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[become] / src / class.h

/* -*-c-*-
 *
 * $Id: class.h,v 1.7 2004/04/08 01:36:20 mdw Exp $
 *
 * Handling classes of things nicely
 *
 * (c) 1998 EBI
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of `become'
 *
 * `Become' is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * `Become' is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with `become'; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifndef CLASS_H
#define CLASS_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Required headers --------------------------------------------------*/

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <mLib/sym.h>

/*----- Data structures ---------------------------------------------------*/

/* --- Class types --- */

enum {

  /* --- Data types (user visible) --- *
   *
   * These bits encode what the user can think of as `types'.  They get used
   * for typechecking and things.
   */

  clType_user = 0x01,			/* Class of users */
  clType_command = 0x02,		/* Class of command strings */
  clType_host = 0x04,			/* Class of host names */
  clType_all = 0x0F,			/* All of the above (maintain me) */
  clType_mask = 0x0F,		       	/* Mask for type flags */

  /* --- Node types --- *
   *
   * A class actually looks suspiciously like a tree once things start
   * getting complicated.  These bits encode the type of node we've got here.
   */

  clNode_any = 0x10,			/* Magic type for the `all' class */
  clNode_immed = 0x20,			/* Immediate data item */
  clNode_hash = 0x30,			/* Hashtable of values */
  clNode_binop = 0x40,			/* Binary operations start here */
  clNode_union = 0x40,			/* Union of two classes */
  clNode_diff = 0x50,			/* Difference of two classes */
  clNode_isect = 0x60,			/* Intersection of two classes */
  clNode_mask = 0xF0,			/* Mask for picking these out */

  /* --- Other useful flags --- */

  clFlag_friendly = 0x100		/* Item can be hashed with others */
};

/* --- Class block --- */

typedef struct class_node {
  unsigned type;			/* Class and node type, and flags */
  unsigned ref;				/* Reference count */
  union {
    uid_t u;				/* Immediate user id number */
    char *s;				/* Immediate string value */
    sym_table t;			/* Hash table for this class */
    struct {
      struct class_node *l, *r;		/* Left and right operands */
    } c;				/* Class operands for binops */
  } v;					/* Value of this class node */
} class_node;

/*----- Global variables --------------------------------------------------*/

extern class_node *class_all;		/* The match-everything class */
extern class_node *class_none;		/* The match-nothing class */

/*----- Functions provided ------------------------------------------------*/

/* --- @class_fromString@ --- *
 *
 * Arguments:	@unsigned type@ = a type field
 *		@const char *s@ = pointer to string to copy
 *
 * Returns:	A pointer to a class node containing that string, typed to
 *		be the right thing.
 *
 * Use:		Given a string, wrap a class node around it.  The node has
 *		one reference (the one you get returned).  The string is
 *		copied, so you can get rid of your original one if you like.
 */

extern class_node *class_fromString(unsigned /*type*/, const char */*s*/);

/* --- @class_fromUser@ --- *
 *
 * Arguments:	@unsigned type@ = a type field
 *		@uid_t u@ = a user-id number
 *
 * Returns:	A pointer to a class node containing the uid, typed to be
 *		the thing you asked for.  Hopefully this will be
 *		@clType_user@.
 *
 * Use:		Given a uid, wrap a class node around it.
 */

extern class_node *class_fromUser(unsigned /*type*/, uid_t /*u*/);

/* --- @class_inc@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to a class block
 *
 * Returns:	---
 *
 * Use:		Adds a reference to the class definition.
 */

extern void class_inc(class_node */*c*/);

/* --- @class_dec@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to a class block
 *
 * Returns:	---
 *
 * Use:		Removes a reference to a class block.
 */

extern void class_dec(class_node */*c*/);

/* --- @class_mod@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to a class node
 *
 * Returns:	A pointer to a class node, maybe the same one, maybe not,
 *		with a reference count of 1, containing the same data.
 *
 * Use:		Gives you a node which you can modify.  Don't call this
 *		for @class_all@ or @class_none@.
 */

extern class_node *class_mod(class_node */*c*/);

/* --- @class_union@ --- *
 *
 * Arguments:	@class_node *l@ = left argument
 *		@class_node *r@ = right argument
 *
 * Returns:	A class node representing the union of the two classes.
 *
 * Use:		Performs the union operation on classes.  If the types don't
 *		match, then a null pointer is returned.  Both @l@ and @r@
 *		may be modified, and will be decremented before they get
 *		returned to you.  If you don't want that to happen, ensure
 *		that you've claimed a reference to the original versions.
 */

extern class_node *class_union(class_node */*l*/, class_node */*r*/);

/* --- @class_diff@ --- *
 *
 * Arguments:	@class_node *l@ = left argument
 *		@class_node *r@ = right argument
 *
 * Returns:	A class node representing the difference of the two classes.
 *
 * Use:		Performs the set difference operation on classes.  If the
 *		types don't match, then a null pointer is returned.  Both
 *		@l@ and @r@ may be modified, and will be decremented before
 *		they get returned to you.  If you don't want that to happen,
 *		ensure that you've claimed a reference to the original
 *		versions.
 */

extern class_node *class_diff(class_node */*l*/, class_node */*r*/);

/* --- @class_isect@ --- *
 *
 * Arguments:	@class_node *l@ = left argument
 *		@class_node *r@ = right argument
 *
 * Returns:	A class node representing the intersection of the two
 *		classes.
 *
 * Use:		Performs the intersecion operation on classes.  If the types
 *		don't match, then a null pointer is returned.  Both @l@ and
 *		@r@ may be modified, and will be decremented before they get
 *		returned to you.  If you don't want that to happen, ensure
 *		that you've claimed a reference to the original versions.
 */

extern class_node *class_isect(class_node */*l*/, class_node */*r*/);

/* --- @class_addUser@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to a class node (may be null)
 *		@uid_t u@ = user id number
 *
 * Returns:	Pointer to the combined node.
 *
 * Use:		Adds a user to a node, maybe hashifying it.
 */

extern class_node *class_addUser(class_node */*c*/, uid_t /*u*/);

/* --- @class_addString@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to a class node (may be null)
 *		@const char *s@ = pointer to a string
 *
 * Returns:	Pointer to the combined node.
 *
 * Use:		Adds a user to a node, maybe hashifying it.
 */

extern class_node *class_addString(class_node */*c*/, const char */*s*/);

/* --- @class_matchUser@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to root class node
 *		@uid_t u@ = user id number
 *
 * Returns:	Nonzero if it matches, zero if it doesn't.
 *
 * Use:		Determines whether a user is matched by a class.  Assumes
 *		that the types are correct.
 */

extern int class_matchUser(class_node */*c*/, uid_t /*u*/);

/* --- @class_matchCommand@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to root class node
 *		@const char *s@ = pointer to a string
 *
 * Returns:	Nonzero if it matches, zero if it doesn't.
 *
 * Use:		Determines whether a string is matched by a class.  Assumes
 *		that the types are correct.
 */

extern int class_matchCommand(class_node */*c*/, const char */*s*/);

/* --- @class_matchHost@ --- *
 *
 * Arguments:	@class_node *c@ = pointer to root class node
 *		@struct in_addr a@ = IP address to match
 *
 * Returns:	Nonzero if it matches, zero if it doesn't.
 *
 * Use:		Determines whether a host matches a host class.  Assumes
 *		that the types are correct.  The actual mechanism is a bit
 *		odd here, but I think this is the Right Thing.  At each stage
 *		I try to match %%@/all/%% of the possible names for the host.
 *		Thus host `splat' with address 1.2.3.4 would fail to match
 *		the class "1.2.*" - "splat".  This seems to be what the
 *		author intuitively expects.  It's just a bit weird.
 */

extern int class_matchHost(class_node */*c*/, struct in_addr /*a*/);

/* --- @class_dump@ --- *
 *
 * Argumemnts:	@class_node *c@ = pointer to root node
 *		@int indent@ = indent depth
 *
 * Returns:	---
 *
 * Use:		Dumps a class to the trace output.
 */

extern void class_dump(class_node */*c*/, int /*indent*/);

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif