Date: Tue, 24 Aug 2004 13:03:23 -0700 From: Sean McNeil <sean@mcneil.com> To: Harti Brandt <harti@freebsd.org> Cc: current@freebsd.org Subject: Re: bsdtar core dumps Message-ID: <1093377802.43728.11.camel@server.mcneil.com> In-Reply-To: <20040824205417.L517@beagle.kn.op.dlr.de> References: <1092777586.92327.9.camel@server.mcneil.com> <20040817213813.GE3827@gothmog.gr><4127841D.6050104@freebsd.org> <1093369220.10362.6.camel@server.mcneil.com> <20040824200225.V517@beagle.kn.op.dlr.de> <1093371600.10464.23.camel@server.mcneil.com> <20040824205417.L517@beagle.kn.op.dlr.de>
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On Tue, 2004-08-24 at 12:03, Harti Brandt wrote:
> On Tue, 24 Aug 2004, Sean McNeil wrote:
>
> SM>On Tue, 2004-08-24 at 11:08, Harti Brandt wrote:
> SM>> On Tue, 24 Aug 2004, Sean McNeil wrote:
> SM>>
> SM>[snip]
> SM>>
> SM>> Sorry to jump in.
> SM>>
> SM>> You cannot use a va_list twice. As soon as someone call va_arg() on the
> SM>> ap all the aps in the calling functions get invalid. The only thing that
> SM>> can and must be done is that the function that did the va_start() must
> SM>> call va_end.
> SM>>
> SM>> If you need it twice you must make a copy as in the patch below.
> SM>> But the function call va_copy must also call va_end() on that copy
> SM>> (this seems missing in the patch).
> SM>
> SM>I took the lead from /usr/src/lib/libc/stdio/vfprintf.c
> SM>
> SM>It happens to do a va_copy(orgap,ap) but never does a va_end(orgap).
> SM>Either vfprintf.c is incorrect or it is not necessary to call va_end().
>
> vfprintf.c is wrong. Paragraph 1 of 7.15.1 of C99 states: "Each invocation
> of the va_start and va_copy macros shall be matched by a corresponding
> invocation of the va_end macro in the same function."
C99 is good enough for me. I suppose this is so that va_copy can be
implemented with some sort of allocation scheme. Could someone commit
fixes to vfprintf.c and archive_string_sprintf.c?
*** lib/libarchive/archive_string_sprintf.c.orig Fri Aug 13
20:45:45 2004--- lib/libarchive/archive_string_sprintf.c Tue Aug 24
12:58:24 2004
*************** __archive_string_vsprintf(struct archive
*** 47,65 ****
va_list ap)
{
size_t l;
if (fmt == NULL) {
as->s[0] = 0;
return;
}
l = vsnprintf(as->s, as->buffer_length, fmt, ap);
/* If output is bigger than the buffer, resize and try again. */
if (l+1 >= as->buffer_length) {
__archive_string_ensure(as, l + 1);
! l = vsnprintf(as->s, as->buffer_length, fmt, ap);
}
as->length = l;
}
/*
--- 47,68 ----
va_list ap)
{
size_t l;
+ va_list ap1;
if (fmt == NULL) {
as->s[0] = 0;
return;
}
+ va_copy(ap1,ap);
l = vsnprintf(as->s, as->buffer_length, fmt, ap);
/* If output is bigger than the buffer, resize and try again. */
if (l+1 >= as->buffer_length) {
__archive_string_ensure(as, l + 1);
! l = vsnprintf(as->s, as->buffer_length, fmt, ap1);
}
as->length = l;
+ va_end(ap1);
}
/*
*** lib/libc/stdio/vfprintf.c.orig Mon Aug 23 20:35:43 2004
--- lib/libc/stdio/vfprintf.c Tue Aug 24 13:01:45 2004
*************** error:
*** 1237,1242 ****
--- 1237,1243 ----
if (dtoaresult != NULL)
freedtoa(dtoaresult);
#endif
+ va_end(orgap);
if (convbuf != NULL)
free(convbuf);
if (__sferror(fp))
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