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glibc  2.9
Classes | Functions | Variables
grpcache.c File Reference
#include <alloca.h>
#include <assert.h>
#include <errno.h>
#include <error.h>
#include <grp.h>
#include <libintl.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <stackinfo.h>
#include "nscd.h"
#include "dbg_log.h"

Go to the source code of this file.

Classes

union  keytype

Functions

static void cache_addgr (struct database_dyn *db, int fd, request_header *req, const void *key, struct group *grp, uid_t owner, struct hashentry *he, struct datahead *dh, int errval)
static int lookup (int type, union keytype key, struct group *resultbufp, char *buffer, size_t buflen, struct group **grp)
static void addgrbyX (struct database_dyn *db, int fd, request_header *req, union keytype key, const char *keystr, uid_t uid, struct hashentry *he, struct datahead *dh)
void addgrbyname (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid)
void readdgrbyname (struct database_dyn *db, struct hashentry *he, struct datahead *dh)
void addgrbygid (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid)
void readdgrbygid (struct database_dyn *db, struct hashentry *he, struct datahead *dh)

Variables

static const gr_response_header disabled
static const gr_response_header notfound

Class Documentation

union keytype

Definition at line 401 of file grpcache.c.

Class Members
gid_t g
uid_t u
void * v

Function Documentation

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

Definition at line 508 of file grpcache.c.

{
  char *ep;
  gid_t gid = strtoul ((char *) key, &ep, 10);

  if (*(char *) key == '\0' || *ep != '\0')  /* invalid numeric uid */
    {
      if (debug_level > 0)
        dbg_log (_("Invalid numeric gid \"%s\"!"), (char *) key);

      errno = EINVAL;
      return;
    }

  union keytype u = { .g = gid };

  addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
}

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

Definition at line 483 of file grpcache.c.

{
  union keytype u = { .v = key };

  addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
}

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static void addgrbyX ( struct database_dyn db,
int  fd,
request_header req,
union keytype  key,
const char *  keystr,
uid_t  uid,
struct hashentry he,
struct datahead dh 
) [static]

Definition at line 420 of file grpcache.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.  */
  size_t buflen = 1024;
  char *buffer = (char *) alloca (buflen);
  struct group resultbuf;
  struct group *grp;
  bool use_malloc = false;
  int errval = 0;

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

  while (lookup (req->type, key, &resultbuf, buffer, buflen, &grp) != 0
        && (errval = errno) == ERANGE)
    {
      errno = 0;

      if (__builtin_expect (buflen > 32768, 0))
       {
         char *old_buffer = buffer;
         buflen *= 2;
         buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
         if (buffer == NULL)
           {
             /* We ran out of memory.  We cannot do anything but
               sending a negative response.  In reality this should
               never happen.  */
             grp = NULL;
             buffer = old_buffer;

             /* We set the error to indicate this is (possibly) a
               temporary error and that it does not mean the entry
               is not available at all.  */
             errval = EAGAIN;
             break;
           }
         use_malloc = true;
       }
      else
       /* Allocate a new buffer on the stack.  If possible combine it
          with the previously allocated buffer.  */
       buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
    }

  cache_addgr (db, fd, req, keystr, grp, uid, he, dh, errval);

  if (use_malloc)
    free (buffer);
}

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static void cache_addgr ( struct database_dyn db,
int  fd,
request_header req,
const void *  key,
struct group grp,
uid_t  owner,
struct hashentry he,
struct datahead dh,
int  errval 
) [static]

Definition at line 75 of file grpcache.c.

{
  ssize_t total;
  ssize_t written;
  time_t t = time (NULL);

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

  assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data));

  if (grp == NULL)
    {
      if (he != NULL && errval == EAGAIN)
       {
         /* 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)
           /* Do not reset the value if we never not reload the record.  */
           dh->nreloads = reload_count - 1;

         written = total = 0;
       }
      else
       {
         /* We have no data.  This means we send the standard reply for this
            case.  */
         total = sizeof (notfound);

         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 = t + db->negtimeout;

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

             /* Copy the key data.  */
             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, &dataset->strdata, req->key_len,
                            &dataset->head, true, db, owner, he == NULL);

             pthread_rwlock_unlock (&db->lock);

             /* Mark the old entry as obsolete.  */
             if (dh != NULL)
              dh->usable = false;
           }
         else
           ++db->head->addfailed;
       }
    }
  else
    {
      /* Determine the I/O structure.  */
      size_t gr_name_len = strlen (grp->gr_name) + 1;
      size_t gr_passwd_len = strlen (grp->gr_passwd) + 1;
      size_t gr_mem_cnt = 0;
      uint32_t *gr_mem_len;
      size_t gr_mem_len_total = 0;
      char *gr_name;
      char *cp;
      const size_t key_len = strlen (key);
      const size_t buf_len = 3 * sizeof (grp->gr_gid) + key_len + 1;
      char *buf = alloca (buf_len);
      ssize_t n;
      size_t cnt;

      /* We need this to insert the `bygid' entry.  */
      int key_offset;
      n = snprintf (buf, buf_len, "%d%c%n%s", grp->gr_gid, '\0',
                  &key_offset, (char *) key) + 1;

      /* Determine the length of all members.  */
      while (grp->gr_mem[gr_mem_cnt])
       ++gr_mem_cnt;
      gr_mem_len = (uint32_t *) alloca (gr_mem_cnt * sizeof (uint32_t));
      for (gr_mem_cnt = 0; grp->gr_mem[gr_mem_cnt]; ++gr_mem_cnt)
       {
         gr_mem_len[gr_mem_cnt] = strlen (grp->gr_mem[gr_mem_cnt]) + 1;
         gr_mem_len_total += gr_mem_len[gr_mem_cnt];
       }

      written = total = (offsetof (struct dataset, strdata)
                      + gr_mem_cnt * sizeof (uint32_t)
                      + gr_name_len + gr_passwd_len + gr_mem_len_total);

      /* 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 + n,
                                                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 + n);

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

      dataset->head.allocsize = total + n;
      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 = t + db->postimeout;

      dataset->resp.version = NSCD_VERSION;
      dataset->resp.found = 1;
      dataset->resp.gr_name_len = gr_name_len;
      dataset->resp.gr_passwd_len = gr_passwd_len;
      dataset->resp.gr_gid = grp->gr_gid;
      dataset->resp.gr_mem_cnt = gr_mem_cnt;

      cp = dataset->strdata;

      /* This is the member string length array.  */
      cp = mempcpy (cp, gr_mem_len, gr_mem_cnt * sizeof (uint32_t));
      gr_name = cp;
      cp = mempcpy (cp, grp->gr_name, gr_name_len);
      cp = mempcpy (cp, grp->gr_passwd, gr_passwd_len);

      for (cnt = 0; cnt < gr_mem_cnt; ++cnt)
       cp = mempcpy (cp, grp->gr_mem[cnt], gr_mem_len[cnt]);

      /* Finally the stringified GID value.  */
      memcpy (cp, buf, n);
      char *key_copy = cp + key_offset;
      assert (key_copy == (char *) rawmemchr (cp, '\0') + 1);

      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 + n == 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 + n,
                                              IDX_result_data);
             if (newp != NULL)
              {
                /* Adjust pointers into the memory block.  */
                gr_name = (char *) newp + (gr_name - (char *) dataset);
                cp = (char *) newp + (cp - (char *) dataset);
                key_copy = (char *) newp + (key_copy - (char *) dataset);

                dataset = memcpy (newp, dataset, total + n);
                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 + n,
                   MS_ASYNC);
           }

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

         /* NB: in the following code we always must add the entry
            marked with FIRST first.  Otherwise we end up with
            dangling "pointers" in case a latter hash entry cannot be
            added.  */
         bool first = true;

         /* If the request was by GID, add that entry first.  */
         if (req->type == GETGRBYGID)
           {
             if (cache_add (GETGRBYGID, cp, key_offset, &dataset->head, true,
                          db, owner, he == NULL) < 0)
              goto out;

             first = false;
           }
         /* If the key is different from the name add a separate entry.  */
         else if (strcmp (key_copy, gr_name) != 0)
           {
             if (cache_add (GETGRBYNAME, key_copy, key_len + 1,
                          &dataset->head, true, db, owner, he == NULL) < 0)
              goto out;

             first = false;
           }

         /* We have to add the value for both, byname and byuid.  */
         if ((req->type == GETGRBYNAME || db->propagate)
             && __builtin_expect (cache_add (GETGRBYNAME, gr_name,
                                         gr_name_len,
                                         &dataset->head, first, db, owner,
                                         he == NULL)
                               == 0, 1))
           {
             if (req->type == GETGRBYNAME && db->propagate)
              (void) cache_add (GETGRBYGID, cp, key_offset, &dataset->head,
                              false, db, owner, false);
           }

       out:
         pthread_rwlock_unlock (&db->lock);
       }
    }

  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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static int lookup ( int  type,
union keytype  key,
struct group resultbufp,
char *  buffer,
size_t  buflen,
struct group **  grp 
) [static]

Definition at line 409 of file grpcache.c.

{
  if (type == GETGRBYNAME)
    return __getgrnam_r (key.v, resultbufp, buffer, buflen, grp);
  else
    return __getgrgid_r (key.g, resultbufp, buffer, buflen, grp);
}

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

Definition at line 530 of file grpcache.c.

{
  char *ep;
  gid_t gid = strtoul (db->data + he->key, &ep, 10);

  /* Since the key has been added before it must be OK.  */
  assert (*(db->data + he->key) != '\0' && *ep == '\0');

  request_header req =
    {
      .type = GETGRBYGID,
      .key_len = he->len
    };
  union keytype u = { .g = gid };

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

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

Definition at line 493 of file grpcache.c.

{
  request_header req =
    {
      .type = GETGRBYNAME,
      .key_len = he->len
    };
  union keytype u = { .v = db->data + he->key };

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

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Variable Documentation

Initial value:
{
  .version = NSCD_VERSION,
  .found = -1,
  .gr_name_len = 0,
  .gr_passwd_len = 0,
  .gr_gid = -1,
  .gr_mem_cnt = 0,
}

Definition at line 44 of file grpcache.c.

Initial value:
{
  .version = NSCD_VERSION,
  .found = 0,
  .gr_name_len = 0,
  .gr_passwd_len = 0,
  .gr_gid = -1,
  .gr_mem_cnt = 0,
}

Definition at line 63 of file grpcache.c.