Re: [PATCH 05/19] mingw: prepare the TMPDIR environment variable for shell scripts

> On Sun, Jan 24, 2016 at 10:43 AM, Johannes Schindelin
> <johannes.schindelin@gmx.de> wrote:
> > When shell scripts access a $TMPDIR variable containing backslashes,
> > they will be mistaken for escape characters. Let's not let that happen
> > by converting them to forward slashes.
> >
> > This partially fixes t7800 with MSYS2.
> >
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> > ---
> > diff --git a/compat/mingw.c b/compat/mingw.c
> > @@ -2042,13 +2042,28 @@ int xwcstoutf(char *utf, const wchar_t *wcs, size_t utflen)
> >  static void setup_windows_environment()
> >  {
> > +       char *tmp = getenv("TMPDIR");
> > +
> >         /* on Windows it is TMP and TEMP */
> > -       if (!getenv("TMPDIR")) {
> > -               const char *tmp = getenv("TMP");
> > -               if (!tmp)
> > +       if (tmp) {
> > +               if (!(tmp = getenv("TMP")))
> >                         tmp = getenv("TEMP");
> > -               if (tmp)
> > +               if (tmp) {
> >                         setenv("TMPDIR", tmp, 1);
> > +                       tmp = getenv("TMPDIR");
> > +               }
> > +       }
> 
> Let me see if I understand this...
> 
> In the original code, if TMPDIR was *not* set, it would assign the
> value of TMP or TEMP to TEMPDIR.
> 
> The new code, however, checks TMP and TEMP only if TMPDIR is *already*
> set. Am I reading this correctly? Is this revised behavior correct?

> > +       if (tmp) {
> > +               /*
> > +                * Convert all dir separators to forward slashes,
> > +                * to help shell commands called from the Git
> > +                * executable (by not mistaking the dir separators
> > +                * for escape characters).
> > +                */
> > +               for (; *tmp; tmp++)
> > +                       if (*tmp == '\\')
> > +                               *tmp = '/';
> 
> This transformation is performed on whatever memory was returned by
> getenv(). It is also performed after setenv(), so presumably setenv()
> isn't making a copy of the incoming string.