Re: malloc question

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On Tue, Apr 26, 2011 at 1:54 PM, ratheesh kannoth
<ratheesh.ksz@xxxxxxxxx> wrote:
> On Tue, Apr 26, 2011 at 4:10 PM, Daniel Baluta <daniel.baluta@xxxxxxxxx> wrote:
>> On Tue, Apr 26, 2011 at 1:33 PM, Randi Botse <nightdecoder@xxxxxxxxx> wrote:
>>> Hi All,
>>>
>>> I want to ask malloc() behaviour, consider these codes;
>>>
>>> ...
>>> char *ptr = malloc(1);
>>> strcpy(ptr, "what");
>>> puts(ptr);
>>> ....
>>>
>>> Confusingly, the strcpy() copied all bytes to ptr, but I just manage
>>> to allocate ptr only for 1 byte, I guess I will have segfault here,
>>> why this happen? why the string successfully copied into ptr? , is
>>> those code legal?
>>
>> You didn't get segfault because you were lucky.
>>
>> Memory is allocated in multiples of page size (usually 4K).
>> The memory after your allocated byte is valid in your case.
>>
>> thanks,
>> Daniel.
>> --
>
> U could read a little more about vm_page_struct. ( virtual address
> space to  physical page ).

Can you elaborate on this?

Daniel.
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