Re: [Boost-users] [interprocess] file_mapping/mapped_region on empty file throws?

Subject: Re: [Boost-users] [interprocess] file_mapping/mapped_region on empty file throws?
From: Jeff Flinn (TriumphSprint2000_at_[hidden])
Date: 2010-11-29 16:09:52

Ion Gaztañaga wrote:
> On 29/11/2010 19:05, Jeff Flinn wrote:
>> The following appears to throw an interprocess_exception with
>> boost_1_44_0 compiled with MSVC8 running on windows XP.
>>
>> using namespace boost::interprocess;
>>
>> file_mapping fm("empty.txt", read_only);
>> mapped_region mr( fm, read_only);
>>
>> Is there a reason I can't just get back a null address and zero size?
> 
> It's common practice not to support empty mappings. Windows mapped files 
> don't support an empty file. In Unix, mapping zero bytes is an error:
> 
> http://www.opengroup.org/onlinepubs/009695399/functions/mmap.html
> 
> "If len is zero, mmap() shall fail and no mapping shall be established"

Thanks Ion. I'll just deal with the exception appropriately then.

Jeff