Currently pcap_frame() assumes that if write() doesn't return an error, it
has written everything we want. That's not necessarily true, because it
could return a short write. That's not likely to happen on a regular file,
but there's not a lot of reason not to be robust here; it's conceivable we
might want to direct the pcap fd at a named pipe or similar.
So, make pcap_frame() handle short frames by using the write_remainder()
helper.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
pcap.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/pcap.c b/pcap.c
index 8876a051..eeb71a3c 100644
--- a/pcap.c
+++ b/pcap.c
@@ -77,15 +77,18 @@ static void pcap_frame(const struct iovec *iov, size_t offset,
const struct timeval *tv)
{
size_t len = iov->iov_len - offset;
- struct pcap_pkthdr h;
-
- h.tv_sec = tv->tv_sec;
- h.tv_usec = tv->tv_usec;
- h.caplen = h.len = len;
-
- if (write(pcap_fd, &h, sizeof(h)) < 0 ||
- write(pcap_fd, (char *)iov->iov_base + offset, len) < 0)
- debug("Cannot log packet, length %zu", len);
+ struct pcap_pkthdr h = {
+ .tv_sec = tv->tv_sec,
+ .tv_usec = tv->tv_usec,
+ .caplen = len,
+ .len = len
+ };
+ struct iovec hiov = { &h, sizeof(h) };
+
+ if (write_remainder(pcap_fd, &hiov, 1, 0) < 0 ||
+ write_remainder(pcap_fd, iov, 1, offset) < 0)
+ debug("Cannot log packet, length %zu: %s",
+ len, strerror(errno));
}
/**
--
2.43.2