On Mon, Nov 18, 2013 at 12:38:24AM -0500, Benjamin Vanheuverzwijn wrote:
> Hi,
Hi Benjamin,
>
> libpcap version: 1.4.0 (on archlinux)
I am running Fedora 19 (libpcap-1.4.0).
>
> Is it possible to have multiple call to "pcap_open_live()" followed by
> pcap_close() ?
It shouldn't be a problem.
>
> It seems like pcap_close() doesn't cleanly close opened resources, if you
> strace the following program, you will see file descriptors growing up.
I am unable to reproduce the issue. In strace output I see only descriptor 3
which is acquired and closed on every iteration. Tried with two NICs, wired and
wireless.
>
> Am i doing it wrong? How it should be done?
>From output you have provided I have a suspicion that your problem is somehow
caused by calling open() on those /sys/bus/usb/* files. I don't have those in my
strace output, probably because interface you have used is hotplugged wireless
usb dongle, I guess (judging by interface name from udev).
I might be able to try again with wireless USB dongle tomorrow. Will keep you
posted on my findings.
>
> Thanks,
Cheers,
Michal
>
> To reproduce:
> // Compile with gcc -o openlive openlive.c -l pcap
> #include <pcap.h>
>
> int main(int argc, char *argv[]) {
> int i=0;
> for (i = 0; i != 2000; ++i) {
> char errbuf[256];
> pcap_t *pcap = pcap_open_live("wls3", 1024, 1, 0, errbuf);
> pcap_close(pcap);
> }
> return 0;
> }
>
> $ strace ./openlive
> [...]
> open("/sys/bus/usb/devices/4-2/devnum", O_RDONLY) = 16
> fstat(16, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
> 0x7f5e040f0000
> read(16, "8\n", 4096) = 2
> [...]
> open("/sys/bus/usb/devices/usb4/speed", O_RDONLY) = 91
> fstat(91, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
> 0x7fc006371000
> read(91, "480\n", 4096) = 4
>
>
> --
> Benjamin Vanheuverzwijn
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