Re: Boost serialization : Stream error exception

"kanze" <>
24 Aug 2006 09:34:22 -0400
<> wrote:

{ not sure you're aware of that but there are the newsgroups for all
  major operating systems. you might want to try asking in the forum
  'comp.os.linux.development.apps', since memory-mapped files are not
  a language-supported structure, they are platform-specific. -mod }

I'm trying to use boost serialization to serialize/deserialize data to
and from a mmap'd file. I have my own ostream/istream classes that
essentially read/write bytes from a mmap'd file. The process works fine
except on some rare occasions (With different objects/number of
objects), in which case boost throws a "stream error" exception.

On reading, or on writing? And what does "stream error" mean: I
would expect that it refers to an error returned by the
iostream, but it would be best to be sure---it could also refer
to an error in the format of the input stream (unexpected EOF,

Any ideas what could trigger this? A search of the Boost
archives indicated other people had the same problem, where
the solution was "use binary mode when you open the file"...
but I'm not using a file on disk, I'm using a mmap'd file.

The image must be binary, i.e. when you read, you must be
guaranteed to see exactly the same bytes as when you wrote.

Writing to a mmap'd file can be tricky. Basically, mmap (at
least under Unix) presents a view of a fixed length file; if a
write would extend the file, you have to take special actions.
If you don't, it's entirely possible that when you reread the
file, you loose a bit at the end. (It's also possible, of
course, that you core dump on writing.)

James Kanze GABI Software
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