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
by Wiretap, to indicate whether certain fields in that structure
actually have data in them.
Use the "time stamp present" flag to omit showing time stamp information
for packets (and "packets") that don't have time stamps; don't bother
working very hard to "fake" a time stamp for data files.
Use the "interface ID present" flag to omit the interface ID for packets
that don't have an interface ID.
We don't use the "captured length, separate from packet length, present"
flag to omit the captured length; that flag might be present but equal
to the packet length, and if you want to know if a packet was cut short
by a snapshot length, comparing the values would be the way to do that.
More work is needed to have wiretap/pcapng.c properly report the flags,
e.g. reporting no time stamp being present for a Simple Packet Block.
svn path=/trunk/; revision=41185
same.
Add to wiretap/pcap-common.c a routine to fill in the pseudo-header for
ATM (by looking at the VPI, VCI, and packet data, and guessing) and
Ethernet (setting the FCS length appropriately). Use it for both pcap
and pcap-ng files.
svn path=/trunk/; revision=38840
Guy Harris