.

wcfs/client/wcfs_watchlink.cpp

@@ -162,7 +162,7 @@ error _WatchLink::_serveRX(context::Context ctx) {
         if (pkt.stream == 0) { // control/fatal message from wcfs
             log::Errorf("C: watch  : rx fatal: %s\n", v(l));
             wlink.fatalv.push_back(pkt.to_string());
-            continue;   // XXX -> shutdown ?
+            return ErrLinkDown; // XXX correct error
         }
 
         bool reply = (pkt.stream % 2 != 0);
@@ -227,8 +227,15 @@ error _WatchLink::recvReq(context::Context ctx, PinReq *prx) {
     if (_ == 0)
         return E(ctx->err());
 
-    if (!ok)
+    if (!ok) {
+        wlink._rxmu.lock();
+        bool down = wlink._rxdown;
+        wlink._rxmu.unlock();
+
+        if (down)
+            return E(ErrLinkDown);
         return io::EOF_; // NOTE EOF goes without E
+    }
 
     return E(_parsePinReq(prx, &pkt));
 }

wcfs/client/wcfs_watchlink.h

@@ -49,7 +49,7 @@ struct rxPkt {
     StreamID stream;
 
     // raw data received/to-be-sent.
-    // XXX not e.g. string as chan<T> currently does not support types with
+    // XXX not e.g. string, as chan<T> currently does not support types with
     //     non-trivial copy. Note: we anyway need to limit rx line length to
     //     avoid DoS, but just for DoS the limit would be higher.
     uint16_t datalen;
@@ -58,12 +58,12 @@ struct rxPkt {
     error  from_string(const string& rx);
     string to_string() const;
 };
-static_assert(sizeof(rxPkt) == 256, "rxPkt miscompiled");   // NOTE 128 is too low for long error message
+static_assert(sizeof(rxPkt) == 256, "rxPkt miscompiled"); // NOTE 128 is too low for long error message
 
 
 // WatchLink represents /head/watch link opened on wcfs.
 //
-// It is created by WCFS::_openwatch().
+// It is created by WCFS._openwatch().
 //
 // .sendReq()/.recvReq() provides raw IO in terms of wcfs isolation protocol messages.
 // .close() closes the link.
@@ -73,12 +73,12 @@ typedef refptr<class _WatchLink> WatchLink;
 class _WatchLink : public object {
     WCFS            *_wc;
     os::File        _f;      // head/watch file handle
-    string          _rxbuf;  // buffer for read data from _f
+    string          _rxbuf;  // buffer for data already read from _f
 
     // iso.protocol message IO
     chan<rxPkt>     _acceptq;   // server originated messages go here
     sync::Mutex     _rxmu;
-    bool            _rxdown;
+    bool            _rxdown;    // y when the link is no-longer operational
     dict<StreamID, chan<rxPkt>>
                     _rxtab;     // {} stream -> rxq    server replies go via here
     set<StreamID>   _accepted;  // streams we accepted but did not replied yet