lws_buflist: extra apis for in-place use

include/libwebsockets/lws-misc.h

@@ -75,6 +75,31 @@ lws_buflist_next_segment_len(struct lws_buflist **head, uint8_t **buf);
 LWS_VISIBLE LWS_EXTERN int
 lws_buflist_use_segment(struct lws_buflist **head, size_t len);
 
+/**
+ * lws_buflist_total_len(): Get the total size of the buflist
+ *
+ * \param head: list head
+ *
+ * Returns the total number of bytes held on all segments of the buflist
+ */
+LWS_VISIBLE LWS_EXTERN size_t
+lws_buflist_total_len(struct lws_buflist **head);
+
+/**
+ * lws_buflist_linear_copy(): copy everything out as one without consuming
+ *
+ * \param head: list head
+ * \param ofs: start offset into buflist in bytes
+ * \param buf: buffer to copy linearly into
+ * \param len: length of buffer available
+ *
+ * Returns -1 if len is too small, or bytes copied.  Happy to do partial
+ * copies, returns 0 when there are no more bytes to copy.
+ */
+LWS_VISIBLE LWS_EXTERN int
+lws_buflist_linear_copy(struct lws_buflist **head, size_t ofs, uint8_t *buf,
+			size_t len);
+
 /**
  * lws_buflist_destroy_all_segments(): free all segments on the list
  *

lib/core/buflist.c

@@ -158,6 +158,45 @@ lws_buflist_use_segment(struct lws_buflist **head, size_t len)
 	return lws_buflist_next_segment_len(head, NULL);
 }
 
+size_t
+lws_buflist_total_len(struct lws_buflist **head)
+{
+	struct lws_buflist *p = *head;
+	size_t size = 0;
+
+	while (p) {
+		size += p->len;
+		p = p->next;
+	}
+
+	return size;
+}
+
+int
+lws_buflist_linear_copy(struct lws_buflist **head, size_t ofs, uint8_t *buf,
+			size_t len)
+{
+	struct lws_buflist *p = *head;
+	uint8_t *obuf = buf;
+	size_t s;
+
+	while (p && len) {
+		if (ofs < p->len) {
+			s = p->len - ofs;
+			if (s > len)
+				s = len;
+			memcpy(buf, ((uint8_t *)&p[1]) + ofs, s);
+			len -= s;
+			buf += s;
+			ofs = 0;
+		} else
+			ofs -= p->len;
+		p = p->next;
+	}
+
+	return lws_ptr_diff(buf, obuf);
+}
+
 #if defined(_DEBUG)
 void
 lws_buflist_describe(struct lws_buflist **head, void *id, const char *reason)