some PRs

[Sergey Babkin]

Giorgos Keramidas wrote:
> 
> On 2004-07-26 19:49, Sergey Babkin <babkin at bellatlantic.net> wrote:
> > Max Laier wrote:
> > > The question to me is, do we really want to support (read fertilize)
> > > such a stupid thing? Given the chance that once we do support it
> > > people will use it.  In my opinion it is bad to integrate something
> > > into base that we agree is nothing one should ever have created (at
> > > least that's my reading of the thread so far). I see no user-pessure
> > > for this.
> >
> > I'm about a week behind :-) but here are my 2 cents: it's a VERY
> > useful device for testing. Not checking the error code of write(),
> > printf() and such is a typical bug, so making it easy to detect by
> > switching the output to /dev/full (or creating a symlink to it) is a
> > very good idea. Like this:
> >
> >   yourprogram >/dev/full \
> >      && echo "The program does not check for success of write()"
> 
> If a program doesn't check the return code of write() but merrily goes
> on doing other stuff or even terminates with a zero return value, how
> will the redirection affect its operation?  I think it won't, as shown
> in the test below (run on a Linux machine):

If you run a test in which you know the program must fail (such
as writing to /dev/full) yet it does not, this means that there
is abug in the program.
 
> : $ ls -ld /dev/full
> : crw-rw-rw-    1 root     root       1,   7 Jun 14 00:24 /dev/full
> : $ cat -n lala.c
> :      1  #include <sys/types.h>
> :      2  #include <string.h>
> :      3  #include <unistd.h>
> :      4
> :      5  int
> :      6  main(void)
> :      7  {
> :      8      char buf[] = "hello world\n";
> :      9      size_t len;
> :     10
> :     11      len = strlen(buf);
> :     12      write(1, buf, len);
> :     13      return 0;
> :     14  }
> : $ cc -O -W -Wall -o lala lala.c
> : $ ./lala
> : hello world
> : $ ./lala >/dev/full
> : $ echo $?
> : 0
> : $
> 
> The fact that /dev/full was used as the output device didn't reveal the
> potential write() problem.

That's _exactly my point: if the program writes to /dev/full
and yet does produce an error exit code or an error message,
there is a bug in the program.
 
> I must have misunderstood something.  How do you mean that we could use
> /dev/full for testing?

Well, as described above: for each file that your program can produce,
try to substitute it with /dev/full and watch the prgoram fail.
If it does not fail, there is a bug. That's much easier than producing
an actual full filesystem.

-SB