On Thursday, 13 July 2017 at 20:35:19 UTC, Moritz Maxeiner wrote:
On Thursday, 13 July 2017 at 18:22:34 UTC, FoxyBrown wrote:
The following code is pretty screwed up, even though it
doesn't look like it. I have a buf, a simple malloc which hold
the results of a win32 call. I am then trying to copy over the
data in buf to a D struct.
But when copying the strings, the buf location changes,
screwing up the copying process. It shouldn't happen, buf
never changes value anywhere except the first malloc(which is
once). Somehow it is getting changed, but where?
[...]
The buf value changes when calling cstr2dstr but I've had it
with other values to(any function call such as to!string, etc
seems to trigger it).
[...]
- Does this happen every time, or only sometimes?
yes, but I've been having this problem and not sure if it was
quite as consistent as before or that I just recognized it.
- At which loop iteration does it occur?
Now it seems to occur after the first iteration, but I've add it
happen after a while and in other cases it's worked.. depends on
if I use malloc, or a D array, or what.
- Which compiler (+version) are you using (with what flags)?
Latest DMD official.. whatever default flags exist in debug mode
with visual D... why should it matter? buf is changing on the
only source of that change could be through the winapi call or
the temp pointer used to index it.. which is never assigned to,
so it can't be modifying it. The c2d function, when called,
clearly has no understanding of buff, yet after it returns, it is
causing the problem. This seems like the stack is being corrupted
by the function call.
- What are the steps to reproduce (i.e. does this e.g. happen
with a main that consist of one call to EnumServices) ?
Yes, It is basically the first thing I do when I run my program.
It is a rather isolated function(Just trying to get a list of
current services, which has been a total PITA because D is not
interfacing well with C. First, the win32 function does not
simply fill in an array but adds additional junk at the
end(didn't know that until after a few wasted hours trying to get
it to fill in an array properly). Hence now I'm trying to convert
the returned data one iteration at a time rather than all at
once, but I can't get that to work because the pointer to the
buffer I created is changing. I could use a temp and get it to
work, but that doesn't explain what the hell is going on. The
value of buff seems to be erratic, I've had it point valid
stuff(other data) and then have small values in it like 8.
I don't know how any stack corruption could be occurring but that
is exactly what it looks like. "Return from function call and
"static variables"(with respect to the call) are changed.". But
that seems really hard to sell given that it's pretty simple and
D should have all those basics well covered.
