llvm dev - Dec 2013 - [LLVMdev] How can I obtain upper bound of a pointer?

Hi,
How can I obtain the upper bound of a pointer in the code? For example, I
have
a pointer Ptr which points to a block of memory that is allocated by
malloc, say,

Ptr = malloc(size);


Then what should I do if I am going to get the upper bound of the memory
block
that is pointed to by Ptr in the runtime?

Thanks,
Ben
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This is rather off-topic for LLVM, it's a C programming question and the C
answer is: you can't. C doesn't expose any way to find the upper limit
of
'Ptr' you just have to keep track of what size you used yourself.


On Sun, Dec 15, 2013 at 6:22 PM, 李永超 <lyc364 at gmail.com> wrote:
> Hi,
> How can I obtain the upper bound of a pointer in the code? For example, I
> have
> a pointer Ptr which points to a block of memory that is allocated by
> malloc, say,
>
> Ptr = malloc(size);
>
>
> Then what should I do if I am going to get the upper bound of the memory
> block
> that is pointed to by Ptr in the runtime?
>
> Thanks,
> Ben
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
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If you want an exact "upper bound", you'll have to use something
like
SoftBound (acg.cis.upenn.edu/softbound), which keeps track of the size of
each allocated region at runtime.

H.


On Mon, Dec 16, 2013 at 4:26 AM, David Blaikie <dblaikie at gmail.com>
wrote:
> This is rather off-topic for LLVM, it's a C programming question and
the C
> answer is: you can't. C doesn't expose any way to find the upper
limit of
> 'Ptr' you just have to keep track of what size you used yourself.
>
>
> On Sun, Dec 15, 2013 at 6:22 PM, 李永超 <lyc364 at gmail.com> wrote:
>
>> Hi,
>> How can I obtain the upper bound of a pointer in the code? For example,
I
>> have
>> a pointer Ptr which points to a block of memory that is allocated by
>> malloc, say,
>>
>> Ptr = malloc(size);
>>
>>
>> Then what should I do if I am going to get the upper bound of the
memory
>> block
>> that is pointed to by Ptr in the runtime?
>>
>> Thanks,
>> Ben
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
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On 12/15/13 8:22 PM, 李永超 wrote:
> Hi,
> How can I obtain the upper bound of a pointer in the code? For 
> example, I have
> a pointer Ptr which points to a block of memory that is allocated by 
> malloc, say,
>
> Ptr = malloc(size);
>
>
> Then what should I do if I am going to get the upper bound of the 
> memory block
> that is pointed to by Ptr in the runtime?
Both SAFECode (http://safecode.cs.illinois.edu) and SoftBound 
(http://acg.cis.upenn.edu/softbound) have run-time support for finding 
the bounds of an object given a pointer into the object. SAFECode and 
SoftBound are combined into a single tool available in the SAFECode 
source code repository (see the SAFECode website for directions on how 
to download and compile the software).  You can play with both of them 
and see which will suite your needs better.

-- John T.
>
> Thanks,
> Ben
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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