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/* GNU Mailutils -- a suite of utilities for electronic mail
   Copyright (C) 1999, 2000, 2001, 2002, 2005, 2006,
   2007 Free Software Foundation, Inc.

   GNU Mailutils is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   GNU Mailutils is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Mailutils; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301 USA */

#define MF_SOURCE_NAME  MF_SOURCE_MU_DBM

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <errno.h>
#include <mailutils/error.h>
#include <mailutils/errno.h>
#include <mailfromd.h>

#ifndef MU_ERR_EXISTS
# define MU_ERR_EXISTS EEXIST
#endif

int
mu_fcheck_perm (int fd, int mode)
{
  struct stat st;

  if (fstat (fd, &st) == -1)
    {
      if (errno == ENOENT)
	return ENOENT;
      else
	return MU_ERR_FAILURE;
    }
  if ((st.st_mode & 0777) != mode)
    return errno = MU_ERR_UNSAFE_PERMS;
  return 0;
}

int
mu_check_perm (const char *name, int mode)
{
  struct stat st;

  if (mode == 0)
    return 0;
  if (stat (name, &st) == -1)
    {
      if (errno == ENOENT)
	return ENOENT;
      else
	return MU_ERR_FAILURE;
    }
  if ((st.st_mode & 0777) != mode)
    return errno = MU_ERR_UNSAFE_PERMS;

  return 0;
}

#if defined(WITH_GDBM)

int
mu_dbm_open (char *name, DBM_FILE *db, int flags, int mode, int *ro)
{
  int rc;
  int f;
  size_t i;
  GDBM_FILE gdbm;
  
  if (mu_check_perm (name, mode))
    return MU_ERR_UNSAFE_PERMS;

  if (ro)
    *ro = 0;
  
  switch (flags)
    {
    case MU_STREAM_CREAT:
      f = GDBM_NEWDB;
      break;
      
    case MU_STREAM_READ:
      f = GDBM_READER;
      break;
      
    case MU_STREAM_RDWR:
      f = GDBM_WRCREAT;
      break;
      
    default:
      errno = EINVAL;
      return 1;
    }
  
  for (i = 0; i < lock_retry_count_option; i++)
    {
      gdbm = gdbm_open (name, 512, f, mode, NULL);
      if (gdbm || errno != EAGAIN)
	break;
      sleep (lock_retry_timeout_option);
    }

  if (!gdbm)
    {
      if (ro)
	{
	  gdbm = gdbm_open (name, 512, GDBM_READER, mode, NULL);
	  if (gdbm)
	    *ro = 1;
	}
    }
  
  rc = (gdbm == NULL) ? MU_ERR_FAILURE : 0;
  
  if (rc == 0)
    {
      db->db = gdbm;
      db->name = strdup (name);
    }
  
  return rc;
}

int
mu_dbm_close (DBM_FILE *db)
{
  gdbm_close(db->db);
  free (db->name);
  return 0;
}

int
mu_dbm_fetch (DBM_FILE *db, DBM_DATUM key, DBM_DATUM *ret)
{
  *ret = gdbm_fetch(db->db, key);
  if (ret->dptr == NULL)
    return MU_ERR_NOENT;
  return 0;
}

int
mu_dbm_delete (DBM_FILE *db, DBM_DATUM key)
{
  return gdbm_delete (db->db, key) ? MU_ERR_FAILURE : 0;
}

int
mu_dbm_insert (DBM_FILE *db, DBM_DATUM key, DBM_DATUM contents, int replace)
{
  switch (gdbm_store(db->db, key, contents,
		     replace ? GDBM_REPLACE : GDBM_INSERT))
    {
    case -1:
      return MU_ERR_FAILURE;

    case 0:
      return 0;

    case 1:
      return MU_ERR_EXISTS;
    }
  return MU_ERR_FAILURE;
}

int
mu_dbm_firstkey (DBM_FILE *db, DBM_DATUM *pkey)
{
  *pkey = gdbm_firstkey (db->db);
  return (pkey->dptr == NULL) ? MU_ERR_FAILURE : 0; 
}

int
mu_dbm_nextkey (DBM_FILE *db, DBM_DATUM prevkey, DBM_DATUM *pkey)
{
  *pkey = gdbm_nextkey (db->db, prevkey);
  return (pkey->dptr == NULL) ? MU_ERR_FAILURE : 0; 
}

void
mu_dbm_datum_free (DBM_DATUM *datum)
{
  void *ptr = MU_DATUM_PTR (*datum);
  if (ptr)
    free (ptr);
  MU_DATUM_PTR (*datum) = 0;
}

const char *
mu_dbm_strerror ()
{
  if (errno == MU_ERR_UNSAFE_PERMS)
    return mu_strerror (errno);
  return gdbm_strerror (gdbm_errno);
}

#elif defined(WITH_BDB)

int mu_dbm_errno;

static int
try_lock (int fd, int type, struct flock *fl)
{
  int i, rc;

  for (i = 0; i < lock_retry_count_option; i++)
    {
      alarm (lock_retry_timeout_option);
      rc = fcntl (fd, F_SETLKW, fl);
      alarm (0);
      if (rc == 0)
	return 0;
    }
  return errno;
}

static int
lock_file (const char *name, int fd, int type)
{
  int rc = 0;
  struct flock fl;

  if (type == F_UNLCK)
    debug1(10, "unlocking %s", name);
  else
    debug2(10, "locking %s for %s",
	   name,
	   (type == F_RDLCK) ? "reading" : "writing");
	 
  memset (&fl, 0, sizeof fl);
  fl.l_whence = SEEK_SET;
  fl.l_type = type;

  rc = try_lock (fd, type, &fl);
  if (rc)
    {
      fl.l_pid = 0;
      if (fcntl (fd, F_GETLK, &fl) != -1)
	{
	  if (fl.l_type == F_UNLCK)
	    {
	      memset (&fl, 0, sizeof fl);
	      fl.l_whence = SEEK_SET;
	      fl.l_type = type;
	      rc = try_lock (fd, type, &fl);
	      if (rc)
		mu_error (_("%s: cannot aquire lock: %s"),
			  name, mu_strerror (rc));
	    }      
	  else if (fl.l_pid)
	    {
	      if (kill (fl.l_pid, 0) == 0)
		mu_error (_("%s is locked (%d) by process ID %lu"), 
			  name,
			  fl.l_type, 
			  (unsigned long) fl.l_pid);
	      else if (errno == ESRCH)
		{
		  mu_error (_("%s is locked by nonexisting process ID %lu; "
			    "retrying"),
			    name, (unsigned long) fl.l_pid);
		  if (unlink (name))
		    mu_error (_("Cannot unlink file %s: %s"),
			      name, mu_strerror (errno));  
		  else
		    {
		      rc = try_lock (fd, type, &fl);
		      if (rc)
			mu_error (_("%s: cannot aquire lock: %s"),
				  name, mu_strerror (rc));
		    }
		}
	      else 
		mu_error (_("%s seems locked by process ID %lu, "
			    "but its validity cannot be verified: %s"),
			  name, (unsigned long) fl.l_pid, 
			  mu_strerror (errno));
            }
	  else
	    mu_error (_("%s: cannot aquire lock: %s"),
		      name, mu_strerror (rc));
	}
      else
	mu_error (_("Cannot obtain locker info for %s: %s"),
		  name, mu_strerror (errno)); 
    }
  return rc;
}

#ifndef DB_FCNTL_LOCKING
#define LOCK_SUFFIX ".lock"

static int
make_lockfile (char *name, int lktype, int *pfd, char **plockname)
{
  int rc;
  int fd;
  char *p, *lockname;
  size_t size, namesize;

  size = strlen (mailfromd_state_dir);
  if (strlen (name) > size
      && memcmp (name, mailfromd_state_dir, size) == 0
      && name[size] == '/')
       p = name + size + 1;
  else
       p = name;
     
  namesize = size + 1 + strlen (p) + sizeof LOCK_SUFFIX;
  lockname = malloc (namesize);
  if (!lockname)
    return errno;
  strcpy (lockname, mailfromd_state_dir);
  strcat (lockname, "/");
  strcat (lockname, p);
  strcat (lockname, LOCK_SUFFIX);
  for (p = lockname + size + 1; *p; p++)
     if (*p == '/')
       *p = '-';

  fd = open (lockname, O_CREAT|O_RDWR, 0600);
  if (fd == -1)
    {
      free (lockname);
      return errno;
    }

  rc = lock_file (lockname, fd, lktype);
  if (rc)
    {
      free (lockname);
      return rc;
    }

  *plockname = lockname;
  *pfd = fd;
  return 0;
}
#endif      

static void
mu_dbm_errcall_fcn (const char *errpfx, char *msg)
{
  if (errpfx)
    mu_error ("%s: %s: %s", errpfx, _("Berkeley DB error"), msg);
  else
    mu_error ("%s: %s", _("Berkeley DB error"), msg);
}

#if DB_VERSION_MAJOR >= 4 && DB_VERSION_MINOR >= 1
# define DB_TXN_NULL NULL,
#else
# define DB_TXN_NULL
#endif

int
mu_dbm_open (char *name, DBM_FILE *dbm, int flags, int mode, int *ro)
{
  int f = 0;
  DB *db = NULL;
  int oflags;
# define LKTYPE(o) (((o) & O_RDWR) ? F_WRLCK : F_RDLCK)
  
  debug1(10, "opening database %s", name);
  mu_dbm_errno = mu_check_perm (name, mode);
  
  if (mu_dbm_errno && mu_dbm_errno != ENOENT)
    return MU_ERR_UNSAFE_PERMS;

  if (ro)
    *ro = 0;

  switch (flags)
    {
    case MU_STREAM_CREAT:
      f = DB_CREATE | DB_TRUNCATE;
      oflags = O_CREAT | O_TRUNC | O_RDWR;
      break;
      
    case MU_STREAM_READ:
      if (mu_dbm_errno == ENOENT)
	return MU_ERR_FAILURE;
      f = DB_RDONLY;
      oflags = O_RDONLY;
      break;
      
    case MU_STREAM_RDWR:
      f = DB_CREATE;
      oflags = O_CREAT | O_RDWR;
      if (mu_dbm_errno == ENOENT)
	f |= DB_TRUNCATE;
      break;
      
    default:
      mu_dbm_errno = EINVAL;
      return MU_ERR_FAILURE;
   }

  dbm->lockname = NULL;
#ifdef DB_FCNTL_LOCKING
  f |= DB_FCNTL_LOCKING;

  dbm->lockfd = open (name, oflags, mode);
  if (dbm->lockfd == -1)
    {
      mu_dbm_errno = errno;
      return MU_ERR_FAILURE;
    }
  mu_dbm_errno = lock_file (name, dbm->lockfd, LKTYPE(oflags));
  if (mu_dbm_errno)
    {
      mu_error (_("Cannot lock file %s: %s"),
		name, mu_strerror (mu_dbm_errno));
      close (dbm->lockfd);
      return MU_ERR_FAILURE;
      
    }
#else
  mu_dbm_errno = make_lockfile (name, LKTYPE(oflags), &dbm->lockfd,
				&dbm->lockname);
  if (mu_dbm_errno)
    {
      mu_error (_("Cannot lock file %s: %s"),
		name, mu_strerror (mu_dbm_errno));
      return MU_ERR_FAILURE;
    }
#endif

#if DB_VERSION_MAJOR == 2
  mu_dbm_errno = db_open (name, DB_HASH, f, mode, NULL, NULL, &db);
#else
  mu_dbm_errno = db_create (&db, NULL, 0);
  if (mu_dbm_errno != 0 || db == NULL)
    return MU_ERR_FAILURE;
# if DB_VERSION_MAJOR == 3
  mu_dbm_errno = db->open (db, name, NULL, DB_HASH, f, mode);
# else
  mu_dbm_errno = db->open (db, DB_TXN_NULL name, NULL, DB_HASH, f, mode);
# endif
#endif
  if (mu_dbm_errno)
    {
      if (dbm->lockname)
	{
	  unlink (dbm->lockname);
	  free (dbm->lockname);
	}
      close (dbm->lockfd);
      return MU_ERR_FAILURE;
    }

  db->sync (db, 0);

  __DBG(1)
    {
#if DB_VERSION_MAJOR > 2
      db->set_errcall (db, mu_dbm_errcall_fcn);
#endif
    }
  
  dbm->name = strdup (name);
  dbm->db = db;
  dbm->dbc = NULL;

  return 0;
}

int
mu_dbm_close (DBM_FILE *db)
{
  debug1(10, "closing database %s", db->name);
  if (db->dbc)
    {
      mu_dbm_errno = db->dbc->c_close(db->dbc);
      db->dbc = NULL;
      if (mu_dbm_errno)
	return MU_ERR_FAILURE;
    }

  db->db->sync (db->db, 0);
  mu_dbm_errno = db->db->close (db->db, 0);
  if (db->lockname)
    {
      debug1(10, "removing lock file %s", db->lockname);
      unlink (db->lockname);
      free (db->lockname);
    }
  close (db->lockfd);
  
  free (db->name);
  return (mu_dbm_errno == 0) ? 0 : MU_ERR_FAILURE;
}

int
mu_dbm_fetch (DBM_FILE *db, DBM_DATUM key, DBM_DATUM *ret)
{
  mu_dbm_errno = db->db->get (db->db, NULL, &key, ret, 0);
  switch (mu_dbm_errno)
    {
    case 0:
      return 0;
    
    case DB_NOTFOUND:
      return MU_ERR_NOENT;

    default:
      return MU_ERR_FAILURE;
    }
}

int
mu_dbm_delete (DBM_FILE *dbm, DBM_DATUM key)
{
  mu_dbm_errno = dbm->db->del (dbm->db, NULL, &key, 0);
  return mu_dbm_errno ? MU_ERR_FAILURE : 0;
}

int
mu_dbm_insert (DBM_FILE *dbm, DBM_DATUM key, DBM_DATUM contents, int replace)
{
  int flags = replace ? 0 : DB_NOOVERWRITE;
  int rc = 0;
  
  mu_dbm_errno = dbm->db->put (dbm->db, NULL, &key, &contents, flags);
  switch (mu_dbm_errno)
    {
    case 0:
      break;
      
    case DB_KEYEXIST:
      rc = MU_ERR_EXISTS;

    default:
      rc = MU_ERR_FAILURE;
    }
  return rc;
}

int
mu_dbm_firstkey (DBM_FILE *db, DBM_DATUM *pkey)
{
  DBT data;

  memset(pkey, 0, sizeof *pkey);
  memset(&data, 0, sizeof data);

  if (!db->dbc)
    {
      mu_dbm_errno = db->db->cursor(db->db, NULL, &db->dbc
				    BDB2_CURSOR_LASTARG);
      if (mu_dbm_errno)
	return MU_ERR_FAILURE;
    }

  mu_dbm_errno = db->dbc->c_get(db->dbc, pkey, &data, DB_FIRST);
  switch (mu_dbm_errno)
    {
    case 0:
      return 0;
      
    case DB_NOTFOUND:
      return MU_ERR_NOENT;

    default:
      return MU_ERR_FAILURE;
    }
}

int
mu_dbm_nextkey (DBM_FILE *db, DBM_DATUM prevkey /*unused*/, DBM_DATUM *pkey)
{
  DBT data;

  memset(pkey, 0, sizeof *pkey);
  memset(&data, 0, sizeof data);

  if (!db->dbc)
    {
      mu_dbm_errno = EINVAL;
      return MU_ERR_FAILURE;
    }

  mu_dbm_errno = db->dbc->c_get(db->dbc, pkey, &data, DB_NEXT);

  switch (mu_dbm_errno)
    {
    case 0:
      return 0;
      
    case DB_NOTFOUND:
      return MU_ERR_NOENT;

    default:
      return MU_ERR_FAILURE;
    }
}

void
mu_dbm_datum_free(DBM_DATUM *datum)
{
  /* empty */
}

const char *
mu_dbm_strerror ()
{
#if DB_VERSION_MAJOR == 2
  switch (mu_dbm_errno)
    {
    case DB_INCOMPLETE:
      return "Sync didn't finish";

    case DB_KEYEMPTY:
      return "The key/data pair was deleted or was never created by the user";
      break;

    case DB_KEYEXIST:
      return "The key/data pair already exists";
      
    case DB_LOCK_DEADLOCK:
      return "Locker killed to resolve deadlock";

    case DB_LOCK_NOTGRANTED:
      return "Lock unavailable, no-wait set";

    case DB_LOCK_NOTHELD:
      return "Lock not held by locker";

    case DB_NOTFOUND:
      return "Key/data pair not found (EOF)";

    default: 
      return mu_strerror (mu_dbm_errno);
    }
#else
  if (mu_dbm_errno < 0)
    return db_strerror (mu_dbm_errno);
  else
    return mu_strerror (mu_dbm_errno);
#endif
}

#endif

/*
  Local Variables:
  c-file-style: "gnu"
  End:
*/

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