On November 17, 2017 11:20:45 PM GMT+01:00, Qing Zhao <qing.z...@oracle.com>
wrote:
>
>> On Nov 16, 2017, at 6:24 PM, Martin Sebor <mse...@gmail.com> wrote:
>>>
>>> In my current local implementation, I used the following routine to
>get the range info: (and use the MINMAXLEN[1]+1 for the length of the
>non-constant string)
>>>
>>> /* Determine the minimum and maximum value or string length that ARG
>>> refers to and store each in the first two elements of MINMAXLEN.
>>> For expressions that point to strings of unknown lengths that are
>>> character arrays, use the upper bound of the array as the maximum
>>> length. For example, given an expression like 'x ? array : "xyz"'
>>> and array declared as 'char array[8]', MINMAXLEN[0] will be set
>>> to 3 and MINMAXLEN[1] to 7, the longest string that could be
>>> stored in array.
>>> Return true if the range of the string lengths has been obtained
>>> from the upper bound of an array at the end of a struct. Such
>>> an array may hold a string that's longer than its upper bound
>>> due to it being used as a poor-man's flexible array member. */
>>>
>>> bool
>>> get_range_strlen (tree arg, tree minmaxlen[2])
>>> {
>>> }
>>>
>>> However, this routine currently miss a very obvious case as the
>following:
>>>
>>> char s[100] = {'a','b','c','d’};
>>>
>>> __builtin_strcmp(s, "abc") != 0
>>>
>>> So, I have to change this routine to include such common case.
>>
>> There was a discussion some time ago about converting CONSTRUCTOR
>> trees emitted for array initializers like the above to STRING_CST
>> (see bug 71625 for some background). I think that would still be
>> the ideal solution. Then you wouldn't have to change
>> get_range_strlen.
IIRC Martin had a patch for this.
Richard.
>thanks for the info, Martin.
>
>In my case, it’s the size of “100” cannot be collected in the
>MINMAXLEN[1] for the string “s”.
>
>I need to make sure that the size of variable string s is larger than
>the size of constant string “abc” to guarantee the safety of the
>transformation.
>
>currently, “get_range_strlen” cannot identify the simple VAR_DECL with
>array_type to determine the maximum size of the string.
>
>Qing
>>
>> Martin
