Allow bigger snapshot lengths for D-Bus captures.

Use WTAP_MAX_PACKET_SIZE_STANDARD, set to 256KB, for everything except
for D-Bus captures.  Use WTAP_MAX_PACKET_SIZE_DBUS, set to 128MB, for
them, because that's the largest possible D-Bus message size.  See

	https://bugs.freedesktop.org/show_bug.cgi?id=100220

for an example of the problems caused by limiting the snapshot length to
256KB for D-Bus.

Have a snapshot length of 0 in a capture_file structure mean "there is
no snapshot length for the file"; we don't need the has_snap field in
that case, a value of 0 mean "no, we don't have a snapshot length".

In dumpcap, start out with a pipe buffer size of 2KB, and grow it as
necessary.  When checking for a too-big packet from a pipe, check
against the appropriate maximum - 128MB for DLT_DBUS, 256KB for
everything else.

Change-Id: Ib2ce7a0cf37b971fbc0318024fd011e18add8b20
Reviewed-on: https://code.wireshark.org/review/21952
Petri-Dish: Guy Harris <guy@alum.mit.edu>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Guy Harris <guy@alum.mit.edu>
(cherry picked from commit d0865fd619454a9ac06b1c7d287dc438aff50bb0)
Reviewed-on: https://code.wireshark.org/review/21955

1 files changed, 0 insertions, 1 deletions

diff --git a/cfile.c b/cfile.c
index cf30f3b899..265190b3b5 100644
--- a/cfile.c
+++ b/cfile.c
@@ -81,7 +81,6 @@ cap_file_init(capture_file *cf)
 {
   /* Initialize the capture file struct */
   memset(cf, 0, sizeof(capture_file));
-  cf->snap            = WTAP_MAX_PACKET_SIZE;
 }
 
 /*