In pcap_read_linux_mmap(), if there are no frames available, call poll()

even if we're in non-blocking mode, to pick up any error indications -
in that case, use a timeout of 0, so poll() doesn't block.

Don't test individual exceptional-condition bits in the poll() return
unless one of them is set, so we just do one test in the typical (no
exceptional condition) case.

diff --git a/pcap-linux.c b/pcap-linux.c
index 8356ba54ef0d8fea6de6a8f8734bce00980fb211..48cad3aa6635b5bc939eee3e78193252c7f4126b 100644 (file)
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -2929,42 +2929,47 @@ pcap_get_ring_frame(pcap_t *handle, int status)
        return h.raw;
 }
 
+#ifndef POLLRDHUP
+#define POLLRDHUP 0
+#endif
+
 static int
 pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, 
                u_char *user)
 {
+       int timeout;
        int pkts = 0;
        char c;
 
        /* wait for frames availability.*/
-       if ((handle->md.timeout >= 0) &&
-           !pcap_get_ring_frame(handle, TP_STATUS_USER)) {
+       if (!pcap_get_ring_frame(handle, TP_STATUS_USER)) {
                struct pollfd pollinfo;
                int ret;
 
                pollinfo.fd = handle->fd;
                pollinfo.events = POLLIN;
 
+               if (handle->md.timeout == 0)
+                       timeout = -1;   /* block forever */
+               else if (handle->md.timeout > 0)
+                       timeout = handle->md.timeout;   /* block for that amount of time */
+               else
+                       timeout = 0;    /* non-blocking mode - poll to pick up errors */
                do {
-                       /* poll() requires a negative timeout to wait forever */
-                       ret = poll(&pollinfo, 1, (handle->md.timeout > 0)?
-                                               handle->md.timeout: -1);
-                       if ((ret < 0) && (errno != EINTR)) {
+                       ret = poll(&pollinfo, 1, timeout);
+                       if (ret < 0 && errno != EINTR) {
                                snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 
                                        "can't poll on packet socket: %s",
                                        pcap_strerror(errno));
                                return PCAP_ERROR;
-                       } else if (ret > 0) {
+                       } else if (ret > 0 &&
+                           (pollinfo.revents & (POLLHUP|POLLRDHUP|POLLERR|POLLNVAL))) {
                                /*
-                                * There's some indication on the descriptor.
-                                * Check for indications other than
-                                * "you can read on this descriptor".
+                                * There's some indication other than
+                                * "you can read on this descriptor" on
+                                * the descriptor.
                                 */
-#ifdef POLLRDHUP
                                if (pollinfo.revents & (POLLHUP | POLLRDHUP)) {
-#else
-                               if (pollinfo.revents & POLLHUP) {
-#endif
                                        snprintf(handle->errbuf,
                                                PCAP_ERRBUF_SIZE,
                                                "Hangup on packet socket");