[Rd] [New Patch] Fix disk corruption when writing

[Duncan Murdoch]

On 05/07/2017 5:26 AM, January W. wrote:
> I tried the newest patch, but it does not seem to work for me (on
> Linux). Despite the check in Rconn_printf, the write.csv happily writes
> to /dev/full and does not report an error. When I added a printf("%d\n",
> res); to the Rconn_printf() definition, I see only positive values
> returned by the vfprintf call.
>

That's likely because you aren't writing enough to actually trigger a 
write to disk during the write.  Writes are buffered, and the error 
doesn't happen until the buffer is written.  The regression test I put 
in had this problem; I'm working on MacOS and Windows, so I never got to 
actually try it before committing.

Unfortunately, it doesn't look possible to catch the final flush of the 
buffer when the connection is closed, so small writes won't trigger any 
error.

It's also possible that whatever system you're on doesn't signal an 
error when the write fails.

Duncan Murdoch

> Cheers,
>
> j.
>
>
> On 4 July 2017 at 21:37, Duncan Murdoch <murdoch.duncan at gmail.com
> <mailto:murdoch.duncan at gmail.com>> wrote:
>
>     On 04/07/2017 11:50 AM, Jean-Sébastien Bevilacqua wrote:
>
>         Hello,
>         You can find here a patch to fix disk corruption.
>         When your disk is full, the write function exit without error
>         but the file
>         is truncated.
>
>         https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17243
>         <https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17243>
>
>
>     Thanks.  I didn't see that when it came through (or did and forgot).
>     I'll probably move the error check to a lower level (in the
>     Rconn_printf function), if tests show that works.
>
>     Duncan Murdoch
>
>
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> --
> -------- January Weiner --------------------------------------