Date: Wed, 4 Feb 2009 12:27:15 -0600 From: Christian Peron <csjp@freebsd.org> To: Christoph Mallon <christoph.mallon@gmx.de> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>, Christian Peron <csjp@freebsd.org> Subject: Re: write-only variables in src/sys/ - possible bugs Message-ID: <20090204182715.GA75911@jnz.sqrt.ca> In-Reply-To: <4989AC31.6000904@gmx.de> References: <49874CA8.5090605@gmx.de> <20090203231155.GA69101@jnz.sqrt.ca> <4989AC31.6000904@gmx.de>
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On Wed, Feb 04, 2009 at 03:54:41PM +0100, Christoph Mallon wrote: [..] > > Yes, function arguments are considered being read. The problem is > different here: mtod() should be a macro, but the macro declaration was > missing (*cough* hacked build process *cough*). So the parser tried to > parse this as function call. Then it hit the "void *", which confused it > - it got a type while parsing an expression. I improved the error > correction, resolved a few other problems, too, and generated a new list: > > http://tron.homeunix.org/unread_variables.log > (The list has a date at the top, if it is missing, you see the old list > in your browser cache) > > The false positives, which you mentioned, are gone now - thanks for > reporting this. The list now contains about 1.000 entries and about 60 > concern variables named 'error'. Also.. one other thing I noticed: void bpf_buffer_append_mbuf(struct bpf_d *d, caddr_t buf, u_int offset, void *src, u_int len) { const struct mbuf *m; u_char *dst; u_int count; m = (struct mbuf *)src; dst = (u_char *)buf + offset; while (len > 0) { if (m == NULL) panic("bpf_mcopy"); count = min(m->m_len, len); bcopy(mtod(m, void *), dst, count); m = m->m_next; dst += count; len -= count; } } dst += count In this expression, both dst and count are read since this is the same thing as: dst = dst + count;
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