Date: Wed, 16 Jan 2013 11:57:01 -0500 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: Re: REG_STARTEND (regex) On Wed, Jan 16, 2013 at 09:42:01AM -0600, Rob Landley wrote: > On 01/15/2013 12:45:13 PM, Rich Felker wrote: > >> Does anyone have suggestions on how this can be modified to be > >able to > >> use it with musl. > > > >If the start position is 0, which it seems to be here, there's nothing > >to be done but removing REG_STARTEND. All it's doing is allowing you > >to process data with embedded nul bytes, which is not required by the > >standard or useful for any meaningful use of sed. > > Actually people use sed to modify embedded strings in binaries. > (Strange but true.) > > >Nobody will notice > >the difference with it missing unless they're trying to perform > >hideous hacks like patching binary files with sed... > > Which people do. > > However, mostly this involves embedded nuls in the data being > processed, not embedded nuls in the pattern space. So it's merely > creepy rather than outright pathological. And the caller can wrap > the regex library to do its own strlen stuff and restart right after > the embedded NUL if there's data left. (Which was on the todo list > for busybox sed back when Bruce happened, possibly Denys has > implemented it since.) If sed wants to support this without providing its own embedded-NUL-capable regex library, it should just treat NUL as a kind of boundary/line-break so that the pattern space never ends up containing NUL bytes. However, there are still a good many other portability issues with passing binary files to sed, even if you ignore the fact that POSIX sed specifically requires a text file as input, so I think it's rather misguided to cater to these uses anyway. Rich
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