Date: Mon, 19 Jan 2015 01:24:55 -0500 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Subject: Re: getopt_long_only and slightly unambiguous options On Sun, Jan 18, 2015 at 07:27:23PM +0100, Felix Janda wrote: > Rich Felker wrote: > > On Sun, Jan 18, 2015 at 06:51:59PM +0100, Felix Janda wrote: > > > Hello, > > > > > > since widl from wine uses the combination, get_opt_long_only seems to > > > be supposed to be able to differentiate between a short option "-h" > > > and a long option "--help". Together with the possibility of option > > > abbreviations, the behavior we are trying to copy is: > > > > > > -h -> -h > > > --help -> --help > > > -help -> --help > > > -he -> --help > > > --h -> --help > > > > > > However musl maps all of them to --help. > > > > > > The man page is ambiguous about this aspect and I'm not sure if the > > > BSDs have the same behavior here. (However I would suspect that the > > > breakage in widl, when the --help option was added in 2012, would > > > have been noticed.) As always, it is hard to measure how many > > > applications (and scripts written against these applications) might > > > depend on this behavior. Since getopt_long_only is discouraged > > > maybe these are actually quite few, though. > > > > > > All in all I think that this a bug in musl which should be fixed. > > > > > > > > > For the implementation, is it maybe enough in __getopt_long_core to > > > pass options starting with '-' and of exactly two characters > > > directly to getopt? > > > > I would think getopt_long_only would even want to treat "-he" as "-h" > > and "-e", i.e. abbreviations should be suppressed entirely when only a > > single leading "-" appears instead of "--". However I'd rather follow > > historical practice unless it's something stupid and complex (and > > violating the principle of least surprise for users) like checking > > whether each char is a valid short option and basing the decision on > > that. > > I've just checked that even when there are both -h and -e short > options glibc getopt_long_only treats -he as --help. OK, so I'll go ahead with making getopt_long_core ignore abbreviations of the form "-" followed by one character. BTW I realized another related issue we should handle -- in the case of long options containing multibyte characters, the abbreviation code is wrongly accepting incomplete multibyte sequences as "abbreviations" for the full character. I don't know if this is worth fixing, It should be as easy as checking that the next (unmatched) byte of the full option is either in the ASCII range or is a lead-byte. Rich
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