+
+static size_t fill_textconv(struct userdiff_driver *driver,
+ struct diff_filespec *df,
+ char **outbuf)
+{
+ size_t size;
+
+ if (!driver || !driver->textconv) {
+ if (!DIFF_FILE_VALID(df)) {
+ *outbuf = "";
+ return 0;
+ }
+ if (diff_populate_filespec(df, 0))
+ die("unable to read files to diff");
+ *outbuf = df->data;
+ return df->size;
+ }
+
+ if (driver->textconv_cache) {
+ *outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
+ &size);
+ if (*outbuf)
+ return size;
+ }
+
+ *outbuf = run_textconv(driver->textconv, df, &size);
+ if (!*outbuf)
+ die("unable to read files to diff");
+
+ if (driver->textconv_cache) {
+ /* ignore errors, as we might be in a readonly repository */
+ notes_cache_put(driver->textconv_cache, df->sha1, *outbuf,
+ size);
+ /*
+ * we could save up changes and flush them all at the end,
+ * but we would need an extra call after all diffing is done.
+ * Since generating a cache entry is the slow path anyway,
+ * this extra overhead probably isn't a big deal.
+ */
+ notes_cache_write(driver->textconv_cache);
+ }
+
+ return size;
+}