Back to index

glibc  2.9
Functions
nscd_initgroups.c File Reference
#include <assert.h>
#include <errno.h>
#include <grp.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <not-cancel.h>
#include "nscd-client.h"
#include "nscd_proto.h"

Go to the source code of this file.

Functions

 libc_locked_map_ptr (extern, __gr_map_handle)

Function Documentation

libc_locked_map_ptr ( extern  ,
__gr_map_handle   
)

Definition at line 33 of file nscd_initgroups.c.

{
  size_t userlen = strlen (user) + 1;
  int gc_cycle;
  int nretries = 0;

  /* If the mapping is available, try to search there instead of
     communicating with the nscd.  */
  struct mapped_database *mapped;
  mapped = __nscd_get_map_ref (GETFDGR, "group", &__gr_map_handle, &gc_cycle);

 retry:;
  char *respdata = NULL;
  int retval = -1;
  int sock = -1;
  initgr_response_header initgr_resp;

  if (mapped != NO_MAPPING)
    {
      struct datahead *found = __nscd_cache_search (INITGROUPS, user,
                                              userlen, mapped);
      if (found != NULL)
       {
         respdata = (char *) (&found->data[0].initgrdata + 1);
         initgr_resp = found->data[0].initgrdata;
         char *recend = (char *) found->data + found->recsize;

         /* Now check if we can trust initgr_resp fields.  If GC is
            in progress, it can contain anything.  */
         if (mapped->head->gc_cycle != gc_cycle)
           {
             retval = -2;
             goto out;
           }

         if (respdata + initgr_resp.ngrps * sizeof (int32_t) > recend)
           goto out;
       }
    }

  /* If we do not have the cache mapped, try to get the data over the
     socket.  */
  if (respdata == NULL)
    {
      sock = __nscd_open_socket (user, userlen, INITGROUPS, &initgr_resp,
                             sizeof (initgr_resp));
      if (sock == -1)
       {
         /* nscd not running or wrong version.  */
         __nss_not_use_nscd_group = 1;
         goto out;
       }
    }

  if (initgr_resp.found == 1)
    {
      /* The following code assumes that gid_t and int32_t are the
        same size.  This is the case for al existing implementation.
        If this should change some code needs to be added which
        doesn't use memcpy but instead copies each array element one
        by one.  */
      assert (sizeof (int32_t) == sizeof (gid_t));
      assert (initgr_resp.ngrps >= 0);

      /* Make sure we have enough room.  We always count GROUP in even
        though we might not end up adding it.  */
      if (*size < initgr_resp.ngrps + 1)
       {
         gid_t *newp = realloc (*groupsp,
                             (initgr_resp.ngrps + 1) * sizeof (gid_t));
         if (newp == NULL)
           /* We cannot increase the buffer size.  */
           goto out_close;

         *groupsp = newp;
         *size = initgr_resp.ngrps + 1;
       }

      if (respdata == NULL)
       {
         /* Read the data from the socket.  */
         if ((size_t) __readall (sock, *groupsp, initgr_resp.ngrps
                                            * sizeof (gid_t))
             == initgr_resp.ngrps * sizeof (gid_t))
           retval = initgr_resp.ngrps;
       }
      else
       {
         /* Just copy the data.  */
         retval = initgr_resp.ngrps;
         memcpy (*groupsp, respdata, retval * sizeof (gid_t));
       }
    }
  else
    {
      if (__builtin_expect (initgr_resp.found == -1, 0))
       {
         /* The daemon does not cache this database.  */
         __nss_not_use_nscd_group = 1;
         goto out_close;
       }

      /* No group found yet.   */
      retval = 0;

      assert (*size >= 1);
    }

  /* Check whether GROUP is part of the mix.  If not, add it.  */
  if (retval >= 0)
    {
      int cnt;
      for (cnt = 0; cnt < retval; ++cnt)
       if ((*groupsp)[cnt] == group)
         break;

      if (cnt == retval)
       (*groupsp)[retval++] = group;
    }

 out_close:
  if (sock != -1)
    close_not_cancel_no_status (sock);
 out:
  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
    {
      /* When we come here this means there has been a GC cycle while we
        were looking for the data.  This means the data might have been
        inconsistent.  Retry if possible.  */
      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
       {
         /* nscd is just running gc now.  Disable using the mapping.  */
         if (atomic_decrement_val (&mapped->counter) == 0)
           __nscd_unmap (mapped);
         mapped = NO_MAPPING;
       }

      if (retval != -1)
       goto retry;
    }

  return retval;
}

Here is the call graph for this function: