[...] The replayer is the cool part. It takes control whenever the target process executes a system call, annuls the original system call, and overwrites the target process registers and address space with the values that I want to be in there.
[...] If I put memory-access rule checking in at replay time, I can do better than e-fence, on stock binaries with no recompilation. Hell, I can do better than Purify on stock binaries and without tangling with their object-code-insertion patents.
I have enough information available in the proxy ptrace filter to implement PTRACE_SINGLESTEP_BACKWARDS. How would you like to have that capability in gdb? "Execute backwards until this data watchpoint changes." Imagine a graphical debugger with a scrollbar for time, where the top is "beginning of execution" and the bottom is "end of execution."
Ok, the rest of the message reads as a ``why does my genius go unappreciated'' whine, but still, I want this program! The code is still available, but I'm sure not feeling motivated to try and port it to run on a modern kernel (it doesn't even support ELF binaries...)
It looks like after this message was sent to the linux-kernel list in 1999, there was a whole lot of talk, then three years of zilch. (I've mailed to ask if any progress was ever made. I'm doubtful.)
Update: He wrote back. No, nobody ever made it work on modern systems.