symtab.c

早期freebsd实现

/*
 * Copyright (c) 1983, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)symtab.c	8.1 (Berkeley) 6/5/93";
#endif /* not lint */

/*
 * These routines maintain the symbol table which tracks the state
 * of the file system being restored. They provide lookup by either
 * name or inode number. They also provide for creation, deletion,
 * and renaming of entries. Because of the dynamic nature of pathnames,
 * names should not be saved, but always constructed just before they
 * are needed, by calling "myname".
 */

#include <sys/param.h>
#include <sys/stat.h>

#include <ufs/ufs/dinode.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "restore.h"
#include "extern.h"

/*
 * The following variables define the inode symbol table.
 * The primary hash table is dynamically allocated based on
 * the number of inodes in the file system (maxino), scaled by
 * HASHFACTOR. The variable "entry" points to the hash table;
 * the variable "entrytblsize" indicates its size (in entries).
 */
#define HASHFACTOR 5
static struct entry **entry;
static long entrytblsize;

static void		 addino __P((ino_t, struct entry *));
static struct entry	*lookupparent __P((char *));
static void		 removeentry __P((struct entry *));

/*
 * Look up an entry by inode number
 */
struct entry *
lookupino(inum)
	ino_t inum;
{
	register struct entry *ep;

	if (inum < ROOTINO || inum >= maxino)
		return (NULL);
	for (ep = entry[inum % entrytblsize]; ep != NULL; ep = ep->e_next)
		if (ep->e_ino == inum)
			return (ep);
	return (NULL);
}

/*
 * Add an entry into the entry table
 */
static void
addino(inum, np)
	ino_t inum;
	struct entry *np;
{
	struct entry **epp;

	if (inum < ROOTINO || inum >= maxino)
		panic("addino: out of range %d\n", inum);
	epp = &entry[inum % entrytblsize];
	np->e_ino = inum;
	np->e_next = *epp;
	*epp = np;
	if (dflag)
		for (np = np->e_next; np != NULL; np = np->e_next)
			if (np->e_ino == inum)
				badentry(np, "duplicate inum");
}

/*
 * Delete an entry from the entry table
 */
void
deleteino(inum)
	ino_t inum;
{
	register struct entry *next;
	struct entry **prev;

	if (inum < ROOTINO || inum >= maxino)
		panic("deleteino: out of range %d\n", inum);
	prev = &entry[inum % entrytblsize];
	for (next = *prev; next != NULL; next = next->e_next) {
		if (next->e_ino == inum) {
			next->e_ino = 0;
			*prev = next->e_next;
			return;
		}
		prev = &next->e_next;
	}
	panic("deleteino: %d not found\n", inum);
}

/*
 * Look up an entry by name
 */
struct entry *
lookupname(name)
	char *name;
{
	register struct entry *ep;
	register char *np, *cp;
	char buf[MAXPATHLEN];

	cp = name;
	for (ep = lookupino(ROOTINO); ep != NULL; ep = ep->e_entries) {
		for (np = buf; *cp != '/' && *cp != '\0'; )
			*np++ = *cp++;
		*np = '\0';
		for ( ; ep != NULL; ep = ep->e_sibling)
			if (strcmp(ep->e_name, buf) == 0)
				break;
		if (ep == NULL)
			break;
		if (*cp++ == '\0')
			return (ep);
	}
	return (NULL);
}

/*
 * Look up the parent of a pathname
 */
static struct entry *
lookupparent(name)
	char *name;
{
	struct entry *ep;
	char *tailindex;

	tailindex = rindex(name, '/');
	if (tailindex == NULL)
		return (NULL);
	*tailindex = '\0';
	ep = lookupname(name);
	*tailindex = '/';
	if (ep == NULL)
		return (NULL);
	if (ep->e_type != NODE)
		panic("%s is not a directory\n", name);
	return (ep);
}

/*
 * Determine the current pathname of a node or leaf
 */
char *
myname(ep)
	register struct entry *ep;
{
	register char *cp;
	static char namebuf[MAXPATHLEN];

	for (cp = &namebuf[MAXPATHLEN - 2]; cp > &namebuf[ep->e_namlen]; ) {
		cp -= ep->e_namlen;
		bcopy(ep->e_name, cp, (long)ep->e_namlen);
		if (ep == lookupino(ROOTINO))
			return (cp);
		*(--cp) = '/';
		ep = ep->e_parent;
	}
	panic("%s: pathname too long\n", cp);
	return(cp);
}

/*
 * Unused symbol table entries are linked together on a freelist
 * headed by the following pointer.
 */
static struct entry *freelist = NULL;

/*
 * add an entry to the symbol table
 */
struct entry *
addentry(name, inum, type)
	char *name;
	ino_t inum;
	int type;
{
	register struct entry *np, *ep;

	if (freelist != NULL) {
		np = freelist;
		freelist = np->e_next;
		bzero((char *)np, (long)sizeof(struct entry));
	} else {
		np = (struct entry *)calloc(1, sizeof(struct entry));
		if (np == NULL)
			panic("no memory to extend symbol table\n");
	}
	np->e_type = type & ~LINK;
	ep = lookupparent(name);
	if (ep == NULL) {
		if (inum != ROOTINO || lookupino(ROOTINO) != NULL)
			panic("bad name to addentry %s\n", name);
		np->e_name = savename(name);
		np->e_namlen = strlen(name);
		np->e_parent = np;
		addino(ROOTINO, np);
		return (np);
	}
	np->e_name = savename(rindex(name, '/') + 1);
	np->e_namlen = strlen(np->e_name);
	np->e_parent = ep;
	np->e_sibling = ep->e_entries;
	ep->e_entries = np;
	if (type & LINK) {
		ep = lookupino(inum);
		if (ep == NULL)
			panic("link to non-existant name\n");
		np->e_ino = inum;
		np->e_links = ep->e_links;
		ep->e_links = np;
	} else if (inum != 0) {
		if (lookupino(inum) != NULL)
			panic("duplicate entry\n");
		addino(inum, np);
	}
	return (np);
}

/*
 * delete an entry from the symbol table
 */
void
freeentry(ep)
	register struct entry *ep;
{
	register struct entry *np;
	ino_t inum;

	if (ep->e_flags != REMOVED)
		badentry(ep, "not marked REMOVED");
	if (ep->e_type == NODE) {
		if (ep->e_links != NULL)
			badentry(ep, "freeing referenced directory");
		if (ep->e_entries != NULL)
			badentry(ep, "freeing non-empty directory");
	}
	if (ep->e_ino != 0) {
		np = lookupino(ep->e_ino);
		if (np == NULL)
			badentry(ep, "lookupino failed");
		if (np == ep) {
			inum = ep->e_ino;
			deleteino(inum);
			if (ep->e_links != NULL)
				addino(inum, ep->e_links);
		} else {
			for (; np != NULL; np = np->e_links) {
				if (np->e_links == ep) {
					np->e_links = ep->e_links;
					break;
				}
			}
			if (np == NULL)
				badentry(ep, "link not found");
		}
	}
	removeentry(ep);
	freename(ep->e_name);
	ep->e_next = freelist;
	freelist = ep;
}

/*
 * Relocate an entry in the tree structure
 */