/* GNU Mailutils -- a suite of utilities for electronic mail
   Copyright (C) 1999-2025 Free Software Foundation, Inc.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General
   Public License along with this library.  If not, see
   <http://www.gnu.org/licenses/>. */

/* First draft by Sergey Poznyakoff */

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

#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <dirent.h>
#include <limits.h>

#ifdef WITH_PTHREAD
# ifdef HAVE_PTHREAD_H
#  ifndef _XOPEN_SOURCE
#   define _XOPEN_SOURCE  500
#  endif
#  include <pthread.h>
# endif
#endif

#include <string.h>
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif

#include <mailutils/attribute.h>
#include <mailutils/body.h>
#include <mailutils/debug.h>
#include <mailutils/envelope.h>
#include <mailutils/error.h>
#include <mailutils/header.h>
#include <mailutils/message.h>
#include <mailutils/util.h>
#include <mailutils/property.h>
#include <mailutils/stream.h>
#include <mailutils/url.h>
#include <mailutils/observer.h>
#include <mailutils/errno.h>
#include <mailutils/locker.h>
#include <mailutils/sys/mailbox.h>
#include <mailutils/sys/registrar.h>
#include <mailutils/sys/amd.h>
#include <mailutils/io.h>
#include <mailutils/cstr.h>
#include <mailutils/cctype.h>
#include <mailutils/kwd.h>
#include <maildir.h>

#ifndef PATH_MAX
# define PATH_MAX _POSIX_PATH_MAX
#endif

/*
 * Maildir compatibility mode.
 *
 * The terms "modern" and "old-fashionable" delivery identifiers are
 * defined in http://cr.yp.to/proto/maildir.html.
 */
enum
  {
    MAILDIR_COMPAT_DETECT, /* Not set explicitly: use heuristics to detect. */
    MAILDIR_COMPAT_NONE,   /* Plain maildir with modern delivery
			      identifiers. */
    MAILDIR_COMPAT_ISYNC   /* Maildir with old-fashioned delivery identifiers
			      compatible with isync (mbsync) */
  };

#define ISYNC_UIDVALIDITY_FILE ".uidvalidity"

/* The maildir mailbox */
struct _maildir_data
{
  struct _amd_data amd;
  int folder_fd;         /* Descriptor of the top-level maildir directory */
  /* Additional data used during scanning: */
  int needs_attribute_fixup; /* The mailbox is created by mailutils 3.10
				or earlier and needs the attribute fixup
				(see "Maildir attribute fixup"" below) */
  int update_uidvalidity;    /* Some messages have been assigned new UIDS.
				Consequently, the uidvalidity
				value must be updated too. */
  int compat;                /* Compatibility mode (see constants above). */
  /* These two fields are kept during mailbox scanning. */
  size_t next_uid;           /* Predicted next UID. */
  size_t cur_uid;
};

#define HAS_USEC 0x01
#define HAS_PID  0x02
#define HAS_NDLV 0x04

struct _maildir_message
{
  struct _amd_message amd_message;
  int subdir;
  char *file_name;  /* File name */
  size_t uniq_len;  /* Length of the unique file name prefix. */
  size_t uid;
  /* Parsed out delivery information: */
  struct timeval tv;     /* Time of delivery */
  unsigned long pid;     /* PID of the process. */
  unsigned long ndlv;    /* Number of deliveries made by this PID. */
  int flags;             /* Flags indicating presense of these values. */
};

static char *subdir_name[] = { "cur", "new", "tmp" };

char const *
mu_maildir_subdir_name (int subdir)
{
  if (subdir < 0 || subdir >= MU_ARRAY_SIZE (subdir_name))
    {
      errno = EINVAL;
      return NULL;
    }
  return subdir_name[subdir];
}

int
mu_maildir_reserved_name (char const *name)
{
  return strcmp (name, subdir_name[SUB_TMP]) == 0
	 || strcmp (name, subdir_name[SUB_CUR]) == 0
	 || strcmp (name, subdir_name[SUB_NEW]) == 0
	 || (strlen (name) > 3
	     && (memcmp (name, ".mh", 3) == 0 || memcmp (name, ".mu", 3) == 0));
}

static inline void
reset_uid (struct _maildir_data *md)
{
  md->next_uid = 1;
  md->cur_uid = 0;
}

static inline size_t
alloc_uid (struct _maildir_data *md)
{
  return md->next_uid++;
}

static inline size_t
next_uid (struct _maildir_data *md)
{
  return md->next_uid;
}

static inline void
update_uid (struct _maildir_data *md, size_t uid)
{
  md->next_uid = uid + 1;
}

/*
 * Attribute handling.
 */

static struct info_map {
  char letter;
  int flag;
} info_map[] = {
  /* Draft: the user considers this message a draft; toggled at user
     discretion.  */
  { 'D', MU_ATTRIBUTE_DRAFT },
  /* Flagged: user-defined flag; toggled at user discretion. */
  { 'F', MU_ATTRIBUTE_FLAGGED },
  /* Passed: the user has resent/forwarded/bounced this message to
     someone else. */
  { 'P', MU_ATTRIBUTE_FORWARDED },
  /* Replied: the user has replied to this message. */
  { 'R', MU_ATTRIBUTE_ANSWERED },
  /* Seen: the user has viewed this message, though perhaps he didn't
     read all the way through it.
     This corresponds to the MU_ATTRIBUTE_READ attribute. */
  { 'S', MU_ATTRIBUTE_READ },
  /* Trashed: the user has moved this message to the trash; the trash
     will be emptied by a later user action. */
  { 'T', MU_ATTRIBUTE_DELETED },

  /* Mailutils versions prior to 3.10.90 marked replied messages with the
     'a' flag.  The discrepancy with the de-facto standard was reported
     in http://savannah.gnu.org/bugs/?56428.

     This entry is preserved for a while, for backward compatibility.

     Keep it at the end, so the 'R' letter is used when converting
     attributes to maildir info letters.

     Info flags are fixed in maildir_scan_unlocked.
  */
  { 'a', MU_ATTRIBUTE_ANSWERED },
};
#define info_map_size (MU_ARRAY_SIZE (info_map))

/* NOTE: BUF must be at least info_map_size bytes long */
static int
flags_to_info (int flags, char *buf)
{
  struct info_map *p;

  for (p = info_map; p < info_map + info_map_size; p++)
    {
      if (p->flag & flags)
	*buf++ = p->letter;
      /* Avoid handling the same flag again.  See the description of
	 'a' in info_map above and "Maildir attribute fixup" below. */
      flags &= ~p->flag;
    }
  *buf = 0;
  return 0;
}

static int
info_to_flags (char const *buf)
{
  int flags = 0;
  struct info_map *p;

  for (p = info_map; p < info_map + info_map_size; p++)
    if (strchr (buf, p->letter))
      flags |= p->flag;
  return flags;
}

/*
 * Maildir message file handling.
 * ==============================
 *
 * The format of the maildir message file name is described in:
 * http://cr.yp.to/proto/maildir.html.
 *
 * It consists of:
 *
 *   uniq [ ',' attrs ] ':2,' info
 *
 * where:
 *   uniq  - unique name prefix;
 *   info  - message flags in alphabetical order;
 *   attrs - implementation-defined attributes.
 *
 * The specification states that a "unique name can be anything that
 * doesn't contain a colon (or slash) and doesn't start with a dot."
 * This makes it possible to add to the unique prefix a list of comma-
 * separated attributes.  Each attribute consists of the attribute name,
 * immediately followed by '=' and attribute value.  Neither part can
 * contain '=' or ','.
 *
 * Mailutils implementation defines the following attributes:
 *
 *  u  -  UID of the message.
 *  a  -  Additional message attributes: O, for MU_ATTRIBUTE_SEEN and F, for
 *        MU_ATTRIBUTE_FLAGGED.  More attributes can be implemented in
 *        future versions.
 *
 */

/*
 * Each attribute is represented by the following structure:
 */
struct attrib
{
  char *name;             /* Attribute name */
  char *value;            /* Attribute value */
  struct attrib *next;    /* Pointer to the next attribute in list. */
};

/*
 * Both name and value point to the memory allocated in one block with
 * the attrib structure.  Attributes form a singly-linked list with the
 * list head pointing to the first attribute defined in the file name.
 *
 * Functions for accessing attribute lists:
 */

/* Push new attribute at the head of the existing attribute list.

   head - Pointer to the current list head;
   name - Attribute name;
   nlen - Length of the name;
   val  - Value;
   vlen - Length of the value.

   On success, updates head and returns the new head attribute.
   On memory allocation error, return NULL and does not modify head.
*/
static inline struct attrib *
attrib_push (struct attrib **head, char const *name, size_t nlen,
	     char const *val, size_t vlen)
{
  struct attrib *attr;

  attr = malloc (sizeof (*attr) + nlen + vlen + 2);
  attr->next = *head;
  attr->name = (char*)(attr + 1);
  memcpy(attr->name, name, nlen);
  attr->name[nlen] = 0;
  attr->value = attr->name + nlen + 1;
  memcpy(attr->value, val, vlen);
  attr->value[vlen] = 0;
  *head = attr;
  return attr;
}

/* Free the attribute list */
static void
attrib_free (struct attrib *alist)
{
  while (alist)
    {
      struct attrib *next = alist->next;
      free (alist);
      alist = next;
    }
}

static struct attrib *
attrib_locate (struct attrib *alist, int ci, char const *name)
{
  int (*cmp)(const char *, const char *) = ci ? mu_c_strcasecmp : strcmp;

  for (; alist && cmp (alist->name, name); alist = alist->next)
    ;
  return alist;
}

/* If the attribute name is present in the list alist, return its value.
   Otherwise, return NULL. */
static inline char const *
attrib_lookup (struct attrib *alist, char const *name)
{
  struct attrib *ap = attrib_locate (alist, 0, name);
  return ap ? ap->value : NULL;
}

static inline char const *
attrib_lookup_ci (struct attrib *alist, char const *name)
{
  struct attrib *ap = attrib_locate (alist, 1, name);
  return ap ? ap->value : NULL;
}


/* Auxiliary function.  Returns 1 if the string STR of length LEN is
   encountered in the NULL-terminated string list STRLIST, and 0 otherwise.
*/
static inline int
is_member_of (char const *str, size_t len, char **strlist)
{
  char const *p;

  if (!strlist)
    return 1;
  while ((p = *strlist) != NULL)
    {
      if (strlen (p) == len && memcmp (p, str, len) == 0)
	return 1;
      strlist++;
    }
  return 0;
}

/*
 * Message name parser.
 *
 * Alphabet:
 *      0   ANY
 *      1   ','
 *      2   '1'
 *      3   '2'
 *      4   ':'
 *      5   '='
 *
 * Transitions:
 *
 *      \      input
 *      state
 *
 *      \  0 1 2 3 4 5
 *      -+ -----------
 *      0| 0 1 0 0 0 0
 *      1| 0 0 2 3 0 0
 *      2| 0 0 0 0 4 0
 *      3| 0 0 0 0 5 0
 *      4| 6 8 6 6 6 8   experimental semantics: any except ,=
 *      5| 6 8 6 6 6 8   flags : any except ,=
 *      6| 6 8 6 6 6 7   consume value; ends at =
 *      7| 7 6 7 7 7 8   consume keyword; ends at ,
 *      8|<stop>
 */

/* Convert input character to alphabet symbol code. */
static inline int
alpha (int input)
{
  switch (input)
    {
    case ',':
      return 1;

    case '1':
      return 2;

    case '2':
      return 3;

    case ':':
      return 4;

    case '=':
      return 5;
    }

  return 0;
}

/* Extract information from the maildir message name NAME.

   Input:
     name      - Message file name.
     attrnames - Pointer to the array of attribute names we are interested in.
		 NULL means all attributes, if attrs is not NULL.

   Output:
     flags     - Parsed out flags.  Can be NULL.
     attrs     - Linked list of extracted attributes.

   If attrs is NULL, no attributes are returned and attrnames is not
   referenced.

   Returns length of the unique name prefix, or (size_t)-1 if memory
   allocation fails.
*/
static size_t
maildir_message_name_parse (char const *name, char **attrnames,
			    int *flags, struct attrib **attrs)
{
  char const *p = name + strlen (name);
  static int transition[][6] = {
    { 0, 1, 0, 0, 0, 0 },
    { 0, 0, 2, 3, 0, 0 },
    { 0, 0, 0, 0, 4, 0 },
    { 0, 0, 0, 0, 5, 0 },
    { 6, 8, 6, 6, 6, 8 },
    { 6, 8, 6, 6, 6, 8 },
    { 6, 8, 6, 6, 6, 7 },
    { 7, 6, 7, 7, 7, 8 },
  };
  int state = 0, oldstate;
  char const *endp = p;
  char const *startval;
  char const *endval = NULL;
  struct attrib *athead = NULL;
  size_t len;
  int f = 0;

  while (p > name)
    {
      p--;
      oldstate = state;
      state = transition[state][alpha(*p)];
      switch (state)
	{
	case 4:
	  endp = p;
	  endval = p;
	  f = 0;
	  break;

	case 5:
	  endp = p;
	  endval = p;
	  f = info_to_flags (p + 3);
	  break;

	case 6:
	  if (oldstate == 7)
	    {
	      len = startval - p - 2;
	      if (attrs && is_member_of (p + 1, len, attrnames))
		{
		  if (!attrib_push (&athead, p + 1, len,
				    startval, endval - startval))
		    {
		      attrib_free (athead);
		      return (size_t)-1;
		    }
		}
	      endp = p;
	      endval = p;
	    }
	  else if (oldstate != state)
	    endval = p + 1;
	  break;

	case 7:
	  if (oldstate != state)
	    startval = p + 1;
	  break;

	case 8:
	  /* error */
	  if (endval)
	    endp = endval;
	  else
	    endp = p + 2;
	  goto end;
	}
    }
 end:
  if (flags)
    *flags = f;
  if (attrs)
    *attrs = athead;
  return endp - name;
}

static void
parse_delivery_id (struct _maildir_message *msg)
{
  size_t n;
  char *p = memchr (msg->file_name, '.', msg->uniq_len);
  unsigned long val;
  char *q;

  errno = 0;
  val = strtoul (msg->file_name, &q, 10);
  if (errno || !(q - p < msg->uniq_len && *q == '.'))
    return;

  msg->tv.tv_sec = val;

  p = q + 1;
  n = msg->uniq_len - (p - msg->file_name);

  if (mu_isdigit (p[0]))
    {
      /* Old-fashioned delivery identifier */
      switch (sscanf (p, "%lu_%lu", &msg->pid, &msg->ndlv))
	{
	case 2:
	  msg->flags |= HAS_PID | HAS_NDLV;
	  break;

	case 1:
	  msg->flags |= HAS_PID;
	}
      return;
    }
  else
    {
      /* Modern delivery identifiers */
      while ((q = mu_str_skip_cset_comp (p, ".MPQ")) != NULL &&
	     q - p < n &&
	     *q != '.')
	{
	  int c = *q;

	  n -= q - p;

	  q++;
	  n--;

	  errno = 0;
	  val = strtoul (q, &p, 10);
	  if (errno == 0)
	    {
	      switch (c)
		{
		case 'M':
		  msg->tv.tv_usec = val;
		  msg->flags |= HAS_USEC;
		  break;

		case 'P':
		  msg->pid = val;
		  msg->flags |= HAS_PID;
		  break;

		case 'Q':
		  msg->ndlv = val;
		  msg->flags |= HAS_NDLV;
		  break;
		}
	    }
	  n -= p - q;
	}
    }
}

static int
compat_from_url (struct _maildir_data *md)
{
  int rc;
  mu_url_t url;
  size_t parmc;
  char **parmv;

  static struct mu_kwd compat_kwd[] = {
    { "detect",  MAILDIR_COMPAT_DETECT },
    { "none",    MAILDIR_COMPAT_NONE },
    { "mu",      MAILDIR_COMPAT_NONE },
    { "isync",   MAILDIR_COMPAT_ISYNC },
    { NULL }
  };

  /* Check if mailbox URL specifies compatibility mode */
  if ((rc = mu_mailbox_get_url (md->amd.mailbox, &url)) == 0)
    {
      if (mu_url_sget_fvpairs (url, &parmc, &parmv) == 0)
	{
	  size_t i;

	  for (i = 0; i < parmc; i++)
	    {
	      int mode;
	      if (mu_kwd_xlat_name (compat_kwd, parmv[i], &mode) == 0)
		return mode;
	    }
	}
    }
  else
    mu_diag_funcall (MU_DIAG_ERROR, "mu_mailbox_get_url", NULL, rc);
  return MAILDIR_COMPAT_DETECT;
}

static int
maildir_open (struct _maildir_data *md)
{
  if (md->folder_fd == -1)
    {
      int fd = open (md->amd.name, O_RDONLY | O_NONBLOCK | O_DIRECTORY);
      if (fd == -1)
	{
	  int rc = errno;
	  mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		    ("can't open directory %s: %s",
		     md->amd.name, mu_strerror (rc)));
	  return rc;
	}
      else
	md->folder_fd = fd;
    }

  if (md->compat == MAILDIR_COMPAT_DETECT &&
      (md->compat = compat_from_url (md)) == MAILDIR_COMPAT_DETECT)
    {
      int fd;

      fd = openat (md->folder_fd, ISYNC_UIDVALIDITY_FILE, O_RDONLY);
      if (fd != -1)
	{
	  FILE *fp;
	  unsigned uidvalidity, nuid;

	  if ((fp = fdopen (fd, "r")) != NULL)
	    {
	      if (fscanf (fp, "%u\n%u", &uidvalidity, &nuid) == 2)
		{
		  amd_update_uidvalidity (&md->amd, uidvalidity);
		  md->next_uid = nuid + 1;
		  amd_update_uidnext (&md->amd, &md->next_uid);
		  md->compat = MAILDIR_COMPAT_ISYNC;
		}
	      fclose (fp);
	    }
	  else
	    mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		      ("fdopen(%s/%s): %s",
		       md->amd.name, ISYNC_UIDVALIDITY_FILE,
		       mu_strerror (errno)));

	}
      else if (errno != ENOENT)
	mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		  ("can't open %s/%s: %s",
		   md->amd.name, ISYNC_UIDVALIDITY_FILE,
		   mu_strerror (errno)));
    }
  return 0;
}

static void
maildir_close (struct _maildir_data *md)
{
  if (md->folder_fd != -1)
    {
      close (md->folder_fd);
      md->folder_fd = -1;
    }
}

static void
isync_meta_update (struct _maildir_data *md)
{
  unsigned long uidvalidity;
  struct _maildir_message *msg = (struct _maildir_message *)
    _amd_get_message (&md->amd, md->amd.msg_count);

  if (msg && amd_get_uidvalidity (md->amd.mailbox, &uidvalidity) == 0)
    {
      int rc;
      FILE *fp;
      char *filename;
      mu_locker_t lck;
      mu_locker_hints_t hints;

      filename = mu_make_file_name (md->amd.name, ISYNC_UIDVALIDITY_FILE);
      if (!filename)
	return;

      hints.type  = MU_LOCKER_TYPE_KERNEL;
      hints.flags = MU_LOCKER_FLAG_TYPE | MU_LOCKER_FLAG_RETRY;
      hints.retry_count = 5;
      hints.retry_sleep = 1;

      if ((rc = mu_locker_create_ext (&lck, filename, &hints)) == 0)
	{
	  if ((rc = mu_locker_lock (lck)) == 0 || rc == ENOENT)
	    {
	      if ((fp = fopen (filename, "w")) != NULL)
		{
		  fprintf (fp, "%lu\n%zu\n", uidvalidity, msg->uid);
		  fclose (fp);
		}
	      else
		mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
			  ("can't open %s: %s",
			   filename, mu_strerror (errno)));
	      if (rc == 0)
		mu_locker_remove_lock (lck);
	    }
	  else
	    mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		      ("can't lock %s: %s",
		       filename, mu_strerror (rc)));
	  mu_locker_destroy (&lck);
	}
      else
	mu_diag_funcall (MU_DEBUG_ERROR, "mu_locker_create_ext", NULL, rc);
      free (filename);
    }
}

static void
maildir_compat_update (struct _maildir_data *md)
{
  if (md->compat == MAILDIR_COMPAT_ISYNC)
    {
      isync_meta_update (md);
    }
}

/* Open subdirectory SUBDIR in MD.
   Note: maildir must be open.
 */
static int
maildir_subdir_open (struct _maildir_data *md, int subdir,
		     DIR **pdir, int *pfd)
{
  int rc;
  int fd;
  DIR *dir;

  fd = openat (md->folder_fd, subdir_name[subdir],
	       O_RDONLY | O_NONBLOCK | O_DIRECTORY);
  if (fd == -1)
    {
      if (errno == ENOENT)
	{
	  int perms = PERMS | mu_stream_flags_to_mode (md->amd.mailbox->flags, 1);
	  if (mkdirat (md->folder_fd, subdir_name[subdir], perms) == 0)
	    {
	      fd = openat (md->folder_fd, subdir_name[subdir],
			   O_RDONLY | O_NONBLOCK | O_DIRECTORY);
	    }
	  else
	    {
	      rc = errno;
	      mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
			("can't create directory %s/%s: %s",
			 md->amd.name, subdir_name[subdir], mu_strerror (rc)));
	      return rc;

	    }
	}

      if (fd == -1)
	{
	  rc = errno;
	  mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		    ("can't open directory %s/%s: %s",
		     md->amd.name, subdir_name[subdir], mu_strerror (rc)));
	  return rc;
	}
    }

  if (pdir)
    {
      dir = fdopendir (fd);
      if (!dir)
	{
	  rc = errno;
	  mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		    ("can't fdopen directory %s/%s: %s",
		     md->amd.name, subdir_name[subdir], mu_strerror (rc)));
	  close (fd);
	  return rc;
	}

      *pdir = dir;
    }
  *pfd = fd;

  return 0;
}

static int
maildir_message_alloc (struct _maildir_data *md, int subdir, char const *name,
		       struct _maildir_message **pmsg)
{
  struct _maildir_message *msg;
  size_t n;
  static char *attrnames[] = { "a", "u", "U", NULL };
  struct attrib *attrs;
  char const *p;

  msg = calloc (1, sizeof (*msg));
  if (!msg)
    return errno;
  msg->subdir = subdir;
  msg->file_name = strdup (name);
  if (!msg->file_name)
    {
      free (msg);
      return ENOMEM;
    }

  n = maildir_message_name_parse (name, attrnames,
				  &msg->amd_message.attr_flags,
				  &attrs);
  if (n == (size_t)-1)
    {
      free (msg->file_name);
      free (msg);
      return ENOMEM;
    }
  msg->uniq_len = n;
  parse_delivery_id (msg);

  if ((p = attrib_lookup (attrs, "a")) != NULL)
    {
      /* NOTICE: mu_attribute_string_to_flags preserves existing bits
	 in its second argument. */
      mu_attribute_string_to_flags (p, &msg->amd_message.attr_flags);
    }

  switch (md->compat)
    {
    case MAILDIR_COMPAT_DETECT:
      if ((p = attrib_lookup (attrs, "U")) != NULL)
	{
	  char *endp;
	  errno = 0;
	  if ((strtoul (p, &endp, 10) == ULONG_MAX && errno == ERANGE)
	      || *endp)
	    {
	      md->compat = MAILDIR_COMPAT_NONE;
	    }
	  else
	    {
	      md->compat = MAILDIR_COMPAT_ISYNC;
	      break;
	    }
	}
      /* FALLTHROUGH */

    case MAILDIR_COMPAT_NONE:
      p = attrib_lookup (attrs, "u");
      break;

    case MAILDIR_COMPAT_ISYNC:
      p = attrib_lookup (attrs, "U");
      break;
    }

  if (p != NULL)
    {
      char *endp;
      unsigned long n;

      errno = 0;
      n = strtoul (p, &endp, 10);
      if ((n == ULONG_MAX && errno == ERANGE) || *endp)
	/* The uid remains set to 0 and will be fixed up later */;
      else
	msg->uid = n;
    }

  attrib_free (attrs);
  *pmsg = msg;
  return 0;
}

static void
maildir_message_free (struct _amd_message *amsg)
{
  struct _maildir_message *mp = (struct _maildir_message *) amsg;
  if (mp)
    free (mp->file_name);
}

/*
 * Maildir scanning
 */
int
maildir_tmp_flush (struct _maildir_data *md)
{
  int rc;
  int fd;
  DIR *dir;
  struct dirent *entry;

  if (!(md->amd.mailbox->flags & MU_STREAM_WRITE))
    return 0; /* Do nothing in read-only mode */

  rc = maildir_subdir_open (md, SUB_TMP, &dir, &fd);
  if (rc)
    return rc;

  while ((entry = readdir (dir)))
    {
      switch (entry->d_name[0])
	{
	case '.':
	  break;

	default:
	  unlinkat (fd, entry->d_name, 0);
	  break;
	}
    }

  closedir (dir);
  return 0;
}

static int
maildir_subdir_scan (struct _maildir_data *md, int subdir, int initial)
{
  int rc;
  int fd;
  DIR *dir;
  struct dirent *entry;

  rc = maildir_subdir_open (md, subdir, &dir, &fd);
  if (rc)
    return rc;

  while ((entry = readdir (dir)))
    {
      struct stat st;
      struct _maildir_message *msg;
      size_t index;

      if (entry->d_name[0] == '.')
	continue;

      if (fstatat (fd, entry->d_name, &st, 0))
	{
	  if (errno != ENOENT)
	    {
	      mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
			("can't stat %s/%s/%s: %s",
			 md->amd.name, subdir_name[subdir], entry->d_name,
			 mu_strerror (errno)));
	    }
	  continue;
	}

      if (!S_ISREG (st.st_mode))
	continue;

      msg = calloc (1, sizeof (*msg));
      if (!msg)
	{
	  rc = ENOMEM;
	  break;
	}

      rc = maildir_message_alloc (md, subdir, entry->d_name, &msg);
      if (rc)
	continue;

      if (!initial &&
	  !amd_msg_lookup (&md->amd, (struct _amd_message *) msg, &index))
	{
	  maildir_message_free ((struct _amd_message *) msg);
	  continue;
	}

      rc = _amd_message_append (&md->amd, (struct _amd_message *) msg);
      if (rc)
	{
	  maildir_message_free ((struct _amd_message *) msg);
	  break;
	}
    }

  closedir (dir);
  return 0;
}

/*
 * Maildir attribute fixup
 * =======================
 *
 * Message info flags used by Mailutils versions prior to 3.10.90 differ
 * from those described in the reference maildir implementation
 * (http://cr.yp.to/proto/maildir.html)
 * This was reported in http://savannah.gnu.org/bugs/?56428.
 *
 * The difference is summarized in the table below:
 *
 *  Attribute              Reference  MU-3.10
 *  ---------------------  ---------  -------
 *  MU_ATTRIBUTE_READ          S         R
 *  MU_ATTRIBUTE_ANSWERED      R         a
 *  MU_ATTRIBUTE_SEEN          -         S
 *
 * The "Attribute" column lists the mailutils attribute flag, the
 * "Reference" column contains the letter that corresponds to that flag
 * in the reference implementation and the "MU-3.10" column shows the
 * letter in mailutils 3.10 and earlier.
 *
 * Starting from version 3.10.90 this discrepancy is fixed.  To make sure
 * both old and new message attributes are correctly recognized, we try
 * to detect whether the mailbox was created by mailutils versions prior to
 * 3.10.90 and fix up the attributes if so.  This is done after the initial
 * mailbox scan.
 *
 * To detect whether attributes need to be fixed, the .mu-prop file is
 * examined.  If it does not exist, it is assumed that the mailbox was
 * not created by mailutils and no fixup is needed.  If it exists and
 * does not contain the "version" property, or if the value of that
 * property is less than or equal to 3.10, then the fixup is needed.
 * Otherwise, fixup is not needed.  This is done by the needs_fixup
 * function.
 *
 * To assist in diagnostics, new AMD flag MU_AMD_F_PROP has been
 * added.  It is set if the .mu-prop file existed when the mailbox
 * was opened.
 *
 * During fixup, the internal attribute flags are changed according to
 * the table above.  If the mailbox is writable, each message file is
 * renamed if its attributes changed.  Otherwise, changes remain
 * in memory.  This is done by the maildir_attribute_fixup function.
 *
 * After successfully opening the (writable) mailbox, the "version"
 * property in its .mu-prop file is updated so that subsequent accesses
 * avoid performing the fixup again.
 *
 * The code below (up to the form feed character) will live for a couple
 * of releases after 3.11 to make sure all existing mailboxes have been
 * fixed up.
 */

static int
needs_fixup (struct _amd_data *amd)
{
  char const *amd_version;
  int rc;

  if (!(amd->flags & MU_AMD_F_PROP))
    {
      /* Absence of the mu-prop file indicates that this mailbox was
	 not created by mailutils (unless the file has been deleted,
	 of course).  Let's assume the former.  This means that no
	 attribute fixup is needed. */
      return 0;
    }

  if (amd->prop)
    {
      switch (mu_property_sget_value (amd->prop, "version", &amd_version))
	{
	case 0:
	  break;

	case MU_ERR_NOENT:
	  return 1;

	default:
	  return 0;
	}
      if (mu_version_string_cmp (amd_version, "3.10", 0, &rc) == 0)
	return rc <= 0;
    }
  return 0;
}

static void
maildir_message_fixup (struct _maildir_data *md, struct _maildir_message *msg,
		       int update)
{
  if (md->needs_attribute_fixup)
    {
      int flags = msg->amd_message.attr_flags;

      if (flags & MU_ATTRIBUTE_READ)
	{
	  flags &= ~MU_ATTRIBUTE_READ;
	  flags |= MU_ATTRIBUTE_SEEN;
	}

      if (flags & MU_ATTRIBUTE_ANSWERED)
	{
	  flags &= ~MU_ATTRIBUTE_ANSWERED;
	  flags |= MU_ATTRIBUTE_READ;
	}

      if (msg->amd_message.attr_flags != flags)
	{
	  msg->amd_message.attr_flags = flags;
	  update = 1;
	}
    }

  if (msg->uid == 0 || msg->uid <= md->cur_uid)
    {
      msg->uid = alloc_uid (md);
      update = 1;
      md->update_uidvalidity = 1;
    }
  else
    update_uid (md, msg->uid);
  md->cur_uid = msg->uid;

  if (update && (md->amd.mailbox->flags & MU_STREAM_WRITE))
    {
      md->amd.chattr_msg (&msg->amd_message, 0);
    }
}

static int
maildir_scan_unlocked (mu_mailbox_t mailbox, size_t *pcount, int do_notify)
{
  struct _maildir_data *md = mailbox->data;
  int rc;
  char const *s;
  struct stat st;
  size_t i;
  int initial = !(md->amd.flags & MU_AMD_F_INIT_SCAN);

  rc = maildir_open (md);
  if (rc)
    return rc;
  md->needs_attribute_fixup = needs_fixup (&md->amd);
  md->update_uidvalidity = 0;
  reset_uid (md);

  /* Flush tmp/ */
  rc = maildir_tmp_flush (md);
  if (rc)
    goto err;

  /* Scan cur/ */
  rc = maildir_subdir_scan (md, SUB_CUR, initial);
  if (rc)
    goto err;

  /* Scan new/ */
  rc = maildir_subdir_scan (md, SUB_NEW, initial);
  if (rc)
    goto err;

  if (md->compat == MAILDIR_COMPAT_DETECT)
    md->compat = MAILDIR_COMPAT_NONE;

  /* Sort messages */
  amd_sort (&md->amd);

  /* Fix up messages and send out dispatch notifications, if necessary. */
  for (i = 1; i <= md->amd.msg_count; i++)
    {
      struct _maildir_message *msg = (struct _maildir_message *)
	_amd_get_message (&md->amd, i);
      int force_chattr = 0;

      if (msg->subdir == SUB_NEW)
	{
	  if (msg->uid == 0)
	    {
	      amd_update_uidnext (&md->amd, &md->next_uid);
	      msg->uid = alloc_uid (md);
	    }
	  force_chattr = 1;
	}
      maildir_message_fixup (md, msg, force_chattr);
      if (do_notify)
	DISPATCH_ADD_MSG (mailbox, &md->amd, i);
    }

  /* Update predicted next UID either way */
  amd_update_uidnext (&md->amd, &md->next_uid);

  /* Reset uidvalidity if any of the UIDs changed */
  if (md->update_uidvalidity)
    {
      amd_reset_uidvalidity (&md->amd);
      maildir_compat_update (md);
      md->update_uidvalidity = 0;
    }

  /* Update version marker in the property file */
  if ((md->amd.mailbox->flags & MU_STREAM_WRITE) &&
      (mu_property_sget_value (md->amd.prop, "version", &s) ||
       strcmp (s, PACKAGE_VERSION)))
    {
      rc = mu_property_set_value (md->amd.prop, "version", PACKAGE_VERSION, 1);
      if (rc)
	{
	  mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		    ("maildir_scan_dir: mu_property_set_value failed during attribute fixup: %s",
		     mu_strerror (rc)));
	}
    }

  if (md->amd.mailbox->flags & MU_STREAM_WRITE)
    {
      rc = mu_property_save (md->amd.prop);
      if (rc)
	{
	  mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		    ("maildir_scan_dir: mu_property_save failed during attribute fixup: %s",
		     mu_strerror (rc)));
	}
      rc = 0;
    }

  if (stat (md->amd.name, &st) == 0)
    md->amd.mtime = st.st_mtime;
  else
    md->amd.mtime = time (NULL);
  if (rc == 0 && pcount)
    *pcount = md->amd.msg_count;

 err:
  maildir_close (md);

  return rc;
}

/*
 * Functions for generating the unique part of the filename.
 */

/* Auxiliary functions operate on a buffer of the following structure: */
struct string_buffer
{
  char *base;   /* Buffer pointer. */
  size_t size;  /* Number of bytes allocated for base. */
  size_t off;   /* Offset of the first uninitialized byte. */
};

#define STRING_BUFFER_INITIALIZER { NULL, 0, 0 }

static void
string_buffer_free (struct string_buffer *buf)
{
  free (buf->base);
}

/* Expand the buffer to approx. 3/2 of its current size. */
static int
string_buffer_expand (struct string_buffer *buf)
{
  size_t n;
  char *p;

  if (!buf->base)
    {
      n = 64;
    }
  else
    {
      n = buf->size;

      if ((size_t) -1 / 3 * 2 <= n)
	return ENOMEM;

      n += (n + 1) / 2;
    }
  p = realloc (buf->base, n);
  if (!p)
    return ENOMEM;
  buf->base = p;
  buf->size = n;
  return 0;
}

/* Append LEN bytes from S to the buffer. */
static int
string_buffer_append (struct string_buffer *buf, char const *s, size_t len)
{
  while (buf->off + len > buf->size)
    {
      if (string_buffer_expand (buf))
	return ENOMEM;
    }
  memcpy (buf->base + buf->off, s, len);
  buf->off += len;
  return 0;
}

/* Append nul-terminated string S. */
static inline int
string_buffer_appendz (struct string_buffer *buf, char const *s)
{
  return string_buffer_append (buf, s, strlen (s));
}

static char const digits[] = "0123456789ABCDEF";

/* Format the number N to the buffer.  BASE must be 10 or 16, no other
   value is allowed. */
static int
string_buffer_format_long (struct string_buffer *buf, unsigned long n,
			   int base)
{
  size_t start = buf->off;
  char *p, *q;
  do
    {
      if (string_buffer_append (buf, &digits[n % base], 1))
	return ENOMEM;
      n /= base;
    }
  while (n > 0);
  p = buf->base + start;
  q = buf->base + buf->off - 1;
  while (p < q)
    {
      int t = *q;
      *q = *p;
      *p = t;
      p++;
      q--;
    }
  return 0;
}

/* Format this host name to the buffer. */
static int
string_buffer_format_hostname (struct string_buffer *buf)
{
  size_t start = buf->off;
  size_t len, i;

  while (gethostname (buf->base + buf->off, buf->size - buf->off) != 0)
    {
      if (errno != 0 && errno != ENAMETOOLONG && errno != EINVAL
	  && errno != ENOMEM)
	return errno;
      if (string_buffer_expand (buf))
	return ENOMEM;
    }

  len = strlen (buf->base + buf->off);
  buf->off += len;

  /* encode '/', ':', '.', and ',' */
  for (i = start; i < buf->off; i++)
    {
      switch (buf->base[i])
	{
	case '/':
	case ':':
	case ',':
	  break;

	default:
	  continue;
	}

      while (buf->off + 3 > buf->size)
	{
	  if (string_buffer_expand (buf))
	    return ENOMEM;
	}
      memmove (buf->base + i + 4, buf->base + i + 1, buf->off - i - 1);
      buf->base[i+1] = digits[(buf->base[i] >> 6) & 7];
      buf->base[i+2] = digits[(buf->base[i] >> 3) & 7];
      buf->base[i+3] = digits[buf->base[i] & 7];
      buf->base[i] = '\\';
      i += 3;
      buf->off += 3;
    }

  return 0;
}

/* Format message flags to buffer. */
static int
string_buffer_format_flags (struct string_buffer *buf, int flags)
{
  int rc;
  char fbuf[info_map_size + 1];

  flags_to_info (flags, fbuf);
  if ((rc = string_buffer_append (buf, ":2,", 3)) != 0)
    return rc;
  return string_buffer_appendz (buf, fbuf);
}

/* Format mailutils-specific attribute flags to the string buffer.
   Mailutils-specific flags are the flags that have no corresponding
   info letter in the maildir memo.  These flags are encoded in the
   'a' attribute setting.
*/
static int
string_buffer_format_mu_flags (struct string_buffer *buf, int flags)
{
  int rc = 0;
  char fb[MU_STATUS_BUF_SIZE];
  size_t len;

  mu_attribute_flags_to_string (flags & (MU_ATTRIBUTE_FLAGGED|MU_ATTRIBUTE_SEEN),
				fb, sizeof (fb), &len);
  if (len > 0)
    {
      if ((rc = string_buffer_append (buf, ",a=", 3)) == 0)
	rc = string_buffer_append (buf, fb, len);
    }
  return rc;
}

static inline struct _maildir_data *
message_maildir (struct _maildir_message *msg)
{
  return (struct _maildir_data *)msg->amd_message.amd;
}

static int
string_buffer_format_message_name (struct string_buffer *buf,
				   struct _maildir_message *msg,
				   int flags)
{
  static char *uidattr[] = { "u", "U" };
  struct _maildir_data *md = message_maildir (msg);

  return string_buffer_append (buf, msg->file_name, msg->uniq_len) ||
	  string_buffer_format_mu_flags (buf, flags) ||
	  string_buffer_append (buf, ",", 1) ||
	  string_buffer_append (buf,
				uidattr[md->compat == MAILDIR_COMPAT_ISYNC],
				1) ||
	  string_buffer_append (buf, "=", 1) ||
	  string_buffer_format_long (buf, msg->uid, 10) ||
	  string_buffer_format_flags (buf, flags);
}

enum
  {
    FMT_OUT,
    FMT_IF,
    FMT_ELSE,
    FMT_ENDIF,
    FMT_END
  };

struct delivery
{
  struct _maildir_data *md;
  struct timeval tv;
  unsigned long rv;
  struct stat st;
  int fd;
};

struct format_part
{
  int type;
  int (*form) (struct string_buffer *sb, struct delivery *dlv, void *data);
  void *data;
};

#define MAXCOND 3

static int
maildir_format (struct string_buffer *sb,
		struct format_part const *fmt, struct delivery *dlv)
{
  int rc;
  int t[MAXCOND] = { 1 };
  int tos = 0;

  for (; fmt->type != FMT_END; fmt++)
    {
      switch (fmt->type)
	{
	case FMT_OUT:
	  if (t[tos] && (rc = fmt->form (sb, dlv, fmt->data)) != 0)
	    return rc;
	  break;

	case FMT_IF:
	  if (++tos == MAXCOND)
	    return ERANGE;
	  if (t[tos-1])
	    {
	      if ((rc = fmt->form (sb, dlv, fmt->data)) != 0 && rc != 1)
		return rc;
	    }
	  else
	    rc = 0;
	  t[tos] = rc;
	  break;

	case FMT_ELSE:
	  t[tos] = !t[tos];
	  break;

	case FMT_ENDIF:
	  if (tos == 0)
	    return ERANGE;
	  --tos;
	  break;
	}
    }
  return string_buffer_append (sb, "", 1);
}

static int
form_string (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_append (sb, data, strlen (data));
}

static int
form_sec (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_long (sb, (unsigned long) dlv->tv.tv_sec, 10);
}

static int
form_usec (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_long (sb, (unsigned long) dlv->tv.tv_usec, 10);
}

static int
read_random (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  ssize_t rc;
  unsigned long n;

  int fd = open ("/dev/urandom", O_RDONLY);
  if (fd == -1)
    return 0;
  rc = read (fd, &n, sizeof (n));
  close (fd);
  if (rc != sizeof (n))
    return 0;
  dlv->rv = n;
  return 1;
}

static int
form_reg (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_long (sb, dlv->rv, 16);
}

static int
cond_fdvalid (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return dlv->fd >= 0;
}

static int
cond_compat_none (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return dlv->md->compat == MAILDIR_COMPAT_NONE;
}

static int
form_ino (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_long (sb, dlv->st.st_ino, 16);
}

static int
form_dev (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_long (sb, dlv->st.st_dev, 16);
}

static int
form_pid (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_long (sb, getpid (), 10);
}

static int
form_deliv (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_long (sb, dlv->md->amd.msg_count, 10);
}

static int
form_hostname (struct string_buffer *sb, struct delivery *dlv, void *data)
{
  return string_buffer_format_hostname (sb);
}

/* Create unique part.  If FD is supplied, use its inode and dev numbers
   as part of the created string.  Return the allocated string or NULL on
   memory shortage.
 */
static char *
maildir_uniq_create (struct _amd_data *amd, int fd)
{
  static struct format_part fmt[] = {
    /* Common part */
    { FMT_OUT, form_sec },
    { FMT_OUT, form_string, "." },

    { FMT_IF,  cond_compat_none },

    /* Modern delivery ID */
    { FMT_IF,  read_random },
    { FMT_OUT, form_string, "R" },
    { FMT_OUT, form_reg },
    { FMT_ENDIF },
    { FMT_IF,  cond_fdvalid },
    { FMT_OUT, form_string, "I" },
    { FMT_OUT, form_ino },
    { FMT_OUT, form_string, "V" },
    { FMT_OUT, form_dev },
    { FMT_ENDIF },
    { FMT_OUT, form_string, "M" },
    { FMT_OUT, form_usec },
    { FMT_OUT, form_string, "P" },
    { FMT_OUT, form_pid },
    { FMT_OUT, form_string, "Q" },

    { FMT_ELSE },

    /* Old-fashionable ID */
    { FMT_OUT, form_pid },
    { FMT_OUT, form_string, "_" },

    { FMT_ENDIF },

    { FMT_OUT, form_deliv },
    { FMT_OUT, form_string, "." },
    { FMT_OUT, form_hostname },
    { FMT_END }
  };
  struct string_buffer sb = STRING_BUFFER_INITIALIZER;
  struct delivery dlv;

  memset (&dlv, 0, sizeof (dlv));
  dlv.md = (struct _maildir_data *)amd;
  gettimeofday (&dlv.tv, NULL);
  if (fd > 0 && fstat (dlv.fd, &dlv.st))
    dlv.fd = fd;
  else
    dlv.fd = -1;

  if (maildir_format (&sb, fmt, &dlv))
    {
      mu_diag_funcall (MU_DEBUG_ERROR, __func__, NULL, errno);
      string_buffer_free (&sb);
      return NULL;
    }
  return sb.base;
}

/*
 * AMD interface functions.
 */
static int
maildir_cur_message_name (struct _amd_message *amsg, int abs, char **pname)
{
  struct _maildir_message *msg = (struct _maildir_message *) amsg;
  struct string_buffer sb = STRING_BUFFER_INITIALIZER;
  int rc;

  if (abs)
    {
      if ((rc = string_buffer_appendz (&sb, amsg->amd->name)) == 0)
	rc = string_buffer_append (&sb, "/", 1);
    }
  else
    rc = 0;

  if (rc == 0 &&
      (rc = string_buffer_appendz (&sb, subdir_name[msg->subdir])) == 0 &&
      (rc = string_buffer_append (&sb, "/", 1)) == 0 &&
      (rc = string_buffer_appendz (&sb, msg->file_name)) == 0 &&
      (rc = string_buffer_append (&sb, "", 1)) == 0)
    {
      *pname = sb.base;
      sb.base = NULL;
    }
  string_buffer_free (&sb);
  return rc;
}

static int
maildir_new_message_name (struct _amd_message *amsg, int flags, int expunge,
			  char **pname)
{
  struct _maildir_message *msg = (struct _maildir_message *) amsg;
  int rc = 0;

  if (expunge && (flags & MU_ATTRIBUTE_DELETED))
    {
      /* Force amd.c to unlink the file. */
      *pname = NULL;
    }
  else
    {
      struct string_buffer sb = STRING_BUFFER_INITIALIZER;
      if ((rc = string_buffer_appendz (&sb, amsg->amd->name) ||
		 string_buffer_append (&sb, "/", 1) ||
		 string_buffer_appendz (&sb, subdir_name[msg->subdir]) ||
		 string_buffer_append (&sb, "/", 1)) == 0)
	{
	  if (msg->subdir == SUB_TMP)
	    rc = string_buffer_appendz (&sb, msg->file_name);
	  else
	    rc = string_buffer_format_message_name (&sb, msg, flags);
	  if (rc == 0)
	    rc = string_buffer_append (&sb, "", 1);
	}
      if (rc == 0)
	*pname = sb.base;
      else
	string_buffer_free (&sb);
    }
  return rc;
}

static int
maildir_create (struct _amd_data *amd, int flags)
{
  int rc;
  struct _maildir_data *md = (struct _maildir_data *)amd;

  rc = maildir_open (md);
  if (rc == 0)
    {
      int i;

      reset_uid (md);
      for (i = 0; i < MU_ARRAY_SIZE (subdir_name); i++)
	{
	  int fd;
	  rc = maildir_subdir_open (md, i, NULL, &fd);
	  if (rc)
	    break;
	  close (fd);
	}
      maildir_close (md);
    }

  return rc;
}

static int
maildir_msg_finish_delivery (struct _amd_data *amd, struct _amd_message *amm,
			     const mu_message_t orig_msg,
			     mu_attribute_t atr)
{
  struct _maildir_data *md = (struct _maildir_data *)amd;
  struct _maildir_message *msg = (struct _maildir_message *) amm;
  int flags;
  int rc;
  int src_fd = -1, dst_fd = -1;
  struct string_buffer sb = STRING_BUFFER_INITIALIZER;
  char const *newname;

  if ((atr || mu_message_get_attribute (orig_msg, &atr) == 0)
      && mu_attribute_get_flags (atr, &flags) == 0
      && flags)
    {
      msg->subdir = SUB_CUR;
    }
  else
    {
      msg->subdir = SUB_NEW;
    }

  rc = string_buffer_format_message_name (&sb, msg, flags);
  if (rc == 0)
    rc = string_buffer_append (&sb, "", 1);
  if (rc)
    {
      string_buffer_free (&sb);
      return rc;
    }
  newname = sb.base;

  rc = maildir_open (md);
  if (rc)
    goto err;

  rc = maildir_subdir_open (md, SUB_TMP, NULL, &src_fd);
  if (rc)
    goto err;

  rc = maildir_subdir_open (md, msg->subdir, NULL, &dst_fd);
  if (rc)
    goto err;

  if (unlinkat (dst_fd, newname, 0) && errno != ENOENT)
    {
      rc = errno;
      mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		("can't unlink %s/%s/%s: %s",
		 amd->name, subdir_name[msg->subdir],
		 newname, mu_strerror (rc)));
    }
  else if (linkat (src_fd, msg->file_name, dst_fd, newname, 0) == 0)
    {
      if (unlinkat (src_fd, msg->file_name, 0))
	{
	  mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		    ("can't unlink %s/%s/%s: %s",
		     amd->name, subdir_name[SUB_TMP], msg->file_name,
		     mu_strerror (errno)));
	}

      if (strcmp (msg->file_name, newname))
	{
	  char *p = strdup (newname);
	  if (!p)
	    rc = errno;
	  else
	    {
	      free (msg->file_name);
	      msg->file_name = p;
	      /* uniq_len remains the same */
	    }
	}
      amd_update_uidnext (&md->amd, &md->next_uid);
      maildir_compat_update (md);
    }
  else
    {
      rc = errno;

      mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
		("renaming %s/%s to %s/%s in %s failed: %s",
		 subdir_name[SUB_TMP], msg->file_name,
		 subdir_name[msg->subdir], newname,
		 amd->name, mu_strerror (rc)));
    }

 err:
  string_buffer_free (&sb);
  close (src_fd);
  close (dst_fd);
  maildir_close (md);

  return rc;
}

static int
maildir_scan0 (mu_mailbox_t mailbox, size_t msgno MU_ARG_UNUSED,
	       size_t *pcount, int do_notify)
{
  struct _amd_data *amd = mailbox->data;
  int rc;

  if (amd == NULL)
    return EINVAL;
  mu_monitor_wrlock (mailbox->monitor);
  rc = maildir_scan_unlocked (mailbox, pcount, do_notify);
  mu_monitor_unlock (mailbox->monitor);
  return rc;
}

static int
maildir_qfetch (struct _amd_data *amd, mu_message_qid_t qid)
{
  struct _maildir_data *md = (struct _maildir_data *)amd;
  struct _maildir_message *msg;
  char *name = (char*)qid;
  char *p;
  int rc;
  int subdir;
  struct stat st;

  p = strrchr (name, '/');
  if (!p || p - qid != 3)
    return EINVAL;

  if (memcmp (name, subdir_name[SUB_CUR], strlen (subdir_name[SUB_CUR])) == 0)
    subdir = SUB_CUR;
  else if (memcmp (name, subdir_name[SUB_NEW], strlen (subdir_name[SUB_NEW])) == 0)
    subdir = SUB_NEW;
  else
    return EINVAL;

  rc = maildir_open (md);
  if (fstatat (md->folder_fd, name, &st, 0) == 0)
    {
      name = p + 1;

      rc = maildir_message_alloc (md, subdir, name, &msg);
      if (rc == 0)
	{
	  rc = _amd_message_insert (amd, (struct _amd_message*) msg);
	  if (rc)
	    maildir_message_free ((struct _amd_message*) msg);
	}
    }
  else
    rc = errno;

  maildir_close (md);

  return rc;
}

/*
 * Compare two maildir messages A and B.  The purpose is to determine
 * which one was delivered prior to another.
 *
 * Compare seconds, microseconds and number of deliveries (if both messages
 * were delivered by the same process), in that order.  If all match,
 * compare UIDs (if set).  Otherwise, resort to lexicographical comparison. (FIXME)
 *
 */
static int
maildir_message_cmp (struct _amd_message *a, struct _amd_message *b)
{
  struct _maildir_message *ma = (struct _maildir_message *) a;
  struct _maildir_message *mb = (struct _maildir_message *) b;

  if (ma->tv.tv_sec > mb->tv.tv_sec)
    return 1;
  if (ma->tv.tv_sec < mb->tv.tv_sec)
    return -1;

  if ((ma->flags & HAS_USEC) && (mb->flags & HAS_USEC))
    {
      if (ma->tv.tv_usec > mb->tv.tv_usec)
	return 1;
      if (ma->tv.tv_usec < mb->tv.tv_usec)
	return -1;
    }

  if ((ma->flags & HAS_PID) && (mb->flags & HAS_PID) &&
      ma->pid == mb->pid &&
      (ma->flags & HAS_NDLV) && (mb->flags & HAS_NDLV))
    {
      if (ma->ndlv > mb->ndlv)
	return 1;
      if (ma->ndlv < mb->ndlv)
	return -1;
    }

  if (ma->uid && mb->uid)
    {
      if (ma->uid > mb->uid)
	return 1;
      if (ma->uid < mb->uid)
	return -1;
    }

  return 0;
}

static int
maildir_message_uid (mu_message_t msg, size_t *puid)
{
  struct _maildir_message *mp = mu_message_get_owner (msg);
  if (puid)
    *puid = mp->uid;
  return 0;
}

static int
maildir_remove (struct _amd_data *amd)
{
  int i;
  int rc = 0;
  struct string_buffer sb = STRING_BUFFER_INITIALIZER;
  size_t off;

  /* FIXME: amd_remove_dir requires absolute file names */
  if ((rc = string_buffer_appendz (&sb, amd->name)) == 0 &&
      (rc = string_buffer_append (&sb, "/", 1)) == 0)
    {
      off = sb.off;
      for (i = 0; i < MU_ARRAY_SIZE (subdir_name); i++)
	{
	  string_buffer_appendz (&sb, subdir_name[i]);
	  string_buffer_append (&sb, "", 1);

	  rc = amd_remove_dir (sb.base);
	  if (rc)
	    {
	      mu_diag_output (MU_DIAG_WARNING,
			      "removing contents of %s failed: %s", sb.base,
			      mu_strerror (rc));
	      break;
	    }
	  sb.off = off;
	}
    }
  string_buffer_free (&sb);
  return rc;
}

static int
maildir_chattr_msg (struct _amd_message *amsg, int expunge)
{
  struct _maildir_message *mp = (struct _maildir_message *) amsg;
  struct _amd_data *amd = amsg->amd;
  int rc;
  int old_subdir;
  char *cur_name, *new_name;

  rc = maildir_cur_message_name (amsg, 1, &cur_name);
  if (rc)
    return rc;

  old_subdir = mp->subdir;
  mp->subdir = SUB_CUR;
  rc = amd->new_msg_file_name (amsg, amsg->attr_flags, expunge, &new_name);
  if (rc == 0)
    {
      if (!new_name)
	{
	  if (unlink (mp->file_name))
	    {
	      rc = errno;
	      mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
			("can't unlink %s: %s",
			 mp->file_name, mu_strerror (rc)));
	    }
	}
      else
	{
	  if (rename (cur_name, new_name))
	    {
	      rc = errno;
	      if (rc == ENOENT)
		mu_observable_notify (amd->mailbox->observable,
				      MU_EVT_MAILBOX_CORRUPT,
				      amd->mailbox);
	      else
		{
		  mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
			    ("renaming %s to %s failed: %s",
			     cur_name, new_name, mu_strerror (rc)));
		}
	    }
	}
      if (rc)
	mp->subdir = old_subdir;
      else
	{
	  free (mp->file_name);
	  mp->file_name = strdup (strrchr (new_name, '/') + 1);
	  if (!mp->file_name)
	    rc = errno;
	  else
	    {
	      mp->uniq_len = maildir_message_name_parse (mp->file_name,
							 NULL, NULL, NULL);
	      parse_delivery_id (mp);
	    }
	}
      free (new_name);
    }

  free (cur_name);

  return rc;
}

/* Compute size of the subdirectory SUBDIR.  Add the computed value to
   *PSIZE.
   Note: Maildir must be open. */
static int
maildir_subdir_size (struct _maildir_data *md, int subdir, mu_off_t *psize)
{
  int fd;
  DIR *dir;
  struct dirent *entry;
  int rc = 0;
  struct stat st;
  mu_off_t size = 0;

  rc = maildir_subdir_open (md, subdir, &dir, &fd);
  if (rc)
    return rc;

  while ((entry = readdir (dir)))
    {
      switch (entry->d_name[0])
	{
	case '.':
	  break;

	default:
	  if (fstatat (fd, entry->d_name, &st, 0))
	    {
	      mu_debug (MU_DEBCAT_MAILBOX, MU_DEBUG_ERROR,
			("can't stat %s/%s/%s: %s",
			 md->amd.name, subdir_name[subdir], entry->d_name,
			 mu_strerror (errno)));
	      continue;
	    }
	  if (S_ISREG (st.st_mode))
	    size += st.st_size;
	}
    }

  closedir (dir);
  *psize += size;

  return 0;
}

static int
maildir_size_unlocked (struct _amd_data *amd, mu_off_t *psize)
{
  struct _maildir_data *md = (struct _maildir_data *) amd;
  mu_off_t size = 0;
  int rc;

  rc = maildir_open (md);
  if (rc == 0)
    {
      rc = maildir_subdir_size (md, SUB_NEW, &size);
      if (rc == 0)
	{
	  rc = maildir_subdir_size (md, SUB_CUR, &size);
	  if (rc == 0)
	    *psize = size;
	}
      maildir_close (md);
    }
  return rc;
}

static int
maildir_size (mu_mailbox_t mailbox, mu_off_t *psize)
{
  struct _amd_data *amd = mailbox->data;
  int rc;

  if (amd == NULL)
    return EINVAL;

  mu_monitor_wrlock (mailbox->monitor);
  rc = maildir_size_unlocked (amd, psize);
  mu_monitor_unlock (mailbox->monitor);

  return rc;
}

/* Delivery to "dir/new" */
#define NTRIES 30

static int
maildir_msg_init (struct _amd_data *amd, struct _amd_message *amm)
{
  struct _maildir_data *md = (struct _maildir_data *)amd;
  struct _maildir_message *msg = (struct _maildir_message *) amm;
  struct stat st;
  int i;
  int rc;
  char *name = NULL;
  int fd;

  rc = maildir_open (md);
  if (rc == 0)
    {
      rc = maildir_subdir_open (md, SUB_TMP, NULL, &fd);
      if (rc == 0)
	{
	  name = maildir_uniq_create (amd, -1);
	  rc = EAGAIN;
	  for (i = NTRIES; i > 0; i--)
	    {
	      if (fstatat (fd, name, &st, 0) == 0)
		{
		  mu_diag_output (MU_DIAG_WARNING,
				  "%s/%s/%s exists during delivery",
				  md->amd.name, subdir_name[SUB_TMP], name);
		  if (i > 1)
		    sleep (2);
		}
	      else if (errno == ENOENT)
		{
		  msg->subdir = SUB_TMP;
		  msg->uid = alloc_uid (md);
		  msg->file_name = name;
		  msg->uniq_len = strlen (name);
		  parse_delivery_id (msg);
		  name = NULL;
		  rc = 0;
		  break;
		}
	      else
		{
		  mu_diag_output (MU_DIAG_WARNING, "cannot stat %s/%s/%s: %s",
				  md->amd.name, subdir_name[SUB_TMP], name,
				  mu_strerror (errno));
		  break;
		}
	    }
	  close (fd);
	}
      maildir_close (md);
    }
  free (name);
  return rc;
}

int
_mailbox_maildir_init (mu_mailbox_t mailbox)
{
  int rc;
  struct _amd_data *amd;
  struct _maildir_data *md;

  rc = amd_init_mailbox (mailbox, sizeof (struct _maildir_data), &amd);
  if (rc)
    return rc;

  amd->msg_size = sizeof (struct _maildir_message);
  amd->msg_free = maildir_message_free;
  amd->create = maildir_create;
  amd->msg_init_delivery = maildir_msg_init;
  amd->msg_finish_delivery = maildir_msg_finish_delivery;
  amd->cur_msg_file_name = maildir_cur_message_name;
  amd->new_msg_file_name = maildir_new_message_name;
  amd->scan0 = maildir_scan0;
  amd->qfetch = maildir_qfetch;
  amd->msg_cmp = maildir_message_cmp;
  amd->message_uid = maildir_message_uid;
  amd->remove = maildir_remove;
  amd->chattr_msg = maildir_chattr_msg;
  amd->capabilities = MU_AMD_STATUS;
  amd->mailbox_size = maildir_size;

  /* Set our properties.  */
  {
    mu_property_t property = NULL;
    mu_mailbox_get_property (mailbox, &property);
    mu_property_set_value (property, "TYPE", "MAILDIR", 1);
  }

  md = (struct _maildir_data *) amd;
  md->folder_fd = -1;

  return 0;
}