On Aug 16, 2013, at 1:46 PM, [email protected] wrote:
> http://anonsvn.wireshark.org/viewvc/viewvc.cgi?view=rev&revision=51395
>
> User: cmaynard
> Date: 2013/08/16 01:46 PM
>
> Log:
> Initialize val_len to avoid Clang warning: The right operand of '-' is a
> garbage value. While in there, add some protection against
> tvb_length_remaining() possibly returning -1, or possibly being less than
> val_len.
Neither of those can happen - get_self_describing_var_len_val() would have
thrown an exception if either
1) there was no data left in the tvbuff
or
2) there weren't enough bytes left in the tvbuff for the value.
The fix produces uninitialized-variable warnings about next_tvb.
(In addition, val_len should always be set; in the if statement in
get_self_describing_var_len_val():
the first code path is run if the high-order bit of the first octet
isn't set;
the second code path is run if the high-order bit is set but the next
bit isn't set;
the third code path is run if the high-order bit and the next bit are
set but the third bit down isn't set;
the fourth code path is run if all three of those bits are set;
so there's no other way out of the function, and *val_len will always be set.
Unfortunately, Clang isn't recognizing that (if it were recognizing it, it'd
probably also not bother testing, in the fourth code path, whether all three of
those bits are set, as the previous three tests failing ensure that they are).)
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