libdtrace/common/dt_strtab.c

/*
 * 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.
 */

/*
 * Portions Copyright 2016 Pedro Giffuni.  All rights reserved.
 */

#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 = calloc(nbuckets, sizeof (dt_strhash_t *));

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

          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) {
                    free(hp);
                    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);
}