[Dnsmasq-discuss] pending works before 2.57 (was: config error after 2.56 upgrade)

[Carlos Carvalho]

Matthias Andree (matthias.andree at gmx.de) wrote on 16 February 2011 15:45:
 >I have some issues:
 >
 >#1 ...and before 2.57, please audit all tolower/toupper() and is*() 
 >ctype.h functions for proper casts.
 >
 >The code currently reads:
 >
 >   char *r;
 >   ...
 >   if (*r != '*' && !isxdigit((int)*r))
 >
 >But should be ...!isxdigit((unsigned char)*r)) - mind the cast. Using 
 >(int) is extraneous and doesn't have any effect, but instead, it gives 
 >you the wrong sign extension and undefined behaviour on systems where 
 >the char type is not unsigned for *r between -128 and -2 inclusively.
 >
 >Quoting SUSv4: "The c argument is an int, the value of which the 
 >application shall ensure is a character representable as an unsigned 
 >char or equal to the value of the macro EOF. If the argument has any 
 >other value, the behavior is undefined." -- and that's what you get by 
 >casting to unsigned char (you can't get EOF here because it's not 
 >representable in a char without aliasing 0xFF -- that's useful however 
 >to apply the is*() functions to fgetc() results and thereabouts.)

This is actually a bug so it should be corrected now.

 >#3 I'm also wondering if the stuff above shouldn't rather be 
 >!ishexnumber() for locale compatibility.

For the case of ethernet addresses there should be no problem.