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                 /* Matches user.  Insert this group.  */
  62                 if (__builtin_expect (*start == *size, 0))
  63                   {
  64                     /* Need a bigger buffer.  */
  65                     gid_t *newgroups;
  66                     long int newsize;
  67
  68                     if (limit > 0 && *size == limit)
  69                       /* We reached the maximum.  */
  70                       goto done;
  71
  72                     if (limit <= 0)
  73                       newsize = 2 * *size;
  74                     else
  75                       newsize = MIN (limit, 2 * *size);
  76
  77                     newgroups = realloc (groups, newsize * sizeof (*groups));
  78                     if (newgroups == NULL)
  79                       goto done;
  80                     *groupsp = groups = newgroups;
  81                     *size = newsize;
  82                   }
  83
  84                 groups[*start] = grpbuf.gr_gid;
  85                 *start += 1;
  86
  87                 break;
  88               }
  89         }
  90     }
  91   while (status == NSS_STATUS_SUCCESS);
  92
  93  done:
  94   if (endgrent_fct)
  95     DL_CALL_FCT (endgrent_fct, ());
  96
  97   return NSS_STATUS_SUCCESS;
  98 }