/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2005-2008 Poul-Henning Kamp
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <time.h>
#include <sys/endian.h>

#include <zlib.h>

#include "fifolog.h"
#include "libfifolog_int.h"
#include "fifolog_write.h"
#include "miniobj.h"

static int fifolog_write_gzip(struct fifolog_writer *f, time_t now);

#define ALLOC(ptr, size) do {                   \
        (*(ptr)) = calloc(1, size);             \
        assert(*(ptr) != NULL);                 \
} while (0)


const char *fifolog_write_statnames[] = {
        [FIFOLOG_PT_BYTES_PRE] =        "Bytes before compression",
        [FIFOLOG_PT_BYTES_POST] =       "Bytes after compression",
        [FIFOLOG_PT_WRITES] =           "Writes",
        [FIFOLOG_PT_FLUSH] =            "Flushes",
        [FIFOLOG_PT_SYNC] =             "Syncs",
        [FIFOLOG_PT_RUNTIME] =          "Runtime"
};

/**********************************************************************
 * Check that everything is all right
 */
static void
fifolog_write_assert(const struct fifolog_writer *f)
{

        CHECK_OBJ_NOTNULL(f, FIFOLOG_WRITER_MAGIC);
        assert(f->ff->zs->next_out + f->ff->zs->avail_out == \
            f->obuf + f->obufsize);
}

/**********************************************************************
 * Allocate/Destroy a new fifolog writer instance
 */

struct fifolog_writer *
fifolog_write_new(void)
{
        struct fifolog_writer *f;

        ALLOC_OBJ(f, FIFOLOG_WRITER_MAGIC);
        assert(f != NULL);
        return (f);
}

void
fifolog_write_destroy(struct fifolog_writer *f)
{

        free(f->obuf);
        free(f->ibuf);
        FREE_OBJ(f);
}

/**********************************************************************
 * Open/Close the fifolog
 */

void
fifolog_write_close(struct fifolog_writer *f)
{
        time_t now;

        CHECK_OBJ_NOTNULL(f, FIFOLOG_WRITER_MAGIC);
        fifolog_write_assert(f);

        f->cleanup = 1;
        time(&now);
        fifolog_write_gzip(f, now);
        fifolog_write_assert(f);
        fifolog_int_close(&f->ff);
        free(f->ff);
}

const char *
fifolog_write_open(struct fifolog_writer *f, const char *fn,
    unsigned writerate, unsigned syncrate, unsigned compression)
{
        const char *es;
        int i;
        time_t now;
        off_t o;

        CHECK_OBJ_NOTNULL(f, FIFOLOG_WRITER_MAGIC);

        /* Check for legal compression value */
        if (compression > Z_BEST_COMPRESSION)
                return ("Illegal compression value");

        f->writerate = writerate;
        f->syncrate = syncrate;
        f->compression = compression;

        /* Reset statistics */
        memset(f->cnt, 0, sizeof f->cnt);

        es = fifolog_int_open(&f->ff, fn, 1);
        if (es != NULL)
                return (es);
        es = fifolog_int_findend(f->ff, &o);
        if (es != NULL)
                return (es);
        i = fifolog_int_read(f->ff, o);
        if (i)
                return ("Read error, looking for seq");
        f->seq = be32dec(f->ff->recbuf);
        if (f->seq == 0) {
                /* Empty fifolog */
                f->seq = random();
        } else {
                f->recno = o + 1;
                f->seq++;
        }

        f->obufsize = f->ff->recsize;
        ALLOC(&f->obuf, f->obufsize);

        f->ibufsize = f->obufsize * 10;
        ALLOC(&f->ibuf, f->ibufsize);
        f->ibufptr = 0;

        i = deflateInit(f->ff->zs, (int)f->compression);
        assert(i == Z_OK);

        f->flag |= FIFOLOG_FLG_RESTART;
        f->flag |= FIFOLOG_FLG_SYNC;
        f->ff->zs->next_out = f->obuf + 9;
        f->ff->zs->avail_out = f->obufsize - 9;

        time(&now);
        f->starttime = now;
        f->lastsync = now;
        f->lastwrite = now;

        fifolog_write_assert(f);
        return (NULL);
}

/**********************************************************************
 * Write an output record
 * Returns -1 if there are trouble writing data
 */

static int
fifolog_write_output(struct fifolog_writer *f, int fl, time_t now)
{
        long h, l = f->ff->zs->next_out - f->obuf;
        ssize_t i, w;
        int retval = 0;

        h = 4;                                  /* seq */
        be32enc(f->obuf, f->seq);
        f->obuf[h] = f->flag;
        h += 1;                                 /* flag */
        if (f->flag & FIFOLOG_FLG_SYNC) {
                be32enc(f->obuf + h, now);
                h += 4;                         /* timestamp */
        }

        assert(l <= (long)f->ff->recsize);      /* NB: l includes h */
        assert(l >= h);

        /* We will never write an entirely empty buffer */
        if (l == h)
                return (0);

        if (l < (long)f->ff->recsize && fl == Z_NO_FLUSH)
                return (0);

        w = f->ff->recsize - l;
        if (w >  255) {
                be32enc(f->obuf + f->ff->recsize - 4, w);
                f->obuf[4] |= FIFOLOG_FLG_4BYTE;
        } else if (w > 0) {
                f->obuf[f->ff->recsize - 1] = (uint8_t)w;
                f->obuf[4] |= FIFOLOG_FLG_1BYTE;
        }

        f->cnt[FIFOLOG_PT_BYTES_POST] += l - h;

        i = pwrite(f->ff->fd, f->obuf, f->ff->recsize,
            (f->recno + 1) * f->ff->recsize);
        if (i != f->ff->recsize)
                retval = -1;
        else
                retval = 1;

        f->cnt[FIFOLOG_PT_WRITES]++;
        f->cnt[FIFOLOG_PT_RUNTIME] = now - f->starttime;

        f->lastwrite = now;
        /*
         * We increment these even on error, so as to properly skip bad,
         * sectors or other light trouble.
         */
        f->seq++;
        f->recno++;

        /*
         * Ensure we wrap recno once we hit the file size (in records.)
         */
        if (f->recno >= f->ff->logsize)
                /* recno 0 is header; skip */
                f->recno = 1;

        f->flag = 0;

        memset(f->obuf, 0, f->obufsize);
        f->ff->zs->next_out = f->obuf + 5;
        f->ff->zs->avail_out = f->obufsize - 5;
        return (retval);
}

/**********************************************************************
 * Run the compression engine
 * Returns -1 if there are trouble writing data
 */

static int
fifolog_write_gzip(struct fifolog_writer *f, time_t now)
{
        int i, fl, retval = 0;

        assert(now != 0);
        if (f->cleanup || now >= (int)(f->lastsync + f->syncrate)) {
                f->cleanup = 0;
                fl = Z_FINISH;
                f->cnt[FIFOLOG_PT_SYNC]++;
        } else if (now >= (int)(f->lastwrite + f->writerate)) {
                fl = Z_SYNC_FLUSH;
                f->cnt[FIFOLOG_PT_FLUSH]++;
        } else if (f->ibufptr == 0)
                return (0);
        else
                fl = Z_NO_FLUSH;

        f->ff->zs->avail_in = f->ibufptr;
        f->ff->zs->next_in = f->ibuf;

        while (1) {
                i = deflate(f->ff->zs, fl);
                assert(i == Z_OK || i == Z_BUF_ERROR || i == Z_STREAM_END);

                i = fifolog_write_output(f, fl, now);
                if (i == 0)
                        break;
                if (i < 0)
                        retval = -1;
        }
        assert(f->ff->zs->avail_in == 0);
        f->ibufptr = 0;
        if (fl == Z_FINISH) {
                f->flag |= FIFOLOG_FLG_SYNC;
                f->ff->zs->next_out = f->obuf + 9;
                f->ff->zs->avail_out = f->obufsize - 9;
                f->lastsync = now;
                assert(Z_OK == deflateReset(f->ff->zs));
        }
        return (retval);
}

/**********************************************************************
 * Poll to see if we need to flush out a record
 * Returns -1 if there are trouble writing data
 */

int
fifolog_write_poll(struct fifolog_writer *f, time_t now)
{

        if (now == 0)
                time(&now);
        return (fifolog_write_gzip(f, now));
}

/**********************************************************************
 * Attempt to write an entry into the ibuf.
 * Return zero if there is no space, one otherwise
 */

int
fifolog_write_record(struct fifolog_writer *f, uint32_t id, time_t now,
    const void *ptr, ssize_t len)
{
        const unsigned char *p;
        uint8_t buf[9];
        ssize_t bufl;

        fifolog_write_assert(f);
        assert(!(id & (FIFOLOG_TIMESTAMP|FIFOLOG_LENGTH)));
        assert(ptr != NULL);

        p = ptr;
        if (len == 0) {
                len = strlen(ptr);
                len++;
        } else {
                assert(len <= 255);
                id |= FIFOLOG_LENGTH;
        }
        assert (len > 0);

        /* Do a timestamp, if needed */
        if (now == 0)
                time(&now);

        if (now != f->last)
                id |= FIFOLOG_TIMESTAMP;

        /* Emit instance+flag */
        be32enc(buf, id);
        bufl = 4;

        if (id & FIFOLOG_TIMESTAMP) {
                be32enc(buf + bufl, (uint32_t)now);
                bufl += 4;
        }
        if (id & FIFOLOG_LENGTH)
                buf[bufl++] = (u_char)len;

        if (bufl + len + f->ibufptr > f->ibufsize)
                return (0);

        memcpy(f->ibuf + f->ibufptr, buf, bufl);
        f->ibufptr += bufl;
        memcpy(f->ibuf + f->ibufptr, p, len);
        f->ibufptr += len;
        f->cnt[FIFOLOG_PT_BYTES_PRE] += bufl + len;

        if (id & FIFOLOG_TIMESTAMP)
                f->last = now;
        return (1);
}

/**********************************************************************
 * Write an entry, polling the gzip/writer until success.
 * Long binary entries are broken into 255 byte chunks.
 * Returns -1 if there are problems writing data
 */

int
fifolog_write_record_poll(struct fifolog_writer *f, uint32_t id, time_t now,
    const void *ptr, ssize_t len)
{
        u_int l;
        const unsigned char *p;
        int retval = 0;

        if (now == 0)
                time(&now);
        fifolog_write_assert(f);

        assert(!(id & (FIFOLOG_TIMESTAMP|FIFOLOG_LENGTH)));
        assert(ptr != NULL);

        if (len == 0) {
                if (!fifolog_write_record(f, id, now, ptr, len)) {
                        if (fifolog_write_gzip(f, now) < 0)
                                retval = -1;
                        /* The string could be too long for the ibuf, so... */
                        if (!fifolog_write_record(f, id, now, ptr, len))
                                retval = -1;
                }
        } else {
                for (p = ptr; len > 0; len -= l, p += l) {
                        l = len;
                        if (l > 255)
                                l = 255;
                        while (!fifolog_write_record(f, id, now, p, l))
                                if (fifolog_write_gzip(f, now) < 0)
                                        retval = -1;
                }
        }
        if (fifolog_write_gzip(f, now) < 0)
                retval = -1;
        fifolog_write_assert(f);
        return (retval);
}