file_seek() used to be a wrapper around fseek() or gzseek(), both of

which could use lseek() and were thus expensive due to system call
overhead.  To avoid making a system call for every packet on a
sequential read, we maintained a data_offset field in the wtap structure
for sequential reads.

It's now a routine that just returns information from the FILE_T data
structure, so it's cheap.  Use it, rather than maintaining the data_offset
field.

Readers for some file formats need to maintain file offset themselves;
have them do so in their private data structures.

svn path=/trunk/; revision=42423

1 files changed, 5 insertions, 4 deletions

diff --git a/wiretap/tnef.c b/wiretap/tnef.c
index f7772509d0..1ab28e2bb0 100644
--- a/wiretap/tnef.c
+++ b/wiretap/tnef.c
@@ -37,17 +37,20 @@
 
 static gboolean tnef_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
 {
+  gint64 offset;
   guint8 *buf;
   gint64 file_size;
   int packet_size;
 
   *err = 0;
 
+  offset = file_tell(wth->fh);
+
   /* there is only ever one packet */
-  if(wth->data_offset)
+  if (offset)
     return FALSE;
 
-  *data_offset = wth->data_offset;
+  *data_offset = offset;
 
   if ((file_size = wtap_file_size(wth, err)) == -1)
     return FALSE;
@@ -69,8 +72,6 @@ static gboolean tnef_read(wtap *wth, int *err, gchar **err_info, gint64 *data_of
 
   wtap_file_read_expected_bytes(buf, packet_size, wth->fh, err, err_info);
 
-  wth->data_offset += packet_size;
-
   wth->phdr.presence_flags = 0; /* no time stamp, no "real length" */
 
   wth->phdr.caplen = packet_size;