# HG changeset patch
# User timeless <timeless@mozdev.org>
# Date 2016-03-31 02:05:28
# Node ID f736f98e16ca8e304bb85c9b742e967b72d892a3
# Parent  c042b98a6ff8ee65a681f4a14c71c37c20193c16

mpatch: unify mpatchError (issue5182)

The pure version was mpatch was throwing struct.error or ValueError
for errors, whereas the C version was throwing an "mpatch.mpatchError".

Introducing an mpatch.mpatchError into pure and using it consistently
is fairly easy, but the actual form for it is mercurial.mpatch.mpatchError,
so with this commit, we change the C implementation to match the naming
convention too.

diff --git a/mercurial/mpatch.c b/mercurial/mpatch.c
--- a/mercurial/mpatch.c
+++ b/mercurial/mpatch.c
@@ -404,7 +404,8 @@ PyMODINIT_FUNC PyInit_mpatch(void)
 	if (m == NULL)
 		return NULL;
 
-	mpatch_Error = PyErr_NewException("mpatch.mpatchError", NULL, NULL);
+	mpatch_Error = PyErr_NewException("mercurial.mpatch.mpatchError",
+					  NULL, NULL);
 	Py_INCREF(mpatch_Error);
 	PyModule_AddObject(m, "mpatchError", mpatch_Error);
 
@@ -415,6 +416,7 @@ PyMODINIT_FUNC
 initmpatch(void)
 {
 	Py_InitModule3("mpatch", methods, mpatch_doc);
-	mpatch_Error = PyErr_NewException("mpatch.mpatchError", NULL, NULL);
+	mpatch_Error = PyErr_NewException("mercurial.mpatch.mpatchError",
+					  NULL, NULL);
 }
 #endif
diff --git a/mercurial/pure/mpatch.py b/mercurial/pure/mpatch.py
--- a/mercurial/pure/mpatch.py
+++ b/mercurial/pure/mpatch.py
@@ -12,6 +12,10 @@ import struct
 
 StringIO = cStringIO.StringIO
 
+class mpatchError(Exception):
+    """error raised when a delta cannot be decoded
+    """
+
 # This attempts to apply a series of patches in time proportional to
 # the total size of the patches, rather than patches * len(text). This
 # means rather than shuffling strings around, we shuffle around
@@ -84,7 +88,10 @@ def patches(a, bins):
         last = 0
         while pos < end:
             m.seek(pos)
-            p1, p2, l = struct.unpack(">lll", m.read(12))
+            try:
+                p1, p2, l = struct.unpack(">lll", m.read(12))
+            except struct.error:
+                raise mpatchError("patch cannot be decoded")
             _pull(new, frags, p1 - last) # what didn't change
             _pull([], frags, p2 - p1)    # what got deleted
             new.append((l, pos + 12))   # what got added
@@ -114,7 +121,7 @@ def patchedsize(orig, delta):
         outlen += length
 
     if bin != binend:
-        raise ValueError("patch cannot be decoded")
+        raise mpatchError("patch cannot be decoded")
 
     outlen += orig - last
     return outlen
diff --git a/tests/test-revlog.t b/tests/test-revlog.t
--- a/tests/test-revlog.t
+++ b/tests/test-revlog.t
@@ -11,5 +11,5 @@ Test for CVE-2016-3630
      rev    offset  length  delta linkrev nodeid       p1           p2
        0         0      19     -1       2 99e0332bd498 000000000000 000000000000
        1        19      12      0       3 6674f57a23d8 99e0332bd498 000000000000
-  $ hg debugdata a.i 1 2>&1 | grep decoded
-  mpatch.mpatchError: patch cannot be decoded
+  $ hg debugdata a.i 1 2>&1 | egrep 'Error:.*decoded'
+  mercurial.mpatch.mpatchError: patch cannot be decoded