Paul Eggert wrote:
> On 07/01/10 15:59, Jim Meyering wrote:
>
>> Can you give me a backtrace?
>> Even if your patch is clearly better, I'd like to know
>> how my code is malfunctioning.
>
> Sure. This uses your older patch, not the newer gnulib one.
>
> Program received signal SIGABRT, Aborted.
> 0x0012d422 in __kernel_vsyscall ()
> (gdb) where
> #0 0x0012d422 in __kernel_vsyscall ()
> #1 0x00158651 in *__GI_raise (sig=6) at
> ../nptl/sysdeps/unix/sysv/linux/raise.c:64
> #2 0x0015ba82 in *__GI_abort () at abort.c:92
> #3 0x08054826 in hash_insert0 (table=0x805f208, entry=0x8017384d,
> matched_ent=0x0) at hash.c:1078
> #4 0x0804bdba in di_set_insert (dis=0x805e2f4, dev=2049, ino=380435) at
> di-set.c:264
> #5 0x0804ab0f in hash_ins (argc=52, argv=0xbffff304) at du.c:335
> #6 process_file (argc=52, argv=0xbffff304) at du.c:467
> #7 du_files (argc=52, argv=0xbffff304) at du.c:592
> #8 main (argc=52, argv=0xbffff304) at du.c:962
>
> The test case, by the way, is "./du ../../cu*", where the
> globbing pattern expands to 51 directories, each a copy of coreutils,
> with several hard links because many are git clones of each other.
> Arf arf! (I'm eating my own dog food.)
Thanks again for the report.
However, while I was able to reproduce it (on Paul's system)
and debug it, it appears to be due to a miscompilation of di-set.o
when using a private copy of gcc-4.5.0. When I recompiled
that one file with gcc-Ubuntu 4.4.3-4ubuntu5 and -g -O2
or with 4.5.0 and -g -O, the code works as expected.
The problem arose in the di_ent_compare function and its use
of the tiny decode_ptr. For the record, here they are:
static struct di_ent
decode_ptr (struct di_ent const *v)
{
if (!is_encoded_ptr (v))
return *v;
struct di_ent di;
di.u.ptr = (void *) v;
return di;
}
/* Compare two di_ent structs.
Return true if they are the same. */
static bool
di_ent_compare (void const *x, void const *y)
{
struct di_ent a = decode_ptr (x);
struct di_ent b = decode_ptr (y);
if (a.u.di4.mode != b.u.di4.mode)
return false;
if (a.u.di4.mode == DI_MODE_4)
return (a.u.di4.short_ino == b.u.di4.short_ino
&& a.u.di4.mapped_dev == b.u.di4.mapped_dev);
if (a.u.di8.mode == DI_MODE_8)
return (a.u.di8.short_ino == b.u.di8.short_ino
&& a.u.di8.mapped_dev == b.u.di8.mapped_dev);
return (a.u.full.ino == b.u.full.ino
&& a.u.full.dev == b.u.full.dev);
}
Even though they're obviously distinct encoded values (see the
hexadecimal values below), di_ent_compare (aka table->comparator)
reports they're equal when using gcc-4.5.0 -g -O2, and that causes
the failed assertion:
(gdb) p table->comparator (entry, bucket->data)
$9 = true
(gdb) p bucket->data
$10 = (void *) 0x80143c4d
(gdb) p entry
$11 = (const void *) 0x80173851
I expect to push this series shortly.
Paul, if you end up improving further, you're welcome to revert
any pieces that are no longer used.
