grp/compat-initgroups.c

   1 /* Prototype for the setgrent functions we use here.  */
   2 typedef enum nss_status (*set_function) (void);
   3
   4 /* Prototype for the endgrent functions we use here.  */
   5 typedef enum nss_status (*end_function) (void);
   6
   7 /* Prototype for the setgrent functions we use here.  */
   8 typedef enum nss_status (*get_function) (struct group *, char *,
   9                                          size_t, int *);
  10
  11 static enum nss_status
  12 compat_call (service_user *nip, const char *user, gid_t group, long int *start,
  13              long int *size, gid_t **groupsp, long int limit, int *errnop)
  14 {
  15   struct group grpbuf;
  16   size_t buflen = __sysconf (_SC_GETGR_R_SIZE_MAX);
  17   char *tmpbuf;
  18   enum nss_status status;
  19   set_function setgrent_fct;
  20   get_function getgrent_fct;
  21   end_function endgrent_fct;
  22   gid_t *groups = *groupsp;
  23
  24   getgrent_fct = __nss_lookup_function (nip, "getgrent_r");
  25   if (getgrent_fct == NULL)
  26     return NSS_STATUS_UNAVAIL;
  27
  28   setgrent_fct = __nss_lookup_function (nip, "setgrent");
  29   if (setgrent_fct)
  30     {
  31       status = DL_CALL_FCT (setgrent_fct, ());
  32       if (status != NSS_STATUS_SUCCESS)
  33         return status;
  34     }
  35
  36   endgrent_fct = __nss_lookup_function (nip, "endgrent");
  37
  38   tmpbuf = __alloca (buflen);
  39
  40   do
  41     {
  42       while ((status = DL_CALL_FCT (getgrent_fct,
  43                                      (&grpbuf, tmpbuf, buflen, errnop)),
  44               status == NSS_STATUS_TRYAGAIN)
  45              && *errnop == ERANGE)
  46         {
  47           buflen *= 2;
  48           tmpbuf = __alloca (buflen);
  49         }
  50
  51       if (status != NSS_STATUS_SUCCESS)
  52         goto done;
  53
  54       if (grpbuf.gr_gid != group)
  55         {
  56           char **m;
  57
  58           for (m = grpbuf.gr_mem; *m != NULL; ++m)
  59             if (strcmp (*m, user) == 0)
  60               {
  61                 /* Check whether the group is already on the list.  */
  62                 long int cnt;
  63                 for (cnt = 0; cnt < *start; ++cnt)
  64                   if (groups[cnt] == grpbuf.gr_gid)
  65                     break;
  66
  67                 if (cnt == *start)
  68                   {
  69                     /* Matches user and not yet on the list.  Insert
  70                        this group.  */
  71                     if (__builtin_expect (*start == *size, 0))
  72                       {
  73                         /* Need a bigger buffer.  */
  74                         gid_t *newgroups;
  75                         long int newsize;
  76
  77                         if (limit > 0 && *size == limit)
  78                           /* We reached the maximum.  */
  79                           goto done;
  80
  81                         if (limit <= 0)
  82                           newsize = 2 * *size;
  83                         else
  84                           newsize = MIN (limit, 2 * *size);
  85
  86                         newgroups = realloc (groups,
  87                                              newsize * sizeof (*groups));
  88                         if (newgroups == NULL)
  89                           goto done;
  90                         *groupsp = groups = newgroups;
  91                         *size = newsize;
  92                       }
  93
  94                     groups[*start] = grpbuf.gr_gid;
  95                     *start += 1;
  96                   }
  97
  98                 break;
  99               }
 100         }
 101     }
 102   while (status == NSS_STATUS_SUCCESS);
 103
 104  done:
 105   if (endgrent_fct)
 106     DL_CALL_FCT (endgrent_fct, ());
 107
 108   return NSS_STATUS_SUCCESS;
 109 }