log_get.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

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2002
 *	Sleepycat Software.  All rights reserved.
 */
#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: log_get.c,v 11.81 2002/08/14 20:09:27 bostic Exp $";
#endif /* not lint */

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

#include <string.h>
#include <unistd.h>
#endif

#include "db_int.h"
#include "dbinc/crypto.h"
#include "dbinc/db_page.h"
#include "dbinc/hmac.h"
#include "dbinc/log.h"
#include "dbinc/hash.h"

typedef enum { L_ALREADY, L_ACQUIRED, L_NONE } RLOCK;

static int __log_c_close __P((DB_LOGC *, u_int32_t));
static int __log_c_get __P((DB_LOGC *, DB_LSN *, DBT *, u_int32_t));
static int __log_c_get_int __P((DB_LOGC *, DB_LSN *, DBT *, u_int32_t));
static int __log_c_hdrchk __P((DB_LOGC *, HDR *, int *));
static int __log_c_incursor __P((DB_LOGC *, DB_LSN *, HDR *, u_int8_t **));
static int __log_c_inregion __P((DB_LOGC *,
	       DB_LSN *, RLOCK *, DB_LSN *, HDR *, u_int8_t **));
static int __log_c_io __P((DB_LOGC *,
	       u_int32_t, u_int32_t, void *, size_t *, int *));
static int __log_c_ondisk __P((DB_LOGC *,
	       DB_LSN *, DB_LSN *, int, HDR *, u_int8_t **, int *));
static int __log_c_set_maxrec __P((DB_LOGC *, char *));
static int __log_c_shortread __P((DB_LOGC *, int));

/*
 * __log_cursor --
 *	Create a log cursor.
 *
 * PUBLIC: int __log_cursor __P((DB_ENV *, DB_LOGC **, u_int32_t));
 */
int
__log_cursor(dbenv, logcp, flags)
	DB_ENV *dbenv;
	DB_LOGC **logcp;
	u_int32_t flags;
{
	DB_LOGC *logc;
	int ret;

	PANIC_CHECK(dbenv);
	ENV_REQUIRES_CONFIG(dbenv,
	    dbenv->lg_handle, "DB_ENV->log_cursor", DB_INIT_LOG);

	*logcp = NULL;

	/* Validate arguments. */
	if ((ret = __db_fchk(dbenv, "DB_ENV->log_cursor", flags, 0)) != 0)
		return (ret);

	/* Allocate memory for the cursor. */
	if ((ret = __os_calloc(dbenv, 1, sizeof(DB_LOGC), &logc)) != 0)
		goto err;
	if ((ret = __os_calloc(dbenv, 1, sizeof(DB_FH), &logc->c_fh)) != 0)
		goto err;

	logc->bp_size = DB_LOGC_BUF_SIZE;
	if ((ret = __os_malloc(dbenv, logc->bp_size, &logc->bp)) != 0)
		goto err;

	logc->dbenv = dbenv;
	logc->close = __log_c_close;
	logc->get = __log_c_get;

	*logcp = logc;
	return (0);

err:	if (logc != NULL) {
		if (logc->c_fh != NULL)
			__os_free(dbenv, logc->c_fh);
		__os_free(dbenv, logc);
	}

	return (ret);
}

/*
 * __log_c_close --
 *	Close a log cursor.
 */
static int
__log_c_close(logc, flags)
	DB_LOGC *logc;
	u_int32_t flags;
{
	DB_ENV *dbenv;
	int ret;

	dbenv = logc->dbenv;

	PANIC_CHECK(dbenv);
	if ((ret = __db_fchk(dbenv, "DB_LOGC->close", flags, 0)) != 0)
		return (ret);

	if (F_ISSET(logc->c_fh, DB_FH_VALID))
		(void)__os_closehandle(dbenv, logc->c_fh);

	if (logc->c_dbt.data != NULL)
		__os_free(dbenv, logc->c_dbt.data);

	__os_free(dbenv, logc->bp);
	__os_free(dbenv, logc->c_fh);
	__os_free(dbenv, logc);

	return (0);
}

/*
 * __log_c_get --
 *	Get a log record.
 */
static int
__log_c_get(logc, alsn, dbt, flags)
	DB_LOGC *logc;
	DB_LSN *alsn;
	DBT *dbt;
	u_int32_t flags;
{
	DB_ENV *dbenv;
	DB_LSN saved_lsn;
	int ret;

	dbenv = logc->dbenv;

	PANIC_CHECK(dbenv);

	/* Validate arguments. */
	switch (flags) {
	case DB_CURRENT:
	case DB_FIRST:
	case DB_LAST:
	case DB_NEXT:
	case DB_PREV:
		break;
	case DB_SET:
		if (IS_ZERO_LSN(*alsn)) {
			__db_err(dbenv, "DB_LOGC->get: invalid LSN");
			return (EINVAL);
		}
		break;
	default:
		return (__db_ferr(dbenv, "DB_LOGC->get", 1));
	}

	/*
	 * On error, we take care not to overwrite the caller's LSN.  This
	 * is because callers looking for the end of the log loop using the
	 * DB_NEXT flag, and expect to take the last successful lsn out of
	 * the passed-in structure after DB_LOGC->get fails with DB_NOTFOUND.
	 *
	 * !!!
	 * This line is often flagged an uninitialized memory read during a
	 * Purify or similar tool run, as the application didn't initialize
	 * *alsn.  If the application isn't setting the DB_SET flag, there is
	 * no reason it should have initialized *alsn, but we can't know that
	 * and we want to make sure we never overwrite whatever the application
	 * put in there.
	 */
	saved_lsn = *alsn;

	/*
	 * If we get one of the log's header records as a result of doing a
	 * DB_FIRST, DB_NEXT, DB_LAST or DB_PREV, repeat the operation, log
	 * file header records aren't useful to applications.
	 */
	if ((ret = __log_c_get_int(logc, alsn, dbt, flags)) != 0) {
		*alsn = saved_lsn;
		return (ret);
	}
	if (alsn->offset == 0 && (flags == DB_FIRST ||
	    flags == DB_NEXT || flags == DB_LAST || flags == DB_PREV)) {
		switch (flags) {
		case DB_FIRST:
			flags = DB_NEXT;
			break;
		case DB_LAST:
			flags = DB_PREV;
			break;
		}
		if (F_ISSET(dbt, DB_DBT_MALLOC)) {
			__os_free(dbenv, dbt->data);
			dbt->data = NULL;
		}
		if ((ret = __log_c_get_int(logc, alsn, dbt, flags)) != 0) {
			*alsn = saved_lsn;
			return (ret);
		}
	}

	return (0);
}

/*
 * __log_c_get_int --
 *	Get a log record; internal version.
 */
static int
__log_c_get_int(logc, alsn, dbt, flags)
	DB_LOGC *logc;
	DB_LSN *alsn;
	DBT *dbt;
	u_int32_t flags;
{
	DB_CIPHER *db_cipher;
	DB_ENV *dbenv;
	DB_LOG *dblp;
	DB_LSN last_lsn, nlsn;
	HDR hdr;
	LOG *lp;
	RLOCK rlock;
	logfile_validity status;
	u_int32_t cnt;
	u_int8_t *rp;
	int eof, is_hmac, ret;

	dbenv = logc->dbenv;
	dblp = dbenv->lg_handle;
	lp = dblp->reginfo.primary;
	is_hmac = 0;

	/*
	 * We don't acquire the log region lock until we need it, and we
	 * release it as soon as we're done.
	 */
	rlock = F_ISSET(logc, DB_LOG_LOCKED) ? L_ALREADY : L_NONE;

	nlsn = logc->c_lsn;
	switch (flags) {
	case DB_NEXT:				/* Next log record. */
		if (!IS_ZERO_LSN(nlsn)) {
			/* Increment the cursor by the cursor record size. */
			nlsn.offset += logc->c_len;
			break;
		}
		flags = DB_FIRST;
		/* FALLTHROUGH */
	case DB_FIRST:				/* First log record. */
		/* Find the first log file. */
		if ((ret = __log_find(dblp, 1, &cnt, &status)) != 0)
			goto err;

		/*
		 * DB_LV_INCOMPLETE:
		 *	Theoretically, the log file we want could be created
		 *	but not yet written, the "first" log record must be
		 *	in the log buffer.
		 * DB_LV_NORMAL:
		 * DB_LV_OLD_READABLE:
		 *	We found a log file we can read.
		 * DB_LV_NONEXISTENT:
		 *	No log files exist, the "first" log record must be in
		 *	the log buffer.
		 * DB_LV_OLD_UNREADABLE:
		 *	No readable log files exist, we're at the cross-over
		 *	point between two versions.  The "first" log record
		 *	must be in the log buffer.
		 */
		switch (status) {
		case DB_LV_INCOMPLETE:
			DB_ASSERT(lp->lsn.file == cnt);
			/* FALLTHROUGH */
		case DB_LV_NORMAL:
		case DB_LV_OLD_READABLE:
			nlsn.file = cnt;
			break;
		case DB_LV_NONEXISTENT:
			nlsn.file = 1;
			DB_ASSERT(lp->lsn.file == nlsn.file);
			break;
		case DB_LV_OLD_UNREADABLE:
			nlsn.file = cnt + 1;
			DB_ASSERT(lp->lsn.file == nlsn.file);
			break;
		}
		nlsn.offset = 0;
		break;
	case DB_CURRENT:			/* Current log record. */
		break;
	case DB_PREV:				/* Previous log record. */
		if (!IS_ZERO_LSN(nlsn)) {
			/* If at start-of-file, move to the previous file. */
			if (nlsn.offset == 0) {
				if (nlsn.file == 1 ||
				    __log_valid(dblp,
					nlsn.file - 1, 0, &status) != 0) {
					ret = DB_NOTFOUND;
					goto err;
				}

				if (status != DB_LV_NORMAL &&
				    status != DB_LV_OLD_READABLE) {
					ret = DB_NOTFOUND;
					goto err;
				}

				--nlsn.file;
			}
			nlsn.offset = logc->c_prev;
			break;
		}
		/* FALLTHROUGH */
	case DB_LAST:				/* Last log record. */
		if (rlock == L_NONE) {
			rlock = L_ACQUIRED;
			R_LOCK(dbenv, &dblp->reginfo);
		}
		nlsn.file = lp->lsn.file;
		nlsn.offset = lp->lsn.offset - lp->len;
		break;
	case DB_SET:				/* Set log record. */
		nlsn = *alsn;
		break;
	}

	if (0) {				/* Move to the next file. */
next_file:	++nlsn.file;
		nlsn.offset = 0;
	}

	/*
	 * The above switch statement should have set nlsn to the lsn of
	 * the requested record.
	 */

	if (CRYPTO_ON(dbenv)) {
		hdr.size = HDR_CRYPTO_SZ;
		is_hmac = 1;
	} else {
		hdr.size = HDR_NORMAL_SZ;
		is_hmac = 0;
	}
	/* Check to see if the record is in the cursor's buffer. */
	if ((ret = __log_c_incursor(logc, &nlsn, &hdr, &rp)) != 0)
		goto err;
	if (rp != NULL)
		goto cksum;

	/*
	 * Look to see if we're moving backward in the log with the last record
	 * coming from the disk -- it means the record can't be in the region's
	 * buffer.  Else, check the region's buffer.
	 *
	 * If the record isn't in the region's buffer, we're going to have to
	 * read the record from disk.  We want to make a point of not reading
	 * past the end of the logical log (after recovery, there may be data
	 * after the end of the logical log, not to mention the log file may
	 * have been pre-allocated).  So, zero out last_lsn, and initialize it
	 * inside __log_c_inregion -- if it's still zero when we check it in
	 * __log_c_ondisk, that's OK, it just means the logical end of the log
	 * isn't an issue for this request.
	 */
	ZERO_LSN(last_lsn);
	if (!F_ISSET(logc, DB_LOG_DISK) ||
	    log_compare(&nlsn, &logc->c_lsn) > 0) {
		F_CLR(logc, DB_LOG_DISK);

		if ((ret = __log_c_inregion(logc,
		    &nlsn, &rlock, &last_lsn, &hdr, &rp)) != 0)
			goto err;
		if (rp != NULL)
			goto cksum;
	}

	/*
	 * We have to read from an on-disk file to retrieve the record.
	 * If we ever can't retrieve the record at offset 0, we're done,
	 * return EOF/DB_NOTFOUND.
	 *
	 * Discard the region lock if we're still holding it, the on-disk
	 * reading routines don't need it.
	 */
	if (rlock == L_ACQUIRED) {
		rlock = L_NONE;
		R_UNLOCK(dbenv, &dblp->reginfo);
	}
	if ((ret = __log_c_ondisk(
	    logc, &nlsn, &last_lsn, flags, &hdr, &rp, &eof)) != 0)
		goto err;
	if (eof == 1) {
		/*
		 * Only DB_NEXT automatically moves to the next file, and
		 * it only happens once.
		 */
		if (flags != DB_NEXT || nlsn.offset == 0)
			return (DB_NOTFOUND);
		goto next_file;
	}
	F_SET(logc, DB_LOG_DISK);

cksum:	/*
	 * Discard the region lock if we're still holding it.  (The path to
	 * get here is that we acquired the lock because of the caller's
	 * flag argument, but we found the record in the cursor's buffer.
	 * Improbable, but it's easy to avoid.
	 */
	if (rlock == L_ACQUIRED) {
		rlock = L_NONE;
		R_UNLOCK(dbenv, &dblp->reginfo);
	}

	/*
	 * Checksum: there are two types of errors -- a configuration error
	 * or a checksum mismatch.  The former is always bad.  The latter is
	 * OK if we're searching for the end of the log, and very, very bad
	 * if we're reading random log records.
	 */
	db_cipher = dbenv->crypto_handle;
	if ((ret = __db_check_chksum(dbenv, db_cipher,
	    hdr.chksum, rp + hdr.size, hdr.len - hdr.size, is_hmac)) != 0) {
		if (F_ISSET(logc, DB_LOG_SILENT_ERR)) {
			if (ret == 0 || ret == -1)
				ret = EIO;
		} else if (ret == -1) {
			__db_err(dbenv,
		    "DB_LOGC->get: log record checksum mismatch");
			__db_err(dbenv,
		    "DB_LOGC->get: catastrophic recovery may be required");
			ret = __db_panic(dbenv, DB_RUNRECOVERY);
		}
		goto err;
	}

	/*
	 * If we got a 0-length record, that means we're in the midst of
	 * some bytes that got 0'd as the result of a vtruncate.  We're
	 * going to have to retry.
	 */
	if (hdr.len == 0) {
		switch (flags) {
		case DB_FIRST:
		case DB_NEXT:
			/* Zero'd records always indicate the end of a file. */
			goto next_file;

		case DB_LAST:
		case DB_PREV:
			/*
			 * We should never get here.  If we recover a log
			 * file with 0's at the end, we'll treat the 0'd
			 * headers as the end of log and ignore them.  If
			 * we're reading backwards from another file, then
			 * the first record in that new file should have its
			 * prev field set correctly.
			 */
			 __db_err(dbenv,
		"Encountered zero length records while traversing backwards");
			 DB_ASSERT(0);
		case DB_SET:
		default:
			/* Return the 0-length record. */
			break;
		}
	}

	/* Copy the record into the user's DBT. */
	if ((ret = __db_retcopy(dbenv, dbt, rp + hdr.size,
	    (u_int32_t)(hdr.len - hdr.size),
	    &logc->c_dbt.data, &logc->c_dbt.ulen)) != 0)
		goto err;

	if (CRYPTO_ON(dbenv)) {
		if ((ret = db_cipher->decrypt(dbenv, db_cipher->data,
		    hdr.iv, dbt->data, hdr.len - hdr.size)) != 0) {
			ret = EAGAIN;
			goto err;
		}
		/*
		 * Return the original log record size to the user,
		 * even though we've allocated more than that, possibly.
		 * The log record is decrypted in the user dbt, not in
		 * the buffer, so we must do this here after decryption,
		 * not adjust the len passed to the __db_retcopy call.
		 */
		dbt->size = hdr.orig_size;
	}

	/* Update the cursor and the returned LSN. */
	*alsn = nlsn;
	logc->c_lsn = nlsn;
	logc->c_len = hdr.len;
	logc->c_prev = hdr.prev;

err:	if (rlock == L_ACQUIRED)
		R_UNLOCK(dbenv, &dblp->reginfo);

	return (ret);
}

/*
 * __log_c_incursor --
 *	Check to see if the requested record is in the cursor's buffer.
 */
static int
__log_c_incursor(logc, lsn, hdr, pp)
	DB_LOGC *logc;
	DB_LSN *lsn;
	HDR *hdr;
	u_int8_t **pp;
{
	u_int8_t *p;

	*pp = NULL;

	/*
	 * Test to see if the requested LSN could be part of the cursor's
	 * buffer.
	 *
	 * The record must be part of the same file as the cursor's buffer.
	 * The record must start at a byte offset equal to or greater than
	 * the cursor buffer.
	 * The record must not start at a byte offset after the cursor
	 * buffer's end.
	 */