[PATCH] D141389: [DFSAN] Add support for strnlen, strncat, strsep, sscanf and _tolower

[Andrew via Phabricator via llvm-commits]

browneee added inline comments.


================
Comment at: compiler-rt/lib/dfsan/dfsan_custom.cpp:221
+  if (flags().strict_data_dependencies) {
+    *ret_label = res ? s_label : 0;
+  } else {
----------------
tkuchta wrote:
> browneee wrote:
> > When `res != NULL`, then `res` is derived from `*s`, not from `s`.
> > 
> > e.g.
> > 
> > ```
> > *ret_label = res ? dfsan_get_label(base) : 0;
> > ```
> Apologies for a delay.
> 
> I came across some difficulty with using dfsan_get_label inside the dfsan_custom.cpp file.
> It seems that including the dfsan_interface.h header there, which would be needed for dfsan_get_label, causes other conflicts and build errors.
> Would there be another way to use that function inside dfsan_custom.cpp? 
```
char *base = *s;
```

Here base is loaded, so we can also load the shadow.

`dfsan_get_label(base) == dfsan_read_label(s, sizeof(*s))`

If base was an argument, then it would have a corresponding label argument as part of the wrapper function, so you also wouldn't need `dfsan_get_label`.


Repository:
  rCRT Compiler Runtime

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D141389/new/

https://reviews.llvm.org/D141389