a2)
		return 0;
	return a1->ai_idtype == a2->ai_idtype && a1->ai_id == a2->ai_id;
}

static int32
aclitemgt(AclItem *a1, AclItem *a2)
{
	if (a1 && !a2)
		return 1;
	if (!a1 || !a2)