[cfe-commits] r84930 - /cfe/trunk/lib/Frontend/PCHReader.cpp
Ted Kremenek
kremenek at apple.com
Thu Oct 22 21:45:32 PDT 2009
Author: kremenek
Date: Thu Oct 22 23:45:31 2009
New Revision: 84930
URL: http://llvm.org/viewvc/llvm-project?rev=84930&view=rev
Log:
Add comment.
Modified:
cfe/trunk/lib/Frontend/PCHReader.cpp
Modified: cfe/trunk/lib/Frontend/PCHReader.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/PCHReader.cpp?rev=84930&r1=84929&r2=84930&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/PCHReader.cpp (original)
+++ cfe/trunk/lib/Frontend/PCHReader.cpp Thu Oct 22 23:45:31 2009
@@ -2515,6 +2515,9 @@
// All of the strings in the PCH file are preceded by a 16-bit
// length. Extract that 16-bit length to avoid having to execute
// strlen().
+ // NOTE: 'StrLenPtr' is an 'unsigned char*' so that we load bytes as
+ // unsigned integers. This is important to avoid integer overflow when
+ // we cast them to 'unsigned'.
const unsigned char *StrLenPtr = (const unsigned char*) Str - 2;
unsigned StrLen = (((unsigned) StrLenPtr[0])
| (((unsigned) StrLenPtr[1]) << 8)) - 1;
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