TBL missing coverage in cfe_tbl_api.c function CFE_TBL_Update

[nmullane]

Is your feature request related to a problem? Please describe.
CFE_TBL_Update function contains two hard to reach lines (953-954) that remains untested, preventing us from reaching 100% line coverage. It's actually just one uncovered line, but lcov thinks it's two.

    : 919:  /* Verify access rights and get a valid Application ID for calling App */
   6: 920:  Status = CFE_TBL_ValidateAccess(TblHandle, &ThisAppId);
    : 921: 
   6: 922:  if (Status == CFE_SUCCESS)
    : 923:  {
    : 924:      /* Get pointers to pertinent records in registry and handles */
   4: 925:      AccessDescPtr = &CFE_TBL_Global.Handles[TblHandle];
   4: 926:      RegRecPtr     = &CFE_TBL_Global.Registry[AccessDescPtr->RegIndex];
    : 927: 
   4: 928:      Status = CFE_TBL_UpdateInternal(TblHandle, RegRecPtr, AccessDescPtr);
    : 929: 
   4: 930:      if (Status != CFE_SUCCESS)
    : 931:      {
   2: 932:          CFE_ES_WriteToSysLog("%s: App(%lu) fail to update Tbl '%s' (Stat=0x%08X)\n", __func__,
   2: 933:                               CFE_RESOURCEID_TO_ULONG(ThisAppId), RegRecPtr->Name, (unsigned int)Status);
    : 934:      }
    : 935:  }
    : 936:  else
    : 937:  {
   2: 938:      CFE_ES_WriteToSysLog("%s: App(%lu) does not have access to Tbl Handle=%d\n", __func__,
    : 939:                           CFE_RESOURCEID_TO_ULONG(ThisAppId), (int)TblHandle);
    : 940:  }
    : 941: 
   6: 942:  if (Status != CFE_TBL_ERR_BAD_APP_ID)
    : 943:  {
    : 944:      /* Translate AppID of caller into App Name */
   6: 945:      CFE_ES_GetAppName(AppName, ThisAppId, sizeof(AppName));
    : 946:  }
    : 947: 
    : 948:  /* On Error conditions, notify ground of screw up */
   6: 949:  if (Status < 0)
    : 950:  {
   2: 951:      if (RegRecPtr != NULL)
    : 952:      {
## 0: 953:          CFE_EVS_SendEventWithAppID(CFE_TBL_UPDATE_ERR_EID, CFE_EVS_EventType_ERROR, CFE_TBL_Global.TableTaskAppId,
## 0: 954:                                     "%s Failed to Update '%s', Status=0x%08X", AppName, RegRecPtr->Name,
    : 955:                                     (unsigned int)Status);
    : 956:      }
    : 957:      else
    : 958:      {
   2: 959:          CFE_EVS_SendEventWithAppID(CFE_TBL_UPDATE_ERR_EID, CFE_EVS_EventType_ERROR, CFE_TBL_Global.TableTaskAppId,
    : 960:                                     "%s Failed to Update '?', Status=0x%08X", AppName, (unsigned int)Status);
    : 961:      }
    : 962:  }

Describe the solution you'd like
These lines should be safe to leave uncovered because they do not contain any potential to access a NULL pointer or anything else similarly dangerous.

Additional context
Line 953 is currently impossible to reach because CFE_TBL_UpdateInternal does not throw any error status codes (< 0), so the only way to trigger the if statement on line 949 is from CFE_TBL_ValidateAccess on line 920 which would always mean RegRecPtr is NULL. Thus the if statement on line 951 can never be true, leaving line 953 uncovered.

Requester Info
Niall Mullane - GSFC 582 Intern

[avan989]

The targeted condition is:

1. Status < 0 and RegRecPtr != NULL

By default RegRecPtr is NULL. The only way to update RegRecPtr is by taking the following path:

1. CFE_TBL_ValidateAccess -> Return CFE_SUCCESS -> CFE_TBL_UpdateInternal (cfe_tbl_internal.c)
2. CFE_TBL_UpdateInternal (Not a stub) also updates "Status" but only with the following possible value:
   a. CFE_SUCCESS 0
   b. CFE_TBL_INFO_NO_UPDATE_PENDING 0x4c000017
   c. CFE_TBL_INFO_TABLE_LOCKED 0x4c000018

There is no way to have both Status < 0 and RegRecPtr != NULL without changing the implementation. Code Coverage is not possible.