Remove libipm_msg_in_start()

The semantics of this call allowed it to be called more than once when
parsing a message to restart a parse. This is not likely to be
useful in practice, and it also makes reading file descriptors
more complicated. Consequently this function has been removed and
replaced with with libipm_msg_in_get_msgno()

libipm/libipm.h

@@ -219,6 +219,12 @@ libipm_msg_out_erase(struct trans *trans);
  * @param trans libipm transport
  * @param[out] available != 0 if a complete message is available
  * @return != 0 for error
+ *
+ * When 'available' becomes set, the buffer is guaranteed to
+ * be in a parseable state.
+ *
+ * The results of calling this function after starting to parse a message
+ * and before calling libipm_msg_in_reset() are undefined.
  */
 enum libipm_status
 libipm_msg_in_check_available(struct trans *trans, int *available);
@@ -233,6 +239,9 @@ libipm_msg_in_check_available(struct trans *trans, int *available);
  * While the call is active, data-in callbacks for the transport are
  * disabled.
  *
+ * The results of calling this function after starting to parse a message
+ * and before calling libipm_msg_in_reset() are undefined.
+ *
  * Only use this call if you have nothing to do until a message
  * arrives on the transport. If you have other transports to service, use
  * libipm_msg_in_check_available()
@@ -241,7 +250,7 @@ enum libipm_status
 libipm_msg_in_wait_available(struct trans *trans);
 
 /**
- * Start parsing a message
+ * Get the message number for a message in the input buffer.
  *
  * @param trans libipm transport
  * @return message number in the buffer
@@ -250,12 +259,9 @@ libipm_msg_in_wait_available(struct trans *trans);
  * libipm_msg_in_reset() and before a successful call to
  * libipm_msg_in_check_available() (or libipm_msg_wait_available())
  * are undefined.
- *
- * Calling this function resets the message parsing pointer to the start
- * of the message
  */
 unsigned short
-libipm_msg_in_start(struct trans *trans);
+libipm_msg_in_get_msgno(const struct trans *trans);
 
 /**
  * Returns a letter corresponding to the next available type in the

libipm/libipm_recv.c

@@ -187,11 +187,10 @@ libipm_msg_in_wait_available(struct trans *trans)
 /*****************************************************************************/
 
 unsigned short
-libipm_msg_in_start(struct trans *trans)
+libipm_msg_in_get_msgno(const struct trans *trans)
 {
     struct libipm_priv *priv = (struct libipm_priv *)trans->extra_data;
 
-    trans->in_s->p = trans->in_s->data + HEADER_SIZE;
     return (priv == NULL) ? 0 : priv->in_msgno;
 }
 

libipm/scp.c

@@ -212,18 +212,18 @@ scp_msg_in_wait_available(struct trans *trans)
 
 /*****************************************************************************/
 
-void
-scp_msg_in_reset(struct trans *trans)
+enum scp_msg_code
+scp_msg_in_get_msgno(const struct trans *trans)
 {
-    libipm_msg_in_reset(trans);
+    return (enum scp_msg_code)libipm_msg_in_get_msgno(trans);
 }
 
 /*****************************************************************************/
 
-enum scp_msg_code
-scp_msg_in_start(struct trans *trans)
+void
+scp_msg_in_reset(struct trans *trans)
 {
-    return (enum scp_msg_code)libipm_msg_in_start(trans);
+    libipm_msg_in_reset(trans);
 }
 
 /*****************************************************************************/

libipm/scp.h

@@ -164,19 +164,16 @@ scp_msg_in_wait_available(struct trans *trans);
 
 
 /**
- * Start parsing an SCP message
+ * Gets the SCP message number of an incoming message
  *
  * @param trans SCP transport
  * @return message in the buffer
  *
  * The results of calling this routine before scp_msg_in_check_available()
  * states a message is available are undefined.
- *
- * Calling this function rests the message parsing pointer to the start
- * of the message
  */
 enum scp_msg_code
-scp_msg_in_start(struct trans *trans);
+scp_msg_in_get_msgno(const struct trans *trans);
 
 /**
  * Resets an SCP message buffer ready to receive the next message