ref: 20a1d2268d69a0bbe66d0f21999649133878377c
dir: /sys/src/cmd/disk/9660/uid.c/
#include <u.h> #include <libc.h> /* * /adm/users is * id:user/group:head member:other members * * /etc/{passwd,group} * name:x:nn:other stuff */ static int isnumber(char *s); sniff(Biobuf *b) { read first line of file into p; nf = getfields(p, f, nelem(f), ":"); if(nf < 4) return nil; if(isnumber(f[0]) && !isnumber(f[2])) return _plan9; if(!isnumber(f[0]) && isnumber(f[2])) return _unix; return nil; } int isnumber(char *s) { char *q; strtol(s, &q, 10); return *q == '\0'; } /* EOF */