/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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
 */

/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/types.h>
#include <sys/sysmacros.h>
#include <strings.h>
#include <stdlib.h>
#include <assert.h>

#include <dt_strtab.h>
#include <dt_impl.h>

static int
dt_strtab_grow(dt_strtab_t *sp)
{
        char *ptr, **bufs;

        if ((ptr = malloc(sp->str_bufsz)) == NULL)
                return (-1);

        bufs = realloc(sp->str_bufs, (sp->str_nbufs + 1) * sizeof (char *));

        if (bufs == NULL) {
                free(ptr);
                return (-1);
        }

        sp->str_nbufs++;
        sp->str_bufs = bufs;
        sp->str_ptr = ptr;
        sp->str_bufs[sp->str_nbufs - 1] = sp->str_ptr;

        return (0);
}

dt_strtab_t *
dt_strtab_create(size_t bufsz)
{
        dt_strtab_t *sp = malloc(sizeof (dt_strtab_t));
        uint_t nbuckets = _dtrace_strbuckets;

        assert(bufsz != 0);

        if (sp == NULL)
                return (NULL);

        bzero(sp, sizeof (dt_strtab_t));
        sp->str_hash = malloc(nbuckets * sizeof (dt_strhash_t *));

        if (sp->str_hash == NULL)
                goto err;

        bzero(sp->str_hash, nbuckets * sizeof (dt_strhash_t *));
        sp->str_hashsz = nbuckets;
        sp->str_bufs = NULL;
        sp->str_ptr = NULL;
        sp->str_nbufs = 0;
        sp->str_bufsz = bufsz;
        sp->str_nstrs = 1;
        sp->str_size = 1;

        if (dt_strtab_grow(sp) == -1)
                goto err;

        *sp->str_ptr++ = '\0';
        return (sp);

err:
        dt_strtab_destroy(sp);
        return (NULL);
}

void
dt_strtab_destroy(dt_strtab_t *sp)
{
        dt_strhash_t *hp, *hq;
        ulong_t i;

        for (i = 0; i < sp->str_hashsz; i++) {
                for (hp = sp->str_hash[i]; hp != NULL; hp = hq) {
                        hq = hp->str_next;
                        free(hp);
                }
        }

        for (i = 0; i < sp->str_nbufs; i++)
                free(sp->str_bufs[i]);

        if (sp->str_hash != NULL)
                free(sp->str_hash);
        if (sp->str_bufs != NULL)
                free(sp->str_bufs);

        free(sp);
}

ulong_t
dt_strtab_hash(const char *key, size_t *len)
{
        ulong_t g, h = 0;
        const char *p;
        size_t n = 0;

        for (p = key; *p != '\0'; p++, n++) {
                h = (h << 4) + *p;

                if ((g = (h & 0xf0000000)) != 0) {
                        h ^= (g >> 24);
                        h ^= g;
                }
        }

        if (len != NULL)
                *len = n;

        return (h);
}

static int
dt_strtab_compare(dt_strtab_t *sp, dt_strhash_t *hp,
    const char *str, size_t len)
{
        ulong_t b = hp->str_buf;
        const char *buf = hp->str_data;
        size_t resid, n;
        int rv;

        while (len != 0) {
                if (buf == sp->str_bufs[b] + sp->str_bufsz)
                        buf = sp->str_bufs[++b];

                resid = sp->str_bufs[b] + sp->str_bufsz - buf;
                n = MIN(resid, len);

                if ((rv = strncmp(buf, str, n)) != 0)
                        return (rv);

                buf += n;
                str += n;
                len -= n;
        }

        return (0);
}

static int
dt_strtab_copyin(dt_strtab_t *sp, const char *str, size_t len)
{
        char *old_p = sp->str_ptr;
        ulong_t old_n = sp->str_nbufs;

        ulong_t b = sp->str_nbufs - 1;
        size_t resid, n;

        while (len != 0) {
                if (sp->str_ptr == sp->str_bufs[b] + sp->str_bufsz) {
                        if (dt_strtab_grow(sp) == -1)
                                goto err;
                        b++;
                }

                resid = sp->str_bufs[b] + sp->str_bufsz - sp->str_ptr;
                n = MIN(resid, len);
                bcopy(str, sp->str_ptr, n);

                sp->str_ptr += n;
                str += n;
                len -= n;
        }

        return (0);

err:
        while (sp->str_nbufs != old_n)
                free(sp->str_bufs[--sp->str_nbufs]);

        sp->str_ptr = old_p;
        return (-1);
}

ssize_t
dt_strtab_index(dt_strtab_t *sp, const char *str)
{
        dt_strhash_t *hp;
        size_t len;
        ulong_t h;

        if (str == NULL || str[0] == '\0')
                return (0); /* we keep a \0 at offset 0 to simplify things */

        h = dt_strtab_hash(str, &len) % sp->str_hashsz;

        for (hp = sp->str_hash[h]; hp != NULL; hp = hp->str_next) {
                if (dt_strtab_compare(sp, hp, str, len + 1) == 0)
                        return (hp->str_off);
        }

        return (-1);
}

ssize_t
dt_strtab_insert(dt_strtab_t *sp, const char *str)
{
        dt_strhash_t *hp;
        size_t len;
        ssize_t off;
        ulong_t h;

        if ((off = dt_strtab_index(sp, str)) != -1)
                return (off);

        h = dt_strtab_hash(str, &len) % sp->str_hashsz;

        /*
         * Create a new hash bucket, initialize it, and insert it at the front
         * of the hash chain for the appropriate bucket.
         */
        if ((hp = malloc(sizeof (dt_strhash_t))) == NULL)
                return (-1L);

        hp->str_data = sp->str_ptr;
        hp->str_buf = sp->str_nbufs - 1;
        hp->str_off = sp->str_size;
        hp->str_len = len;
        hp->str_next = sp->str_hash[h];

        /*
         * Now copy the string data into our buffer list, and then update
         * the global counts of strings and bytes.  Return str's byte offset.
         */
        if (dt_strtab_copyin(sp, str, len + 1) == -1)
                return (-1L);

        sp->str_nstrs++;
        sp->str_size += len + 1;
        sp->str_hash[h] = hp;

        return (hp->str_off);
}

size_t
dt_strtab_size(const dt_strtab_t *sp)
{
        return (sp->str_size);
}

ssize_t
dt_strtab_write(const dt_strtab_t *sp, dt_strtab_write_f *func, void *private)
{
        ssize_t res, total = 0;
        ulong_t i;
        size_t n;

        for (i = 0; i < sp->str_nbufs; i++, total += res) {
                if (i == sp->str_nbufs - 1)
                        n = sp->str_ptr - sp->str_bufs[i];
                else
                        n = sp->str_bufsz;

                if ((res = func(sp->str_bufs[i], n, total, private)) <= 0)
                        break;
        }

        if (total == 0 && sp->str_size != 0)
                return (-1);

        return (total);
}