in_tail: detect, skip UTF-8 BOM

If unicode input data is not converted, check if there is a UTF-8 BOM
present and skip it.

Signed-off-by: Erik Cederberg <[email protected]>

Author: erikced

plugins/in_tail/tail_file.c

@@ -471,6 +471,14 @@ static int process_content(struct flb_tail_file *file, size_t *bytes)
         }
         else if (ret == FLB_UNICODE_CONVERT_NOP) {
             flb_plg_debug(ctx->ins, "nothing to convert encoding '%.*s'", end - data, data);
+            /* Skip the UTF-8 BOM */
+            if (file->buf_len >= 3 && 
+                data[0] == '\xEF' &&
+                data[1] == '\xBB' &&
+                data[2] == '\xBF') {
+                data += 3;
+                processed_bytes += 3;
+            }
         }
         else {
             flb_plg_error(ctx->ins, "encoding failed '%.*s'", end - data, data);