Re: [boost] [Boost-users] base 64 encoding

From: Eames, Andrew (andrew_at_[hidden])
Date: 2008-01-09 08:49:15

I posted this on the boost users group but got no final answer - this
looks like a bug to me or am I just using it incorrectly?

  Andrew

 

From: Eames, Andrew 
Sent: Friday, January 04, 2008 1:13 PM
To: 'boost-users_at_[hidden]'
Subject: Re: [Boost-users] base 64 encoding

 

I must be missing something fundamental here. The following code
fragment doesn't work (VC++ 8.0 SP1) - the checked iterators in STL
catch walking off the end of the source - transform_width is attempting
to access the second element of the vector

 

typedef

    base64_from_binary<

        transform_width<vector<char>::const_iterator, 6, 8>

        > base64_t;

 

  vector<char> hippo(1);

  string enc(base64_t(hippo.begin()), base64_t(hippo.end())); // ->
checked iterator assertion fires

 

In basic_text_oprimitive.ipp, the iterator is a pointer so it's possible
it may be silently doing something bad

  Andrew

 

From: boost-users-bounces_at_[hidden]
[mailto:boost-users-bounces_at_[hidden]] On Behalf Of Robert Ramey
Sent: Friday, January 04, 2008 11:58 AM
To: boost-users_at_[hidden]
Subject: [Spam:***** SpamScore] Re: [Boost-users] base 64 encoding

 

Take a look at basic_text_oprimitive.ipp around line # 64.

 

Note that I add "padding" here to address this problem.  Perhaps that is
the missing

magic.  Hmmm. perhaps that code should be part of the iterator.

 

Also look at the code text_iterators_base64 in the serialization test
suite.

 

Robert Ramey

 

        "Eames, Andrew" <andrew_at_[hidden]> wrote in message
news:8F37BF6F420455468C4BD57DD6BE199004C6146B_at_cobra.pc.cognex.com...

        But there is still the problem with running off the end of the
source - If the source is not a multiple of 3 bytes then the input
iterator will run off the end of the input sequence which can cause an
error. 

          Andrew

         

        From: boost-users-bounces_at_[hidden]
[mailto:boost-users-bounces_at_[hidden]] On Behalf Of Robert Ramey
        Sent: Thursday, January 03, 2008 6:47 PM
        To: boost-users_at_[hidden]
        Subject: Re: [Boost-users] base 64 encoding

         

        I had to separately record the number of bytes.  Then when I
decode, just pull off that number of bytes.

         

        Robert Ramey

         

                "Eames, Andrew" <andrew_at_[hidden]> wrote in message
news:8F37BF6F420455468C4BD57DD6BE199004C613F8_at_cobra.pc.cognex.com...

                Hi,

                I'm trying to encode base64 data by composing
base64_from_binary with transform_width but this doesn't appear to work
correctly when the data is not a multiple of 3 long. What is the correct
way to handle this  - do I have to handle the padding myself by
extending the input data and then patching the tail of the result?

                   Thanks

                       Andrew

                 

                
________________________________

                _______________________________________________
                Boost-users mailing list
                Boost-users_at_[hidden]
                http://lists.boost.org/mailman/listinfo.cgi/boost-users