|
From: | Paul Eggert |
Subject: | Re: malloca, freea are not thread-safe |
Date: | Fri, 2 Feb 2018 15:59:01 -0800 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 02/02/2018 03:41 PM, Bruno Haible wrote:
Regarding the parentheses, I disagree: If we put parentheses they should be like this: size_t nplus = (n + sizeof (small_t)) + (2 * sa_alignment_max - 1); because we want n + sizeof (small_t) consecutive bytes in memory, and the other summand is for the alignment. Parenthesizing it in the way you suggest would make the expression_more_ confusing.
Well, it is a matter of style. Personally I find the expression confusing and would find it even more confusing with the extra parentheses. But perhaps that is because I am worried about integer overflow.
If SIZE_MAX <= INT_MAX we know that INT_MAX >= 2*SIZE_MAX-1 > SIZE_MAX + 100, therefore no 'int' overflow is possible here.
I was thinking about platforms where SIZE_MAX == INT_MAX, which POSIX and ISO C both allow; on such platforms 'int' overflow is possible. Admittedly platforms with idiosyncrasies like that are rare nowadays. I think Unisys stopped selling their oddball platforms in late 2015.
[Prev in Thread] | Current Thread | [Next in Thread] |