+ int up = 0;
+ if (l0==2 && stack[p-2]=='.' && stack[p-1]=='.') {
+ up = 1;
+ /* Any non-.. path components we could cancel start
+ * after nup repetitions of the 3-byte string "../";
+ * if there are none, accumulate .. components to
+ * later apply to cwd, if needed. */
+ if (q <= 3*nup) {
+ nup++;
+ q += l;
+ continue;
+ }
+ /* When previous components are already known to be
+ * directories, processing .. can skip readlink. */
+ if (!check_dir) goto skip_readlink;
+ }
+ ssize_t k = readlink(output, stack, p);
+ if (k==p) goto toolong;
+ if (!k) {
+ errno = ENOENT;
+ return 0;
+ }
+ if (k<0) {
+ if (errno != EINVAL) return 0;
+skip_readlink:
+ check_dir = 0;
+ if (up) {
+ while(q && output[q-1]!='/') q--;
+ if (q>1 && (q>2 || output[0]!='/')) q--;
+ continue;
+ }
+ if (l0) q += l;
+ check_dir = stack[p];
+ continue;
+ }
+ if (++cnt == SYMLOOP_MAX) {
+ errno = ELOOP;
+ return 0;
+ }
+
+ /* If link contents end in /, strip any slashes already on
+ * stack to avoid /->// or //->/// or spurious toolong. */
+ if (stack[k-1]=='/') while (stack[p]=='/') p++;
+ p -= k;
+ memmove(stack+p, stack, k);
+
+ /* Skip the stack advancement in case we have a new
+ * absolute base path. */
+ goto restart;
+ }
+
+ output[q] = 0;
+
+ if (output[0] != '/') {
+ if (!getcwd(stack, sizeof stack)) return 0;
+ l = strlen(stack);
+ /* Cancel any initial .. components. */
+ p = 0;
+ while (nup--) {
+ while(l>1 && stack[l-1]!='/') l--;
+ if (l>1) l--;
+ p += 2;
+ if (p<q) p++;
+ }
+ if (q-p && stack[l-1]!='/') stack[l++] = '/';
+ if (l + (q-p) + 1 >= PATH_MAX) goto toolong;
+ memmove(output + l, output + p, q - p + 1);
+ memcpy(output, stack, l);
+ q = l + q-p;