+/* Take a filename and filename length and return the most significant
+ * filename suffix we can find. This ignores suffixes such as "~",
+ * ".bak", ".orig", ".~1~", etc. */
+const char *find_filename_suffix(const char *fn, int fn_len, int *len_ptr)
+{
+ const char *suf, *s;
+ BOOL had_tilde;
+ int s_len;
+
+ /* One or more dots at the start aren't a suffix. */
+ while (fn_len && *fn == '.') fn++, fn_len--;
+
+ /* Ignore the ~ in a "foo~" filename. */
+ if (fn_len > 1 && fn[fn_len-1] == '~')
+ fn_len--, had_tilde = True;
+ else
+ had_tilde = False;
+
+ /* Assume we don't find an suffix. */
+ suf = "";
+ *len_ptr = 0;
+
+ /* Find the last significant suffix. */
+ for (s = fn + fn_len; fn_len > 1; ) {
+ while (*--s != '.' && s != fn) {}
+ if (s == fn)
+ break;
+ s_len = fn_len - (s - fn);
+ fn_len = s - fn;
+ if (s_len == 4) {
+ if (strcmp(s+1, "bak") == 0
+ || strcmp(s+1, "old") == 0)
+ continue;
+ } else if (s_len == 5) {
+ if (strcmp(s+1, "orig") == 0)
+ continue;
+ } else if (s_len > 2 && had_tilde
+ && s[1] == '~' && isdigit(*(uchar*)(s+2)))
+ continue;
+ *len_ptr = s_len;
+ suf = s;
+ if (s_len == 1)
+ break;
+ /* Determine if the suffix is all digits. */
+ for (s++, s_len--; s_len > 0; s++, s_len--) {
+ if (!isdigit(*(uchar*)s))
+ return suf;
+ }
+ /* An all-digit suffix may not be that signficant. */
+ s = suf;