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
  12 static enum nss_status
  13 compat_call (nss_action_list nip, const char *user, gid_t group, long int *start,
  14              long int *size, gid_t **groupsp, long int limit, int *errnop)
  15 {
  16   struct group grpbuf;
  17   enum nss_status status;
  18   set_function setgrent_fct;
  19   get_function getgrent_fct;
  20   end_function endgrent_fct;
  21   gid_t *groups = *groupsp;
  22
  23   getgrent_fct = __nss_lookup_function (nip, "getgrent_r");
  24   if (getgrent_fct == NULL)
  25     return NSS_STATUS_UNAVAIL;
  26
  27   setgrent_fct = __nss_lookup_function (nip, "setgrent");
  28   if (setgrent_fct)
  29     {
  30       status = DL_CALL_FCT (setgrent_fct, ());
  31       if (status != NSS_STATUS_SUCCESS)
  32         return status;
  33     }
  34
  35   endgrent_fct = __nss_lookup_function (nip, "endgrent");
  36
  37   struct scratch_buffer tmpbuf;
  38   scratch_buffer_init (&tmpbuf);
  39   enum nss_status result = NSS_STATUS_SUCCESS;
  40
  41   do
  42     {
  43       while ((status = DL_CALL_FCT (getgrent_fct,
  44                                      (&grpbuf, tmpbuf.data, tmpbuf.length,
  45                                       errnop)),
  46               status == NSS_STATUS_TRYAGAIN)
  47              && *errnop == ERANGE)
  48         {
  49           if (!scratch_buffer_grow (&tmpbuf))
  50             {
  51               result = NSS_STATUS_TRYAGAIN;
  52               goto done;
  53             }
  54         }
  55
  56       if (status != NSS_STATUS_SUCCESS)
  57         goto done;
  58
  59       if (grpbuf.gr_gid != group)
  60         {
  61           char **m;
  62
  63           for (m = grpbuf.gr_mem; *m != NULL; ++m)
  64             if (strcmp (*m, user) == 0)
  65               {
  66                 /* Check whether the group is already on the list.  */
  67                 long int cnt;
  68                 for (cnt = 0; cnt < *start; ++cnt)
  69                   if (groups[cnt] == grpbuf.gr_gid)
  70                     break;
  71
  72                 if (cnt == *start)
  73                   {
  74                     /* Matches user and not yet on the list.  Insert
  75                        this group.  */
  76                     if (__glibc_unlikely (*start == *size))
  77                       {
  78                         /* Need a bigger buffer.  */
  79                         gid_t *newgroups;
  80                         long int newsize;
  81
  82                         if (limit > 0 && *size == limit)
  83                           /* We reached the maximum.  */
  84                           goto done;
  85
  86                         if (limit <= 0)
  87                           newsize = 2 * *size;
  88                         else
  89                           newsize = MIN (limit, 2 * *size);
  90
  91                         newgroups = realloc (groups,
  92                                              newsize * sizeof (*groups));
  93                         if (newgroups == NULL)
  94                           goto done;
  95                         *groupsp = groups = newgroups;
  96                         *size = newsize;
  97                       }
  98
  99                     groups[*start] = grpbuf.gr_gid;
 100                     *start += 1;
 101                   }
 102
 103                 break;
 104               }
 105         }
 106     }
 107   while (status == NSS_STATUS_SUCCESS);
 108
 109  done:
 110   scratch_buffer_free (&tmpbuf);
 111
 112   if (endgrent_fct)
 113     DL_CALL_FCT (endgrent_fct, ());
 114
 115   return result;
 116 }