libdtrace/common/dt_strtab.c

	dt_strtab.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * 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
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

#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_insert(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;

    /*
     * If the string is already in our hash table, just return the offset
     * of the existing string element and do not add a duplicate string.
     */
    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);
    }

    /*
     * 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);
}