Cannot seek stdin on pipe

bandit/core/manager.py

@@ -16,6 +16,7 @@
 
 import collections
 import fnmatch
+import io
 import json
 import logging
 import os
@@ -248,7 +249,9 @@ def run_tests(self):
                     sys.stderr.flush()
             try:
                 if fname == '-':
-                    sys.stdin = os.fdopen(sys.stdin.fileno(), 'rb', 0)
+                    sys.stdin = _Seeker(os.fdopen(sys.stdin.fileno(), 'rb', 0))
+                    new_files_list = ["<stdin>" if x == "-" else
+                                      x for x in new_files_list]
                     self._parse_file('<stdin>', sys.stdin, new_files_list)
                 else:
                     with open(fname, 'rb') as fdata:
@@ -325,6 +328,37 @@ def _execute_ast_visitor(self, fname, data, nosec_lines):
         return score
 
 
+class _Seeker(object):
+    def __init__(self, fileobj):
+        self.fileobj = fileobj
+        self.buf = io.BytesIO()
+
+    def _append_to_buf(self, contents):
+        oldpos = self.buf.tell()
+        self.buf.seek(0, os.SEEK_END)
+        self.buf.write(contents)
+        self.buf.seek(oldpos)
+
+    def seek(self, size):
+        contents = self.fileobj.read(size)
+        self._append_to_buf(contents)
+        return contents
+
+    def read(self, size=None):
+        if size is None:
+            return self.buf.read() + self.fileobj.read()
+        contents = self.buf.read(size)
+        if len(contents) < size:
+            contents += self.fileobj.read(size - len(contents))
+        return contents
+
+    def readline(self):
+        line = self.buf.readline()
+        if not line.endswith("\n".encode()):
+            line += self.fileobj.readline()
+        return line
+
+
 def _get_files_from_dir(files_dir, included_globs=None,
                         excluded_path_strings=None):
     if not included_globs: