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;
  22   gid_t rgid, egid;
  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;
  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, "u")) != EOF) {
  56         switch(c) {
  57                 case 'u':
  58                         uopt = 1;
  59                         break;
  60                 default:
  61                         fprintf(stderr, "%s: unrecognized option\n", argv[0]);
  62                         return(1);
  63         }
  64   }
  65
  66   if(uopt) {
  67         printf("%d\n", euid);
  68         return 0;
  69   }
  70
  71   if ((pwd = getpwuid(ruid)) == NULL)
  72         printf("uid=%d", ruid);
  73   else
  74         printf("uid=%d(%s)", ruid, pwd->pw_name);
  75
  76   if ((grp = getgrgid(rgid)) == NULL)
  77         printf(" gid=%d", rgid);
  78   else
  79         printf(" gid=%d(%s)", rgid, grp->gr_name);
  80
  81   if (euid != ruid)
  82         if ((pwd = getpwuid(euid)) != NULL)
  83                 printf(" euid=%d(%s)", euid, pwd->pw_name);
  84         else
  85                 printf(" euid=%d", euid);
  86
  87   if (egid != rgid)
  88         if ((grp = getgrgid(egid)) != NULL)
  89                 printf(" egid=%d(%s)", egid, grp->gr_name);
  90         else
  91                 printf(" egid=%d", egid);
  92
  93   if (suid != euid)
  94         if ((pwd = getpwuid(suid)) != NULL)
  95                 printf(" suid=%d(%s)", suid, pwd->pw_name);
  96         else
  97                 printf(" suid=%d", suid);
  98
  99   if (sgid != egid)
 100         if ((grp = getgrgid(sgid)) != NULL)
 101                 printf(" sgid=%d(%s)", sgid, grp->gr_name);
 102         else
 103                 printf(" sgid=%d", sgid);
 104
 105   if (isug) {
 106         printf(" issetugid");
 107   }
 108
 109   if (ngroups > 0) {
 110         printf(" groups=");
 111         for (g = 0; g < ngroups; g++) {
 112                 if (g > 0) fputc(',', stdout);
 113                 if ((grp = getgrgid(groups[g])) == NULL)
 114                         printf("%d", groups[g]);
 115                 else
 116                         printf("%d(%s)", groups[g], grp->gr_name);
 117         }
 118   }
 119
 120   printf("\n");
 121   return(0);
 122 }