/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *      Sleepycat Software.  All rights reserved.
 */
#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)log.c 10.63 (Sleepycat) 10/10/98";
#endif /* not lint */

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

#include <errno.h>
#include <shqueue.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#endif

#include "db_int.h"
#include "shqueue.h"
#include "log.h"
#include "db_dispatch.h"
#include "txn.h"
#include "txn_auto.h"
#include "common_ext.h"

static int __log_recover __P((DB_LOG *));

/*
 * log_open --
 *      Initialize and/or join a log.
 */
int
log_open(path, flags, mode, dbenv, lpp)
        const char *path;
        u_int32_t flags;
        int mode;
        DB_ENV *dbenv;
        DB_LOG **lpp;
{
        DB_LOG *dblp;
        LOG *lp;
        int ret;

        /* Validate arguments. */
#ifdef HAVE_SPINLOCKS
#define OKFLAGS (DB_CREATE | DB_THREAD)
#else
#define OKFLAGS (DB_CREATE)
#endif
        if ((ret = __db_fchk(dbenv, "log_open", flags, OKFLAGS)) != 0)
                return (ret);

        /* Create and initialize the DB_LOG structure. */
        if ((ret = __os_calloc(1, sizeof(DB_LOG), &dblp)) != 0)
                return (ret);

        if (path != NULL && (ret = __os_strdup(path, &dblp->dir)) != 0)
                goto err;

        dblp->dbenv = dbenv;
        dblp->lfd = -1;
        ZERO_LSN(dblp->c_lsn);
        dblp->c_fd = -1;

        /*
         * The log region isn't fixed size because we store the registered
         * file names there.  Make it fairly large so that we don't have to
         * grow it.
         */
#define DEF_LOG_SIZE    (30 * 1024)

        /* Map in the region. */
        dblp->reginfo.dbenv = dbenv;
        dblp->reginfo.appname = DB_APP_LOG;
        if (path == NULL)
                dblp->reginfo.path = NULL;
        else
                if ((ret = __os_strdup(path, &dblp->reginfo.path)) != 0)
                        goto err;
        dblp->reginfo.file = DB_DEFAULT_LOG_FILE;
        dblp->reginfo.mode = mode;
        dblp->reginfo.size = DEF_LOG_SIZE;
        dblp->reginfo.dbflags = flags;
        dblp->reginfo.flags = REGION_SIZEDEF;
        if ((ret = __db_rattach(&dblp->reginfo)) != 0)
                goto err;

        /*
         * The LOG structure is first in the region, the rest of the region
         * is free space.
         */
        dblp->lp = dblp->reginfo.addr;
        dblp->addr = (u_int8_t *)dblp->lp + sizeof(LOG);

        /* Initialize a created region. */
        if (F_ISSET(&dblp->reginfo, REGION_CREATED)) {
                __db_shalloc_init(dblp->addr, DEF_LOG_SIZE - sizeof(LOG));

                /* Initialize the LOG structure. */
                lp = dblp->lp;
                lp->persist.lg_max = dbenv == NULL ? 0 : dbenv->lg_max;
                if (lp->persist.lg_max == 0)
                        lp->persist.lg_max = DEFAULT_MAX;
                lp->persist.magic = DB_LOGMAGIC;
                lp->persist.version = DB_LOGVERSION;
                lp->persist.mode = mode;
                SH_TAILQ_INIT(&lp->fq);

                /* Initialize LOG LSNs. */
                lp->lsn.file = 1;
                lp->lsn.offset = 0;
        }

        /* Initialize thread information, mutex. */
        if (LF_ISSET(DB_THREAD)) {
                F_SET(dblp, DB_AM_THREAD);
                if ((ret = __db_shalloc(dblp->addr,
                    sizeof(db_mutex_t), MUTEX_ALIGNMENT, &dblp->mutexp)) != 0)
                        goto err;
                (void)__db_mutex_init(dblp->mutexp, 0);
        }

        /*
         * If doing recovery, try and recover any previous log files before
         * releasing the lock.
         */
        if (F_ISSET(&dblp->reginfo, REGION_CREATED) &&
            (ret = __log_recover(dblp)) != 0)
                goto err;

        UNLOCK_LOGREGION(dblp);
        *lpp = dblp;
        return (0);

err:    if (dblp->reginfo.addr != NULL) {
                if (dblp->mutexp != NULL)
                        __db_shalloc_free(dblp->addr, dblp->mutexp);

                UNLOCK_LOGREGION(dblp);
                (void)__db_rdetach(&dblp->reginfo);
                if (F_ISSET(&dblp->reginfo, REGION_CREATED))
                        (void)log_unlink(path, 1, dbenv);
        }

        if (dblp->reginfo.path != NULL)
                __os_freestr(dblp->reginfo.path);
        if (dblp->dir != NULL)
                __os_freestr(dblp->dir);
        __os_free(dblp, sizeof(*dblp));
        return (ret);
}

/*
 * __log_panic --
 *      Panic a log.
 *
 * PUBLIC: void __log_panic __P((DB_ENV *));
 */
void
__log_panic(dbenv)
        DB_ENV *dbenv;
{
        if (dbenv->lg_info != NULL)
                dbenv->lg_info->lp->rlayout.panic = 1;
}

/*
 * __log_recover --
 *      Recover a log.
 */
static int
__log_recover(dblp)
        DB_LOG *dblp;
{
        DBT dbt;
        DB_LSN lsn;
        LOG *lp;
        u_int32_t chk;
        int cnt, found_checkpoint, ret;

        lp = dblp->lp;

        /*
         * Find a log file.  If none exist, we simply return, leaving
         * everything initialized to a new log.
         */
        if ((ret = __log_find(dblp, 0, &cnt)) != 0)
                return (ret);
        if (cnt == 0)
                return (0);

        /*
         * We have the last useful log file and we've loaded any persistent
         * information.  Pretend that the log is larger than it can possibly
         * be, and read the last file, looking for the last checkpoint and
         * the log's end.
         */
        lp->lsn.file = cnt + 1;
        lp->lsn.offset = 0;
        lsn.file = cnt;
        lsn.offset = 0;

        /* Set the cursor.  Shouldn't fail, leave error messages on. */
        memset(&dbt, 0, sizeof(dbt));
        if ((ret = __log_get(dblp, &lsn, &dbt, DB_SET, 0)) != 0)
                return (ret);

        /*
         * Read to the end of the file, saving checkpoints.  This will fail
         * at some point, so turn off error messages.
         */
        found_checkpoint = 0;
        while (__log_get(dblp, &lsn, &dbt, DB_NEXT, 1) == 0) {
                if (dbt.size < sizeof(u_int32_t))
                        continue;
                memcpy(&chk, dbt.data, sizeof(u_int32_t));
                if (chk == DB_txn_ckp) {
                        lp->chkpt_lsn = lsn;
                        found_checkpoint = 1;
                }
        }

        /*
         * We now know where the end of the log is.  Set the first LSN that
         * we want to return to an application and the LSN of the last known
         * record on disk.
         */
        lp->lsn = lp->s_lsn = lsn;
        lp->lsn.offset += dblp->c_len;

        /* Set up the current buffer information, too. */
        lp->len = dblp->c_len;
        lp->b_off = 0;
        lp->w_off = lp->lsn.offset;

        /*
         * It's possible that we didn't find a checkpoint because there wasn't
         * one in the last log file.  Start searching.
         */
        while (!found_checkpoint && cnt > 1) {
                lsn.file = --cnt;
                lsn.offset = 0;

                /* Set the cursor.  Shouldn't fail, leave error messages on. */
                if ((ret = __log_get(dblp, &lsn, &dbt, DB_SET, 0)) != 0)
                        return (ret);

                /*
                 * Read to the end of the file, saving checkpoints.  Shouldn't
                 * fail, leave error messages on.
                 */
                while (__log_get(dblp, &lsn, &dbt, DB_NEXT, 0) == 0) {
                        if (dbt.size < sizeof(u_int32_t))
                                continue;
                        memcpy(&chk, dbt.data, sizeof(u_int32_t));
                        if (chk == DB_txn_ckp) {
                                lp->chkpt_lsn = lsn;
                                found_checkpoint = 1;
                        }
                }
        }
        /*
         * Reset the cursor lsn to the beginning of the log, so that an
         * initial call to DB_NEXT does the right thing.
         */
        ZERO_LSN(dblp->c_lsn);

        /* If we never find a checkpoint, that's okay, just 0 it out. */
        if (!found_checkpoint)
                ZERO_LSN(lp->chkpt_lsn);

        /*
         * !!!
         * The test suite explicitly looks for this string -- don't change
         * it here unless you also change it there.
         */
        __db_err(dblp->dbenv,
            "Finding last valid log LSN: file: %lu offset %lu",
            (u_long)lp->lsn.file, (u_long)lp->lsn.offset);

        return (0);
}

/*
 * __log_find --
 *      Try to find a log file.  If find_first is set, valp will contain
 * the number of the first log file, else it will contain the number of
 * the last log file.
 *
 * PUBLIC: int __log_find __P((DB_LOG *, int, int *));
 */
int
__log_find(dblp, find_first, valp)
        DB_LOG *dblp;
        int find_first, *valp;
{
        u_int32_t clv, logval;
        int cnt, fcnt, ret;
        const char *dir;
        char **names, *p, *q;

        *valp = 0;

        /* Find the directory name. */
        if ((ret = __log_name(dblp, 1, &p, NULL, 0)) != 0)
                return (ret);
        if ((q = __db_rpath(p)) == NULL)
                dir = PATH_DOT;
        else {
                *q = '\0';
                dir = p;
        }

        /* Get the list of file names. */
        ret = __os_dirlist(dir, &names, &fcnt);
        __os_freestr(p);
        if (ret != 0) {
                __db_err(dblp->dbenv, "%s: %s", dir, strerror(ret));
                return (ret);
        }

        /*
         * Search for a valid log file name, return a value of 0 on
         * failure.
         *
         * XXX
         * Assumes that atoi(3) returns a 32-bit number.
         */
        for (cnt = fcnt, clv = logval = 0; --cnt >= 0;) {
                if (strncmp(names[cnt], LFPREFIX, sizeof(LFPREFIX) - 1) != 0)
                        continue;

                clv = atoi(names[cnt] + (sizeof(LFPREFIX) - 1));
                if (find_first) {
                        if (logval != 0 && clv > logval)
                                continue;
                } else
                        if (logval != 0 && clv < logval)
                                continue;

                if (__log_valid(dblp, clv, 1) == 0)
                        logval = clv;
        }

        *valp = logval;

        /* Discard the list. */
        __os_dirfree(names, fcnt);

        return (0);
}

/*
 * log_valid --
 *      Validate a log file.
 *
 * PUBLIC: int __log_valid __P((DB_LOG *, u_int32_t, int));
 */
int
__log_valid(dblp, number, set_persist)
        DB_LOG *dblp;
        u_int32_t number;
        int set_persist;
{
        LOGP persist;
        ssize_t nw;
        char *fname;
        int fd, ret;

        /* Try to open the log file. */
        if ((ret = __log_name(dblp,
            number, &fname, &fd, DB_RDONLY | DB_SEQUENTIAL)) != 0) {
                __os_freestr(fname);
                return (ret);
        }

        /* Try to read the header. */
        if ((ret = __os_seek(fd, 0, 0, sizeof(HDR), 0, SEEK_SET)) != 0 ||
            (ret = __os_read(fd, &persist, sizeof(LOGP), &nw)) != 0 ||
            nw != sizeof(LOGP)) {
                if (ret == 0)
                        ret = EIO;

                (void)__os_close(fd);

                __db_err(dblp->dbenv,
                    "Ignoring log file: %s: %s", fname, strerror(ret));
                goto err;
        }
        (void)__os_close(fd);

        /* Validate the header. */
        if (persist.magic != DB_LOGMAGIC) {
                __db_err(dblp->dbenv,
                    "Ignoring log file: %s: magic number %lx, not %lx",
                    fname, (u_long)persist.magic, (u_long)DB_LOGMAGIC);
                ret = EINVAL;
                goto err;
        }
        if (persist.version < DB_LOGOLDVER || persist.version > DB_LOGVERSION) {
                __db_err(dblp->dbenv,
                    "Ignoring log file: %s: unsupported log version %lu",
                    fname, (u_long)persist.version);
                ret = EINVAL;
                goto err;
        }

        /*
         * If we're going to use this log file, set the region's persistent
         * information based on the headers.
         */
        if (set_persist) {
                dblp->lp->persist.lg_max = persist.lg_max;
                dblp->lp->persist.mode = persist.mode;
        }
        ret = 0;

err:    __os_freestr(fname);
        return (ret);
}

/*
 * log_close --
 *      Close a log.
 */
int
log_close(dblp)
        DB_LOG *dblp;
{
        u_int32_t i;
        int ret, t_ret;

        LOG_PANIC_CHECK(dblp);

        /* We may have opened files as part of XA; if so, close them. */
        __log_close_files(dblp);

        /* Discard the per-thread pointer. */
        if (dblp->mutexp != NULL) {
                LOCK_LOGREGION(dblp);
                __db_shalloc_free(dblp->addr, dblp->mutexp);
                UNLOCK_LOGREGION(dblp);
        }

        /* Close the region. */
        ret = __db_rdetach(&dblp->reginfo);

        /* Close open files, release allocated memory. */
        if (dblp->lfd != -1 && (t_ret = __os_close(dblp->lfd)) != 0 && ret == 0)
                ret = t_ret;
        if (dblp->c_dbt.data != NULL)
                __os_free(dblp->c_dbt.data, dblp->c_dbt.ulen);
        if (dblp->c_fd != -1 &&
            (t_ret = __os_close(dblp->c_fd)) != 0 && ret == 0)
                ret = t_ret;
        if (dblp->dbentry != NULL) {
                for (i = 0; i < dblp->dbentry_cnt; i++)
                        if (dblp->dbentry[i].name != NULL)
                                __os_freestr(dblp->dbentry[i].name);
                __os_free(dblp->dbentry,
                    (dblp->dbentry_cnt * sizeof(DB_ENTRY)));
        }

        if (dblp->dir != NULL)
                __os_freestr(dblp->dir);

        if (dblp->reginfo.path != NULL)
                __os_freestr(dblp->reginfo.path);
        __os_free(dblp, sizeof(*dblp));

        return (ret);
}

/*
 * log_unlink --
 *      Exit a log.
 */
int
log_unlink(path, force, dbenv)
        const char *path;
        int force;
        DB_ENV *dbenv;
{
        REGINFO reginfo;
        int ret;

        memset(&reginfo, 0, sizeof(reginfo));
        reginfo.dbenv = dbenv;
        reginfo.appname = DB_APP_LOG;
        if (path != NULL && (ret = __os_strdup(path, &reginfo.path)) != 0)
                return (ret);
        reginfo.file = DB_DEFAULT_LOG_FILE;
        ret = __db_runlink(&reginfo, force);
        if (reginfo.path != NULL)
                __os_freestr(reginfo.path);
        return (ret);
}

/*
 * log_stat --
 *      Return LOG statistics.
 */
int
log_stat(dblp, gspp, db_malloc)
        DB_LOG *dblp;
        DB_LOG_STAT **gspp;
        void *(*db_malloc) __P((size_t));
{
        LOG *lp;
        int ret;

        *gspp = NULL;
        lp = dblp->lp;

        LOG_PANIC_CHECK(dblp);

        if ((ret = __os_malloc(sizeof(**gspp), db_malloc, gspp)) != 0)
                return (ret);

        /* Copy out the global statistics. */
        LOCK_LOGREGION(dblp);
        **gspp = lp->stat;

        (*gspp)->st_magic = lp->persist.magic;
        (*gspp)->st_version = lp->persist.version;
        (*gspp)->st_mode = lp->persist.mode;
        (*gspp)->st_lg_max = lp->persist.lg_max;

        (*gspp)->st_region_nowait = lp->rlayout.lock.mutex_set_nowait;
        (*gspp)->st_region_wait = lp->rlayout.lock.mutex_set_wait;

        (*gspp)->st_cur_file = lp->lsn.file;
        (*gspp)->st_cur_offset = lp->lsn.offset;

        (*gspp)->st_refcnt = lp->rlayout.refcnt;
        (*gspp)->st_regsize = lp->rlayout.size;

        UNLOCK_LOGREGION(dblp);

        return (0);
}