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Message-ID: <20160224174126.GR9349@brightrain.aerifal.cx> Date: Wed, 24 Feb 2016 12:41:26 -0500 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Cc: Karl Palsson <karlp@...ctica.com> Subject: Re: [PATCH] search: call user compare with "correct" order params On Wed, Feb 24, 2016 at 12:12:29PM +0000, Karl Palsson wrote: > From: Karl Palsson <karlp@...ake.is> > > IEEE Std 1003.1, 2013 Edition only defines the two params to the > user callback as, "The compar argument points to a comparison function > which the application shall supply (for example, strcmp()). It is called > with two arguments that point to the elements being compared." > > Both uclibc and glibc provide the arguments as, " > The comparison function referenced by compar is expected to have two > arguments which point to the key object and to an array member, in that order > " > > Musl currently provides the arguments as array member, then key object. > While this is strictly compliant with the standard, it's equally > compliant to have the parameters in the other order. If you are using > lfind to search a list of complex structures where the key is not the > same type as each entry, having these parameters arrive in unexpectd > order can/will result in segfaults. > > => Swap the order of the arguments to the user function, maintaining > equal compatibility with the standard, and gaining compatibility with > uclibc and glibc. I've read some of the scrollback from the discussion of this on IRC, and I think: 1. Regardless of whether the patch is accepted or not, applications using this interface in non-portable ways should be fixed. 2. As you said, lfind/lsearch are useless functions. Aside from the order of the arguments being unspecified (which doesn't hurt code using them in the intended way), they're just going to be a lot slower than inlining the comparison in your own for loop. Is there existing software that's affected by this issue for which it's hard to get a fix upstream? Rich
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