lib/libnisdb/db_log.cc

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 *  db_log.cc
 *
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <stdio.h>
#include <errno.h>

#include <malloc.h>
#include <string.h>
#ifdef TDRPC
#include <sysent.h>
#endif
#include <unistd.h>

#include "db_headers.h"
#include "db_log.h"

#include "nisdb_mt.h"

static void
delete_log_entry(db_log_entry *lentry)
{
    db_query *q;
    entry_object *obj;
    if (lentry) {
        if ((q = lentry->get_query())) {
            delete q;
        }
        if ((obj = lentry->get_object())) {
            free_entry(obj);
        }
        delete lentry;
    }
}

/*
 * Execute given function 'func' on log.
 * function takes as arguments: pointer to log entry, character pointer to
 * another argument, and pointer to an integer, which is used as a counter.
 * 'func' should increment this value for each successful application.
 * The log is traversed until either 'func' returns FALSE, or when the log
 * is exhausted.  The second argument to 'execute_on_log' is passed as the
 * second argument to 'func'.  The third argument, 'clean' determines whether
 * the log entry is deleted after the function has been applied.
 * Returns the number of times that 'func' incremented its third argument.
 */
int
db_log::execute_on_log(bool_t (*func) (db_log_entry *, char *, int *),
                char* arg, bool_t clean)
{
    db_log_entry    *j;
    int count = 0;
    bool_t done = FALSE;

    WRITELOCK(this, 0, "w db_log::execute_on_log");
    if (open() == TRUE) {   // open log
        while (!done) {
            j = get();
            if (j == NULL)
                break;
            if ((*func)(j, arg, &count) == FALSE) done = TRUE;
            if (clean) delete_log_entry(j);
        }

        sync_log();
        close();
    }
    WRITEUNLOCK(this, count, "wu db_log::execute_on_log");

    return (count);
}

static bool_t
print_log_entry(db_log_entry *j, char * /* dummy */, int *count)
{
    j->print();
    ++ *count;
    return (TRUE);
}

/* Print contents of log file to stdout */
int
db_log::print()
{
    return (execute_on_log(&(print_log_entry), NULL));
}

/* Make copy of current log to log pointed to by 'f'. */
int
db_log::copy(db_log *f)
{
    db_log_entry *j;
    int l, ret = 0;

    WRITELOCK(f, -1, "w f db_log::copy");
    if ((l = acqnonexcl()) != 0) {
        WRITEUNLOCK(f, l, "wu f db_log::copy");
        return (l);
    }
    for (;;) {
        j = get();
        if (j == NULL)
            break;
        if (f->append(j) < 0) {
            WARNING_M(
            "db_log::copy: could not append to log file: ");
            ret = -1;
            break;
        }
        delete_log_entry(j);
    }
    if ((l = relnonexcl()) != 0) {
        ret = l;
    }
    WRITEUNLOCK(f, ret, "wu f db_log::copy");
    return (ret);
}

/* Rewinds current log */
int
db_log::rewind()
{
    return (fseek(file, 0L, 0));
}

/*
 * Return the next element in current log; return NULL if end of log or error.
 * Log must have been opened for READ.
 */
db_log_entry
*db_log::get()
{
    db_log_entry *j;

    READLOCK(this, NULL, "r db_log::get");
    if (mode != PICKLE_READ) {
        READUNLOCK(this, NULL, "ru db_log::get");
        return (NULL);
    }

    j = new db_log_entry;

    if (j == NULL) {
        READUNLOCK(this, NULL, "ru db_log::get");
        return (NULL);
    }
    if (xdr_db_log_entry(&(xdr), j) == FALSE) {
        delete_log_entry (j);
/*    WARNING("Could not sucessfully finish reading log"); */
        READUNLOCK(this, NULL, "ru db_log::get");
        return (NULL);
    }
    if (! j->sane()) {
        WARNING("truncated log entry found");
        delete_log_entry(j);
        j = NULL;
    }
    READUNLOCK(this, j, "ru db_log::get");
    return (j);
}

/* Append given log entry to log. */
int
db_log::append(db_log_entry *j)
{
    int status;

    WRITELOCK(this, -1, "w db_log::append");
    if (mode != PICKLE_APPEND) {
        WRITEUNLOCK(this, -1, "wu db_log::append");
        return (-1);
    }

    /* xdr returns TRUE if successful, FALSE otherwise */
    status = ((xdr_db_log_entry(&(xdr), j)) ? 0 : -1);
    if (status < 0) {
        WARNING("db_log: could not write log entry");
    } else {
        syncstate++;
    }
    WRITEUNLOCK(this, status, "wu db_log::append");
    return (status);
}

int
copy_log_file(char *oldname, char *newname) {

    int from, to, ret = 0;
    ssize_t size, w, b;
    char    buf[8192];

    if ((from = open(oldname, O_RDONLY, 0666)) < 0) {
        if (errno == ENOENT) {
            return (0);
        } else {
            return (errno);
        }
    }
    if ((to = open(newname, O_WRONLY|O_CREAT|O_TRUNC, 0660)) < 0) {
        ret = errno;
        (void) close(from);
        return (ret);
    }

    while ((size = read(from, buf, sizeof (buf))) > 0) {
        b = 0;
        while (size > 0) {
            w = write(to, &buf[b], size);
            if (w < 0) {
                size == -1;
                break;
            }
            size -= w;
            b += w;
        }
        if (size != 0) {
            ret = errno;
            break;
        }
    }

    (void) close(from);

    if (ret != 0) {
        errno = ret;
        WARNING_M("db_log: error copying log file")
        (void) close(to);
        return (ret);
    }

    if (fsync(to) != 0) {
        ret = errno;
        WARNING_M("db_log: error syncing log file");
    }

    (void) close(to);

    return (ret);

}

/*
 * Return value is expected to be the usual C convention of non-zero
 * for success, 0 for failure.
 */
int
db_log::sync_log()
{
    int status, err;

    WRITELOCK(this, -1, "w db_log::sync_log");
    status = fflush(file);
    if (status < 0) {
        WARNING("db_log: could not flush log entry to disk");
        WRITEUNLOCK(this, status, "wu db_log::sync_log");
        return (status);
    }

    status = fsync(fileno(file));
    if (status < 0) {
        WARNING("db_log: could not sync log entry to disk");
    } else if (tmplog != 0) {
        if (syncstate == 0) {
            /* Log already stable; nothing to do */
            err = 0;
        } else if ((err = copy_log_file(tmplog, stablelog)) == 0) {
            if (rename(stablelog, oldlog) != 0) {
                WARNING_M("db_log: could not mv stable log");
            } else {
                syncstate = 0;
            }
        } else {
            errno = err;
            WARNING_M("db_log: could not stabilize log");
        }
        status = (err == 0);
    } else {
        /*
         * Successful sync of file, but no tmplog to sync
         * so we make sure we return 'success'.
         */
        status = 1;
    }
    WRITEUNLOCK(this, status, "wu db_log::sync_log");
    return (status);
}

int
db_log::close() {

    int ret;

    WRITELOCK(this, -1, "w db_log::close");
    if (mode != PICKLE_READ && oldlog != 0) {
        if (syncstate != 0) {
            WARNING("db_log: closing unstable tmp log");
        }
        filename = oldlog;
        oldlog = 0;
    }

    ret = pickle_file::close();
    if (tmplog != 0) {
        (void) unlink(tmplog);
        delete tmplog;
        tmplog = 0;
    }
    if (stablelog != 0) {
        delete stablelog;
        stablelog = 0;
    }
    WRITEUNLOCK(this, ret, "wu db_log::close");
    return (ret);
}

bool_t
db_log::open(void) {

    int len, cpstat;
    bool_t  ret;

    WRITELOCK(this, FALSE, "w db_log::open");
    if (mode == PICKLE_READ || (!copylog)) {
        ret = pickle_file::open();
        WRITEUNLOCK(this, ret, "wu db_log::open");
        return (ret);
    }

    len = strlen(filename);
    tmplog = new char[len + sizeof (".tmp")];
    if (tmplog == 0) {
        WARNING("db_log: could not allocate tmp log name");
        ret = pickle_file::open();
        WRITEUNLOCK(this, ret, "wu db_log::open");
        return (ret);
    }
    stablelog = new char[len + sizeof (".stable")];
    if (stablelog == 0) {
        WARNING("db_log: could not allocate stable log name");
        delete tmplog;
        tmplog = 0;
        ret = pickle_file::open();
        WRITEUNLOCK(this, ret, "wu db_log::open");
        return (ret);
    }
    sprintf(tmplog, "%s.tmp", filename);
    sprintf(stablelog, "%s.stable", filename);

    if ((cpstat = copy_log_file(filename, tmplog)) == 0) {
        oldlog = filename;
        filename = tmplog;
    } else {
        syslog(LOG_WARNING,
            "db_log: Error copying \"%s\" to \"%s\": %s",
            filename, tmplog, strerror(cpstat));
        delete tmplog;
        tmplog = 0;
        delete stablelog;
        stablelog = 0;
    }

    ret = pickle_file::open();
    WRITEUNLOCK(this, ret, "wu db_log::open");
    return (ret);
}