db_overflow.c

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

 *
 * Given a starting page number and a key, return <0, 0, >0 to indicate if the
 * key on the page is less than, equal to or greater than the key specified.
 * We optimize this by doing chunk at a time comparison unless the user has
 * specified a comparison function.  In this case, we need to materialize
 * the entire object and call their comparison routine.
 *
 * PUBLIC: int __db_moff __P((DB *, const DBT *, db_pgno_t, u_int32_t,
 * PUBLIC:     int (*)(DB *, const DBT *, const DBT *), int *));
 */
int
__db_moff(dbp, dbt, pgno, tlen, cmpfunc, cmpp)
	DB *dbp;
	const DBT *dbt;
	db_pgno_t pgno;
	u_int32_t tlen;
	int (*cmpfunc) __P((DB *, const DBT *, const DBT *)), *cmpp;
{
	DBT local_dbt;
	DB_MPOOLFILE *mpf;
	PAGE *pagep;
	void *buf;
	u_int32_t bufsize, cmp_bytes, key_left;
	u_int8_t *p1, *p2;
	int ret;

	mpf = dbp->mpf;

	/*
	 * If there is a user-specified comparison function, build a
	 * contiguous copy of the key, and call it.
	 */
	if (cmpfunc != NULL) {
		memset(&local_dbt, 0, sizeof(local_dbt));
		buf = NULL;
		bufsize = 0;

		if ((ret = __db_goff(dbp,
		    &local_dbt, tlen, pgno, &buf, &bufsize)) != 0)
			return (ret);
		/* Pass the key as the first argument */
		*cmpp = cmpfunc(dbp, dbt, &local_dbt);
		__os_free(dbp->dbenv, buf);
		return (0);
	}

	/* While there are both keys to compare. */
	for (*cmpp = 0, p1 = dbt->data,
	    key_left = dbt->size; key_left > 0 && pgno != PGNO_INVALID;) {
		if ((ret = mpf->get(mpf, &pgno, 0, &pagep)) != 0)
			return (ret);

		cmp_bytes = OV_LEN(pagep) < key_left ? OV_LEN(pagep) : key_left;
		tlen -= cmp_bytes;
		key_left -= cmp_bytes;
		for (p2 = (u_int8_t *)pagep + P_OVERHEAD(dbp);
		    cmp_bytes-- > 0; ++p1, ++p2)
			if (*p1 != *p2) {
				*cmpp = (long)*p1 - (long)*p2;
				break;
			}
		pgno = NEXT_PGNO(pagep);
		if ((ret = mpf->put(mpf, pagep, 0)) != 0)
			return (ret);
		if (*cmpp != 0)
			return (0);
	}
	if (key_left > 0)		/* DBT is longer than the page key. */
		*cmpp = 1;
	else if (tlen > 0)		/* DBT is shorter than the page key. */
		*cmpp = -1;
	else
		*cmpp = 0;

	return (0);
}

/*
 * __db_vrfy_overflow --
 *	Verify overflow page.
 *
 * PUBLIC: int __db_vrfy_overflow __P((DB *, VRFY_DBINFO *, PAGE *, db_pgno_t,
 * PUBLIC:     u_int32_t));
 */
int
__db_vrfy_overflow(dbp, vdp, h, pgno, flags)
	DB *dbp;
	VRFY_DBINFO *vdp;
	PAGE *h;
	db_pgno_t pgno;
	u_int32_t flags;
{
	VRFY_PAGEINFO *pip;
	int isbad, ret, t_ret;

	isbad = 0;
	if ((ret = __db_vrfy_getpageinfo(vdp, pgno, &pip)) != 0)
		return (ret);

	if ((ret = __db_vrfy_datapage(dbp, vdp, h, pgno, flags)) != 0) {
		if (ret == DB_VERIFY_BAD)
			isbad = 1;
		else
			goto err;
	}

	pip->refcount = OV_REF(h);
	if (pip->refcount < 1) {
		EPRINT((dbp->dbenv,
		    "Page %lu: overflow page has zero reference count",
		    (u_long)pgno));
		isbad = 1;
	}

	/* Just store for now. */
	pip->olen = HOFFSET(h);

err:	if ((t_ret = __db_vrfy_putpageinfo(dbp->dbenv, vdp, pip)) != 0)
		ret = t_ret;
	return ((ret == 0 && isbad == 1) ? DB_VERIFY_BAD : ret);
}

/*
 * __db_vrfy_ovfl_structure --
 *	Walk a list of overflow pages, avoiding cycles and marking
 *	pages seen.
 *
 * PUBLIC: int __db_vrfy_ovfl_structure
 * PUBLIC:     __P((DB *, VRFY_DBINFO *, db_pgno_t, u_int32_t, u_int32_t));
 */
int
__db_vrfy_ovfl_structure(dbp, vdp, pgno, tlen, flags)
	DB *dbp;
	VRFY_DBINFO *vdp;
	db_pgno_t pgno;
	u_int32_t tlen;
	u_int32_t flags;
{
	DB *pgset;
	VRFY_PAGEINFO *pip;
	db_pgno_t next, prev;
	int isbad, p, ret, t_ret;
	u_int32_t refcount;

	pgset = vdp->pgset;
	DB_ASSERT(pgset != NULL);
	isbad = 0;

	/* This shouldn't happen, but just to be sure. */
	if (!IS_VALID_PGNO(pgno))
		return (DB_VERIFY_BAD);

	/*
	 * Check the first prev_pgno;  it ought to be PGNO_INVALID,
	 * since there's no prev page.
	 */
	if ((ret = __db_vrfy_getpageinfo(vdp, pgno, &pip)) != 0)
		return (ret);

	/* The refcount is stored on the first overflow page. */
	refcount = pip->refcount;

	if (pip->type != P_OVERFLOW) {
		EPRINT((dbp->dbenv,
		    "Page %lu: overflow page of invalid type %lu",
		    (u_long)pgno, (u_long)pip->type));
		ret = DB_VERIFY_BAD;
		goto err;		/* Unsafe to continue. */
	}

	prev = pip->prev_pgno;
	if (prev != PGNO_INVALID) {
		EPRINT((dbp->dbenv,
	    "Page %lu: first page in overflow chain has a prev_pgno %lu",
		    (u_long)pgno, (u_long)prev));
		isbad = 1;
	}

	for (;;) {
		/*
		 * This is slightly gross.  Btree leaf pages reference
		 * individual overflow trees multiple times if the overflow page
		 * is the key to a duplicate set.  The reference count does not
		 * reflect this multiple referencing.  Thus, if this is called
		 * during the structure verification of a btree leaf page, we
		 * check to see whether we've seen it from a leaf page before
		 * and, if we have, adjust our count of how often we've seen it
		 * accordingly.
		 *
		 * (This will screw up if it's actually referenced--and
		 * correctly refcounted--from two different leaf pages, but
		 * that's a very unlikely brokenness that we're not checking for
		 * anyway.)
		 */

		if (LF_ISSET(ST_OVFL_LEAF)) {
			if (F_ISSET(pip, VRFY_OVFL_LEAFSEEN)) {
				if ((ret =
				    __db_vrfy_pgset_dec(pgset, pgno)) != 0)
					goto err;
			} else
				F_SET(pip, VRFY_OVFL_LEAFSEEN);
		}

		if ((ret = __db_vrfy_pgset_get(pgset, pgno, &p)) != 0)
			goto err;

		/*
		 * We may have seen this elsewhere, if the overflow entry
		 * has been promoted to an internal page.
		 */
		if ((u_int32_t)p > refcount) {
			EPRINT((dbp->dbenv,
			    "Page %lu: encountered twice in overflow traversal",
			    (u_long)pgno));
			ret = DB_VERIFY_BAD;
			goto err;
		}
		if ((ret = __db_vrfy_pgset_inc(pgset, pgno)) != 0)
			goto err;

		/* Keep a running tab on how much of the item we've seen. */
		tlen -= pip->olen;

		/* Send feedback to the application about our progress. */
		if (!LF_ISSET(DB_SALVAGE))
			__db_vrfy_struct_feedback(dbp, vdp);

		next = pip->next_pgno;

		/* Are we there yet? */
		if (next == PGNO_INVALID)
			break;

		/*
		 * We've already checked this when we saved it, but just
		 * to be sure...
		 */
		if (!IS_VALID_PGNO(next)) {
			DB_ASSERT(0);
			EPRINT((dbp->dbenv,
			    "Page %lu: bad next_pgno %lu on overflow page",
			    (u_long)pgno, (u_long)next));
			ret = DB_VERIFY_BAD;
			goto err;
		}

		if ((ret = __db_vrfy_putpageinfo(dbp->dbenv, vdp, pip)) != 0 ||
		    (ret = __db_vrfy_getpageinfo(vdp, next, &pip)) != 0)
			return (ret);
		if (pip->prev_pgno != pgno) {
			EPRINT((dbp->dbenv,
		"Page %lu: bad prev_pgno %lu on overflow page (should be %lu)",
			    (u_long)next, (u_long)pip->prev_pgno,
			    (u_long)pgno));
			isbad = 1;
			/*
			 * It's safe to continue because we have separate
			 * cycle detection.
			 */
		}

		pgno = next;
	}

	if (tlen > 0) {
		isbad = 1;
		EPRINT((dbp->dbenv,
		    "Page %lu: overflow item incomplete", (u_long)pgno));
	}

err:	if ((t_ret =
	    __db_vrfy_putpageinfo(dbp->dbenv, vdp, pip)) != 0 && ret == 0)
		ret = t_ret;
	return ((ret == 0 && isbad == 1) ? DB_VERIFY_BAD : ret);
}

/*
 * __db_safe_goff --
 *	Get an overflow item, very carefully, from an untrusted database,
 *	in the context of the salvager.
 *
 * PUBLIC: int __db_safe_goff __P((DB *, VRFY_DBINFO *, db_pgno_t,
 * PUBLIC:     DBT *, void **, u_int32_t));
 */
int
__db_safe_goff(dbp, vdp, pgno, dbt, buf, flags)
	DB *dbp;
	VRFY_DBINFO *vdp;
	db_pgno_t pgno;
	DBT *dbt;
	void **buf;
	u_int32_t flags;
{
	DB_MPOOLFILE *mpf;
	PAGE *h;
	int ret, t_ret;
	u_int32_t bytesgot, bytes;
	u_int8_t *src, *dest;

	mpf = dbp->mpf;
	h = NULL;
	ret = t_ret = 0;
	bytesgot = bytes = 0;

	while ((pgno != PGNO_INVALID) && (IS_VALID_PGNO(pgno))) {
		/*
		 * Mark that we're looking at this page;  if we've seen it
		 * already, quit.
		 */
		if ((ret = __db_salvage_markdone(vdp, pgno)) != 0)
			break;

		if ((ret = mpf->get(mpf, &pgno, 0, &h)) != 0)
			break;

		/*
		 * Make sure it's really an overflow page, unless we're
		 * being aggressive, in which case we pretend it is.
		 */
		if (!LF_ISSET(DB_AGGRESSIVE) && TYPE(h) != P_OVERFLOW) {
			ret = DB_VERIFY_BAD;
			break;
		}

		src = (u_int8_t *)h + P_OVERHEAD(dbp);
		bytes = OV_LEN(h);

		if (bytes + P_OVERHEAD(dbp) > dbp->pgsize)
			bytes = dbp->pgsize - P_OVERHEAD(dbp);

		if ((ret = __os_realloc(dbp->dbenv,
		    bytesgot + bytes, buf)) != 0)
			break;

		dest = (u_int8_t *)*buf + bytesgot;
		bytesgot += bytes;

		memcpy(dest, src, bytes);

		pgno = NEXT_PGNO(h);

		if ((ret = mpf->put(mpf, h, 0)) != 0)
			break;
		h = NULL;
	}

	/*
	 * If we're being aggressive, salvage a partial datum if there
	 * was an error somewhere along the way.
	 */
	if (ret == 0 || LF_ISSET(DB_AGGRESSIVE)) {
		dbt->size = bytesgot;
		dbt->data = *buf;
	}

	/* If we broke out on error, don't leave pages pinned. */
	if (h != NULL && (t_ret = mpf->put(mpf, h, 0)) != 0 && ret == 0)
		ret = t_ret;

	return (ret);
}