commands/simple/id.c

   1 /* id - return uid and gid              Author: John J. Marco */
   2
   3 /*=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-*/
   4 /*              ----- id.c -----                                        */
   5 /* Id - get real and effective user id and group id                     */
   6 /* Author: John J. Marco                                                */
   7 /*         pa1343@sdcc15.ucsd.edu                                       */
   8 /*-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=*/
   9
  10 #include <sys/types.h>
  11 #include <pwd.h>
  12 #include <grp.h>
  13 #include <unistd.h>
  14 #include <stdio.h>
  15 #include <limits.h>
  16
  17 int main(int argc, char *argv[])
  18 {
  19   struct passwd *pwd;
  20   struct group *grp;
  21   uid_t ruid, euid, uid;
  22   gid_t rgid, egid, gid;
  23 #if __minix_vmd
  24   uid_t suid;
  25   gid_t sgid;
  26 #else
  27 # define suid ruid
  28 # define sgid rgid
  29 #endif
  30 #if NGROUPS_MAX > 0
  31   gid_t groups[NGROUPS_MAX];
  32   int ngroups;
  33 #else
  34 # define groups (&rgid)
  35 # define ngroups 0
  36 #endif
  37   int g;
  38   int isug;
  39   int c, uopt = 0, gopt = 0, nopt = 0, ropt = 0;
  40
  41 #if __minix_vmd
  42   get6id(&ruid, &euid, &suid, &rgid, &egid, &sgid);
  43   isug = issetugid();
  44 #else
  45   ruid = getuid();
  46   euid = geteuid();
  47   rgid = getgid();
  48   egid = getegid();
  49   isug = 0;
  50 #endif
  51 #if NGROUPS_MAX > 0
  52   ngroups = getgroups(NGROUPS_MAX, groups);
  53 #endif
  54
  55   while((c = getopt(argc, argv, "ugnr")) != EOF) {
  56         switch(c) {
  57                 case 'u':
  58                         uopt = 1;
  59                         break;
  60                 case 'g':
  61                         gopt = 1;
  62                         break;
  63                 case 'n':
  64                         nopt = 1;
  65                         break;
  66                 case 'r':
  67                         ropt = 1;
  68                         break;
  69                 default:
  70                         fprintf(stderr, "%s: unrecognized option\n", argv[0]);
  71                         return(1);
  72         }
  73   }
  74
  75   if(uopt && gopt) {
  76         fprintf(stderr, "%s: cannot combine -u and -g\n", argv[0]);
  77         return 1;
  78   }
  79
  80   if((nopt || ropt) && !uopt && !gopt) {
  81         fprintf(stderr, "%s: cannot use -n or -r without -u or -g\n", argv[0]);
  82         return 1;
  83   }
  84
  85   if(uopt) {
  86         uid = ropt ? ruid : euid;
  87         if (!nopt || (pwd = getpwuid(uid)) == NULL)
  88                 printf("%u\n", uid);
  89         else
  90                 printf("%s\n", pwd->pw_name);
  91         return 0;
  92   }
  93   if(gopt) {
  94         gid = ropt ? rgid : egid;
  95         if (!nopt || (grp = getgrgid(gid)) == NULL)
  96                 printf("%u\n", gid);
  97         else
  98                 printf("%s\n", grp->gr_name);
  99         return 0;
 100   }
 101
 102   if ((pwd = getpwuid(ruid)) == NULL)
 103         printf("uid=%d", ruid);
 104   else
 105         printf("uid=%d(%s)", ruid, pwd->pw_name);
 106
 107   if ((grp = getgrgid(rgid)) == NULL)
 108         printf(" gid=%d", rgid);
 109   else
 110         printf(" gid=%d(%s)", rgid, grp->gr_name);
 111
 112   if (euid != ruid)
 113         if ((pwd = getpwuid(euid)) != NULL)
 114                 printf(" euid=%d(%s)", euid, pwd->pw_name);
 115         else
 116                 printf(" euid=%d", euid);
 117
 118   if (egid != rgid)
 119         if ((grp = getgrgid(egid)) != NULL)
 120                 printf(" egid=%d(%s)", egid, grp->gr_name);
 121         else
 122                 printf(" egid=%d", egid);
 123
 124   if (suid != euid)
 125         if ((pwd = getpwuid(suid)) != NULL)
 126                 printf(" suid=%d(%s)", suid, pwd->pw_name);
 127         else
 128                 printf(" suid=%d", suid);
 129
 130   if (sgid != egid)
 131         if ((grp = getgrgid(sgid)) != NULL)
 132                 printf(" sgid=%d(%s)", sgid, grp->gr_name);
 133         else
 134                 printf(" sgid=%d", sgid);
 135
 136   if (isug) {
 137         printf(" issetugid");
 138   }
 139
 140   if (ngroups > 0) {
 141         printf(" groups=");
 142         for (g = 0; g < ngroups; g++) {
 143                 if (g > 0) fputc(',', stdout);
 144                 if ((grp = getgrgid(groups[g])) == NULL)
 145                         printf("%d", groups[g]);
 146                 else
 147                         printf("%d(%s)", groups[g], grp->gr_name);
 148         }
 149   }
 150
 151   printf("\n");
 152   return(0);
 153 }