On Wed, Sep 02, 2015 at 07:58:18PM -0500, Rob Landley wrote: > On 09/02/2015 10:09 AM, enh wrote: > > On Tue, Sep 1, 2015 at 11:26 PM, Rob Landley <[email protected]> wrote: > >> On 09/01/2015 08:35 PM, enh wrote: > >>> Make yesno printf-like. > >> > >> This just makes me uncomfortable that it's nonobvious enough somebody's > >> going to yesno(1, usersupplieddata);. > > > > that seems unlikely, especially given that yesno doesn't supply the > > "?". (and you really ought to get out of the habit of being so tricky > > at the cost of readability all the time anyway!) > > > > btw, though this distracts from my point and will probably only > > encourage you to stick with the status quo... toybox already blindly > > uses user-supplied strings as format strings. random example: > > > > $ seq -f '%s' 1 3 > > seq: format ‘%s’ has unknown %s directive > > > > $ ./toybox seq -f '%s' 1 3 > > Segmentation fault (core dumped) > > That's a bug and I need to fix it. > > Except... Grrr. No posix entry for this, and the LSB spec is crap as usual. > > seq -f %d 1 3 > seq -f %s 1 3 > seq -f "" 1 3 > seq -f %f 1 3 > seq -f %e 1 3 > seq -f %g 1 3 > seq -f "boo %f yah" 1 3 > seq -f "boo %f %f yah" 1 3 > seq -f "% f" 1 3 > seq -f "%*f" 1 3 > seq -f "%-1.2f" 1 3 > seq -f "%-1.2.3f" 1 3 > seq -f "%1-f" 1 3 > seq -f "%1 f" 1 3 > seq -f "%+-f" 1 3 > seq -f "%+ - f" 1 3 > seq -f "%.2f" 1 3 > seq -f "%3.f" 1 3 > seq -f "%2..2f" 1 3 > seq -f "%'.2f" 1 3 > > Ok, it looks like the sanitization pass is using: > > 1) search for one % (must exist in string) > 2) skip all "+- " > 3) skip all digits 0-9 > 4) skip at most one "." > 5) skip all digits 0-9 > 6) ensure next char is [feg] > > Now let's read man 3 printf and see what ELSE I forgot: accept %% > literal, the target is aAeEfFgG, flags are ['#-+ ]... > > seq -f "%LF" 1 3 > > Really? Sigh. I don't think I'm allowing that one because it's INSANE.
This should work: ([^%]|%%)*%[-#0 +']?[0-9]*.[0-9]*[aAeEfFgG]([^%]|%%)* If you're already linking regcomp/regexec, using them to match it is probably the smallest/simplest implementation. If not you can write a state machine for it. Rich _______________________________________________ Toybox mailing list [email protected] http://lists.landley.net/listinfo.cgi/toybox-landley.net
