Etc.systmpdir

static VALUE
etc_systmpdir(VALUE _)
{
    VALUE tmpdir;
#ifdef _WIN32
    WCHAR path[_MAX_PATH];
    UINT len = rb_w32_system_tmpdir(path, numberof(path));
    if (!len) return Qnil;
    tmpdir = rb_w32_conv_from_wchar(path, rb_filesystem_encoding());
#else
    const char default_tmp[] = "/tmp";
    const char *tmpstr = default_tmp;
    size_t tmplen = strlen(default_tmp);
# if defined _CS_DARWIN_USER_TEMP_DIR
    #ifndef MAXPATHLEN
    #define MAXPATHLEN 1024
    #endif
    char path[MAXPATHLEN];
    size_t len;
    len = confstr(_CS_DARWIN_USER_TEMP_DIR, path, sizeof(path));
    if (len > 0) {
        tmpstr = path;
        tmplen = len - 1;
        if (len > sizeof(path)) tmpstr = 0;
    }
# endif
    tmpdir = rb_filesystem_str_new(tmpstr, tmplen);
# if defined _CS_DARWIN_USER_TEMP_DIR
    if (!tmpstr) {
        confstr(_CS_DARWIN_USER_TEMP_DIR, RSTRING_PTR(tmpdir), len);
    }
# endif
#endif
#ifndef RB_PASS_KEYWORDS
    /* untaint on Ruby < 2.7 */
    FL_UNSET(tmpdir, FL_TAINT);
#endif
    return tmpdir;
}