strtok and function call

Question

I have this extremely strange behavior coming :

In the below code: If I comment the call to MyLogger then everything works fine that is I get the sTempNr tokenized and 4 tokens are printed . But if I uncomment the call to MyLogger for logging then only the iteration takes place once and in other testing class with similar code as below there is a looping taking place more than 4 times with redundant info being sent to MyLogger.

So, I checked with Purify tool to determine if there were some memory issues in MyLogger. Could not find any. MyLogger is using vaargs to extract args and vfprintf call to print.

I am not sure how to debug this code further. Any guidance would be appreciated!.

char sTempNr[41] = "1129Z13589.2.9.10";
char *sTempStr;
sTempStr = NULL;

sTempStr = strtok(sTempNr,".");
while (sTempStr)
{
     printf("in in TempStr[%s]\n",sTempStr);
      //MyLogger("write","","Temp String[%s]",sTempStr);

     sTempStr = strtok(NULL,".");
}

Answer 1

Is the logger calling strtok?

Answer 2

strtok() keeps some static data inside so probably MyLogger calls strtok(), either directly or indirectly.

Replace strtok() with strtok_r() (reentrant version of strtok()) to get around this problem.

Answer 3

Is MyLogger using strtok as well? Note that strtok is not stateless.

Answer 4

Sounds like MyLogger is corrupting the string in sTempStr. Try printing it out again after the call to MyLogger. eg

 printf("in in TempStr[%s]\n",sTempStr);
 MyLogger("write","","Temp String[%s]",sTempStr);
 printf("in in TempStr[%s]\n",sTempStr);

and see if anything has changed