db_vrfy.c

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/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2000-2004
 *	Sleepycat Software.  All rights reserved.
 *
 * $Id: db_vrfy.c,v 1.138 2004/10/11 18:47:50 bostic Exp $
 */

#include "db_config.h"

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/db_page.h"
#include "dbinc/db_shash.h"
#include "dbinc/db_swap.h"
#include "dbinc/db_verify.h"
#include "dbinc/btree.h"
#include "dbinc/hash.h"
#include "dbinc/lock.h"
#include "dbinc/mp.h"
#include "dbinc/qam.h"
#include "dbinc/txn.h"

/*
 * This is the code for DB->verify, the DB database consistency checker.
 * For now, it checks all subdatabases in a database, and verifies
 * everything it knows how to (i.e. it's all-or-nothing, and one can't
 * check only for a subset of possible problems).
 */

static u_int __db_guesspgsize __P((DB_ENV *, DB_FH *));
static int   __db_is_valid_magicno __P((u_int32_t, DBTYPE *));
static int   __db_is_valid_pagetype __P((u_int32_t));
static int   __db_meta2pgset
		__P((DB *, VRFY_DBINFO *, db_pgno_t, u_int32_t, DB *));
static int   __db_salvage_subdbpg __P((DB *, VRFY_DBINFO *,
		PAGE *, void *, int (*)(void *, const void *), u_int32_t));
static int   __db_salvage_subdbs __P((DB *, VRFY_DBINFO *, void *,
		int(*)(void *, const void *), u_int32_t, int *));
static int   __db_salvage_unknowns __P((DB *, VRFY_DBINFO *, void *,
		int (*)(void *, const void *), u_int32_t));
static int   __db_verify __P((DB *, const char *, const char *,
		void *, int (*)(void *, const void *), u_int32_t));
static int   __db_verify_arg __P((DB *, const char *, void *, u_int32_t));
static int   __db_vrfy_freelist
		__P((DB *, VRFY_DBINFO *, db_pgno_t, u_int32_t));
static int   __db_vrfy_invalid
		__P((DB *, VRFY_DBINFO *, PAGE *, db_pgno_t, u_int32_t));
static int   __db_vrfy_orderchkonly __P((DB *,
		VRFY_DBINFO *, const char *, const char *, u_int32_t));
static int   __db_vrfy_pagezero __P((DB *, VRFY_DBINFO *, DB_FH *, u_int32_t));
static int   __db_vrfy_subdbs
		__P((DB *, VRFY_DBINFO *, const char *, u_int32_t));
static int   __db_vrfy_structure
		__P((DB *, VRFY_DBINFO *, const char *, db_pgno_t, u_int32_t));
static int   __db_vrfy_walkpages __P((DB *, VRFY_DBINFO *,
		void *, int (*)(void *, const void *), u_int32_t));

#define	VERIFY_FLAGS							\
    (DB_AGGRESSIVE |							\
     DB_NOORDERCHK | DB_ORDERCHKONLY | DB_PRINTABLE | DB_SALVAGE | DB_UNREF)

/*
 * __db_verify_pp --
 *	DB->verify public interface.
 *
 * PUBLIC: int __db_verify_pp
 * PUBLIC:     __P((DB *, const char *, const char *, FILE *, u_int32_t));
 */
int
__db_verify_pp(dbp, file, database, outfile, flags)
	DB *dbp;
	const char *file, *database;
	FILE *outfile;
	u_int32_t flags;
{
	/*
	 * __db_verify_pp is a wrapper to __db_verify_internal, which lets
	 * us pass appropriate equivalents to FILE * in from the non-C APIs.
	 */
	return (__db_verify_internal(dbp,
	    file, database, outfile, __db_pr_callback, flags));
}

/*
 * __db_verify_internal --
 *
 * PUBLIC: int __db_verify_internal __P((DB *, const char *,
 * PUBLIC:     const char *, void *, int (*)(void *, const void *), u_int32_t));
 */
int
__db_verify_internal(dbp, fname, dname, handle, callback, flags)
	DB *dbp;
	const char *fname, *dname;
	void *handle;
	int (*callback) __P((void *, const void *));
	u_int32_t flags;
{
	DB_ENV *dbenv;
	int ret, t_ret;

	dbenv = dbp->dbenv;

	PANIC_CHECK(dbenv);
	DB_ILLEGAL_AFTER_OPEN(dbp, "DB->verify");

#ifdef HAVE_FTRUNCATE
	/*
	 * If we're using ftruncate to abort page-allocation functions, there
	 * should never be unreferenced pages.  Always check for unreferenced
	 * pages on those systems.
	 */
	if (!LF_ISSET(DB_SALVAGE))
		LF_SET(DB_UNREF);
#endif

	if ((ret = __db_verify_arg(dbp, dname, handle, flags)) != 0)
		goto err;

	/*
	 * Forbid working in an environment that uses transactions or
	 * locking;  we're going to be looking at the file freely,
	 * and while we're not going to modify it, we aren't obeying
	 * locking conventions either.
	 */
	if (TXN_ON(dbenv) || LOCKING_ON(dbenv) || LOGGING_ON(dbenv)) {
		__db_err(dbenv,
    "DB->verify may not be used with transactions, logging, or locking");
		ret = EINVAL;
		goto err;
	}

	ret = __db_verify(dbp, fname, dname, handle, callback, flags);

	/* Db.verify is a DB handle destructor. */
err:	if ((t_ret = __db_close(dbp, NULL, 0)) != 0 && ret == 0)
		ret = t_ret;

	return (ret);
}

/*
 * __db_verify_arg --
 *	Check DB->verify arguments.
 */
static int
__db_verify_arg(dbp, dname, handle, flags)
	DB *dbp;
	const char *dname;
	void *handle;
	u_int32_t flags;
{
	DB_ENV *dbenv;
	int ret;

	dbenv = dbp->dbenv;

	if ((ret = __db_fchk(dbenv, "DB->verify", flags, VERIFY_FLAGS)) != 0)
		return (ret);

	/*
	 * DB_SALVAGE is mutually exclusive with the other flags except
	 * DB_AGGRESSIVE, DB_PRINTABLE.
	 *
	 * DB_AGGRESSIVE and DB_PRINTABLE are only meaningful when salvaging.
	 *
	 * DB_SALVAGE requires an output stream.
	 */
	if (LF_ISSET(DB_SALVAGE)) {
		if (LF_ISSET(~(DB_AGGRESSIVE | DB_PRINTABLE | DB_SALVAGE)))
			return (__db_ferr(dbenv, "DB->verify", 1));
		if (handle == NULL) {
			__db_err(dbenv,
			    "DB_SALVAGE requires a an output handle");
			return (EINVAL);
		}
	} else
		if (LF_ISSET(DB_AGGRESSIVE | DB_PRINTABLE))
			return (__db_ferr(dbenv, "DB->verify", 1));

	/* 
	 * DB_ORDERCHKONLY is mutually exclusive with DB_SALVAGE and
	 * DB_NOORDERCHK, and requires a database name.
	 */
	if ((ret = __db_fcchk(dbenv, "DB->verify", flags,
	    DB_ORDERCHKONLY, DB_SALVAGE | DB_NOORDERCHK)) != 0)
		return (ret);
	if (LF_ISSET(DB_ORDERCHKONLY) && dname == NULL) {
		__db_err(dbenv, "DB_ORDERCHKONLY requires a database name");
		return (EINVAL);
	}
	return (0);
}

/*
 * __db_verify --
 *	Walk the entire file page-by-page, either verifying with or without
 *	dumping in db_dump -d format, or DB_SALVAGE-ing whatever key/data
 *	pairs can be found and dumping them in standard (db_load-ready)
 *	dump format.
 *
 *	(Salvaging isn't really a verification operation, but we put it
 *	here anyway because it requires essentially identical top-level
 *	code.)
 *
 *	flags may be 0, DB_NOORDERCHK, DB_ORDERCHKONLY, or DB_SALVAGE
 *	(and optionally DB_AGGRESSIVE).
 */
static int
__db_verify(dbp, name, subdb, handle, callback, flags)
	DB *dbp;
	const char *name, *subdb;
	void *handle;
	int (*callback) __P((void *, const void *));
	u_int32_t flags;
{
	DB_ENV *dbenv;
	DB_FH *fhp;
	VRFY_DBINFO *vdp;
	int has, isbad, ret, t_ret;
	char *real_name;

	dbenv = dbp->dbenv;
	fhp = NULL;
	vdp = NULL;
	real_name = NULL;
	has = ret = isbad = 0;

	F_SET(dbp, DB_AM_VERIFYING);

	/* Initialize any feedback function. */
	if (!LF_ISSET(DB_SALVAGE) && dbp->db_feedback != NULL)
		dbp->db_feedback(dbp, DB_VERIFY, 0);

	/*
	 * We don't know how large the cache is, and if the database
	 * in question uses a small page size--which we don't know
	 * yet!--it may be uncomfortably small for the default page
	 * size [#2143].  However, the things we need temporary
	 * databases for in dbinfo are largely tiny, so using a
	 * 1024-byte pagesize is probably not going to be a big hit,
	 * and will make us fit better into small spaces.
	 */
	if ((ret = __db_vrfy_dbinfo_create(dbenv, 1024, &vdp)) != 0)
		goto err;

	/*
	 * Note whether the user has requested that we use printable
	 * chars where possible.  We won't get here with this flag if
	 * we're not salvaging.
	 */
	if (LF_ISSET(DB_PRINTABLE))
		F_SET(vdp, SALVAGE_PRINTABLE);

	/* Find the real name of the file. */
	if ((ret = __db_appname(dbenv,
	    DB_APP_DATA, name, 0, NULL, &real_name)) != 0)
		goto err;

	/*
	 * Our first order of business is to verify page 0, which is
	 * the metadata page for the master database of subdatabases
	 * or of the only database in the file.  We want to do this by hand
	 * rather than just calling __db_open in case it's corrupt--various
	 * things in __db_open might act funny.
	 *
	 * Once we know the metadata page is healthy, I believe that it's
	 * safe to open the database normally and then use the page swapping
	 * code, which makes life easier.
	 */
	if ((ret = __os_open(dbenv, real_name, DB_OSO_RDONLY, 0, &fhp)) != 0)
		goto err;

	/* Verify the metadata page 0; set pagesize and type. */
	if ((ret = __db_vrfy_pagezero(dbp, vdp, fhp, flags)) != 0) {
		if (ret == DB_VERIFY_BAD)
			isbad = 1;
		else
			goto err;
	}

	/*
	 * We can assume at this point that dbp->pagesize and dbp->type are
	 * set correctly, or at least as well as they can be, and that
	 * locking, logging, and txns are not in use.  Thus we can trust
	 * the memp code not to look at the page, and thus to be safe
	 * enough to use.
	 *
	 * The dbp is not open, but the file is open in the fhp, and we
	 * cannot assume that __db_open is safe.  Call __db_dbenv_setup,
	 * the [safe] part of __db_open that initializes the environment--
	 * and the mpool--manually.
	 */
	if ((ret = __db_dbenv_setup(dbp, NULL,
	    name, TXN_INVALID, DB_ODDFILESIZE | DB_RDONLY)) != 0)
		return (ret);

	/*
	 * Set our name in the Queue subsystem;  we may need it later
	 * to deal with extents.
	 */
	if (dbp->type == DB_QUEUE &&
	    (ret = __qam_set_ext_data(dbp, name)) != 0)
		return (ret);

	/* Mark the dbp as opened, so that we correctly handle its close. */
	F_SET(dbp, DB_AM_OPEN_CALLED);

	/* Find out the page number of the last page in the database. */
	__memp_last_pgno(dbp->mpf, &vdp->last_pgno);

	/*
	 * DB_ORDERCHKONLY is a special case;  our file consists of
	 * several subdatabases, which use different hash, bt_compare,
	 * and/or dup_compare functions.  Consequently, we couldn't verify
	 * sorting and hashing simply by calling DB->verify() on the file.
	 * DB_ORDERCHKONLY allows us to come back and check those things;  it
	 * requires a subdatabase, and assumes that everything but that
	 * database's sorting/hashing is correct.
	 */
	if (LF_ISSET(DB_ORDERCHKONLY)) {
		ret = __db_vrfy_orderchkonly(dbp, vdp, name, subdb, flags);
		goto done;
	}

	/*
	 * When salvaging, we use a db to keep track of whether we've seen a
	 * given overflow or dup page in the course of traversing normal data.
	 * If in the end we have not, we assume its key got lost and print it
	 * with key "UNKNOWN".
	 */
	if (LF_ISSET(DB_SALVAGE)) {
		if ((ret = __db_salvage_init(vdp)) != 0)
			return (ret);

		/*
		 * If we're not being aggressive, attempt to crack subdbs.
		 * "has" will indicate whether the attempt has succeeded
		 * (even in part), meaning that we have some semblance of
		 * subdbs;  on the walkpages pass, we print out
		 * whichever data pages we have not seen.
		 */
		if (!LF_ISSET(DB_AGGRESSIVE) && (__db_salvage_subdbs(dbp,
		    vdp, handle, callback, flags, &has)) != 0)
			isbad = 1;

		/*
		 * If we have subdatabases, we need to signal that if
		 * any keys are found that don't belong to a subdatabase,
		 * they'll need to have an "__OTHER__" subdatabase header
		 * printed first.  Flag this.  Else, print a header for
		 * the normal, non-subdb database.
		 */
		if (has == 1)
			F_SET(vdp, SALVAGE_PRINTHEADER);
	}

	if ((ret =
	    __db_vrfy_walkpages(dbp, vdp, handle, callback, flags)) != 0) {
		if (ret == DB_VERIFY_BAD)
			isbad = 1;
		else
			goto err;
	}

	/* If we're verifying, verify inter-page structure. */
	if (!LF_ISSET(DB_SALVAGE) && isbad == 0)
		if ((ret =
		    __db_vrfy_structure(dbp, vdp, name, 0, flags)) != 0) {
			if (ret == DB_VERIFY_BAD)
				isbad = 1;
			else
				goto err;
		}

	/*
	 * If we're salvaging, output with key UNKNOWN any overflow or dup pages
	 * we haven't been able to put in context.  Then destroy the salvager's
	 * state-saving database.
	 */
	if (LF_ISSET(DB_SALVAGE)) {
		if ((ret = __db_salvage_unknowns(dbp,
		    vdp, handle, callback, flags)) != 0)
			isbad = 1;
		/* No return value, since there's little we can do. */
		__db_salvage_destroy(vdp);
	}

err:	if (LF_ISSET(DB_SALVAGE) &&
	    (has == 0 || F_ISSET(vdp, SALVAGE_PRINTFOOTER)))
		(void)__db_prfooter(handle, callback);

	/* Send feedback that we're done. */
done:	if (!LF_ISSET(DB_SALVAGE) && dbp->db_feedback != NULL)
		dbp->db_feedback(dbp, DB_VERIFY, 100);

	if (fhp != NULL &&
	    (t_ret = __os_closehandle(dbenv, fhp)) != 0 && ret == 0)
		ret = t_ret;
	if (vdp != NULL &&
	    (t_ret = __db_vrfy_dbinfo_destroy(dbenv, vdp)) != 0 && ret == 0)
		ret = t_ret;
	if (real_name != NULL)
		__os_free(dbenv, real_name);

	/*
	 * DB_VERIFY_FATAL is a private error, translate to a public one.
	 *
	 * If we didn't find a page, it's probably a page number was corrupted.
	 * Return the standard corruption error.
	 *
	 * Otherwise, if we found corruption along the way, set the return.
	 */
	if (ret == DB_VERIFY_FATAL ||
	    ret == DB_PAGE_NOTFOUND || (ret == 0 && isbad == 1))
		ret = DB_VERIFY_BAD;

	/* Make sure there's a public complaint if we found corruption. */
	if (ret != 0)
		__db_err(dbenv, "%s: %s", name, db_strerror(ret));

	return (ret);
}

/*
 * __db_vrfy_pagezero --
 *	Verify the master metadata page.  Use seek, read, and a local buffer
 *	rather than the DB paging code, for safety.
 *
 *	Must correctly (or best-guess) set dbp->type and dbp->pagesize.
 */
static int
__db_vrfy_pagezero(dbp, vdp, fhp, flags)
	DB *dbp;
	VRFY_DBINFO *vdp;
	DB_FH *fhp;
	u_int32_t flags;
{
	DBMETA *meta;
	DB_ENV *dbenv;
	VRFY_PAGEINFO *pip;
	db_pgno_t freelist;
	size_t nr;
	int isbad, ret, swapped;
	u_int8_t mbuf[DBMETASIZE];

	isbad = ret = swapped = 0;
	freelist = 0;
	dbenv = dbp->dbenv;
	meta = (DBMETA *)mbuf;
	dbp->type = DB_UNKNOWN;

	/*
	 * Seek to the metadata page.
	 * Note that if we're just starting a verification, dbp->pgsize
	 * may be zero;  this is okay, as we want page zero anyway and
	 * 0*0 == 0.
	 */
	if ((ret = __os_seek(dbenv, fhp, 0, 0, 0, 0, DB_OS_SEEK_SET)) != 0 ||
	    (ret = __os_read(dbenv, fhp, mbuf, DBMETASIZE, &nr)) != 0) {
		__db_err(dbenv,
		    "Metadata page %lu cannot be read: %s",
		    (u_long)PGNO_BASE_MD, db_strerror(ret));
		return (ret);
	}

	if (nr != DBMETASIZE) {
		EPRINT((dbenv,
		    "Page %lu: Incomplete metadata page",
		    (u_long)PGNO_BASE_MD));
		return (DB_VERIFY_FATAL);
	}

	if ((ret = __db_chk_meta(dbenv, dbp, meta, 1)) != 0) {
		EPRINT((dbenv,
		    "Page %lu: metadata page corrupted", (u_long)PGNO_BASE_MD));
		isbad = 1;
		if (ret != -1) {
			EPRINT((dbenv,
			    "Page %lu: could not check metadata page",
			    (u_long)PGNO_BASE_MD));
			return (DB_VERIFY_FATAL);
		}
	}

	/*
	 * Check all of the fields that we can.
	 *
	 * 08-11: Current page number.  Must == pgno.
	 * Note that endianness doesn't matter--it's zero.
	 */
	if (meta->pgno != PGNO_BASE_MD) {
		isbad = 1;
		EPRINT((dbenv, "Page %lu: pgno incorrectly set to %lu",
		    (u_long)PGNO_BASE_MD, (u_long)meta->pgno));
	}