libpcap double reads pcap data from file under Ubuntu 16.04

[jelu]

Weird problem, libpcap seems to reset the file handle after clone() and then rereads all data. Need to report upstreams.

Strace diff output:

 open("./1458044657.pcap.dist", O_RDONLY) = 3
 fstat(3, {st_mode=S_IFREG|0664, st_size=1020, ...}) = 0
 read(3, "\324\303\262\241\2\0\4\0\0\0\0\0\0\0\0\0\377\377\0\0\1\0\0\0\357\376\347V \354\3\0"..., 4096) = 1020
-clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f76ad71aa10) = 7448
...
-lseek(3, -996, SEEK_CUR <unfinished ...>
...
-read(3, "\357\376\347V \354\3\0I\0\0\0I\0\0\0>1\220\201\223\263\2B\254\21\0\20\10\0E\0"..., 4096) = 996
...
 read(3, "", 4096)                 = 0