[pacman-dev] Bug in libalpm: sizeof(off_t)

[Allan McRae]

On 25/11/13 23:43, Andrew Gregory wrote:
> On 11/25/13 at 09:08pm, Allan McRae wrote:
>> On 22/11/13 22:37, Jeremy Heiner wrote:
>>> On Thu, Nov 21, 2013 at 3:52 PM, Allan McRae <allan at archlinux.org> wrote:
>>>> Nope - documenting is the only real way to deal with this.  For example:
>>>>
>>>> http://www.gnupg.org/documentation/manuals/gpgme/Largefile-Support-_0028LFS_0029.html
>>>
>>> How about the approach outlined in the attachment? It passes 'make
>>> check' and performs correctly when a libalpm client app goofs up.
>>>
>>
>> Please send patches inline so we can easily comment.
>>
>> I was quite surprised this worked:
>>
>> +#define alpm_initialize(root,dbpath,err) \
>> +  alpm_initialize_check_largefile(root, dbpath, err, sizeof(off_t))
>>
>> The sizeof(off_t) gets evaluated before the #define?  That can't be
>> right...   So must be optimised out?  I'm either missing something here
>> or this is prone to breakage.
> 
> If I'm not mistaken, sizeof is evaluated at compile time.  This works
> because the sizeof(off_t) in the #define is evaluated when the calling
> program is compiled and the sizeof(off_t) inside
> alpm_initialize_check_largefile is evaluated when alpm is compiled.
> 

Ah - compile time evaluation...  I understand what this is doing now.
However, I don't like that this is a runtime check.

>From searching around, we are definitely not the first people to run
into this issue, but seem to be the only ones who are trying to code around.

Allan