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Re: [ob/pushed] dwarf2read.c: fix latent buglet
- From: Pedro Alves <palves at redhat dot com>
- To: Doug Evans <dje at google dot com>
- Cc: gdb-patches <gdb-patches at sourceware dot org>
- Date: Mon, 03 Aug 2015 19:14:38 +0100
- Subject: Re: [ob/pushed] dwarf2read.c: fix latent buglet
- Authentication-results: sourceware.org; auth=none
- References: <1438624857-18851-1-git-send-email-palves at redhat dot com> <CADPb22RcZcRsK8e=cYEhx+wuzfrjNa=-zcrgZQ=P+v8zQ+Q6Tg at mail dot gmail dot com>
On 08/03/2015 07:06 PM, Doug Evans wrote:
> On Mon, Aug 3, 2015 at 11:00 AM, Pedro Alves <palves@redhat.com> wrote:
>> cust->includes is:
>>
>> struct compunit_symtab
>> {
>> ...
>> struct compunit_symtab **includes;
>>
>> gdb/ChangeLog:
>> 2015-08-03 Pedro Alves <palves@redhat.com>
>>
>> * dwarf2read.c (compute_compunit_symtab_includes): Use size of struct
>> compunit_symtab pointer.
>> ---
>> gdb/dwarf2read.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
>> index 24a4022..b5ffd04 100644
>> --- a/gdb/dwarf2read.c
>> +++ b/gdb/dwarf2read.c
>> @@ -7983,7 +7983,7 @@ compute_compunit_symtab_includes (struct dwarf2_per_cu_data *per_cu)
>> len = VEC_length (compunit_symtab_ptr, result_symtabs);
>> cust->includes
>> = obstack_alloc (&dwarf2_per_objfile->objfile->objfile_obstack,
>> - (len + 1) * sizeof (struct symtab *));
>> + (len + 1) * sizeof (struct compunit_symtab *));
>> for (ix = 0;
>> VEC_iterate (compunit_symtab_ptr, result_symtabs, ix,
>> compunit_symtab_iter);
>
> Bleah.
> Since sizeof (struct symtab) < sizeof (struct compunit_symtab) (64 vs
> 112 for amd64)
Yes, but that's not the case here -- this is 'sizeof (foo *)' not
'sizeof (foo)'. So it's actually pretty harmless. Should have called
that out explicitly, sorry.
This was caught in the C++ conversion, where the "insert-casts"
script would generate:
cust->includes
- = obstack_alloc (&dwarf2_per_objfile->objfile->objfile_obstack,
+ = (struct symtab **) obstack_alloc (&dwarf2_per_objfile->objfile->objfile_obstack,
(len + 1) * sizeof (struct symtab *));
which would then fail to compile.
Thanks,
Pedro Alves