wiretap: register most built-in file types from its module.

Remove most of the built-in file types from the table in
wiretap/file_access.c and, instead, have the file types register
themselves, using wtap_register_file_type_subtypes().

This reduces the source code changes needed to add a new file type from
three (add the handler, add the file type to the table in file_access.c,
add a #define for the file type in wiretap/wtap.h) to one (add the
handler).  (It also requires adding the handler's source file to
wiretap/CMakeLists.txt, but that's required in both cases.)

A few remain because the WTAP_FILE_TYPE_SUBTYPE_ #define is used
elsewhere; that needs to be fixed.

Fix the wiretap/CMakefile.txt file to scan k12text.l, as that now
contains a registration routine.  In the process, avoid scanning files
that don't implement a file type and won't ever have a registration
routine.

Add a Lua routine to fetch the total number of file types; we use that
in some code to construct the wtap_filetypes table, which we need to do
in order to continue to have all the values that used to come from the
WTAP_FILE_TYPE_SUBTYPE_ types.

While we're at it, add modelines to a file that lacked them.

1 files changed, 17 insertions, 1 deletions

diff --git a/wiretap/mp2t.c b/wiretap/mp2t.c
index 36ad7274ee..b43370bb68 100644
--- a/wiretap/mp2t.c
+++ b/wiretap/mp2t.c
@@ -46,6 +46,10 @@ typedef struct {
     guint8  trailer_len;
 } mp2t_filetype_t;
 
+static int mp2t_file_type_subtype = -1;
+
+void register_mp2t(void);
+
 static gboolean
 mp2t_read_packet(mp2t_filetype_t *mp2t, FILE_T fh, gint64 offset,
                  wtap_rec *rec, Buffer *buf, int *err,
@@ -374,7 +378,7 @@ found:
         return WTAP_OPEN_ERROR;
     }
 
-    wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MPEG_2_TS;
+    wth->file_type_subtype = mp2t_file_type_subtype;
     wth->file_encap = WTAP_ENCAP_MPEG_2_TS;
     wth->file_tsprec = WTAP_TSPREC_NSEC;
     wth->subtype_read = mp2t_read;
@@ -391,6 +395,18 @@ found:
     return WTAP_OPEN_MINE;
 }
 
+static const struct file_type_subtype_info mp2t_info = {
+    "MPEG2 transport stream", "mp2t", "mp2t", "ts;mpg",
+    FALSE, FALSE, 0,
+    NULL, NULL, NULL
+};
+
+void register_mp2t(void)
+{
+    mp2t_file_type_subtype = wtap_register_file_type_subtypes(&mp2t_info,
+                                                              WTAP_FILE_TYPE_SUBTYPE_UNKNOWN);
+}
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *