dt_strtab.c

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/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only.
 * See the file usr/src/LICENSING.NOTICE in this distribution or
 * http://www.opensolaris.org/license/ for details.
 */

#pragma ident	"@(#)dt_strtab.c	1.2	04/11/13 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);
}