+ prevbuf[0] = '\0';
+ tf = triewalk_next(tw, buf);
+ assert(tf);
+ while (1) {
+ int i;
+
+ if (totalsize - indexbuild_realsize(ib) < delta) {
+ const void *oldfile = mappedfile;
+ ptrdiff_t diff;
+
+ /*
+ * Unmap the file, grow it, and remap it.
+ */
+ munmap(mappedfile, totalsize);
+
+ totalsize += delta;
+ totalsize += totalsize / 10;
+
+ if (lseek(fd, totalsize-1, SEEK_SET) < 0) {
+ perror(PNAME ": lseek");
+ return 1;
+ }
+ if (write(fd, "\0", 1) < 1) {
+ perror(PNAME ": write");
+ return 1;
+ }
+
+ mappedfile = mmap(NULL, totalsize, PROT_READ|PROT_WRITE,MAP_SHARED, fd, 0);
+ if (!mappedfile) {
+ perror(PNAME ": mmap");
+ return 1;
+ }
+
+ indexbuild_rebase(ib, mappedfile);
+ triewalk_rebase(tw, mappedfile);
+ diff = (const unsigned char *)mappedfile -
+ (const unsigned char *)oldfile;
+ if (prevtf)
+ prevtf = (const struct trie_file *)
+ (((const unsigned char *)prevtf) + diff);
+ if (tf)
+ tf = (const struct trie_file *)
+ (((const unsigned char *)tf) + diff);
+ }
+
+ /*
+ * Get the next file from the index. So we are
+ * currently holding, and have not yet
+ * indexed, prevtf (with pathname prevbuf) and
+ * tf (with pathname buf).
+ */
+ prevtf = tf;
+ memcpy(prevbuf, buf, maxpathlen);
+ tf = triewalk_next(tw, buf);
+
+ if (!tf)
+ buf[0] = '\0';
+
+ /*
+ * Find the first differing character position
+ * between our two pathnames.
+ */
+ for (i = 0; prevbuf[i] && prevbuf[i] == buf[i]; i++);
+
+ /*
+ * If prevbuf was a directory name and buf is
+ * something inside that directory, then
+ * trie_before() will be called on prevbuf
+ * itself. Hence we must drop a tag before it,
+ * so that the resulting index is usable.
+ */
+ if ((!prevbuf[i] && (buf[i] == pathsep ||
+ (i > 0 && buf[i-1] == pathsep))))
+ indexbuild_tag(ib);
+
+ /*
+ * Add prevtf to the index.
+ */
+ indexbuild_add(ib, prevtf);
+
+ if (!tf) {
+ /*
+ * Drop an unconditional final tag, and
+ * get out of this loop.
+ */
+ indexbuild_tag(ib);
+ break;
+ }
+
+ /*
+ * If prevbuf was a filename inside some
+ * directory which buf is outside, then
+ * trie_before() will be called on some
+ * pathname either equal to buf or epsilon
+ * less than it. Either way, we're going to
+ * need to drop a tag after prevtf.
+ */
+ if (strchr(prevbuf+i, pathsep) || !tf)
+ indexbuild_tag(ib);
+ }
+