[patch] Avoid bogus pointer->int cast

[Ralf Corsepius]

On 07/17/2012 07:45 PM, Eric Blake wrote:
> On 07/17/2012 11:26 AM, Ralf Corsepius wrote:
>> On 07/17/2012 07:21 PM, Ralf Corsepius wrote:
>>> Hi,
>>>
>>> The patch below addresses a (minor) bug in readdir.c. It replaces a
>>> (bogus) pointer->int cast with a pointer->intptr_t cast.
>
> Rather than "fixing" the bogus pointer check, why not just nuke that
> code altogether?

My goal was to make the existing code compilable by removing invalid 
code, not rewrite it.

>> +#include <stdint.h>
>
> In other words, no need to drag this in...
>
>>   #include <dirent.h>
>>
>>   extern int getdents (int fd, void *dp, int count);
>> @@ -75,7 +76,7 @@ _DEFUN(readdir, (dirp),
>>         continue;
>>       }
>>       dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
>
> and everything between here...
>
>> -    if ((int)dp & 03) {	/* bogus pointer check */
>> +    if ((intptr_t)dp & 03) {	/* bogus pointer check */
>>   #ifdef HAVE_DD_LOCK
>>         __lock_release_recursive(dirp->dd_lock);
>>   #endif
>        return NULL;
>      }
>
> ...and here is just stupid.  POSIX already states that behavior is
> undefined if you pass in a bogus pointer; and in a compliant program,
> readdir should only ever be called on a valid pointer, making this check
> look like nothing more than dead code.  I see no need to bloat the code
> with an attempt to gracefully deal with a bogus pointer.

This is a different issue than I was addressing.

Ralf