libwebsockets/lib/core/buflist.c

/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "private-lib-core.h"

#ifdef LWS_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

/* lws_buflist */

int
lws_buflist_append_segment(struct lws_buflist **head, const uint8_t *buf,
			   size_t len)
{
	struct lws_buflist *nbuf;
	int first = !*head;
	void *p = *head;
	int sanity = 1024;

	assert(buf);
	assert(len);

	/* append at the tail */
	while (*head) {
		if (!--sanity) {
			lwsl_err("%s: buflist reached sanity limit\n", __func__);
			return -1;
		}
		if (*head == (*head)->next) {
			lwsl_err("%s: corrupt list points to self\n", __func__);
			return -1;
		}
		head = &((*head)->next);
	}

	(void)p;
	lwsl_info("%s: len %u first %d %p\n", __func__, (unsigned int)len,
					      first, p);

	nbuf = (struct lws_buflist *)lws_malloc(sizeof(**head) + len, __func__);
	if (!nbuf) {
		lwsl_err("%s: OOM\n", __func__);
		return -1;
	}

	nbuf->len = len;
	nbuf->pos = 0;
	nbuf->next = NULL;

	p = (void *)nbuf->buf;
	memcpy(p, buf, len);

	*head = nbuf;

	return first; /* returns 1 if first segment just created */
}

static int
lws_buflist_destroy_segment(struct lws_buflist **head)
{
	struct lws_buflist *old = *head;

	assert(*head);
	*head = old->next;
	old->next = NULL;
	lws_free(old);

	return !*head; /* returns 1 if last segment just destroyed */
}

void
lws_buflist_destroy_all_segments(struct lws_buflist **head)
{
	struct lws_buflist *p = *head, *p1;

	while (p) {
		p1 = p->next;
		p->next = NULL;
		lws_free(p);
		p = p1;
	}

	*head = NULL;
}

size_t
lws_buflist_next_segment_len(struct lws_buflist **head, uint8_t **buf)
{
	if (!*head) {
		if (buf)
			*buf = NULL;

		return 0;
	}

	if (!(*head)->len && (*head)->next)
		lws_buflist_destroy_segment(head);

	if (!*head) {
		if (buf)
			*buf = NULL;

		return 0;
	}

	assert((*head)->pos < (*head)->len);

	if (buf)
		*buf = (*head)->buf + (*head)->pos;

	return (*head)->len - (*head)->pos;
}

int
lws_buflist_use_segment(struct lws_buflist **head, size_t len)
{
	assert(*head);
	assert(len);
	assert((*head)->pos + len <= (*head)->len);

	(*head)->pos += len;
	if ((*head)->pos == (*head)->len)
		lws_buflist_destroy_segment(head);

	if (!*head)
		return 0;

	return (int)((*head)->len - (*head)->pos);
}

void
lws_buflist_describe(struct lws_buflist **head, void *id)
{
	struct lws_buflist *old;
	int n = 0;

	if (*head == NULL)
		lwsl_notice("%p: buflist empty\n", id);

	while (*head) {
		lwsl_notice("%p: %d: %llu / %llu (%llu left)\n", id, n,
			    (unsigned long long)(*head)->pos,
			    (unsigned long long)(*head)->len,
			    (unsigned long long)(*head)->len - (*head)->pos);
		old = *head;
		head = &((*head)->next);
		if (*head == old) {
			lwsl_err("%s: next points to self\n", __func__);
			break;
		}
		n++;
	}
}