Re: native Win32 guile 1.7.0

[Kevin Ryde <user42@zip.com.au>]

stefan <stefan@lkcc.org> writes:
>
> I just added a check for unsetenv() in the configure script and used it in
> posix.c appropiately for mingw32 hosts.  Which means that a
> putenv("name="); would remove the environment variable 'name'.

I guess this means it's not possible to use putenv("name=") to set
name to an empty string.  I'm pretty sure it's valid to do so on other
systems.

On wine, which might not be the same as a real mingw, setting "name= "
and then changing that space to a \0 does the trick.  Bit nasty to go
changing putenvs strings like that, but unless there's a setenv or
some function hiding then there might be no choice.  Eg, (untested),



      /* If str is "FOO=", ie. attempting to set an empty string, then we
         need to see if it's been successful.  On MINGW, "FOO=" means remove
         FOO from the environment.  As a workaround, we set "FOO= ", ie. a
         space, and then modify the string returned by getenv.  It's not
         enough just to modify the string we set, because MINGW putenv
         copies it.  */
      if (ptr[SCM_STRING_LENGTH(str)-1] == '=')
        {
          SCM name = scm_substring (str, SCM_MAKINUM (0),
                                    SCM_MAKINUM (SCM_STRING_LENGTH (str) - 1));
          if (getenv (SCM_STRING_CHARS (name)) == NULL)
            {
              char  *alt = scm_malloc (SCM_STRING_LENGTH (str) + 2);
              memcpy (alt, SCM_STRING_CHARS (str), SCM_STRING_LENGTH(str));
              alt[SCM_STRING_LENGTH(str)] = ' ';
              alt[SCM_STRING_LENGTH(str)+1] = '\0';
              rv = putenv (alt);
              if (rv < 0)
                SCM_SYSERROR;
              free (ptr);   /* don't need the old string we gave to putenv */
              alt = getenv (SCM_STRING_CHARS (name));
              alt[SCM_STRING_LENGTH(str)] = '\0';
            }
        }


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