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| From | Richard Heathfield <rjh@cpax.org.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Why is this outputting alternate blank lines? |
| Date | 2016-12-14 20:05 +0000 |
| Organization | Fix this later |
| Message-ID | <o2s8ir$uk5$1@dont-email.me> (permalink) |
| References | <o2qh45$9ae$1@dont-email.me> <o2r7cs$6l1$1@dont-email.me> <o2s0sb$tb$1@dont-email.me> <o2s1i8$3qt$1@dont-email.me> <ln4m26nv0o.fsf@kst-u.example.com> |
On 14/12/16 19:57, Keith Thompson wrote: > Richard Heathfield <rjh@cpax.org.uk> writes: >> On 14/12/16 17:53, DFS wrote: > [...] >>> Any idea why it crashes above 1 million? >> >> Do you remember when I suggested checking the return value of malloc? >> >> I again suggest that you check the return value of malloc. >> >> The malloc function returns NULL when it fails to allocate memory. Since >> you're not checking for this, if ever it /does/ return NULL you will be >> scribbling all over memory you don't own, hence the segfault. > > On the other hand, on some systems malloc() generally doesn't report > failure; rather if you allocate too much memory, a crash occurs when you > try to access it. (This is arguably non-conforming.) Arguably? I'd have said it's absolutely definitely non-conforming. The malloc function is /required/ to report failure if the memory can't be allocated. 7.22.3(1): The order and contiguity of storage allocated by successive calls to the aligned_alloc, calloc, malloc, and realloc functions is unspecified. The pointer returned if the allocation succeeds is suitably aligned so that it may be assigned to a pointer to any type of object with a fundamental alignment requirement and then used to access such an object or an array of such objects in the space allocated (until the space is explicitly deallocated). The lifetime of an allocated object extends from the allocation until the deallocation. Each such allocation shall yield a pointer to an object disjoint from any other object. The pointer returned points to the start (lowest byte address) of the allocated space. If the space cannot be allocated, a null pointer is returned. Note the last sentence: if the space can't be allocated, malloc has to return a null pointer. If it returns a non-null pointer, this can only mean that the allocation succeeded. So if malloc returns a non-null pointer when the allocation in fact failed, the implementation fails to conform to 7.22.3(1). What intrigues me, though, is why you think this is arguable. I suspect that you probably share my take on this. If you were to play Devil's Advocate, though, what arguments would you muster for such behaviour being conforming? -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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Why is this outputting alternate blank lines? DFS <nospam@dfs.com> - 2016-12-13 23:18 -0500
Re: Why is this outputting alternate blank lines? Melzzzzz <mel@zzzzz.com> - 2016-12-14 05:30 +0100
Re: Why is this outputting alternate blank lines? mark.bluemel@gmail.com - 2016-12-14 00:59 -0800
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-14 10:38 +0000
Re: Why is this outputting alternate blank lines? DFS <nospam@dfs.com> - 2016-12-14 12:53 -0500
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-14 18:05 +0000
Re: Why is this outputting alternate blank lines? Keith Thompson <kst-u@mib.org> - 2016-12-14 11:57 -0800
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-14 20:05 +0000
Re: Why is this outputting alternate blank lines? "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-14 15:21 -0500
Re: Why is this outputting alternate blank lines? Keith Thompson <kst-u@mib.org> - 2016-12-14 12:28 -0800
Re: Why is this outputting alternate blank lines? supercat@casperkitty.com - 2016-12-14 13:09 -0800
Re: Why is this outputting alternate blank lines? Jean-Marc Bourguet <jm@bourguet.org> - 2016-12-14 22:53 +0100
Re: Why is this outputting alternate blank lines? <william@wilbur.25thandClement.com> - 2016-12-14 15:47 -0800
Re: Why is this outputting alternate blank lines? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-14 15:41 -0700
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-14 23:26 +0000
Re: Why is this outputting alternate blank lines? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-14 17:33 -0700
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-15 00:42 +0000
Re: Why is this outputting alternate blank lines? supercat@casperkitty.com - 2016-12-14 17:05 -0800
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-15 08:21 +0000
Re: Why is this outputting alternate blank lines? supercat@casperkitty.com - 2016-12-15 09:15 -0800
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-15 17:50 +0000
Re: Why is this outputting alternate blank lines? supercat@casperkitty.com - 2016-12-15 12:15 -0800
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-15 20:37 +0000
Re: Why is this outputting alternate blank lines? raltbos@xs4all.nl (Richard Bos) - 2016-12-15 20:08 +0000
Re: Why is this outputting alternate blank lines? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-14 20:40 -0700
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-15 08:36 +0000
Re: Why is this outputting alternate blank lines? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-15 17:43 -0700
Re: Why is this outputting alternate blank lines? Richard Heathfield <rjh@cpax.org.uk> - 2016-12-16 01:05 +0000
Re: Why is this outputting alternate blank lines? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-12-15 18:34 -0700
Re: Why is this outputting alternate blank lines? <william@wilbur.25thandClement.com> - 2016-12-15 10:14 -0800
Re: Why is this outputting alternate blank lines? raltbos@xs4all.nl (Richard Bos) - 2016-12-15 20:15 +0000
Re: Why is this outputting alternate blank lines? Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-15 01:51 -0800
Re: Why is this outputting alternate blank lines? asetofsymbols@gmail.com - 2016-12-15 06:09 -0800
Re: Why is this outputting alternate blank lines? Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-15 17:47 -0800
Re: Why is this outputting alternate blank lines? Keith Thompson <kst-u@mib.org> - 2016-12-14 12:15 -0800
Re: Why is this outputting alternate blank lines? <william@wilbur.25thandClement.com> - 2016-12-15 10:24 -0800
Re: overcommit is the plague Noob <root@127.0.0.1> - 2016-12-17 01:17 +0100
Re: Why is this outputting alternate blank lines? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-14 20:19 +0000
Re: Why is this outputting alternate blank lines? DFS <nospam@dfs.com> - 2016-12-14 17:44 -0500
Re: Why is this outputting alternate blank lines? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-15 00:21 +0000
Re: Why is this outputting alternate blank lines? mark.bluemel@gmail.com - 2016-12-15 00:56 -0800
Re: Why is this outputting alternate blank lines? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-15 22:08 +0000
Re: Why is this outputting alternate blank lines? Geoff <geoff@invalid.invalid> - 2016-12-14 13:39 -0800
Re: Why is this outputting alternate blank lines? Ike Naar <ike@iceland.freeshell.org> - 2016-12-16 07:12 +0000
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