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From: dylan_nicholson (dylan_nicholson_at_[hidden])
Date: 2002-03-05 18:22:43

--- In boost_at_y..., Beman Dawes <bdawes_at_a...> wrote:
> At 03:08 AM 2/26/2002, Jan Langer wrote:
> At 08:43 AM 2/26/2002, Jan Langer wrote:
> I've been thinking a lot about Jan's two messages above, and I'm
> he has identified a serious weakness. We don't want any trap doors
> allow access to the current working directory.
> (Rationale: "current working directory" is in effect a global
variable. For
> why that is a serious problem, put "global variables considered
> into Google.)
But "Current working directory" is not really a global variable, it's
an operating system concept, just as "active window", "currently
logged in user" etc. are.
While I agree it's generally better to write code that uses absolute
paths where possible (mainly because using the wd is not thread-
safe), you can't always avoid needing to know it.
For one thing certain third party libraries either a) silently change
the working directory or b) require it to be set correctly to work.
A good example of a) is the Win32 ::GetOpenFileName call that
displays a dialog box allowing you to choose a file. By default it
changes the working directory, so that the next time you call it
starts up in the same directory. If absolute(...) didn't make use of
the correct current directory (as opposed to the initial working
directory when the application started), then code like:

/* fill in ofn structure */
name = absolute(ofn.lpstrFileTitle);

would unexpectedly not work (I don't want to use GetFullPathName,
because it is a pain to call).

I have seen examples of b) that are inhouse legacy libraries that for
one reason or another are too hard to change. So for these
situations I need to be able to set the working directory.

I really don't see what going out of your way to "ban" users from
accessing this is supposed to achieve.

Btw no-one has yet answered my concerned about supporting passing
char* and wchar_t* strings to file system functions. If the only
forms available are templated on basic_string this isn't possible
without explicitly creating the string yourself, meaning the above
would be:

name = absolute(std::basic_string<TCHAR>(ofn.lpstrFileTitle));

assuming I wanted to be able to compile my application as Unicode or
non-Unicode (we still write a lot of software like this).


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