Re: problem in usage of grub_errno...

[Joel Buckley <leojava@comcast.net>]

There is a second bug though...

A possible stack memory-leak is possible.  Replace the
first line with the following to avoid the memory leak:

    if (grub_errno != GRUB_ERR_NONE) {
       grub_error_push();
    }

Otherwise, a useless push is done.

leoJ.


Vesa Jääskeläinen wrote:

>Tomáš Ebenlendr wrote:
>  
>
>>I think there is a 'bug' in the example. Or maybe I'm missing something.
>>    
>>
>
>Nope, it was intentional. :)
>
>  
>
>>On 17 Prosinec 2005, 18:40, Vesa Jääskeläinen napsal(a):
>>....
>>    
>>
>>>---
>>>/* Save possible old error message.  */
>>>grub_error_push ();
>>>
>>>/* Do your stuff here.  */
>>>call_possibly_failing_function ();
>>>
>>>if (grub_errno != GRUB_ERR_NONE)
>>>  {
>>>    /* Inform rest of the code that there is error (grub_errno
>>>       is set). */
>>>    return;
>>>  }
>>>
>>>/* Restore old error state by popping previous item from stack. */
>>>grub_error_pop ();
>>>---
>>>      
>>>
>>....
>>
>>When grub_errno != GRUB_ERR_NONE (branching into the 'if'), then
>>there is no grub_error_pop() in the example.
>>If the whole thing will be called in a loop, then unwanted
>>stack overflow can simply occur.
>>    
>>
>
>Error stack is statically allocated and it is protected so that it
>cannot overflow. Error stack is defined as being static to file
>kern/err.c so there is no direct access possible to error stack.
>
>Error stack is emptied in grub_print_error function. (And this is called
>before prompt is printed to screen)
>
>Idea of the error stack is to record all error messages before they are
>printed.
>
>Or did I miss your idea with the "unwanted stack overflow" ?
>
>Thanks,
>Vesa Jääskeläinen
>
>
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>  
>