#456 example receiveHello crashes with memory fault

[Renaat Debaene]

The example receiveHello sometimes crashes with a memory fault when the receive loop begins:

$ ./receiveHello -o 192.168.2.1 -c 40000
...
20240101-02:41:13.326326     Info: tlc_if.c:420 TRDP Stack Version 3.0.24.39(trunk): successfully initiated
20240101-02:41:13.326326     Info: tlc_if.c:424 VOS Version 3.0.0.1(trunk): successfully initiated
...
20240101-02:41:13.331326     Info: tlc_if.c:672 TRDP session opened successfully
Memory fault

The problem seems to be caused by an uninitialzed variable noDesc. The problem disappears after initializing the variable with VOS_INVALID_SOCKET either in receiveHello.c or in tlc_if.c:

--- src/common/tlc_if.c (revision 2439)
+++ src/common/tlc_if.c (working copy)
@@ -1434,6 +1434,7 @@
                 vos_getTime(&now);
                 vos_clearTime(&appHandle->nextJob);


+                *pNoDesc = VOS_INVALID_SOCKET;
                 trdp_pdCheckPending(appHandle, pFileDesc, pNoDesc, TRUE);

 #if MD_SUPPORT

[Armin-Hagen Weiss]

It has to be ensured that the calling application is calling tlc_getIntervall for the first time with NoDesc == VOS_INVALID_SOCKET. For the following calls it is correct to call tlc_getInterva() with the last returned NoDesc.

[Renaat Debaene]

Dear Armin-Hagen,

OK, that's understood.
But in that case: multiple examples don't follow this rule. They use declare "INT32 noDesc" in the loop, so this variable is not initialized at all. Suggested patch: move it outside the loop and initialize it.

Patch for examples receiveHello.c / sendData.c / sendHello.c:

--- example/receiveHello.c      (revision 2442)
+++ example/receiveHello.c      (working copy)
@@ -249,10 +249,10 @@
     /*
      Enter the main processing loop.
      */

+    INT32 noDesc = VOS_INVALID_SOCKET;
     while (1)
     {
         TRDP_FDS_T rfds;
-        INT32 noDesc;
         TRDP_TIME_T tv = {0, 0};
         const TRDP_TIME_T   max_tv  = {1, 0};
         const TRDP_TIME_T   min_tv  = {0, TRDP_PROCESS_DEFAULT_CYCLE_TIME};
Index: example/sendData.c
===================================================================
--- example/sendData.c  (revision 2442)
+++ example/sendData.c  (working copy)
@@ -288,10 +288,10 @@
     /*
        Enter the main processing loop.
      */
+    INT32 noDesc = VOS_INVALID_SOCKET;
     while (1)
     {
         TRDP_FDS_T rfds;
-        INT32 noDesc;
         TRDP_TIME_T tv;
         const TRDP_TIME_T   max_tv  = {1, 0};
         const TRDP_TIME_T   min_tv  = {0, TRDP_PROCESS_DEFAULT_CYCLE_TIME};
Index: example/sendHello.c
===================================================================
--- example/sendHello.c (revision 2442)
+++ example/sendHello.c (working copy)
@@ -312,10 +312,10 @@
     /*
        Enter the main processing loop.
      */
+    INT32 noDesc = VOS_INVALID_SOCKET;
     while (1)
     {
         TRDP_FDS_T          rfds;
-        INT32               noDesc;
         TRDP_TIME_T         tv;
         const TRDP_TIME_T   max_tv  = {0, 1000000};
         const TRDP_TIME_T   min_tv  = {0, TRDP_PROCESS_DEFAULT_CYCLE_TIME};

[Armin-Hagen Weiss]

All tests/examples handling noDesc now in the same way - definition and initialisation with TRDP_INVALID_SOCKET outside the loop with tlc_getInterval()/voc_select().