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Path: ...!npeer.as286.net!npeer-ng0.as286.net!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: bart <bc@freeuk.com> Newsgroups: comp.lang.c Subject: Re: C23 thoughts and opinions Date: Sun, 2 Jun 2024 00:39:39 +0100 Organization: A noiseless patient Spider Lines: 36 Message-ID: <v3gbfr$30v15$1@dont-email.me> References: <v2l828$18v7f$1@dont-email.me> <v3758s$14hfp$1@raubtier-asyl.eternal-september.org> <v38of2$1gsj2$1@dont-email.me> <v39v87$1n7bk$1@dont-email.me> <20240530170836.00005fa0@yahoo.com> <v3a3k5$1ntrn$1@dont-email.me> <20240530180345.00003d9f@yahoo.com> <v3chc4$27uij$1@dont-email.me> <20240531161937.000063af@yahoo.com> <20240531162811.00006719@yahoo.com> <20240531164835.00007128@yahoo.com> <v3cldt$28n91$2@dont-email.me> <20240531173437.00003bee@yahoo.com> <v3d3ct$2b5sl$1@dont-email.me> <yMo6O.3723$zfC8.2197@fx35.iad> <v3dem9$2d2v4$1@dont-email.me> <20240602011135.00004810@yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Sun, 02 Jun 2024 01:39:39 +0200 (CEST) Injection-Info: dont-email.me; posting-host="67b8fee0090bd0bfbe16789769c90f58"; logging-data="3177509"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+j8t4s3MJ4rNNOHcKUz6xq" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:/DxWl6HOwW7r4n5FppG2D85JWe8= Content-Language: en-GB In-Reply-To: <20240602011135.00004810@yahoo.com> Bytes: 2663 On 01/06/2024 23:11, Michael S wrote: > On Fri, 31 May 2024 22:15:54 +0100 > bart <bc@freeuk.com> wrote: > >> If I run this: >> >> printf("%p\n", &_binary_hello_c_start); >> printf("%p\n", &_binary_hello_c_end); >> printf("%p\n", &_binary_hello_c_size); >> >> I get: >> >> 00007ff6ef252010 >> 00007ff6ef252056 >> 00007ff5af240046 >> >> I can see that the first two can be subtracted to give the sizes of >> the data, which is 70 or 0x46. 0x46 is the last byte of the address >> of _size, so what's happening there? What's with the crap in bits >> 16-47? >> > > It looks like ASLR. I don't see it because I test on Win7. > I understand those are high-loading addresses. I was asking what they were doing as part of the size. Apparently, that size value is wrongly relocated by some versions of gcc-ld. Since allocations work on 64KB blocks, that explains why the bottom 16 bits are unaffected. So such a size value could still be used for objects up 64KB-1, but it sounds dodgy.