From: Daniel Baluta <daniel.baluta@gmail.com>
To: ratheesh kannoth <ratheesh.ksz@gmail.com>
Cc: Randi Botse <nightdecoder@gmail.com>,
linux-c-programming@vger.kernel.org
Subject: Re: malloc question
Date: Tue, 26 Apr 2011 13:57:56 +0300 [thread overview]
Message-ID: <BANLkTikL+p2dBYBGKjwKkUUMYoPm7XxKGg@mail.gmail.com> (raw)
In-Reply-To: <BANLkTinW-j2DiwbVC5u8BfJMU7jK3_KbwA@mail.gmail.com>
On Tue, Apr 26, 2011 at 1:54 PM, ratheesh kannoth
<ratheesh.ksz@gmail.com> wrote:
> On Tue, Apr 26, 2011 at 4:10 PM, Daniel Baluta <daniel.baluta@gmail.com> wrote:
>> On Tue, Apr 26, 2011 at 1:33 PM, Randi Botse <nightdecoder@gmail.com> 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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next prev parent reply other threads:[~2011-04-26 10:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-26 10:33 malloc question Randi Botse
2011-04-26 10:40 ` Daniel Baluta
2011-04-26 10:54 ` ratheesh kannoth
2011-04-26 10:57 ` Daniel Baluta [this message]
2011-04-26 11:50 ` ratheesh kannoth
2011-04-26 15:05 ` Glynn Clements
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