open, close, dup, dup2, lseek, read, write, fileno, etc.

[Bruce Adams]

On Mon, 11 Feb 2008 15:52:54 -0000, David Wilson <dw at botanicus.net> wrote:

> On 2/9/08, Bruce Adams <tortoise_74 at yeah.who.co.uk> wrote:
>
>> Unfortunately this is so. A long time ago the POSIX standard was  
>> invented
>> (or rather brought together from some early Unixes) and though low-level
>> (not OO for a start) it is solid and reliable.
>> The idea being if you want to write portable code you write it using  
>> only
>> POSIX
>> functionality.
>> M$ in their finite wisdom chose to tear up the standard and invent their
>> own
>> and then pretend they supported it. The result is it is practically
>> impossible
>> to write portable code without having another wrapper layer inbetween.
>
> ANSI C (including the standard library) wasn't standardised until
> 1990. The first versions of MS-DOS appeared in 1982. POSIX didn't
> appear until 1988. Which standard are you referring to, or is this
> just more of the same uninformed Microsoft bashing?
>
>
> David.
>
Same as what uninformed M$ bashing?
Windows NT 3.1 appeared around 1993 -  
http://www.microsoft.com/windows/WinHistoryDesktop.mspx
Microsoft were required to include a POSIX subsystem in order be used in  
the defence industry.
I cannot find a reference for that. I think it may have been from Inside  
the Windows NT Kernel.
Anyway, the POSIX sub-system in windows despite misquotes to the contrary  
is hideously broken in
several key areas that make it unusable for anything non-trivial. This is  
why cygwin exists.
There are numerous examples but the one that most often trip people up are  
non-blocking IO and
signal handling.
Nowhere will you find documentation of these incompatabilities on MSDN.  
They will happily describe
the basic API and state that it complies with POSIX 1001.3 whilst  
blissfully remaining broken.
Unaccountably the 'posix' functions in win32 all have a leading  
underscores.
Just compare the documentation for read and _read. Note the distinct  
absence of any mention of
non-blocking IO. The only reliable way to do this on windows is to use the  
win32 API and even then
I believe (I may be wrong here) you need multiple threads.

  http://msdn2.microsoft.com/en-us/library/wyssk1bs.aspx

vs

  http://www.opengroup.org/onlinepubs/7990989775/xsh/read.html

>
>> This is
>> where language standard libraries are a godsend. Though its hard to find
>> good
>> portable implementations of non-blocking IO and file locking.
>> I suspect this may be an area where Tango is ahead of Phobos but not
>> knowing
>> both APIs well I'm not in a position to comment.
>>
I am always glad of languages that successful wrap a POSIX like API on  
both platforms.
However, they tend to stumble on the same trip-wires mentioned above. At  
leat in their documentation
they have the humility (or rather clarity) to admit that some  
functionality will only work
on one platform or the other.

Regards,

Bruce.