POSIX bindings for GNAT

POSIX bindings for GNAT

[Lowell S. Von Ruden]

Are there any POSIX bindings for GNAT?

-- 
+--------------------------------------+------------------------------------+
| Lowell S. Von Ruden                  | Sanders, A Lockheed Martin Company |
| lvonrude@rapnet.sanders.lockheed.com | (603) 885-5294                     |
+--------------------------------------+------------------------------------+

Re: POSIX bindings for GNAT

[David Shochat]

In article <4j8ubv$15j@news.sanders.lockheed.com> 
"Lowell S. Von Ruden" <lvonrude@rapnet.sanders.lockheed.com> writes:

> Are there any POSIX bindings for GNAT?  --

ftp://cs.nyu.edu/pub/gnat/contrib/forest/forest-1.4beta.tar.gz

Unfortunately, there are some code fixes that need to be made to 
make this compile with the current (3.03) version of gnat.
-- 
David Shochat
dshochat@logicon.com  shochat@roosevelt.logicon.com

Re: POSIX bindings for GNAT

[David Emery]

In article <wgcspevmm1w.fsf@roosevelt.logicon.com>,
shochat@roosevelt.logicon.com (David Shochat) wrote:

> In article <4j8ubv$15j@news.sanders.lockheed.com> 
> "Lowell S. Von Ruden" <lvonrude@rapnet.sanders.lockheed.com> writes:
> 
> > Are there any POSIX bindings for GNAT?  --
> 
> ftp://cs.nyu.edu/pub/gnat/contrib/forest/forest-1.4beta.tar.gz
> 
> Unfortunately, there are some code fixes that need to be made to 
> make this compile with the current (3.03) version of gnat.
> -- 
> David Shochat
> dshochat@logicon.com  shochat@roosevelt.logicon.com

It's not clear to me that GNAT/Forest are compliant with 
IEEE Std 1003.5-1992/ISO 14519.1:1995...  

Does Forest claim to be complaint with the standard?  Of course, there is
no validation suite for POSIX/Ada, but the standard does contain a clear
statement of what 'conformance' means, even if it is not formally tested.

               dave

Re: POSIX bindings for GNAT

[John Hutchison x2141]

Forest is not compliant with Posix.5 nor does it claim to be, see the
documentation which comes with the code. It uses the 1003.5-1992 standard. 
Most of it follows the standard carefully and provides extensions in child 
packages, which is within the guidelines specified by the standard.

However, there is one change which can cause problems for users. 
Forest adds a new alternative to the type Signal_Masking, called Restart, 
which specifies that the Posix.5 support should automatically handling 
restarting of interupted actions. This is not a particularly bad extension
and it is easy to support, unfortunately Forest makes this the default value
for the signal masking parameter. This can provide suprises for client code 
expecting the default value to be RTS_Signals or when moving to another
implementation of Posix.5 which does not support the Restart option.

Re: POSIX bindings for GNAT

[David Emery]

In article <4je5s7$ne3@tel.den.mmc.com>, hutchiso@epi.syr.ge.com wrote:

> However, there is one change which can cause problems for users. 
> Forest adds a new alternative to the type Signal_Masking, called Restart, 
> which specifies that the Posix.5 support should automatically handling 
> restarting of interupted actions. This is not a particularly bad extension
> and it is easy to support, unfortunately Forest makes this the default value
> for the signal masking parameter. This can provide suprises for client code 
> expecting the default value to be RTS_Signals or when moving to another
> implementation of Posix.5 which does not support the Restart option.

This was an option that we discussed when doing POSIX.5.  We concluded that
it was way too dangerous to support as a 'primitive'.  Consider a file
open that takes 1 minute, and you are on a system that has a 30 second timer.
THe open will never succeed (It'll always get EINTER).  With any sort of
auto-retry, the process will go into infinite loop.  ANd, this loop will be
very hard to understand, since the process will spend 99% of its time blocked
on the kernel.

            dave