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Message-ID: <20130323212704.GV20323@brightrain.aerifal.cx>
Date: Sat, 23 Mar 2013 17:27:04 -0400
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: Proposed syslog patch [Re: Further bugs in
syslog()]
On Sat, Mar 23, 2013 at 05:17:55PM +0100, Szabolcs Nagy wrote:
> looks ok, one nitpick
>
> * Rich Felker <dalias@...ifal.cx> [2013-03-23 00:05:58 -0400]:
> > void openlog(const char *ident, int opt, int facility)
> > @@ -59,7 +54,14 @@ void openlog(const char *ident, int opt, int facility)
> > int cs;
> > pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
> > LOCK(lock);
> > - __openlog(ident, opt, facility);
> > +
> > + free(log_ident);
> > + log_ident = strdup(ident);
>
> this can fail and then log_ident = 0
Yes, this was the intent; there's no way to report errors, and being
in a status of NULL log_ident is the same as the case where it was
never set at all. However I agree with your reasoning below...
> ....
> > @@ -90,14 +89,14 @@ static void _vsyslog(int priority, const char *message, va_list ap)
> > priority, timebuf,
> > log_ident ? log_ident : "",
> > "["+!pid, pid, "]"+!pid);
> > + if (l >= sizeof buf) return;
>
> if ident is longer than buf, then syslog will silently fail here,
> but if ident is so big that strdup fails above it does not fail here
That it violates the principle of least surprise that moderately long
values of log_ident will prevent any log message from appearing, but
insanely long ones will be silently replaced with a blank string.
> maybe we should limit ident to a sensible value and truncate it
> (i dont know if posix allows that but seems more consistent
> and then no dynamic allocation is needed in openlog)
POSIX provides no way to inspect the output that's produced, so there
are no testable conformance requirements on the output...
I think I like your approach: just using a small fixed-size buffer.
Rich
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