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, 18 insertions, 1 deletions

diff --git a/wiretap/mpeg.c b/wiretap/mpeg.c
index f7db4f96bc..366358cf4e 100644
--- a/wiretap/mpeg.c
+++ b/wiretap/mpeg.c
@@ -35,6 +35,10 @@ typedef struct {
 	time_t t0;
 } mpeg_t;
 
+static int mpeg_file_type_subtype = -1;
+
+void register_mpeg(void);
+
 static int
 mpeg_resync(FILE_T fh, int *err)
 {
@@ -245,7 +249,7 @@ good_magic:
 	if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
 		return WTAP_OPEN_ERROR;
 
-	wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MPEG;
+	wth->file_type_subtype = mpeg_file_type_subtype;
 	wth->file_encap = WTAP_ENCAP_MPEG;
 	wth->file_tsprec = WTAP_TSPREC_NSEC;
 	wth->subtype_read = mpeg_read;
@@ -261,6 +265,19 @@ good_magic:
 	return WTAP_OPEN_MINE;
 }
 
+static const struct file_type_subtype_info mpeg_info = {
+	"MPEG", "mpeg", "mpeg", "mpg;mp3",
+	FALSE, FALSE, 0,
+	NULL, NULL, NULL
+};
+
+void register_mpeg(void)
+{
+	mpeg_file_type_subtype =
+	    wtap_register_file_type_subtypes(&mpeg_info,
+	        WTAP_FILE_TYPE_SUBTYPE_UNKNOWN);
+}
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *