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glibc  2.9
Typedefs | Functions | Variables
initgrcache.c File Reference
#include <assert.h>
#include <errno.h>
#include <grp.h>
#include <libintl.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/mman.h>
#include "dbg_log.h"
#include "nscd.h"
#include "../nss/nsswitch.h"
#include "../grp/compat-initgroups.c"

Go to the source code of this file.

Typedefs

typedef enum nss_status(* initgroups_dyn_function )(const char *, gid_t, long int *, long int *, gid_t **, long int, int *)

Functions

static void addinitgroupsX (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid, struct hashentry *he, struct datahead *dh)
void addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid)
void readdinitgroups (struct database_dyn *db, struct hashentry *he, struct datahead *dh)

Variables

static const initgr_response_header notfound

Typedef Documentation

typedef enum nss_status(* initgroups_dyn_function)(const char *, gid_t, long int *, long int *, gid_t **, long int, int *)

Definition at line 39 of file initgrcache.c.


Function Documentation

void addinitgroups ( struct database_dyn db,
int  fd,
request_header req,
void *  key,
uid_t  uid 
)

Definition at line 423 of file initgrcache.c.

{
  addinitgroupsX (db, fd, req, key, uid, NULL, NULL);
}

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static void addinitgroupsX ( struct database_dyn db,
int  fd,
request_header req,
void *  key,
uid_t  uid,
struct hashentry he,
struct datahead dh 
) [static]

Definition at line 56 of file initgrcache.c.

{
  /* Search for the entry matching the key.  Please note that we don't
     look again in the table whether the dataset is now available.  We
     simply insert it.  It does not matter if it is in there twice.  The
     pruning function only will look at the timestamp.  */


  /* We allocate all data in one memory block: the iov vector,
     the response header and the dataset itself.  */
  struct dataset
  {
    struct datahead head;
    initgr_response_header resp;
    char strdata[0];
  } *dataset = NULL;

  if (__builtin_expect (debug_level > 0, 0))
    {
      if (he == NULL)
       dbg_log (_("Haven't found \"%s\" in group cache!"), (char *) key);
      else
       dbg_log (_("Reloading \"%s\" in group cache!"), (char *) key);
    }

  static service_user *group_database;
  service_user *nip = NULL;
  int no_more;

  if (group_database != NULL)
    {
      nip = group_database;
      no_more = 0;
    }
  else
    no_more = __nss_database_lookup ("group", NULL,
                                 "compat [NOTFOUND=return] files", &nip);

 /* We always use sysconf even if NGROUPS_MAX is defined.  That way, the
     limit can be raised in the kernel configuration without having to
     recompile libc.  */
  long int limit = __sysconf (_SC_NGROUPS_MAX);

  long int size;
  if (limit > 0)
    /* We limit the size of the intially allocated array.  */
    size = MIN (limit, 64);
  else
    /* No fixed limit on groups.  Pick a starting buffer size.  */
    size = 16;

  long int start = 0;
  bool all_tryagain = true;
  bool any_success = false;

  /* This is temporary memory, we need not (and must not) call
     mempool_alloc.  */
  // XXX This really should use alloca.  need to change the backends.
  gid_t *groups = (gid_t *) malloc (size * sizeof (gid_t));
  if (__builtin_expect (groups == NULL, 0))
    /* No more memory.  */
    goto out;

  /* Nothing added yet.  */
  while (! no_more)
    {
      long int prev_start = start;
      enum nss_status status;
      initgroups_dyn_function fct;
      fct = __nss_lookup_function (nip, "initgroups_dyn");

      if (fct == NULL)
       {
         status = compat_call (nip, key, -1, &start, &size, &groups,
                            limit, &errno);

         if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
           break;
       }
      else
       status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups,
                                limit, &errno));

      /* Remove duplicates.  */
      long int cnt = prev_start;
      while (cnt < start)
       {
         long int inner;
         for (inner = 0; inner < prev_start; ++inner)
           if (groups[inner] == groups[cnt])
             break;

         if (inner < prev_start)
           groups[cnt] = groups[--start];
         else
           ++cnt;
       }

      if (status != NSS_STATUS_TRYAGAIN)
       all_tryagain = false;

      /* This is really only for debugging.  */
      if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
       __libc_fatal ("illegal status in internal_getgrouplist");

      any_success |= status == NSS_STATUS_SUCCESS;

      if (status != NSS_STATUS_SUCCESS
         && nss_next_action (nip, status) == NSS_ACTION_RETURN)
        break;

      if (nip->next == NULL)
       no_more = -1;
      else
       nip = nip->next;
    }

  ssize_t total;
  ssize_t written;
 out:
  if (!any_success)
    {
      /* Nothing found.  Create a negative result record.  */
      written = total = sizeof (notfound);

      if (he != NULL && all_tryagain)
       {
         /* If we have an old record available but cannot find one now
            because the service is not available we keep the old record
            and make sure it does not get removed.  */
         if (reload_count != UINT_MAX && dh->nreloads == reload_count)
           /* Do not reset the value if we never not reload the record.  */
           dh->nreloads = reload_count - 1;
       }
      else
       {
         /* We have no data.  This means we send the standard reply for this
            case.  */
         if (fd != -1)
           written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
                                          MSG_NOSIGNAL));

         dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len,
                               IDX_result_data);
         /* If we cannot permanently store the result, so be it.  */
         if (dataset != NULL)
           {
             dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
             dataset->head.recsize = total;
             dataset->head.notfound = true;
             dataset->head.nreloads = 0;
             dataset->head.usable = true;

             /* Compute the timeout time.  */
             dataset->head.timeout = time (NULL) + db->negtimeout;

             /* This is the reply.  */
             memcpy (&dataset->resp, &notfound, total);

             /* Copy the key data.  */
             char *key_copy = memcpy (dataset->strdata, key, req->key_len);

             /* If necessary, we also propagate the data to disk.  */
             if (db->persistent)
              {
                // XXX async OK?
                uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
                msync ((void *) pval,
                      ((uintptr_t) dataset & pagesize_m1)
                      + sizeof (struct dataset) + req->key_len, MS_ASYNC);
              }

             /* Now get the lock to safely insert the records.  */
             pthread_rwlock_rdlock (&db->lock);

             (void) cache_add (req->type, key_copy, req->key_len,
                            &dataset->head, true, db, uid, he == NULL);

             pthread_rwlock_unlock (&db->lock);

             /* Mark the old entry as obsolete.  */
             if (dh != NULL)
              dh->usable = false;
           }
         else
           ++db->head->addfailed;
       }
    }
  else
    {

      written = total = (offsetof (struct dataset, strdata)
                      + start * sizeof (int32_t));

      /* If we refill the cache, first assume the reconrd did not
        change.  Allocate memory on the cache since it is likely
        discarded anyway.  If it turns out to be necessary to have a
        new record we can still allocate real memory.  */
      bool alloca_used = false;
      dataset = NULL;

      if (he == NULL)
       {
         dataset = (struct dataset *) mempool_alloc (db,
                                                total + req->key_len,
                                                IDX_result_data);
         if (dataset == NULL)
           ++db->head->addfailed;
       }

      if (dataset == NULL)
       {
         /* We cannot permanently add the result in the moment.  But
            we can provide the result as is.  Store the data in some
            temporary memory.  */
         dataset = (struct dataset *) alloca (total + req->key_len);

         /* We cannot add this record to the permanent database.  */
         alloca_used = true;
       }

      dataset->head.allocsize = total + req->key_len;
      dataset->head.recsize = total - offsetof (struct dataset, resp);
      dataset->head.notfound = false;
      dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
      dataset->head.usable = true;

      /* Compute the timeout time.  */
      dataset->head.timeout = time (NULL) + db->postimeout;

      dataset->resp.version = NSCD_VERSION;
      dataset->resp.found = 1;
      dataset->resp.ngrps = start;

      char *cp = dataset->strdata;

      /* Copy the GID values.  If the size of the types match this is
        very simple.  */
      if (sizeof (gid_t) == sizeof (int32_t))
       cp = mempcpy (cp, groups, start * sizeof (gid_t));
      else
       {
         gid_t *gcp = (gid_t *) cp;

         for (int i = 0; i < start; ++i)
           *gcp++ = groups[i];

         cp = (char *) gcp;
       }

      /* Finally the user name.  */
      memcpy (cp, key, req->key_len);

      assert (cp == dataset->strdata + total - offsetof (struct dataset,
                                                  strdata));

      /* Now we can determine whether on refill we have to create a new
        record or not.  */
      if (he != NULL)
       {
         assert (fd == -1);

         if (total + req->key_len == dh->allocsize
             && total - offsetof (struct dataset, resp) == dh->recsize
             && memcmp (&dataset->resp, dh->data,
                      dh->allocsize - offsetof (struct dataset, resp)) == 0)
           {
             /* The data has not changed.  We will just bump the
               timeout value.  Note that the new record has been
               allocated on the stack and need not be freed.  */
             dh->timeout = dataset->head.timeout;
             ++dh->nreloads;
           }
         else
           {
             /* We have to create a new record.  Just allocate
               appropriate memory and copy it.  */
             struct dataset *newp
              = (struct dataset *) mempool_alloc (db, total + req->key_len,
                                              IDX_result_data);
             if (newp != NULL)
              {
                /* Adjust pointer into the memory block.  */
                cp = (char *) newp + (cp - (char *) dataset);

                dataset = memcpy (newp, dataset, total + req->key_len);
                alloca_used = false;
              }
             else
              ++db->head->addfailed;

             /* Mark the old record as obsolete.  */
             dh->usable = false;
           }
       }
      else
       {
         /* We write the dataset before inserting it to the database
            since while inserting this thread might block and so would
            unnecessarily let the receiver wait.  */
         assert (fd != -1);

#ifdef HAVE_SENDFILE
         if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
           {
             assert (db->wr_fd != -1);
             assert ((char *) &dataset->resp > (char *) db->data);
             assert ((char *) &dataset->resp - (char *) db->head
                    + total
                    <= (sizeof (struct database_pers_head)
                       + db->head->module * sizeof (ref_t)
                       + db->head->data_size));
             written = sendfileall (fd, db->wr_fd,
                                 (char *) &dataset->resp
                                 - (char *) db->head, total);
# ifndef __ASSUME_SENDFILE
             if (written == -1 && errno == ENOSYS)
              goto use_write;
# endif
           }
         else
# ifndef __ASSUME_SENDFILE
         use_write:
# endif
#endif
           written = writeall (fd, &dataset->resp, total);
       }


      /* Add the record to the database.  But only if it has not been
        stored on the stack.  */
      if (! alloca_used)
       {
         /* If necessary, we also propagate the data to disk.  */
         if (db->persistent)
           {
             // XXX async OK?
             uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
             msync ((void *) pval,
                   ((uintptr_t) dataset & pagesize_m1) + total +
                   req->key_len, MS_ASYNC);
           }

         /* Now get the lock to safely insert the records.  */
         pthread_rwlock_rdlock (&db->lock);

         (void) cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true,
                         db, uid, he == NULL);

         pthread_rwlock_unlock (&db->lock);
       }
    }

  free (groups);

  if (__builtin_expect (written != total, 0) && debug_level > 0)
    {
      char buf[256];
      dbg_log (_("short write in %s: %s"), __FUNCTION__,
              strerror_r (errno, buf, sizeof (buf)));
    }
}

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void readdinitgroups ( struct database_dyn db,
struct hashentry he,
struct datahead dh 
)

Definition at line 431 of file initgrcache.c.

{
  request_header req =
    {
      .type = INITGROUPS,
      .key_len = he->len
    };

  addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh);
}

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Variable Documentation

Initial value:
{
  .version = NSCD_VERSION,
  .found = 0,
  .ngrps = 0
}

Definition at line 44 of file initgrcache.c.