[Octave-bug-tracker] [bug #50234] c++ file_stat with non existant crashes octave in windows

[Rik]

Update of bug #50234 (project octave):

                  Status:                    None => Confirmed              

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Follow-up Comment #10:

Confirmed.  For completeness, I booted an old Windows XP VM and ran 4.2.0 to
create a .oct file and it segfaults in the manner reported here.

Looking at the code in liboctave/system/file-ops.cc I see


    std::string
    octave::sys::file_ops::tilde_expand (const std::string& name)
    {
      if (name.find ('~') == std::string::npos)
        return name;
      else
        {
          std::string result;


I'm grasping here, but I see that name is passed in by reference, and that the
function prototype declares this const which means it is making a promise not
to change it.  However, tilde_expand just returns a std::string object.  When
a '~' is found, the function declares a temporary "std::string result" and
then proceeds to construct that string before ending with "return result;".

On the other hand, if no '~' is found then the function actually passes a
reference to a string ("return name;") rather than a string object.  It is
possible that eventually the reference is invalid but downstream functions
which called tilde_expand continue to try and use it.

As a quick test, one might try altering the return statement to


return std::string (name);





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