mbuf: docs and setters/getters (#663)

include/re_mbuf.h

@@ -28,7 +28,18 @@
 #define MBUF_CHECK_END(mb)
 #endif
 
-/** Defines a memory buffer */
+/**
+ * Defines a memory buffer.
+ *
+ * This is a dynamic and linear buffer for storing raw bytes.
+ * It is designed for network protocols, and supports automatic
+ * resizing of the buffer.
+ *
+ * - Writing to the buffer
+ * - Reading from the buffer
+ * - Automatic growing of buffer size
+ * - Print function for formatting printing
+ */
 struct mbuf {
 	uint8_t *buf;   /**< Buffer memory      */
 	size_t size;    /**< Size of buffer     */
@@ -67,6 +78,7 @@ int      mbuf_printf(struct mbuf *mb, const char *fmt, ...);
 int      mbuf_write_pl_skip(struct mbuf *mb, const struct pl *pl,
 			    const struct pl *skip);
 int      mbuf_fill(struct mbuf *mb, uint8_t c, size_t n);
+void     mbuf_set_posend(struct mbuf *mb, size_t pos, size_t end);
 int      mbuf_debug(struct re_printf *pf, const struct mbuf *mb);
 
 
@@ -168,3 +180,29 @@ static inline void mbuf_skip_to_end(struct mbuf *mb)
 {
 	mb->pos = mb->end;
 }
+
+
+/**
+ * Get the current MBUF position
+ *
+ * @param mb Memory buffer
+ *
+ * @return Current position
+ */
+static inline size_t mbuf_pos(const struct mbuf *mb)
+{
+	return mb ? mb->pos : 0;
+}
+
+
+/**
+ * Get the current MBUF end position
+ *
+ * @param mb Memory buffer
+ *
+ * @return Current end position
+ */
+static inline size_t mbuf_end(const struct mbuf *mb)
+{
+	return mb ? mb->end : 0;
+}

src/mbuf/mbuf.c

@@ -365,7 +365,7 @@ int mbuf_read_mem(struct mbuf *mb, uint8_t *buf, size_t size)
 		return EINVAL;
 
 	if (size > mbuf_get_left(mb)) {
-		DEBUG_WARNING("tried to read beyond mbuf end (%u > %u)\n",
+		DEBUG_WARNING("tried to read beyond mbuf end (%zu > %zu)\n",
 			      size, mbuf_get_left(mb));
 		return EOVERFLOW;
 	}
@@ -618,6 +618,37 @@ int mbuf_fill(struct mbuf *mb, uint8_t c, size_t n)
 }
 
 
+/**
+ * Set absolute position and end position
+ *
+ * @param mb  Memory buffer
+ * @param pos Position
+ * @param end End position
+ */
+void mbuf_set_posend(struct mbuf *mb, size_t pos, size_t end)
+{
+	if (!mb)
+		return;
+
+	if (pos > end) {
+		DEBUG_WARNING("set_posend: pos %zu > end %zu\n",
+			      pos, end);
+		return;
+	}
+	if (end > mb->size) {
+		DEBUG_WARNING("set_posend: end %zu > size %zu\n",
+			      end, mb->size);
+		return;
+	}
+
+	mb->pos = pos;
+	mb->end = end;
+
+	MBUF_CHECK_POS(mb);
+	MBUF_CHECK_END(mb);
+}
+
+
 /**
  * Debug the memory buffer
  *