OPENZAP-207 --resolve Rework the zt_read function

Break the read loop when receiving ELAST

diff --git a/libs/freetdm/src/ftmod/ftmod_zt/ftmod_zt.c b/libs/freetdm/src/ftmod/ftmod_zt/ftmod_zt.c
index c937c1bcd25231c2364ab91520ba29baf102d052..6ca005165c2f521dd88f2d8ad0ad2851688dad36 100644 (file)
--- a/libs/freetdm/src/ftmod/ftmod_zt/ftmod_zt.c
+++ b/libs/freetdm/src/ftmod/ftmod_zt/ftmod_zt.c
@@ -1311,37 +1311,52 @@ FIO_SPAN_NEXT_EVENT_FUNCTION(zt_next_event)
 static FIO_READ_FUNCTION(zt_read)
 {
        ftdm_ssize_t r = 0;
+       int read_errno = 0;
        int errs = 0;
 
        while (errs++ < 30) {
-               if ((r = read(ftdmchan->sockfd, data, *datalen)) > 0) {
+               r = read(ftdmchan->sockfd, data, *datalen);
+               if (r > 0) {
+                       /* successful read, bail out now ... */
                        break;
                }
-               else if (r == 0) {
+
+               /* Timeout ... retry after a bit */
+               if (r == 0) {
                        ftdm_sleep(10);
                        if (errs) errs--;
+                       continue;
                }
-               else {
-                       if (errno == EAGAIN || errno == EINTR)
-                               continue;
-                       if (errno == ELAST) {
-                               zt_event_t zt_event_id = 0;
-                               if (ioctl(ftdmchan->sockfd, codes.GETEVENT, &zt_event_id) == -1) {
-                                       ftdm_log_chan(ftdmchan, FTDM_LOG_ERROR, "Failed retrieving event after ELAST on read: %s\n", strerror(errno));
-                                       r = -1;
-                                       break;
-                               }
 
-                               if (handle_dtmf_event(ftdmchan, zt_event_id)) {
-                                       /* we should enqueue this event somewhere so it can be retrieved by the user, for now, dropping it to see what it is! */
-                                       ftdm_log_chan(ftdmchan, FTDM_LOG_ERROR, "Dropping event %d to be able to read data\n", zt_event_id);
-                               }
-                               continue;
+               /* This gotta be an error, save errno in case we do printf(), ioctl() or other operations which may reset it */
+               read_errno = errno;
+               if (read_errno == EAGAIN || read_errno == EINTR) {
+                       /* Reasonable to retry under those errors */
+                       continue;
+               }
+
+               /* When ELAST is returned, it means DAHDI has an out of band event ready and we won't be able to read anything until
+                * we retrieve the event using an ioctl(), so we try to retrieve it here ... */
+               if (read_errno == ELAST) {
+                       zt_event_t zt_event_id = 0;
+                       if (ioctl(ftdmchan->sockfd, codes.GETEVENT, &zt_event_id) == -1) {
+                               ftdm_log_chan(ftdmchan, FTDM_LOG_ERROR, "Failed retrieving event after ELAST on read: %s\n", strerror(errno));
+                               r = -1;
+                               break;
                        }
 
-                       ftdm_log(FTDM_LOG_ERROR, "read failed: %s\n", strerror(errno));
+                       if (handle_dtmf_event(ftdmchan, zt_event_id)) {
+                               /* we should enqueue this event somewhere so it can be retrieved by the user, for now, dropping it to see what it is! */
+                               ftdm_log_chan(ftdmchan, FTDM_LOG_WARNING, "Event %d is not dmtf related. Skipping one media read cycle\n", zt_event_id);
+                       }
+                       ftdm_log_chan_msg(ftdmchan, FTDM_LOG_WARNING, "Skipping one IO read cycle due to events pending in the driver queue\n");
+                       break;
                }
+
+               /* Read error, keep going unless to many errors force us to abort ...*/
+               ftdm_log(FTDM_LOG_ERROR, "IO read failed: %s\n", strerror(read_errno));
        }
+
        if (r > 0) {
                *datalen = r;
                if (ftdmchan->type == FTDM_CHAN_TYPE_DQ921) {
@@ -1349,7 +1364,7 @@ static FIO_READ_FUNCTION(zt_read)
                }
                return FTDM_SUCCESS;
        }
-       else if (errno == ELAST) {
+       else if (read_errno == ELAST) {
                return FTDM_SUCCESS;
        }
        return r == 0 ? FTDM_TIMEOUT : FTDM_FAIL;