0
// add_suffix is in util.c too.
/*
 * Suffix appending for in-place editing under MS-DOS and OS/2 (and now NT!).
 *
 * Here are the rules:
 *
 * Style 0:  Append the suffix exactly as standard perl would do it.
 *           If the filesystem groks it, use it.  (HPFS will always
 *           grok it.  So will NTFS. FAT will rarely accept it.)
 *
 * Style 1:  The suffix begins with a '.'.  The extension is replaced.
 *           If the name matches the original name, use the fallback method.
 *
 * Style 2:  The suffix is a single character, not a '.'.  Try to add the 
 *           suffix to the following places, using the first one that works.
 *               [1] Append to extension.  
 *               [2] Append to filename, 
 *               [3] Replace end of extension, 
 *               [4] Replace end of filename.
 *           If the name matches the original name, use the fallback method.
 *
 * Style 3:  Any other case:  Ignore the suffix completely and use the
 *           fallback method.
 *
 * Fallback method:  Change the extension to ".$$$".  If that matches the
 *           original name, then change the extension to ".~~~".
 *
 * If filename is more than 1000 characters long, we die a horrible
 * death.  Sorry.
 *
 * The filename restriction is a cheat so that we can use buf[] to store
 * assorted temporary goo.
 *
 * Examples, assuming style 0 failed.
 *
 * suffix = ".bak" (style 1)
 *                foo.bar => foo.bak
 *                foo.bak => foo.$$$	(fallback)
 *                foo.$$$ => foo.~~~	(fallback)
 *                makefile => makefile.bak
 *
 * suffix = "~" (style 2)
 *                foo.c => foo.c~
 *                foo.c~ => foo.c~~
 *                foo.c~~ => foo~.c~~
 *                foo~.c~~ => foo~~.c~~
 *                foo~~~~~.c~~ => foo~~~~~.$$$ (fallback)
 *
 *                foo.pas => foo~.pas
 *                makefile => makefile.~
 *                longname.fil => longname.fi~
 *                longname.fi~ => longnam~.fi~
 *                longnam~.fi~ => longnam~.$$$
 *                
 */


static char suffix1[] = ".$$$";
static char suffix2[] = ".~~~";

#define ext (&buf[1000])

#define strEQ(s1,s2) (strcmp(s1,s2) == 0)

void
add_suffix(struct RString *str, char *suffix)
{
    int baselen;
    int extlen = strlen(suffix);
    char *s, *t, *p;
    int slen;
    char buf[1024];

    if (str->len > 1000)
        rb_fatal("Cannot do inplace edit on long filename (%d characters)", str->len);

    /* Style 0 */
    slen = str->len;
    str_cat(str, suffix, extlen);
    if (valid_filename(str->ptr)) return;

    /* Fooey, style 0 failed.  Fix str before continuing. */
    str->ptr[str->len = slen] = '\0';

    slen = extlen;
    t = buf; baselen = 0; s = str->ptr;
    while ( (*t = *s) && *s != '.') {
	baselen++;
	if (*s == '\\' || *s == '/') baselen = 0;
 	s++; t++;
    }
    p = t;

    t = ext; extlen = 0;
    while (*t++ = *s++) extlen++;
    if (extlen == 0) { ext[0] = '.'; ext[1] = 0; extlen++; }

    if (*suffix == '.') {        /* Style 1 */
        if (strEQ(ext, suffix)) goto fallback;
	strcpy(p, suffix);
    } else if (suffix[1] == '\0') {  /* Style 2 */
        if (extlen < 4) { 
	    ext[extlen] = *suffix;
	    ext[++extlen] = '\0';
        } else if (baselen < 8) {
   	    *p++ = *suffix;
	} else if (ext[3] != *suffix) {
	    ext[3] = *suffix;
	} else if (buf[7] != *suffix) {
	    buf[7] = *suffix;
	} else goto fallback;
	strcpy(p, ext);
    } else { /* Style 3:  Panic */
fallback:
	(void)memcpy(p, strEQ(ext, suffix1) ? suffix2 : suffix1, 5);
    }
    str_grow(str, strlen(buf));
    memcpy(str->ptr, buf, str->len);
}
#endif

static int 
valid_filename(char *s)
{
    int fd;

    //
    // if the file exists, then it\'s a valid filename!
    //

    if (_access(s, 0) == 0) {
	return 1;
    }

    //
    // It doesn\'t exist, so see if we can open it.
    //
    
    if ((fd = _open(s, _O_CREAT, 0666)) >= 0) {
	close(fd);
	_unlink (s);	// don\'t leave it laying around
	return 1;
    }
    return 0;
}