From: Philipp Gesang <philipp.gesang@intra2net.com>
Date: Mon, 10 Apr 2017 13:01:56 +0000 (+0200)
Subject: throw error on partial header reading stream
X-Git-Url: http://developer.intra2net.com/git/?a=commitdiff_plain;h=874b9e82f85e6d22b4256b1963d9dd80c4623222;p=python-delta-tar

throw error on partial header reading stream

Throw the EOF exception only if the stream ends exactly at an
object boundary. Otherwise, when less then sizeof(hdr) bytes
are returned from read(), throw InvalidHeader to indicate a
malformed file. This keeps EOF a “benign” exception.
---

diff --git a/deltatar/crypto.py b/deltatar/crypto.py
index 99eaf3a..834b8ac 100755
--- a/deltatar/crypto.py
+++ b/deltatar/crypto.py
@@ -95,7 +95,7 @@ class EndOfFile (Exception):
     """Reached EOF."""
     remainder = 0
     msg       = 0
-    def __init__ (self, n, msg=None):
+    def __init__ (self, n=None, msg=None):
         self.remainder = n
         self.msg       = msg
 
@@ -256,10 +256,11 @@ def hdr_read (data):
 def hdr_read_stream (instr):
     data = instr.read(PDTCRYPT_HDR_SIZE)
     ldata = len (data)
-    if ldata != PDTCRYPT_HDR_SIZE:
-        raise EndOfFile (ldata,
-                         "read: expected %d B, received %d B"
-                         % (PDTCRYPT_HDR_SIZE, len (data)))
+    if ldata == 0:
+        raise EndOfFile
+    elif ldata != PDTCRYPT_HDR_SIZE:
+        raise InvalidHeader ("hdr_read_stream: expected %d B, received %d B"
+                             % (PDTCRYPT_HDR_SIZE, ldata))
     return hdr_read (data)
 
 
diff --git a/deltatar/tarfile.py b/deltatar/tarfile.py
index 704ecc6..e6099be 100644
--- a/deltatar/tarfile.py
+++ b/deltatar/tarfile.py
@@ -767,18 +767,16 @@ class _Stream:
             self.lasthdr = self.fileobj.tell ()
             try:
                 hdr = crypto.hdr_read_stream (self.fileobj)
-            except crypto.EndOfFile as exn:
-                if exn.remainder == 0:
-                    raise EOFHeaderError("end of file header")
-                raise DecryptionError ("Crypto.hdr_read_stream(): hit EOF "
-                                       "reading header %r" % (self.fileobj)) \
-                      from exn
+            except crypto.EndOfFile:
+                return False
             except crypto.InvalidHeader:
                 raise DecryptionError ("Crypto.hdr_read_stream(): error “%s” "
                                        "processing %r" % (hdr, self.fileobj)) \
                       from exn
             self.remainder = hdr ["ctsize"] # distance to next header
-            return self.encryption.next (hdr)
+            self.encryption.next (hdr)
+
+        return True
 
 
     def _finalize_read_encrypt (self):
@@ -914,7 +912,10 @@ class _Stream:
             if self.encryption is not None:
                 if self.remainder <= 0:
                     # prepare next object
-                    self._init_read_encrypt ()
+                    if self._init_read_encrypt () is False: # EOF
+                        buf = None
+                        break # while
+
                 # only read up to the end of the encrypted object
                 todo = min (size, self.remainder)
             buf = self.fileobj.read(todo)