Hi...
I would like to tell about my exp getting 8.6tcl to work with some of the aolserver modules...
Before 8.6, the tcl result was available as a string, with some funcs to set and append to that string.
At 8.6, you actually have a choice, you can rebuild it so it works as before (so result is exposed) or you can alter code which accesses the result, as the patch suggests.
What I found out was, if you want numeric result values, you can have tcl set them as ints or maybe longs (or other object types). This is what I preferred to do when I was trying to get 8.6 going.
You want to be very cautious with sprintf, as this func doesn't limit the writing based on length. So, you either want to use things that append to the string result object, or you want to set as cast to a different type, for example int. 8.6 provides calls for doing either.
Almost every time I've seen uses of sprintf (in -anything-), I knew there was the typical "buffer overrun" possibility, and in the cases where I could, I was able to replace each with calls to snprintf (or to use a different alternative that was also safe).
As an aside, many years ago, when looking at aolserver source for my first time, I happened to look at the call Ns_DStringPrintf, which then used sprintf. I wrote an equivalent using snprintf, and aolserver devs eventually took a whole printf func from some stdio lib source, and adapted it so that it "printf"ed to a DString in a safe manner. To Gustaf, if you hadn't done so already, would you be willing to look at it and at naviserv source to see if it's been incorporated already?
If you're going to use sprintf, get the length of the buffer and use snprintf instead, as not doing so could result in a crash if sprintf overwrites a dynamically allocated buffer.
This may sound like hyperbole, but it's my very stong belief that sprintf is never safe, and should always be replaced with snprintf.
I may still have the sources of other aolserver or naviserv (don't remember which at this moment) modules, where I had to rewrite the pieces that set or get the tcl result.
On request, I'll put something together in the hope it will assist.
-Jim
