[libvirt] [PATCH 1/2] nwfilter: Fix pointer.

GCC 9 complains: nwfilter/nwfilter_dhcpsnoop.c: In function 'virNWFilterDHCPSnoopThread': nwfilter/nwfilter_dhcpsnoop.c:1456:31: error: converting a packed 'virNWFilterSnoopEthHdrPtr' {aka 'struct _virNWFilterSnoopEthHdr *'} pointer (alignment 1) to 'const u_char *' {aka 'const unsigned char *'} (alignment 8) may result in an unaligned pointer value [-Werror=address-of-packed-member] 1456 | (const u_char **)&packet); | ^ nwfilter/nwfilter_dhcpsnoop.c:183:8: note: defined here 183 | struct _virNWFilterSnoopEthHdr { | ^~~~~~~~~~~~~~~~~~~~~~~ However it seems like there's more going on here than just an enhanced GCC warning. The function pcap_next_ex is documented as: the pointer pointed to by the pkt_data argument is set to point to the data in the packet We are passing a struct here rather than a pointer. I changed the code to pass a pointer instead. --- src/nwfilter/nwfilter_dhcpsnoop.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/nwfilter/nwfilter_dhcpsnoop.c b/src/nwfilter/nwfilter_dhcpsnoop.c index 58f0057c3f..45873a542c 100644 --- a/src/nwfilter/nwfilter_dhcpsnoop.c +++ b/src/nwfilter/nwfilter_dhcpsnoop.c @@ -1335,7 +1335,7 @@ virNWFilterDHCPSnoopThread(void *req0) { virNWFilterSnoopReqPtr req = req0; struct pcap_pkthdr *hdr; - virNWFilterSnoopEthHdrPtr packet; + const virNWFilterSnoopEthHdrPtr *packetPtr; int ifindex = 0; int errcount = 0; int tmp = -1, rv, n, pollTo; @@ -1453,7 +1453,7 @@ virNWFilterDHCPSnoopThread(void *req0) n--; rv = pcap_next_ex(pcapConf[i].handle, &hdr, - (const u_char **)&packet); + (const u_char **)&packetPtr); if (rv < 0) { /* error reading from socket */ @@ -1530,7 +1530,7 @@ virNWFilterDHCPSnoopThread(void *req0) continue; } - if (virNWFilterSnoopDHCPDecodeJobSubmit(worker, packet, + if (virNWFilterSnoopDHCPDecodeJobSubmit(worker, *packetPtr, hdr->caplen, pcapConf[i].dir, &pcapConf[i].qCtr) < 0) { -- 2.20.1