+static void diff_fill_sha1_info(struct diff_filespec *one)
+{
+ if (DIFF_FILE_VALID(one)) {
+ if (!one->sha1_valid) {
+ struct stat st;
+ if (stat(one->path, &st) < 0)
+ die("stat %s", one->path);
+ if (index_path(one->sha1, one->path, &st, 0))
+ die("cannot hash %s\n", one->path);
+ }
+ }
+ else
+ memset(one->sha1, 0, 20);
+}
+
+static void run_diff(struct diff_filepair *p)
+{
+ const char *pgm = external_diff();
+ char msg[PATH_MAX*2+300], *xfrm_msg;
+ struct diff_filespec *one;
+ struct diff_filespec *two;
+ const char *name;
+ const char *other;
+ char *name_munged, *other_munged;
+ int complete_rewrite = 0;
+ int len;
+
+ if (DIFF_PAIR_UNMERGED(p)) {
+ /* unmerged */
+ run_external_diff(pgm, p->one->path, NULL, NULL, NULL, NULL,
+ 0);
+ return;
+ }
+
+ name = p->one->path;
+ other = (strcmp(name, p->two->path) ? p->two->path : NULL);
+ name_munged = quote_one(name);
+ other_munged = quote_one(other);
+ one = p->one; two = p->two;
+
+ diff_fill_sha1_info(one);
+ diff_fill_sha1_info(two);
+
+ len = 0;
+ switch (p->status) {
+ case DIFF_STATUS_COPIED:
+ len += snprintf(msg + len, sizeof(msg) - len,
+ "similarity index %d%%\n"
+ "copy from %s\n"
+ "copy to %s\n",
+ (int)(0.5 + p->score * 100.0/MAX_SCORE),
+ name_munged, other_munged);
+ break;
+ case DIFF_STATUS_RENAMED:
+ len += snprintf(msg + len, sizeof(msg) - len,
+ "similarity index %d%%\n"
+ "rename from %s\n"
+ "rename to %s\n",
+ (int)(0.5 + p->score * 100.0/MAX_SCORE),
+ name_munged, other_munged);
+ break;
+ case DIFF_STATUS_MODIFIED:
+ if (p->score) {
+ len += snprintf(msg + len, sizeof(msg) - len,
+ "dissimilarity index %d%%\n",
+ (int)(0.5 + p->score *
+ 100.0/MAX_SCORE));
+ complete_rewrite = 1;
+ break;
+ }
+ /* fallthru */
+ default:
+ /* nothing */
+ ;
+ }
+
+ if (memcmp(one->sha1, two->sha1, 20)) {
+ char one_sha1[41];
+ memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
+
+ len += snprintf(msg + len, sizeof(msg) - len,
+ "index %.7s..%.7s", one_sha1,
+ sha1_to_hex(two->sha1));
+ if (one->mode == two->mode)
+ len += snprintf(msg + len, sizeof(msg) - len,
+ " %06o", one->mode);
+ len += snprintf(msg + len, sizeof(msg) - len, "\n");
+ }
+
+ if (len)
+ msg[--len] = 0;
+ xfrm_msg = len ? msg : NULL;
+
+ if (!pgm &&
+ DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
+ (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
+ /* a filepair that changes between file and symlink
+ * needs to be split into deletion and creation.
+ */
+ struct diff_filespec *null = alloc_filespec(two->path);
+ run_external_diff(NULL, name, other, one, null, xfrm_msg, 0);
+ free(null);
+ null = alloc_filespec(one->path);
+ run_external_diff(NULL, name, other, null, two, xfrm_msg, 0);
+ free(null);
+ }
+ else
+ run_external_diff(pgm, name, other, one, two, xfrm_msg,
+ complete_rewrite);
+
+ free(name_munged);
+ free(other_munged);
+}
+
+void diff_setup(struct diff_options *options)
+{
+ memset(options, 0, sizeof(*options));
+ options->output_format = DIFF_FORMAT_RAW;
+ options->line_termination = '\n';
+ options->break_opt = -1;
+ options->rename_limit = -1;
+
+ options->change = diff_change;
+ options->add_remove = diff_addremove;
+}
+
+int diff_setup_done(struct diff_options *options)
+{
+ if ((options->find_copies_harder || 0 <= options->rename_limit) &&
+ options->detect_rename != DIFF_DETECT_COPY)
+ return -1;
+ if (options->setup & DIFF_SETUP_USE_CACHE) {
+ if (!active_cache)
+ /* read-cache does not die even when it fails
+ * so it is safe for us to do this here. Also
+ * it does not smudge active_cache or active_nr
+ * when it fails, so we do not have to worry about
+ * cleaning it up oufselves either.
+ */
+ read_cache();
+ }
+ if (options->setup & DIFF_SETUP_USE_SIZE_CACHE)
+ use_size_cache = 1;
+
+ return 0;
+}
+
+int diff_opt_parse(struct diff_options *options, const char **av, int ac)