Re: AfxIsValidAddress
On Tue, Jul 14, 2015, at 12:09 PM, Wim Lewis wrote: It checks whether a given address range is mapped (or equivalent terminology on Windows). Windows has another function that programmers like to use, IsBadReadPtr(), that does something similar. Raymond Chen (compatibility engineer at Microsoft) elaborates a little more on what something similar actually means: http://blogs.msdn.com/b/oldnewthing/archive/2006/09/27/773741.aspx :P --Kyle Sluder ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
AfxIsValidAddress
Is there a Cocoa or OS X equivalent to the Windows function AfxIsValidAddress ? Or, is this even a valid consideration for OS X? -rags ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: AfxIsValidAddress
On Jul 14, 2015, at 9:44 AM, Jens Alfke j...@mooseyard.com wrote: On Jul 14, 2015, at 9:13 AM, Raglan T. Tiger r...@crusaderrabbit.net wrote: Is there a Cocoa or OS X equivalent to the Windows function AfxIsValidAddress ? I don’t know, I’m not a Windows programmer. It would help if you told us what that function does. It checks whether a given address range is mapped (or equivalent terminology on Windows). Windows has another function that programmers like to use, IsBadReadPtr(), that does something similar. It's possible to get this information by making some Mach API calls, but unless you're doing something pretty exotic, there isn't a good reason to do it. It's better to construct your program such that you know the memory region is valid; if it isn't valid, you know your program state is corrupt, and the right thing to do in that case is crash and send a crashdump to the developer so that it can be fixed. If you don't know (with enough certainty to omit a call to IsValidAddress) whether a pointer is readable, you certainly don't know whether the data there is what you expect to be there. Memory regions get reused a lot. Wim Lewis / w...@omnigroup.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: AfxIsValidAddress
On Jul 14, 2015, at 9:13 AM, Raglan T. Tiger r...@crusaderrabbit.net wrote: Is there a Cocoa or OS X equivalent to the Windows function AfxIsValidAddress ? I don’t know, I’m not a Windows programmer. It would help if you told us what that function does. —Jens ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: AfxIsValidAddress
On Jul 14, 2015, at 10:44 AM, Jens Alfke j...@mooseyard.com wrote:
I don’t know, I’m not a Windows programmer. It would help if you told us what
that function does.
It appears to be a placebo for debugging memory problems:
http://ofekshilon.com/2011/01/31/afxisvalidaddress-et-al-dont-work-as-advertised/
TL;DR, here you go:
BOOL AfxIsValidAddress(const void *p, size_t nBytes) {
return p != NULL;
}
--
Scott Ribe
scott_r...@elevated-dev.com
http://www.elevated-dev.com/
https://www.linkedin.com/in/scottribe/
(303) 722-0567 voice
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Re: AfxIsValidAddress
On Jul 14, 2015, at 10:09 AM, Wim Lewis w...@omnigroup.com wrote: If you don't know (with enough certainty to omit a call to IsValidAddress) whether a pointer is readable, you certainly don't know whether the data there is what you expect to be there. Plus, preflighting access this way involves race conditions — the memory could be unmapped by another thread after you preflight but before you actually access it. There are ways to dereference a random pointer without crashing if it’s unmapped, but they involve using a signal handler to recover from the exception _after_ it happens. (For example, the Go language’s runtime does this to turn null-pointer derefs into Go-level ‘panic’ exceptions.) But writing signal handlers that can recover and unwind the stack is extremely deep magic, almost certainly not the kind of thing you want to try implementing yourself. —Jens ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: AfxIsValidAddress
On Jul 14, 2015, at 11:22 AM, Scott Ribe scott_r...@elevated-dev.com wrote: This is a definite FUGGEDABOUTIT situation. I already have! -rags ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: AfxIsValidAddress
On Jul 14, 2015, at 11:09 AM, Wim Lewis w...@omnigroup.com wrote: It checks whether a given address range is mapped (or equivalent terminology on Windows). Windows has another function that programmers like to use, IsBadReadPtr(), that does something similar. No, it doesn't. It is *DOCUMENTED* to do that, but it doesn't ;-) Of course the rest of your post, about not depending on it, would be valid even if it worked... This is a definite FUGGEDABOUTIT situation. -- Scott Ribe scott_r...@elevated-dev.com http://www.elevated-dev.com/ https://www.linkedin.com/in/scottribe/ (303) 722-0567 voice ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
