+/*
+ * Link the tempfile to the final place, possibly creating the
+ * last directory level as you do so.
+ *
+ * Returns the errno on failure, 0 on success.
+ */
+static int link_temp_to_file(const char *tmpfile, char *filename)
+{
+ int ret;
+
+ if (!link(tmpfile, filename))
+ return 0;
+
+ /*
+ * Try to mkdir the last path component if that failed
+ * with an ENOENT.
+ *
+ * Re-try the "link()" regardless of whether the mkdir
+ * succeeds, since a race might mean that somebody
+ * else succeeded.
+ */
+ ret = errno;
+ if (ret == ENOENT) {
+ char *dir = strrchr(filename, '/');
+ if (dir) {
+ *dir = 0;
+ mkdir(filename, 0777);
+ *dir = '/';
+ if (!link(tmpfile, filename))
+ return 0;
+ ret = errno;
+ }
+ }
+ return ret;
+}
+
+/*
+ * Move the just written object into its final resting place
+ */
+int move_temp_to_file(const char *tmpfile, char *filename)
+{
+ int ret = link_temp_to_file(tmpfile, filename);
+
+ /*
+ * Coda hack - coda doesn't like cross-directory links,
+ * so we fall back to a rename, which will mean that it
+ * won't be able to check collisions, but that's not a
+ * big deal.
+ *
+ * The same holds for FAT formatted media.
+ *
+ * When this succeeds, we just return 0. We have nothing
+ * left to unlink.
+ */
+ if (ret && ret != EEXIST) {
+ if (!rename(tmpfile, filename))
+ return 0;
+ ret = errno;
+ }
+ unlink(tmpfile);
+ if (ret) {
+ if (ret != EEXIST) {
+ fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
+ return -1;
+ }
+ /* FIXME!!! Collision check here ? */
+ }
+
+ return 0;
+}
+