Error should be more informative

[ndmitchell]

I sometimes get:

Fatal: fsatrace.c:39: CreateProcessW(0, cmd, 0, 0, 0, CREATE_SUSPENDED, 0, 0, &si, &pi), err: 2

It would be really useful if in those circumstances it could also print the command line used, since that can help with debugging various escaping issues (which I think is the problem I'm having here!)

[jacereda]

Is this enough?

https://github.com/jacereda/fsatrace/commit/4e771eb57d16ba21887b7c1fd7aa6d9e578a0424

If you need the full composed line passed to CreateProcessW just tell me.

[ndmitchell]

I now get:

fsatrace.exe(9988): error: forking process:
0:cmd /c echo 1

Which is still confusing since I don't know why it fails. I guess the fully composed line would be helpful here. The 0: also seems somewhat confusing.

[jacereda]

You should probably pass:

0:cmd
1:/c
2:echo 1

[jacereda]

Keep in mind that if we switch to _spawnvp() or similar for process execution that's what the arguments should look like, a single argument won't work.

[ndmitchell]

Ah, now I understand the 0 bit. Maybe even argv[0] = cmd ? Yes, I split up the cmd from the /c and it works.

[ndmitchell]

Yep, entirely my bug, I was just having difficulty tracking back through 3 layers of cmd/Haskell/fsatrace to figure what I ended up with.

[jacereda]

I changed the error messages to say argv[i].

[ndmitchell]

What about argv[i]=... instead of argv[i]:? Since I have Windows, I get argv[i]:C:\foo, which looks a bit confusing, but not terrible if you'd prefer the : style.

[jacereda]

Done

[ndmitchell]

Awesome, thanks a lot.