symtab.c

早期freebsd实现

void
moveentry(ep, newname)
	register struct entry *ep;
	char *newname;
{
	struct entry *np;
	char *cp;

	np = lookupparent(newname);
	if (np == NULL)
		badentry(ep, "cannot move ROOT");
	if (np != ep->e_parent) {
		removeentry(ep);
		ep->e_parent = np;
		ep->e_sibling = np->e_entries;
		np->e_entries = ep;
	}
	cp = rindex(newname, '/') + 1;
	freename(ep->e_name);
	ep->e_name = savename(cp);
	ep->e_namlen = strlen(cp);
	if (strcmp(gentempname(ep), ep->e_name) == 0)
		ep->e_flags |= TMPNAME;
	else
		ep->e_flags &= ~TMPNAME;
}

/*
 * Remove an entry in the tree structure
 */
static void
removeentry(ep)
	register struct entry *ep;
{
	register struct entry *np;

	np = ep->e_parent;
	if (np->e_entries == ep) {
		np->e_entries = ep->e_sibling;
	} else {
		for (np = np->e_entries; np != NULL; np = np->e_sibling) {
			if (np->e_sibling == ep) {
				np->e_sibling = ep->e_sibling;
				break;
			}
		}
		if (np == NULL)
			badentry(ep, "cannot find entry in parent list");
	}
}

/*
 * Table of unused string entries, sorted by length.
 * 
 * Entries are allocated in STRTBLINCR sized pieces so that names
 * of similar lengths can use the same entry. The value of STRTBLINCR
 * is chosen so that every entry has at least enough space to hold
 * a "struct strtbl" header. Thus every entry can be linked onto an
 * apprpriate free list.
 *
 * NB. The macro "allocsize" below assumes that "struct strhdr"
 *     has a size that is a power of two.
 */
struct strhdr {
	struct strhdr *next;
};

#define STRTBLINCR	(sizeof(struct strhdr))
#define allocsize(size)	(((size) + 1 + STRTBLINCR - 1) & ~(STRTBLINCR - 1))

static struct strhdr strtblhdr[allocsize(NAME_MAX) / STRTBLINCR];

/*
 * Allocate space for a name. It first looks to see if it already
 * has an appropriate sized entry, and if not allocates a new one.
 */
char *
savename(name)
	char *name;
{
	struct strhdr *np;
	long len;
	char *cp;

	if (name == NULL)
		panic("bad name\n");
	len = strlen(name);
	np = strtblhdr[len / STRTBLINCR].next;
	if (np != NULL) {
		strtblhdr[len / STRTBLINCR].next = np->next;
		cp = (char *)np;
	} else {
		cp = malloc((unsigned)allocsize(len));
		if (cp == NULL)
			panic("no space for string table\n");
	}
	(void) strcpy(cp, name);
	return (cp);
}

/*
 * Free space for a name. The resulting entry is linked onto the
 * appropriate free list.
 */
void
freename(name)
	char *name;
{
	struct strhdr *tp, *np;
	
	tp = &strtblhdr[strlen(name) / STRTBLINCR];
	np = (struct strhdr *)name;
	np->next = tp->next;
	tp->next = np;
}

/*
 * Useful quantities placed at the end of a dumped symbol table.
 */
struct symtableheader {
	long	volno;
	long	stringsize;
	long	entrytblsize;
	time_t	dumptime;
	time_t	dumpdate;
	ino_t	maxino;
	long	ntrec;
};

/*
 * dump a snapshot of the symbol table
 */
void
dumpsymtable(filename, checkpt)
	char *filename;
	long checkpt;
{
	register struct entry *ep, *tep;
	register ino_t i;
	struct entry temp, *tentry;
	long mynum = 1, stroff = 0;
	FILE *fd;
	struct symtableheader hdr;

	vprintf(stdout, "Check pointing the restore\n");
	if (Nflag)
		return;
	if ((fd = fopen(filename, "w")) == NULL) {
		fprintf(stderr, "fopen: %s\n", strerror(errno));
		panic("cannot create save file %s for symbol table\n",
			filename);
	}
	clearerr(fd);
	/*
	 * Assign indicies to each entry
	 * Write out the string entries
	 */
	for (i = ROOTINO; i < maxino; i++) {
		for (ep = lookupino(i); ep != NULL; ep = ep->e_links) {
			ep->e_index = mynum++;
			(void) fwrite(ep->e_name, sizeof(char),
			       (int)allocsize(ep->e_namlen), fd);
		}
	}
	/*
	 * Convert pointers to indexes, and output
	 */
	tep = &temp;
	stroff = 0;
	for (i = ROOTINO; i < maxino; i++) {
		for (ep = lookupino(i); ep != NULL; ep = ep->e_links) {
			bcopy((char *)ep, (char *)tep,
				(long)sizeof(struct entry));
			tep->e_name = (char *)stroff;
			stroff += allocsize(ep->e_namlen);
			tep->e_parent = (struct entry *)ep->e_parent->e_index;
			if (ep->e_links != NULL)
				tep->e_links =
					(struct entry *)ep->e_links->e_index;
			if (ep->e_sibling != NULL)
				tep->e_sibling =
					(struct entry *)ep->e_sibling->e_index;
			if (ep->e_entries != NULL)
				tep->e_entries =
					(struct entry *)ep->e_entries->e_index;
			if (ep->e_next != NULL)
				tep->e_next =
					(struct entry *)ep->e_next->e_index;
			(void) fwrite((char *)tep, sizeof(struct entry), 1, fd);
		}
	}
	/*
	 * Convert entry pointers to indexes, and output
	 */
	for (i = 0; i < entrytblsize; i++) {
		if (entry[i] == NULL)
			tentry = NULL;
		else
			tentry = (struct entry *)entry[i]->e_index;
		(void) fwrite((char *)&tentry, sizeof(struct entry *), 1, fd);
	}
	hdr.volno = checkpt;
	hdr.maxino = maxino;
	hdr.entrytblsize = entrytblsize;
	hdr.stringsize = stroff;
	hdr.dumptime = dumptime;
	hdr.dumpdate = dumpdate;
	hdr.ntrec = ntrec;
	(void) fwrite((char *)&hdr, sizeof(struct symtableheader), 1, fd);
	if (ferror(fd)) {
		fprintf(stderr, "fwrite: %s\n", strerror(errno));
		panic("output error to file %s writing symbol table\n",
			filename);
	}
	(void) fclose(fd);
}

/*
 * Initialize a symbol table from a file
 */
void
initsymtable(filename)
	char *filename;
{
	char *base;
	long tblsize;
	register struct entry *ep;
	struct entry *baseep, *lep;
	struct symtableheader hdr;
	struct stat stbuf;
	register long i;
	int fd;

	vprintf(stdout, "Initialize symbol table.\n");
	if (filename == NULL) {
		entrytblsize = maxino / HASHFACTOR;
		entry = (struct entry **)
			calloc((unsigned)entrytblsize, sizeof(struct entry *));
		if (entry == (struct entry **)NULL)
			panic("no memory for entry table\n");
		ep = addentry(".", ROOTINO, NODE);
		ep->e_flags |= NEW;
		return;
	}
	if ((fd = open(filename, O_RDONLY, 0)) < 0) {
		fprintf(stderr, "open: %s\n", strerror(errno));
		panic("cannot open symbol table file %s\n", filename);
	}
	if (fstat(fd, &stbuf) < 0) {
		fprintf(stderr, "stat: %s\n", strerror(errno));
		panic("cannot stat symbol table file %s\n", filename);
	}
	tblsize = stbuf.st_size - sizeof(struct symtableheader);
	base = calloc(sizeof(char), (unsigned)tblsize);
	if (base == NULL)
		panic("cannot allocate space for symbol table\n");
	if (read(fd, base, (int)tblsize) < 0 ||
	    read(fd, (char *)&hdr, sizeof(struct symtableheader)) < 0) {
		fprintf(stderr, "read: %s\n", strerror(errno));
		panic("cannot read symbol table file %s\n", filename);
	}
	switch (command) {
	case 'r':
		/*
		 * For normal continuation, insure that we are using
		 * the next incremental tape
		 */
		if (hdr.dumpdate != dumptime) {
			if (hdr.dumpdate < dumptime)
				fprintf(stderr, "Incremental tape too low\n");
			else
				fprintf(stderr, "Incremental tape too high\n");
			done(1);
		}
		break;
	case 'R':
		/*
		 * For restart, insure that we are using the same tape
		 */
		curfile.action = SKIP;
		dumptime = hdr.dumptime;
		dumpdate = hdr.dumpdate;
		if (!bflag)
			newtapebuf(hdr.ntrec);
		getvol(hdr.volno);
		break;
	default:
		panic("initsymtable called from command %c\n", command);
		break;
	}
	maxino = hdr.maxino;
	entrytblsize = hdr.entrytblsize;
	entry = (struct entry **)
		(base + tblsize - (entrytblsize * sizeof(struct entry *)));
	baseep = (struct entry *)(base + hdr.stringsize - sizeof(struct entry));
	lep = (struct entry *)entry;
	for (i = 0; i < entrytblsize; i++) {
		if (entry[i] == NULL)
			continue;
		entry[i] = &baseep[(long)entry[i]];
	}
	for (ep = &baseep[1]; ep < lep; ep++) {
		ep->e_name = base + (long)ep->e_name;
		ep->e_parent = &baseep[(long)ep->e_parent];
		if (ep->e_sibling != NULL)
			ep->e_sibling = &baseep[(long)ep->e_sibling];
		if (ep->e_links != NULL)
			ep->e_links = &baseep[(long)ep->e_links];
		if (ep->e_entries != NULL)
			ep->e_entries = &baseep[(long)ep->e_entries];
		if (ep->e_next != NULL)
			ep->e_next = &baseep[(long)ep->e_next];
	}
}