From: Julian Seward <jseward@acm.org>
Date: Fri, 6 Mar 2015 09:19:38 +0000 (+0000)
Subject: Update comment about range checks with observations from Florian.
X-Git-Tag: svn/VALGRIND_3_11_0~610
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6e9e1112dc719dfe88c2363b2e22d259a507bbd6;p=thirdparty%2Fvalgrind.git

Update comment about range checks with observations from Florian.
No functional change.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14982
---

diff --git a/coregrind/m_debuginfo/image.c b/coregrind/m_debuginfo/image.c
index 964c6338a5..819a77097e 100644
--- a/coregrind/m_debuginfo/image.c
+++ b/coregrind/m_debuginfo/image.c
@@ -405,6 +405,12 @@ static inline Bool is_in_CEnt ( const CEnt* cent, DiOffT off )
          -->  x-LO >= 0 && x-LO < LO+N-LO
          -->  x-LO >= 0 && x-LO < N
          -->  x-LO < N
+      This is however only valid when the original bounds, that is, LO
+      .. LO+N-1, do not wrap around the end of the address space.  That
+      is, we require that LO <= LO+N-1.  But that's OK .. we don't
+      expect wraparounds in CEnts or for that matter any object
+      allocated from C-land.  See Hacker's Delight, Chapter 4.1,
+      "Checking Bounds of Integers", for more details.
    */
    return off - cent->off < cent->used;
 }