Re: [Crash-utility] [PATCH v3] Enhance "net" command to display IPv6 address of network interface

> > +     char str[INET6_ADDRSTRLEN + 1] = {0}; > > +     char buffer[INET6_ADDRSTRLEN + 4] = {0}; > > What are the +1 and +4 for? > > > I noticed that the size of INET6_ADDRSTRLEN is 48 in kernel code as below: > > --- a/include/linux/inet.h > +++ b/include/linux/inet.h > +/* > + * These mimic similar macros defined in user-space for inet_ntop(3). > + * See /usr/include/netinet/in.h . > + */ > +#define INET_ADDRSTRLEN                (16) > +#define INET6_ADDRSTRLEN       (48) > > > And, the size of INET6_ADDRSTRLEN is 46 in my machine as below: > > # cat /usr/include/netinet/in.h |grep INET6_ADDRSTRLEN > #define INET6_ADDRSTRLEN 46

> > > The rfc2460 said that the IPv6 increases the IP address size from 32 bits to 128 bits. > > crash> struct in6_addr > struct in6_addr { >     union { >         __u8 u6_addr8[16]; >         __be16 u6_addr16[8]; >         __be32 u6_addr32[4]; >     } in6_u; > } > SIZE: 16 > > Given that, maybe they should be defined like this? > > +     char str[INET6_ADDRSTRLEN + 2] = {0}; > +     char buffer[INET6_ADDRSTRLEN + 2 + 2] = {0}; > >  Not sure what's the best way for this case. > > Looking at the example in the man page of inet_pton(3), INET6_ADDRSTRLEN > seems enough for the str and contains a null char.  The buffer can have > a comma and a space (", ") so +2 is enough?  i.e. > >    char str[INET6_ADDRSTRLEN] = {0}; >    char buffer[INET6_ADDRSTRLEN + 2] = {0}; > > > > +     uint len = 0; > > + > > +     buf = *bufp; > > +     pos = strlen(buf); > > Ah nicely done :) > > > + > > +     readmem(devaddr + OFFSET(net_device_ip6_ptr), KVADDR, > > +             &ip6_ptr, sizeof(ulong), "ip6_ptr", FAULT_ON_ERROR); > > + > > +     if (!ip6_ptr) > > +             return; > > + > > +     if (VALID_MEMBER(inet6_ifaddr_if_list)) { > > +             struct list_data list_data, *ld; > > +             ulong cnt = 0, i; > > + > > +             ld = &list_data; > > +             BZERO(ld, sizeof(struct list_data)); > > +             ld->flags |= LIST_ALLOCATE; > > +             ld->start = ip6_ptr + OFFSET(inet6_dev_addr_list); > > +             cnt = do_list(ld); > > + > > +             for (i = 1; i < cnt; i++) { > > + > > +                     addr = ld->list_ptr[i] + OFFSET(inet6_ifaddr_addr); > > > +                     addr -= OFFSET(inet6_ifaddr_if_list); > > > The above code is easy to understand, because it actually imitates the container_of(). > > But if you would like to have the same style as show_net_devices_v2() and show_net_devices_v3(), that's also fine to me.