/* GNU mailutils - a suite of utilities for electronic mail
   Copyright (C) 1999, 2000 Free Software Foundation, Inc.

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

   This program 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 Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* First draft by Alain Magloire */

#include <mailbox0.h>
#include <registrar0.h>
#include <message0.h>
#include <url0.h>
#include <stream0.h>
#include <body0.h>
#include <header0.h>
#include <attribute0.h>
#include <mailutils/header.h>
#include <mailutils/auth.h>
#include <mailutils/locker.h>

//#define HAVE_PTHREAD_H

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>
#include <time.h>
#ifdef HAVE_PTHREAD_H
# include <pthread.h>
#else
# define flockfile(arg)
# define funlockfile(arg)
#endif
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <errno.h>

#define ATTRIBUTE_IS_DELETED(flag)        (flag & MU_ATTRIBUTE_DELETED)
#define ATTRIBUTE_IS_EQUAL(flag1, flag2)  (flag1 == flag2)

static int unix_create (mailbox_t *pmbox, const char *name);
static void unix_destroy (mailbox_t *pmbox);

struct mailbox_registrar _mailbox_unix_registrar =
{
  "UNIX MBOX",
  unix_create, unix_destroy
};

/* Keep the position of where the header and body starts and ends.
   old_flags is the "Status:" message.  */
typedef struct _unix_message
{
  /* Offset of the parts of the messages in the mailbox.  */
  off_t header_from;
  off_t header_from_end;
  /* Little hack to make things easier * when updating the attribute.  */
  off_t header_status;
  off_t header_status_end;
  off_t body;
  off_t body_end;

  /* The old_flags contains the definition of Header.  */
  int old_flags;
  /* The new_flags holds the attributes changes for the current session. We
     use this so when expunging we can tell when an attribute been modified.
     This is a big help so we can jump to the first modify email for speed
     in expunging (see mark dirty).  */
  int new_flags;

  size_t header_lines;
  size_t body_lines;
  stream_t stream;

  /* A message attach to it.  */
  message_t message;

} *unix_message_t;

/* The umessages is an array of pointers that contains umessages_count of
   unix_message_t*; umessages[umessages_count].  We do it this because
   realloc() can move everything to a new memory region and invalidating all
   the pointers someone has on the messages.  Thanks to <Dave Inglis> for
   pointing this out.  The messages_count is the count number of messages
   parsed so far.  */
typedef struct _unix_data
{
  unix_message_t *umessages;
  size_t umessages_count;
  size_t messages_count;
  stream_t stream;
#ifdef HAVE_PTHREAD_H
  pthread_mutex_t mutex;
#endif
  off_t size;

  /* The variables below are use to hold the state when appending messages.  */
  enum unix_state
  {
    UNIX_NO_STATE=0, UNIX_STATE_FROM, UNIX_STATE_DATE, UNIX_STATE_APPEND
  } state ;
  char *from;
  char *date;
  off_t off;

} *unix_data_t;

static int unix_open (mailbox_t mbox, int flag);
static int unix_close (mailbox_t mbox);
static int unix_get_message (mailbox_t, size_t msgno, message_t *msg);
static int unix_append_message (mailbox_t, message_t msg);
static int unix_messages_count (mailbox_t, size_t *msgno);
static int unix_expunge (mailbox_t);
static int unix_num_deleted (mailbox_t, size_t *);
static int unix_scan (mailbox_t, size_t count, size_t *pcount);
static int unix_is_updated (mailbox_t);
static int unix_size (mailbox_t, off_t *size);


/* private stuff */
static int unix_scan0 (mailbox_t, size_t count, size_t *pcount, int);
static int unix_get_header_read (stream_t is, char *buffer, size_t len,
				 off_t off, size_t *pnread);
static int unix_get_fd (stream_t is, int *pfd);
static int unix_get_flags (attribute_t, int *);
static int unix_set_flags (attribute_t, int);
static int unix_unset_flags (attribute_t, int);
static int unix_readstream (stream_t is, char *buffer, size_t buflen,
				    off_t off, size_t *pnread);
static int unix_header_size (header_t header, size_t *psize);
static int unix_header_lines (header_t header, size_t *plines);
static int unix_body_size (body_t body, size_t *psize);
static int unix_body_lines (body_t body, size_t *plines);
static int unix_msg_from (message_t msg, char *buf, size_t len,
				  size_t *pnwrite);
static int unix_msg_received (message_t msg, char *buf, size_t len,
				      size_t *pnwrite);
static int unix_lock (mailbox_t mbox, int flag);
static int unix_touchlock (mailbox_t mbox);
static int unix_unlock (mailbox_t mbox);
static int unix_ilock (mailbox_t mbox, int flag);
static int unix_iunlock (mailbox_t mbox);

/* We allocate the mailbox_t struct, but don't do any parsing on the name or
   even test for existence.  However we do strip any leading "unix:" part of
   the name, this is suppose to be the protocol/scheme name. Hopefully there
   will not be a mailbox name "unix:".  */
static int
unix_create (mailbox_t *pmbox, const char *name)
{
  mailbox_t mbox;
  unix_data_t mud;
  size_t name_len;

  /* Sanity check.  */
  if (name == NULL || *name == '\0')
    return EINVAL;

  name_len = strlen (name);

#define UNIX_SCHEME "unix:"
#define UNIX_SCHEME_LEN 5
#define SEPARATOR '/'

  /* Skip the url scheme.  */
  if (name_len > UNIX_SCHEME_LEN
      && (name[0] == 'u' || name[0] == 'U')
      && (name[1] == 'n' || name[1] == 'N')
      && (name[2] == 'i' || name[2] == 'i')
      && (name[3] == 'x' || name[3] == 'x' )
      && name[4] == ':')
    {
      name += UNIX_SCHEME_LEN;
      name_len -= UNIX_SCHEME_LEN;
    }

  /* Allocate memory for mbox (mailbox_t).  */
  mbox = calloc (1, sizeof (*mbox));
  if (mbox == NULL)
    return ENOMEM;

  /* Allocate specific unix mbox data.  */
  mud = mbox->data = calloc (1, sizeof (*mud));
  if (mbox->data == NULL)
    {
      unix_destroy (&mbox);
      return ENOMEM;
    }

  /* Copy the name.
     We do not do any further interpretation after the scheme "unix:"
     Because for example on distributed system like QnX4 a file name is
     //390/etc/passwd.  So the best approach is to let the OS handle it
     for example if we receive: "unix:///var/mail/alain" the mailbox name
     will be "///var/mail/alain" we let open() do the right thing.
     So it will let things like this "unix://390/var/mail/alain" where
     "//390/var/mail/alain" _is_ the filename, pass correctely.  */
  mbox->name = calloc (name_len + 1, sizeof (char));
  if (mbox->name == NULL)
    {
      unix_destroy (&mbox);
      return ENOMEM;
    }
  memcpy (mbox->name, name, name_len);

#ifdef HAVE_PHTREAD_H
  /* Mutex when accessing the structure fields.  */
  /* FIXME: should we use rdwr locks instead ??  */
  pthread_mutex_init (&(mbox->mutex), NULL);
#endif

  mbox->_create = unix_create;
  mbox->_destroy = unix_destroy;

  mbox->_open = unix_open;
  mbox->_close = unix_close;

  /* Messages.  */
  mbox->_get_message = unix_get_message;
  mbox->_append_message = unix_append_message;
  mbox->_messages_count = unix_messages_count;
  mbox->_expunge = unix_expunge;
  mbox->_num_deleted = unix_num_deleted;

  mbox->_scan = unix_scan;
  mbox->_is_updated = unix_is_updated;

  mbox->_size = unix_size;

  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE, "unix_create(%s)\n",
		 mbox->name);
  (*pmbox) = mbox;

  return 0; /* okdoke */
}

static void
unix_destroy (mailbox_t *pmbox)
{
  if (pmbox && *pmbox)
    {
      mailbox_t mbox = *pmbox;
      unix_close (mbox);
      if (mbox->data)
	{
	  size_t i;
	  unix_data_t mud = mbox->data;
	  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE,
			 "unix_destroy (%s/%s)\n", mbox->name);
	  for (i = 0; i < mud->umessages_count; i++)
	    {
	      unix_message_t mum = mud->umessages[i];
	      if (mum == NULL)
		{
		  message_destroy (&(mum->message), mum);
		  free (mum);
		}
	    }
	  free (mud->umessages);
	  free (mbox->data);
	}
      free (mbox->name);
      /* Free the event array.  */
      free (mbox->event);
      /* Destroy the url.  */
      if (mbox->url)
	url_destroy (&(mbox->url));
      if  (mbox->locker)
	locker_destroy (&(mbox->locker));
      if (mbox->auth)
	auth_destroy (&(mbox->auth), mbox);
      if(mbox->stream)
	stream_destroy (&(mbox->stream), mbox);
      unix_iunlock (mbox);
#ifdef HAVE_PTHREAD_H
      if (mbox->mutex)
	ptread_mutex_destroy (&(mbox->mutex));
#endif
      free (mbox);
      *pmbox = NULL;
    }
}

/* Open the file.  */
static int
unix_open (mailbox_t mbox, int flags)
{
  unix_data_t mud = mbox->data;
  int status = 0;

  if (mud == NULL)
    return EINVAL;

  /* Authentication prologues.  */
  if (mbox->auth)
    auth_prologue (mbox->auth);

  /* Get a stream.  */
  if (mbox->stream == NULL)
    {
      /* FIXME: for small mbox we shout try to mmap ().  */

      status = (flags & MU_STREAM_CREAT) || (flags & MU_STREAM_APPEND);
      if (status == 0)
	status = mapfile_stream_create (&(mbox->stream));
      if (status != 0)
	{
	  status = file_stream_create (&(mbox->stream));
	  if (status != 0)
	    return status;
	}
      status = stream_open (mbox->stream, mbox->name, 0, flags);
      if (status != 0)
	return status;
    }
  else
    {
      status = stream_open (mbox->stream, mbox->name, 0, flags);
      if (status != 0)
	return status;
    }

  /* Authentication epilogue.  */
  if (mbox->auth)
    auth_epilogue (mbox->auth);

  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE, "unix_open(%s, %d)\n",
		 mbox->name, flags);

  /* Give an appopriate way to lock.  */
  if (mbox->locker == NULL)
    locker_create (&(mbox->locker), mbox->name, strlen (mbox->name),
		   MU_LOCKER_PID | MU_LOCKER_FCNTL);
  return 0;
}

static int
unix_close (mailbox_t mbox)
{
  unix_data_t mud = mbox->data;
  size_t i;

  if (mud == NULL)
    return EINVAL;

  /* Make sure we do not hold any lock for that file.  */
  unix_unlock (mbox);
  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE,  "unix_close(%s)\n",
		 mbox->name);

  /* Before closing we need to remove all the messages
     - to reclaim the memory
     - to prepare for another scan.  */
  for (i = 0; i < mud->umessages_count; i++)
    {
      unix_message_t mum = mud->umessages[i];
      /* Destroy the attach messages.  */
      if (mum == NULL)
	{
	  message_destroy (&(mum->message), mum);
	  free (mum);
	}
    }
  free (mud->umessages);
  mud->umessages = NULL;
  mud->messages_count = mud->umessages_count = 0;
  mud->size = 0;
  return stream_close (mbox->stream);
}

/* Mailbox Parsing.  */
#include "mbx_unixscan.c"

static int
unix_scan (mailbox_t mbox, size_t msgno, size_t *pcount)
{
  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE, "unix_scan(%s)\n", mbox->name);
  return unix_scan0 (mbox, msgno, pcount, 1);
}


/* FIXME:  How to handle a shrink ? meaning, the &^$^@%#@^& user start two
   browsers and delete files in one.  My views is that we should scream
   bloody murder and hunt them with a machette. But for now just play dumb,
   but maybe the best approach is to pack our things and leave .i.e exit().  */
static int
unix_is_updated (mailbox_t mbox)
{
  off_t size;
  unix_data_t mud = mbox->data;

  if (mud == NULL)
    return EINVAL;
  if (stream_size (mbox->stream, &size) != 0)
    return 0;
  return (mud->size == size);
}

static int
unix_num_deleted (mailbox_t mbox, size_t *pnum)
{
  unix_data_t mud = mbox->data;
  unix_message_t mum;
  size_t i, total;
  if (mud == NULL)
    return EINVAL;
  for (i = total = 0; i < mud->messages_count; i++)
    {
      mum = mud->umessages[i];
      if (ATTRIBUTE_IS_DELETED (mum->new_flags))
	total++;
    }

  if (pnum)
    *pnum = total;
  return 0;
}

/* FIXME: the use of tmpfile() on some system can lead to race condition, We
   should use a safer approach.  */
static FILE *
unix_tmpfile (mailbox_t mbox, char **pbox)
{
  const char *tmpdir;
  int fd;
  FILE *fp;
  const char *basename;

  /*  P_tmpdir should be define in <stdio.h>.  */
#ifndef P_tmpdir
#  define P_tmpdir "/tmp"
#endif

  tmpdir =  getenv ("TEMPDIR") ? getenv ("TEMPDIR") : P_tmpdir;
  basename = strrchr (mbox->name, '/');
  if (basename)
    basename++;
  else
    basename = mbox->name;
  *pbox = calloc (strlen (tmpdir) + strlen ("MBOX_") +
		  strlen (basename) + 1, sizeof (char));
  if (*pbox == NULL)
    return NULL;
  sprintf (*pbox, "%s/%s%s", tmpdir, "MBOX_", basename);

  /* FIXME:  I don't think this is the righ approach, creating an anonymous
     file would be better ?  no trace left behind.  */
  /* Create the file.  It must not exist.  If it does exist, fail.  */
  fd = open (*pbox, O_RDWR|O_CREAT|O_EXCL, 0600);
  if (fd < 0)
    {
      fprintf (stderr,"Can't create %s\n", *pbox);
      fprintf (stderr,"delete file <%s>, Please\n", *pbox);
      fprintf (stderr, "It was likely due to an error when expunging\n");
      return NULL;
    }
  fp = fdopen (fd, "w+");
  if (fp == 0)
    {
      close(fd);
      free (*pbox);
      *pbox = NULL;
    }

  /* Really I should just remove the file here.  */
  /* remove(*pbox); */
  return fp;
}

/* For the expunge bits  we took a very cautionnary approach, meaning
   we create temporary file in the tmpdir copy all the file not mark deleted,
   and skip the deleted ones, truncate the real mailbox to the desired size
   and overwrite with the tmp mailbox.  The approach to do everyting
   in core is tempting but require to much memory, it is not rare now
   a day to have 30 Megs mailbox, also there is danger for filesystems
   with quotas, or some program may not respect the advisory lock and
   decide to append a new message while your expunging etc ...
   The real downside to the approach we take is that when things go wrong
   the temporary file bay be left in /tmp, which is not all that bad
   because at least have something to recuparate when failure.  */
static int
unix_expunge (mailbox_t mbox)
{
  unix_data_t mud = mbox->data;
  unix_message_t mum;
  int status = 0;
  sigset_t sigset;
  FILE *tempfile;
  size_t nread;
  size_t i, j, dirty, first;
  off_t marker = 0;
  off_t total = 0;
  char buffer [BUFSIZ];
  char *tmpmbox = NULL;

  if (mud == NULL)
    return EINVAL;

  /* Noop.  */
  if (mud->messages_count == 0)
    return 0;

  /* Do we have a consistent view of the mailbox.  */
  /* FIXME: this is not enough, we can do better
     - by checking the file size and scream bloody murder if it has shrink.
     - if its bigger we should be able to handle it before the ftruncate ()
     by copying back the new messages.  */
  if (! unix_is_updated (mbox))
    {
      fprintf (stderr, "mailbox is not updated, try again.\n");
      return  EAGAIN;
    }

  /* Mark dirty the first mail with an attribute change.  */
  for (dirty = 0; dirty < mud->messages_count; dirty++)
    {
      mum = mud->umessages[dirty];
      if (mum->new_flags &&
	  ! ATTRIBUTE_IS_EQUAL (mum->old_flags, mum->new_flags))
	break;
    }

  /* Did something change ?  */
  if (dirty == mud->messages_count)
    return 0; /* Nothing change, bail out.  */

  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE, "unix_expunge (%s)\n",
		 mbox->name);

  /* This is redundant, we go to the loop again.  But it's more secure here
     since we don't want to be disturb when expunging.  */
  for (j = 0; j < mud->messages_count; j++)
    {
      mum = mud->umessages[j];
      if (mum && mum->new_flags && ATTRIBUTE_IS_DELETED (mum->new_flags))
	message_destroy (&(mum->message), mum);
    }

  /* Create a tempory file.  */
  tempfile = unix_tmpfile (mbox, &tmpmbox);
  if (tempfile == NULL)
    {
      fprintf (stderr, "Failed to create temporary file when expunging.\n");
      free (tmpmbox);
      return errno;
    }

  /* Get the lock.  */
  if (unix_lock (mbox, MU_LOCKER_WRLOCK) < 0)
    {
      fclose (tempfile);
      remove (tmpmbox);
      free (tmpmbox);
      fprintf (stderr, "Failed to grab the lock\n");
      return ENOLCK;
    }

  /* Critical section, we can not allowed signal here.  */
  sigemptyset (&sigset);
  sigaddset (&sigset, SIGTERM);
  sigaddset (&sigset, SIGHUP);
  sigaddset (&sigset, SIGTSTP);
  sigaddset (&sigset, SIGINT);
  sigaddset (&sigset, SIGWINCH);
  sigprocmask (SIG_BLOCK, &sigset, 0);

  unix_ilock (mbox, MU_LOCKER_RDLOCK);

  /* Set the marker position.  */
  total = marker = mud->umessages[dirty]->header_from;

  /* Copy to tempfile emails not mark deleted.  */
  for (first = 1, i = dirty; i < mud->messages_count; i++)
    {
      mum = mud->umessages[i];

      /* Skip it, if mark for deletion.  */
      if (ATTRIBUTE_IS_DELETED (mum->new_flags))
	continue;

      /* Add a NL separator between messages.  */
      if (first)
	first = 0;
      else
	{
	  fputc ('\n', tempfile);
	  total++;
	}

      /* Begining of header copy.  */
      {
	off_t current;
	/* This is done in two parts first we check if the attribute changed,
	   if yes then we have to update the "Status:" field.  Unfortunately
	   there is no requirement for the "Status:" to be the last field, so
	   we take the long approach; Copy up to the Status, update the
	   Status and copy the rest.  */

	/* Attribute change ?  */
	if (mum->new_flags
	    &&! ATTRIBUTE_IS_EQUAL (mum->old_flags, mum->new_flags)
	    && mum->header_status > mum->header_from)
	  {
	    size_t n = 0;
	    off_t offset = mum->header_from;
	    size_t len = mum->header_status - mum->header_from;
	    current = mum->header_status_end;
	    while (len > 0)
	      {
		nread = (len < sizeof (buffer)) ? len : sizeof (buffer);
		if ((status = stream_read (mbox->stream, buffer,
					   nread, offset, &n) != 0)
		    || fwrite(buffer, sizeof(*buffer), n, tempfile) != n)
		  {
		    if (status == 0)
		      status = errno;
		    fprintf (stderr, "Error expunge:%d: (%s)\n", __LINE__,
			     strerror (status));
		    goto bailout0;
		  }
		len -= n;
		total += n;
		offset += n;
	      }

	    /* Put the new attributes.  */
	    {
	      char abuf[64];
	      size_t na = 0;
	      abuf[0] = '\0';
	      flags_to_string (mum->new_flags, abuf, sizeof(abuf), &na);
	      fputs (abuf, tempfile);
	      total += na;
	    }
	  }
	else /* Attribute did not change.  */
	  current = mum->header_from;

	/* Copy the rest of header without changes.  */
	{
	  size_t n = 0;
	  off_t offset = current;
	  size_t len = mum->body - current;
	  while (len > 0)
	    {
	      nread = (len < sizeof (buffer)) ? len : sizeof (buffer);
	      if ((status = stream_read (mbox->stream, buffer, nread,
					 offset, &n) != 0)
		  || fwrite(buffer, sizeof(*buffer), n, tempfile) != n)
		{
		  if (status == 0)
		    status = errno;
		  fprintf (stderr, "Error expunge:%d: %s", __LINE__,
			   strerror (status));
		  goto bailout0;
		}
	      len -= n;
	      total += n;
	      offset += n;
	    }
	}
      } /* End of header copy.  */

      /* Copy the body.  */
      {
	size_t n = 0;
	off_t offset = mum->body;
	size_t len = mum->body_end - mum->body;
	while (len > 0)
	  {
	    nread = (len < sizeof (buffer)) ? len : sizeof (buffer);
	    if ((status = stream_read (mbox->stream, buffer, nread,
				       offset, &n) != 0)
		|| fwrite(buffer, sizeof(*buffer), n, tempfile) != n)
	      {
		if (status == 0)
		  status = errno;
		fprintf (stderr, "Error expunge:%d: %s", __LINE__,
			 strerror (status));
		goto bailout0;
	      }
	    len -= n;
	    total += n;
	    offset += n;
	  }
      } /* End of body copy.  */
    } /* for (;;) */

  /* Caution: before ftruncate()ing the file see if we've receiving new mail
     Some program may not respect the lock, or the lock was held for too
     long. */
  {
    off_t size = 0;
    if (stream_size (mbox->stream, &size) == 0)
      {
	size_t n = 0;
	off_t offset = size;
	size_t len = size - mud->size;
	while (len > 0)
	  {
	    nread = (len < sizeof (buffer)) ? len : sizeof (buffer);
	    if ((status = stream_read (mbox->stream, buffer, nread,
				       offset, &n) != 0)
		|| fwrite(buffer, sizeof(*buffer), n, tempfile) != n)
	      {
		if (status == 0)
		  status = errno;
		fprintf (stderr, "Error expunge:%d: %s", __LINE__,
			 strerror (status));
		goto bailout0;
	      }
	    len -= n;
	    total += n;
	    offset += n;
	  }
      }
  } /* End of precaution.  */

  /* Seek and rewrite it.  */
  rewind (tempfile);
  if (total > 0)
    {
      size_t n = 0;
      off_t offset = marker;
      while ((nread = fread (buffer, sizeof (*buffer),
			     sizeof (buffer), tempfile)) != 0)
	{
	  while (nread)
	    {
	      status = stream_write (mbox->stream, buffer, nread, offset, &n);
	      if (status != 0)
		{
		  fprintf (stderr, "Error expunge:%d: %s\n", __LINE__,
			   strerror (status));
		  goto bailout;
		}
	      nread -= n;
	      offset += n;
	    }
	}
    }

  /* How can I handle error here ??  */
  clearerr (tempfile);

  /* Flush/truncation.  */
  stream_flush (mbox->stream);
  status = stream_truncate (mbox->stream, total);
  if (status != 0)
    {
      fprintf (stderr, "Error expunging:%d: %s", __LINE__, strerror (status));
      goto bailout;
    }

 bailout0:
  /* Don't remove the tmp mbox in case of errors, when writing back.  */
  remove (tmpmbox);

 bailout:

  free (tmpmbox);
  /* Release the locks.  */
  unix_unlock (mbox);
  unix_iunlock (mbox);
  fclose (tempfile);
  sigprocmask (SIG_UNBLOCK, &sigset, 0);

  /* We need to readjust the pointers.  */
  if (status == 0)
    {
      size_t dlast;
      for (j = dirty, dlast = mud->messages_count - 1;
	   j < mud->messages_count; j++)
	{
	  /* Clear all the references, any attach messages been already
	     destroy above.  */
	  mum = mud->umessages[j];
	  if (mum->new_flags && ATTRIBUTE_IS_DELETED (mum->new_flags))
	    {
	      memmove (mud->umessages + j, mud->umessages + j + 1,
		       (dlast - dirty) * sizeof (mum));
	      mum->header_from = mum->header_from_end = 0;
	      mum->header_status = mum->header_status_end = 0;
	      mum->body = mum->body_end = 0;
	      mum->header_lines = mum->body_lines = 0;
	      mud->umessages[dlast] = mum;
	      dlast--;
	      mum = mud->umessages[j];
	    }
	  mum->header_from = mum->header_from_end = 0;
	  mum->header_status = mum->header_status_end = 0;
	  mum->body = mum->body_end = 0;
	  mum->header_lines = mum->body_lines = 0;
	}
      /* This is should reset the messages_count, the last argument 0 means
	 not to send event notification.  */
      unix_scan0 (mbox, dirty, NULL, 0);
    }
  return status;
}

static int
unix_get_fd (stream_t is, int *pfd)
{
  unix_message_t mum = is->owner;

  if (mum == NULL)
    return EINVAL;

  return stream_get_fd (mum->stream, pfd);
}

static int
unix_get_flags (attribute_t attr, int *pflags)
{
  unix_message_t mum = attr->owner;

  if (mum == NULL)
    return EINVAL;

  if (pflags)
    *pflags = mum->new_flags;
  return 0;
}

static int
unix_set_flags (attribute_t attr, int flags)
{
  unix_message_t mum = attr->owner;

  if (mum == NULL)
    return EINVAL;

  mum->new_flags |= flags;
  return 0;
}

static int
unix_unset_flags (attribute_t attr, int flags)
{
  unix_message_t mum = attr->owner;

  if (mum == NULL)
    return EINVAL;

  mum->new_flags &= ~flags;
  return 0;
}

static int
unix_readstream (stream_t is, char *buffer, size_t buflen,
		 off_t off, size_t *pnread)
{
  unix_message_t mum = is->owner;
  size_t nread = 0;

  if (mum == NULL)
    return EINVAL;

  if (buffer == NULL || buflen == 0)
    {
      if (pnread)
	*pnread = nread;
      return 0;
    }

  {
    off_t ln = mum->body_end - (mum->body + off);
    size_t n = 0;
    int status;
    if (ln > 0)
      {
	nread = ((size_t)ln < buflen) ? ln : buflen;
	/* Position the file pointer and the buffer.  */
	status = stream_read (mum->stream, buffer, nread, mum->body + off, &n);
	if (status != 0)
	  return status;
      }
  }

  if (pnread)
    *pnread = nread;
  return 0;
}

static int
unix_get_header_read (stream_t is, char *buffer, size_t len,
		      off_t off, size_t *pnread)
{
  unix_message_t mum = is->owner;
  size_t nread = 0;
  int status = 0;
  off_t ln;

  if (mum == NULL)
    return EINVAL;

  ln = mum->body - (mum->header_from_end + off);
  if (ln > 0)
    {
      nread = ((size_t)ln < len) ? ln : len;
      /* Position the file pointer and the buffer.  */
      status = stream_read (mum->stream, buffer, nread,
			    mum->header_from_end + off, &nread);
    }
  if (pnread)
    *pnread = nread;
  return status;
}

static int
unix_header_size (header_t header, size_t *psize)
{
  unix_message_t mum = header->owner;
  if (mum == NULL)
    return EINVAL;
  if (psize)
    *psize = mum->body - mum->header_from_end;
  return 0;
}

static int
unix_header_lines (header_t header, size_t *plines)
{
  unix_message_t mum = header->owner;
  if (mum == NULL)
    return EINVAL;
  if (plines)
    *plines = mum->header_lines;
  return 0;
}

static int
unix_body_size (body_t body, size_t *psize)
{
  unix_message_t mum = body->owner;
  if (mum == NULL)
    return EINVAL;
  if (psize)
    *psize = mum->body_end - mum->body + 1;
  return 0;
}

static int
unix_body_lines (body_t body, size_t *plines)
{
  unix_message_t mum = body->owner;
  if (mum == NULL)
    return EINVAL;
  if (plines)
    *plines = mum->body_lines;
  return 0;
}

static int
unix_msg_received (message_t msg, char *buf, size_t len,
			   size_t *pnwrite)
{
  unix_message_t mum = msg->owner;
  size_t n = 0;
  int status;
  char buffer[512];

  if (mum == NULL)
    return EINVAL;

  status = stream_readline (mum->stream, buffer, sizeof(buffer),
			    mum->header_from, &n);
  if (status != 0)
    {
      if (pnwrite)
	*pnwrite = 0;
      if (buf)
	*buf = '\0';
      return status;
    }

  if (n > 5)
    {
      char *s = strchr (buffer + 5, ' ');
      if (s)
	{
	  if (buf && len > 0)
	    {
	      strncpy (buf, s + 1, len);
	      buffer [len - 1] = '\0';
	    }
	  if (pnwrite)
	    *pnwrite = strlen (s + 1);
	  return 0;
	}
    }
  if (pnwrite)
    *pnwrite = 0;
  if (buf)
    *buf = '\0';
  return 0;
}

static int
unix_msg_from (message_t msg, char *buf, size_t len, size_t *pnwrite)
{
  unix_message_t mum = msg->owner;
  size_t n = 0;
  int status;
  char buffer[512];

  if (mum == NULL)
    return EINVAL;

  status = stream_readline (mum->stream, buffer, sizeof(buffer),
			    mum->header_from, &n);
  if (status != 0)
    {
      if (pnwrite)
	*pnwrite = 0;
      if (buf)
	*buf = '\0';
      return status;
    }

  if (n > 5)
    {
      char *s = strchr (buffer + 5, ' ');
      if (s)
	{
	  *s = '\0';
	  if (buf && len > 0)
	    {
	      strncpy (buf, buffer + 5, len);
	      buffer [len - 1] = '\0';
	    }
	  if (pnwrite)
	    *pnwrite = strlen (buffer + 5);
	  return 0;
	}
    }
  if (pnwrite)
    *pnwrite = 0;
  if (buf)
    *buf = '\0';
  return 0;
}

static int
unix_get_message (mailbox_t mbox, size_t msgno, message_t *pmsg)
{
  int status;
  unix_data_t mud = mbox->data;
  unix_message_t mum;
  message_t msg = NULL;

  /* Sanity checks.  */
  if (pmsg == NULL || mud == NULL || (!(mud->messages_count > 0 && msgno > 0
					&& msgno <= mud->messages_count)))
    return EINVAL;

  mum = mud->umessages[msgno - 1];

  /* Check if we already have it.  */
  if (mum->message)
    {
      if (pmsg)
	*pmsg = mum->message;
      return 0;
    }

  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE,
		 "unix_get_message(%s, %d)\n", mbox->name, msgno);

  /* Get an empty message struct.  */
  status = message_create (&msg, mum);
  if (status != 0)
    return status;

  /* Set the header.  */
  {
    header_t header = NULL;
    stream_t stream = NULL;
    if ((status = header_create (&header, NULL, 0, mum)) != 0
	|| (status = stream_create (&stream, MU_STREAM_READ, mum)) != 0)
      {
	stream_destroy (&stream, mum);
	header_destroy (&header, mum);
	message_destroy (&msg, mum);
	return status;
      }
    stream_set_read (stream, unix_get_header_read, mum);
    stream_set_fd (stream, unix_get_fd, mum);
    stream_set_flags (stream, MU_STREAM_READ, mum);
    header_set_stream (header, stream, mum);
    header_set_size (header, unix_header_size, mum);
    header_set_lines (header, unix_header_lines, mum);
    message_set_header (msg, header, mum);
  }

  /* Set the attribute.  */
  {
    attribute_t attribute;
    status = attribute_create (&attribute, mum);
    if (status != 0)
      {
	message_destroy (&msg, mum);
	return status;
      }
    mum->new_flags = mum->old_flags;
    attribute_set_get_flags (attribute, unix_get_flags, mum);
    attribute_set_set_flags (attribute, unix_set_flags, mum);
    attribute_set_unset_flags (attribute, unix_unset_flags, mum);
    message_set_attribute (msg, attribute, mum);
  }

  /* Prepare the body.  */
  {
    body_t body = NULL;
    stream_t stream = NULL;
    int flags = MU_STREAM_READ;
    if ((status = body_create (&body, mum)) != 0
	|| (status = stream_create (&stream, flags, mum)) != 0)
      {
	body_destroy (&body, mum);
	stream_destroy (&stream, mum);
	message_destroy (&msg, mum);
	return status;
      }
    stream_set_read (stream, unix_readstream, mum);
    stream_set_fd (stream, unix_get_fd, mum);
    stream_get_flags (mbox->stream, &flags);
    stream_set_flags (stream, flags, mum);
    body_set_stream (body, stream, mum);
    body_set_size (body, unix_body_size, mum);
    body_set_lines (body, unix_body_lines, mum);
    message_set_body (msg, body, mum);
  }

  /* Set the envelope.  */
  message_set_from (msg, unix_msg_from, mum);
  message_set_received (msg, unix_msg_received, mum);

  /* Attach the message to the mailbox unix data.  */
  mum->message = msg;

  if (pmsg)
    *pmsg = msg;
  return 0;
}

static int
unix_append_message (mailbox_t mbox, message_t msg)
{
  unix_data_t mud = mbox->data;
  if (msg == NULL || mud == NULL)
    return EINVAL;

  mailbox_debug (mbox, MU_MAILBOX_DEBUG_TRACE,
		 "unix_append_message (%s)\n", mbox->name);

  unix_lock (mbox, MU_LOCKER_WRLOCK);
  {
    off_t size;
    int status;
    size_t n = 0;
    char nl = '\n';

    /* Move to the end of the file, not necesary if _APPEND mode.  */
    status = stream_size (mbox->stream, &size);
    if (status != 0)
      {
	unix_unlock (mbox);
	return status;
      }

    switch (mud->state)
      {
      case UNIX_NO_STATE:
	mud->from = calloc (128, sizeof (char));
	if (mud->from == NULL)
	  {
	    unix_unlock (mbox);
	    return ENOMEM;
	  }
	mud->date = calloc (128, sizeof (char));
	if (mud->date == NULL)
	  {
	    free (mud->from);
	    mud->from = NULL;
	    mud->state = UNIX_NO_STATE;
	    unix_unlock (mbox);
	    return ENOMEM;
	  }
	mud->off = 0;
	mud->state = UNIX_STATE_FROM;

      case UNIX_STATE_FROM:
	/* Generate a "From " separator.  */
	{
	  char *s;
	  size_t len = 0;
	  status = message_from (msg, mud->from, 127, &len);
	  if (status != 0)
	    {
	      if (status != EAGAIN)
		{
		  free (mud->from);
		  free (mud->date);
		  mud->date = mud->from = NULL;
		  mud->state = UNIX_NO_STATE;
		  unix_unlock (mbox);
		}
	      return status;
	    }
	  /* Nuke trailing newline.  */
	  s = memchr (mud->from, nl, len);
	  if (s)
	    *s = '\0';
	  mud->state = UNIX_STATE_DATE;
	}

      case UNIX_STATE_DATE:
	/* Generate a date for the "From "  separator.  */
	{
	  char *s;
	  size_t len = 0;
	  status = message_received (msg, mud->date, 127, &len);
	  if (status != 0)
	    {
	      if (status != EAGAIN)
		{
		  free (mud->from);
		  free (mud->date);
		  mud->date = mud->from = NULL;
		  mud->state = UNIX_NO_STATE;
		  unix_unlock (mbox);
		}
	      return status;
	    }
	  /* Nuke trailing newline.  */
	  s = memchr (mud->date, nl, len);
	  if (s)
	    *s = '\0';
	  /* Write the separator to the mailbox.  */
	  stream_write (mbox->stream, "From ", 5, size, &n);
	  size += n;
	  stream_write (mbox->stream, mud->from, strlen (mud->from), size, &n);
	  size += n;
	  stream_write (mbox->stream, " ", 1, size, &n);
	  size += n;
	  stream_write (mbox->stream, mud->date, strlen (mud->date), size, &n);
	  size += n;
	  stream_write (mbox->stream, &nl , 1, size, &n);
	  size += n;
	  free (mud->from);
	  free (mud->date);
	  mud->from = mud->date = NULL;
	  mud->state = UNIX_STATE_APPEND;
	}

      case UNIX_STATE_APPEND:
	/* Append the Message.  */
	{
	  char buffer[BUFSIZ];
	  size_t nread = 0;
	  stream_t is;
	  message_get_stream (msg, &is);
	  do
	    {
	      status = stream_read (is, buffer, sizeof (buffer), mud->off,
				    &nread);
	      if (status != 0)
		{
		  if (status != EAGAIN)
		    {
		      free (mud->from);
		      free (mud->date);
		      mud->date = mud->from = NULL;
		      mud->state = UNIX_NO_STATE;
		      unix_unlock (mbox);
		    }
		  stream_flush (mbox->stream);
		  return status;
		}
	      stream_write (mbox->stream, buffer, nread, size, &n);
	      mud->off += nread;
	      size += n;
	    }
	  while (nread > 0);
	  stream_write (mbox->stream, &nl, 1, size, &n);
	}

      default:
	break;
      }
  }
  stream_flush (mbox->stream);
  mud->state = UNIX_NO_STATE;
  unix_unlock (mbox);
  return 0;
}

static int
unix_size (mailbox_t mbox, off_t *psize)
{
  off_t size;
  int status;

  if (mbox == NULL)
    return EINVAL;

  /* Maybe was not open yet ??  */
  status  = stream_size (mbox->stream, &size);
  if (status != 0)
    return status;
  if (psize)
    *psize = size;
  return 0;
}

static int
unix_messages_count (mailbox_t mbox, size_t *pcount)
{
  unix_data_t mud = mbox->data;
  if (mud == NULL)
    return EINVAL;

  if (! unix_is_updated (mbox))
    return unix_scan0 (mbox,  1, pcount, 1);

  if (pcount)
    *pcount = mud->messages_count;

  return 0;
}

/* Locking.  */
static int
unix_lock (mailbox_t mbox, int flag)
{
  if (mbox && mbox->locker != NULL)
    {
      locker_t locker = mbox->locker;
      locker_lock (locker, flag);
    }
  return 0;
}

static int
unix_touchlock (mailbox_t mbox)
{
  if (mbox && mbox->locker != NULL)
    {
      locker_t locker = mbox->locker;
      locker_touchlock (locker);
    }
  return 0;
}

static int
unix_unlock (mailbox_t mbox)
{
  if (mbox && mbox->locker != NULL)
    {
      locker_t locker = mbox->locker;
      locker_unlock (locker);
    }
  return 0;
}

static int
unix_ilock (mailbox_t mbox, int flag)
{
#ifdef HAVE_PTHREAD_H
  (void)flag; /* We should use rwlocks for more concurency.  */
  if (mbox == NULL)
    return EINVAL;
  return pthread_mutex_lock (&(mbox->mutex));
#else
  (void)mbox; (void)flag;
  return 0;
#endif
}

static int
unix_iunlock (mailbox_t mbox)
{
#ifdef HAVE_PTHREAD_H
  if (mbox == NULL)
    return EINVAL;
  return pthread_mutex_unlock (&(mbox->mutex));
#else
  (void)mbox;
  return 0;
#endif
}