+/*! \brief Copy an msgb. I'd write just "a" here, not "an". I seem to be the English nitpicker among us ;)
+ *
+ * This function allocates a new msgb, copies the data buffer of msg,
+ * and adjusts the pointers (incl l1h-l4h) accordingly. The cb part
+ * is not copied.
+ * \param[in] msg The old msgb object
+ * \param[in] name Human-readable name to be associated with msgb
+ */
+struct msgb *msgb_copy(const struct msgb *msg, const char *name)
+{
[...]
+}
+
+/*! \brief Resize an area within an msgb
+ *
+ * This resizes a sub area of the msgb data and adjusts the pointers (incl
+ * l1h-l4h) accordingly. The cb part is not updated. If the area is extended,
+ * the contents of the extension is undefined. The complete sub area must be a
+ * part of [data,tail].
+ *
+ * \param[inout] msg The msgb object
+ * \param[in] area A pointer to the sub-area
+ * \param[in] old_size The old size of the sub-area
+ * \param[in] new_size The new size of the sub-area
+ * \returns 0 on success, -1 if there is not enough space to extend the area
+ */
+int msgb_resize_area(struct msgb *msg, uint8_t *area,
+ size_t old_size, size_t new_size)
+{
+ int rc;
+ uint8_t *rest = area + old_size;
+ int rest_len = msg->len - old_size - (area - msg->data);
+ int delta_size = (int)new_size - (int)old_size;
+
+ if (area < msg->data || rest > msg->tail)
+ MSGB_ABORT(msg, "Sub area is not fully contained in the msg
data\n");
Just to be super paranoid: old_size is unsigned, sure, but uint8_t *rest
could wrap when old_size is (accidentally/crafted) passed as very very
large. I could pass area > msg->tail with rest < msg->tail.
Also, if new_size were past INT_MAX, (int)new_size would end up negative.
Same for old_size. My head is spinning a bit from trying to figure out the
result of the subtraction in those cases... ;)
What do you think? Not relevant for any normal use, sure, but should we
rule out those cases entirely?
~Neels
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