[240] in Kerberos
Re: reporting of errors.
daemon@TELECOM.MIT.EDU (Bill Sommerfeld)
Thu Oct 29 15:59:34 1987
From: Bill Sommerfeld <wesommer@ATHENA.MIT.EDU>
To: kerberos@ATHENA.MIT.EDU
\begin{flame}
'errno' is a crock which people keep copying it in the vain hope that
they are calling something reasonable.
Global variables shared between libraries and applications are
inherently _evil_, since they clutter up the namespace. In addition,
there are insufficient constraints on when errno can and cannot be
clobbered. Instead, use of Ken's com_err package (which is already in
use by SMS, as well as being in use inside discuss and a few other
places) seems to make a lot of sense.
In the presence of
\end{flame}
Exercise for the reader:
/*
* Explain why this program prints "open: Not a typewriter" when it is
* run with stdout redirected into a file. The "printf" works fine, by
* the way.
*
* Hints: errno, "man 4 tty".
*/
main()
{
int fd;
fd = open("/sadf/asdf/asdf/asd", 0, 0);
if (fd == -1) {
printf("Couldn't open the file\n");
perror("open");
}
exit(0);
}
- Bill
