Add a routine to get the next as-yet-unfetched interface description.

In a wtap, keep track of the first interface description not yet fetched
with wtap_get_next_interface_description() and, when
wtap_get_next_interface_description() is called, have it return that
description, as a wtap_block_t for its IDB.  If there are no
as-yet-unfetched interface descriptions, return NULL; there may, in the
future, be more interface descriptions for the file, so this should be
called:

* after the file is opened;

* after wtap_read() returns TRUE, indicating that it's returned a
record (and *before* you process the record that wtap_read()
returns, as it might be the interface description for the
interface on which the packet in that record arrived);

* after wtap_read() returns FALSE, indicating an EOF or an error
return (as there might have been interfaces at the end of the
file or before the error point).

At each of those points, the caller should loop until
wtap_get_next_interface_description() returns NULL.

Not used yet (but tested with capinfos, which found a reason why you
have to wait until the end of the file before processing the interface
information - there's now a comment in the code giving that reason).

This will probably be used in the future.

1 files changed, 23 insertions, 0 deletions

diff --git a/wiretap/wtap.c b/wiretap/wtap.c
index 2317b30285..ad12531616 100644
--- a/wiretap/wtap.c
+++ b/wiretap/wtap.c
@@ -155,6 +155,29 @@ wtap_file_get_idb_info(wtap *wth)
 	return idb_info;
 }
 
+wtap_block_t
+wtap_get_next_interface_description(wtap *wth)
+{
+	if (wth->next_interface_data < wth->interface_data->len) {
+		/*
+		 * We have an IDB to return.  Advance to the next
+		 * IDB, and return this one.
+		 */
+		wtap_block_t idb;
+
+		idb = g_array_index(wth->interface_data, wtap_block_t,
+		    wth->next_interface_data);
+		wth->next_interface_data++;
+		return idb;
+	}
+
+	/*
+	 * We've returned all the interface descriptions we currently
+	 * have.  (There may be more in the future, if we read more.)
+	 */
+	return NULL;
+}
+
 void
 wtap_add_idb(wtap *wth, wtap_block_t idb)
 {