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glibc  2.9
Functions | Variables
servicescache.c File Reference
#include <alloca.h>
#include <assert.h>
#include <errno.h>
#include <libintl.h>
#include <netdb.h>
#include <unistd.h>
#include <sys/mman.h>
#include <kernel-features.h>
#include "nscd.h"
#include "dbg_log.h"

Go to the source code of this file.

Functions

static void cache_addserv (struct database_dyn *db, int fd, request_header *req, const void *key, struct servent *serv, uid_t owner, struct hashentry *he, struct datahead *dh, int errval)
static int lookup (int type, char *key, struct servent *resultbufp, char *buffer, size_t buflen, struct servent **serv)
static void addservbyX (struct database_dyn *db, int fd, request_header *req, char *key, uid_t uid, struct hashentry *he, struct datahead *dh)
void addservbyname (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid)
void readdservbyname (struct database_dyn *db, struct hashentry *he, struct datahead *dh)
void addservbyport (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid)
void readdservbyport (struct database_dyn *db, struct hashentry *he, struct datahead *dh)

Variables

static const serv_response_header disabled
static const serv_response_header notfound

Function Documentation

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

Definition at line 435 of file servicescache.c.

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

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

Definition at line 457 of file servicescache.c.

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

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

Definition at line 373 of file servicescache.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 servent resultbuf;
  struct servent *serv;
  bool use_malloc = false;
  int errval = 0;

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

  while (lookup (req->type, key, &resultbuf, buffer, buflen, &serv) != 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.  */
             serv = 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_addserv (db, fd, req, key, serv, uid, he, dh, errval);

  if (use_malloc)
    free (buffer);
}

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

Definition at line 65 of file servicescache.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;
    serv_response_header resp;
    char strdata[0];
  } *dataset;

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

  if (serv == 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 s_name_len = strlen (serv->s_name) + 1;
      size_t s_proto_len = strlen (serv->s_proto) + 1;
      uint32_t *s_aliases_len;
      size_t s_aliases_cnt;
      char *aliases;
      char *cp;
      size_t cnt;

      /* Determine the number of aliases.  */
      s_aliases_cnt = 0;
      for (cnt = 0; serv->s_aliases[cnt] != NULL; ++cnt)
       ++s_aliases_cnt;
      /* Determine the length of all aliases.  */
      s_aliases_len = (uint32_t *) alloca (s_aliases_cnt * sizeof (uint32_t));
      total = 0;
      for (cnt = 0; cnt < s_aliases_cnt; ++cnt)
       {
         s_aliases_len[cnt] = strlen (serv->s_aliases[cnt]) + 1;
         total += s_aliases_len[cnt];
       }

      total += (offsetof (struct dataset, strdata)
              + s_name_len
              + s_proto_len
              + s_aliases_cnt * sizeof (uint32_t));
      written = 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 + 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 = t + db->postimeout;

      dataset->resp.version = NSCD_VERSION;
      dataset->resp.found = 1;
      dataset->resp.s_name_len = s_name_len;
      dataset->resp.s_proto_len = s_proto_len;
      dataset->resp.s_port = serv->s_port;
      dataset->resp.s_aliases_cnt = s_aliases_cnt;

      cp = dataset->strdata;

      cp = mempcpy (cp, serv->s_name, s_name_len);
      cp = mempcpy (cp, serv->s_proto, s_proto_len);
      cp = mempcpy (cp, s_aliases_len, s_aliases_cnt * sizeof (uint32_t));

      /* Then the aliases.  */
      aliases = cp;
      for (cnt = 0; cnt < s_aliases_cnt; ++cnt)
       cp = mempcpy (cp, serv->s_aliases[cnt], s_aliases_len[cnt]);

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

      char *key_copy = memcpy (cp, key, req->key_len);

      /* 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 pointers into the memory block.  */
                aliases = (char *) newp + (aliases - (char *) dataset);
                assert (key_copy != NULL);
                key_copy = (char *) newp + (key_copy - (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 keep the receiver waiting.  */
         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 (req->type, key_copy, req->key_len,
                         &dataset->head, true, db, owner, he == NULL);

         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,
char *  key,
struct servent resultbufp,
char *  buffer,
size_t  buflen,
struct servent **  serv 
) [static]

Definition at line 350 of file servicescache.c.

{
  char *proto = strrchr (key, '/');
  if (proto != NULL && proto != key)
    {
      key = strndupa (key, proto - key);
      if (proto[1] == '\0')
       proto = NULL;
      else
       ++proto;
    }

  if (type == GETSERVBYNAME)
    return __getservbyname_r (key, proto, resultbufp, buffer, buflen, serv);

  assert (type == GETSERVBYPORT);
  return __getservbyport_r (atol (key), proto, resultbufp, buffer, buflen,
                         serv);
}

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

Definition at line 443 of file servicescache.c.

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

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

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

Definition at line 465 of file servicescache.c.

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

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

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Variable Documentation

Initial value:
{
  .version = NSCD_VERSION,
  .found = -1,
  .s_name_len = 0,
  .s_proto_len = 0,
  .s_aliases_cnt = 0,
  .s_port = -1
}

Definition at line 34 of file servicescache.c.

Initial value:
{
  .version = NSCD_VERSION,
  .found = 0,
  .s_name_len = 0,
  .s_proto_len = 0,
  .s_aliases_cnt = 0,
  .s_port = -1
}

Definition at line 53 of file servicescache.c.