path: root/imap/src/osdep/unix/unix.c

/* ========================================================================
 * Copyright 1988-2008 University of Washington
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 
 * ========================================================================
 */

/*
 * Program:	UNIX mail routines
 *
 * Author:	Mark Crispin
 *		UW Technology
 *		University of Washington
 *		Seattle, WA  98195
 *		Internet: MRC@Washington.EDU
 *
 * Date:	20 December 1989
 * Last Edited:	June 13 2018 by Eduardo Chappa
 */


/*				DEDICATION
 *
 *  This file is dedicated to my dog, Unix, also known as Yun-chan and
 * Unix J. Terwilliker Jehosophat Aloysius Monstrosity Animal Beast.  Unix
 * passed away at the age of 11 1/2 on September 14, 1996, 12:18 PM PDT, after
 * a two-month bout with cirrhosis of the liver.
 *
 *  He was a dear friend, and I miss him terribly.
 *
 *  Lift a leg, Yunie.  Luv ya forever!!!!
 */

#include <stdio.h>
#include <ctype.h>
#include <errno.h>
extern int errno;		/* just in case */
#include <signal.h>
#include "mail.h"
#include "osdep.h"
#include <time.h>
#include <sys/stat.h>
#include "unix.h"
#include "pseudo.h"
#include "fdstring.h"
#include "misc.h"
#include "dummy.h"

/* UNIX I/O stream local data */

typedef struct unix_local {
  unsigned int dirty : 1;	/* disk copy needs updating */
  unsigned int ddirty : 1;	/* double-dirty, ping becomes checkpoint */
  unsigned int pseudo : 1;	/* uses a pseudo message */
  unsigned int appending : 1;	/* don't mark new messages as old */
  int fd;			/* mailbox file descriptor */
  int ld;			/* lock file descriptor */
  char *lname;			/* lock file name */
  off_t filesize;		/* file size parsed */
  time_t filetime;		/* last file time */
  time_t lastsnarf;		/* last snarf time (for mbox driver) */
  unsigned char *buf;		/* temporary buffer */
  unsigned long buflen;		/* current size of temporary buffer */
  unsigned long uid;		/* current text uid */
  SIZEDTEXT text;		/* current text */
  unsigned long textlen;	/* current text length */
  char *line;			/* returned line */
  char *linebuf;		/* line readin buffer */
  unsigned long linebuflen;	/* current line readin buffer length */
} UNIXLOCAL;


/* Convenient access to local data */

#define LOCAL ((UNIXLOCAL *) stream->local)


/* UNIX protected file structure */

typedef struct unix_file {
  MAILSTREAM *stream;		/* current stream */
  off_t curpos;			/* current file position */
  off_t protect;		/* protected position */
  off_t filepos;		/* current last written file position */
  char *buf;			/* overflow buffer */
  size_t buflen;		/* current overflow buffer length */
  char *bufpos;			/* current buffer position */
} UNIXFILE;

/* Function prototypes */

DRIVER *unix_valid (char *name);
long unix_isvalid_fd (int fd);
void *unix_parameters (long function,void *value);
void unix_scan (MAILSTREAM *stream,char *ref,char *pat,char *contents);
void unix_list (MAILSTREAM *stream,char *ref,char *pat);
void unix_lsub (MAILSTREAM *stream,char *ref,char *pat);
long unix_create (MAILSTREAM *stream,char *mailbox);
long unix_delete (MAILSTREAM *stream,char *mailbox);
long unix_rename (MAILSTREAM *stream,char *old,char *newname);
MAILSTREAM *unix_open (MAILSTREAM *stream);
void unix_close (MAILSTREAM *stream,long options);
char *unix_header (MAILSTREAM *stream,unsigned long msgno,
		   unsigned long *length,long flags);
long unix_text (MAILSTREAM *stream,unsigned long msgno,STRING *bs,long flags);
char *unix_text_work (MAILSTREAM *stream,MESSAGECACHE *elt,
		      unsigned long *length,long flags);
void unix_flagmsg (MAILSTREAM *stream,MESSAGECACHE *elt);
long unix_ping (MAILSTREAM *stream);
void unix_check (MAILSTREAM *stream);
long unix_expunge (MAILSTREAM *stream,char *sequence,long options);
long unix_copy (MAILSTREAM *stream,char *sequence,char *mailbox,long options);
long unix_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data);
int unix_collect_msg (MAILSTREAM *stream,FILE *sf,char *flags,char *date,
		     STRING *msg);
int unix_append_msgs (MAILSTREAM *stream,FILE *sf,FILE *df,SEARCHSET *set);

void unix_abort (MAILSTREAM *stream);
char *unix_file (char *dst,char *name);
int unix_lock (char *file,int flags,int mode,DOTLOCK *lock,int op);
void unix_unlock (int fd,MAILSTREAM *stream,DOTLOCK *lock);
int unix_parse (MAILSTREAM *stream,DOTLOCK *lock,int op);
char *unix_mbxline (MAILSTREAM *stream,STRING *bs,unsigned long *size);
unsigned long unix_pseudo (MAILSTREAM *stream,char *hdr);
unsigned long unix_xstatus (MAILSTREAM *stream,char *status,MESSAGECACHE *elt,
			    unsigned long uid,long flag);
long unix_rewrite (MAILSTREAM *stream,unsigned long *nexp,DOTLOCK *lock,
		   long flags);
long unix_extend (MAILSTREAM *stream,unsigned long size);
void unix_write (UNIXFILE *f,char *s,unsigned long i);
void unix_phys_write (UNIXFILE *f,char *buf,size_t size);

/* mbox mail routines */

/* Function prototypes */

DRIVER *mbox_valid (char *name);
long mbox_create (MAILSTREAM *stream,char *mailbox);
long mbox_delete (MAILSTREAM *stream,char *mailbox);
long mbox_rename (MAILSTREAM *stream,char *old,char *newname);
long mbox_status (MAILSTREAM *stream,char *mbx,long flags);
MAILSTREAM *mbox_open (MAILSTREAM *stream);
long mbox_ping (MAILSTREAM *stream);
void mbox_check (MAILSTREAM *stream);
long mbox_expunge (MAILSTREAM *stream,char *sequence,long options);
long mbox_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data);


/* UNIX mail routines */


/* Driver dispatch used by MAIL */

DRIVER unixdriver = {
  "unix",			/* driver name */
				/* driver flags */
  DR_LOCAL|DR_MAIL|DR_LOCKING|DR_NONEWMAILRONLY|DR_XPOINT,
  (DRIVER *) NIL,		/* next driver */
  unix_valid,			/* mailbox is valid for us */
  unix_parameters,		/* manipulate parameters */
  unix_scan,			/* scan mailboxes */
  unix_list,			/* list mailboxes */
  unix_lsub,			/* list subscribed mailboxes */
  NIL,				/* subscribe to mailbox */
  NIL,				/* unsubscribe from mailbox */
  unix_create,			/* create mailbox */
  unix_delete,			/* delete mailbox */
  unix_rename,			/* rename mailbox */
  mail_status_default,		/* status of mailbox */
  unix_open,			/* open mailbox */
  unix_close,			/* close mailbox */
  NIL,				/* fetch message "fast" attributes */
  NIL,				/* fetch message flags */
  NIL,				/* fetch overview */
  NIL,				/* fetch message envelopes */
  unix_header,			/* fetch message header */
  unix_text,			/* fetch message text */
  NIL,				/* fetch partial message text */
  NIL,				/* unique identifier */
  NIL,				/* message number */
  NIL,				/* modify flags */
  unix_flagmsg,			/* per-message modify flags */
  NIL,				/* search for message based on criteria */
  NIL,				/* sort messages */
  NIL,				/* thread messages */
  unix_ping,			/* ping mailbox to see if still alive */
  unix_check,			/* check for new messages */
  unix_expunge,			/* expunge deleted messages */
  unix_copy,			/* copy messages to another mailbox */
  unix_append,			/* append string message to mailbox */
  NIL,				/* garbage collect stream */
  NIL				/* renew stream */
};

				/* prototype stream */
MAILSTREAM unixproto = {&unixdriver};

				/* driver parameters */
static long unix_fromwidget = T;

/* UNIX mail validate mailbox
 * Accepts: mailbox name
 * Returns: our driver if name is valid, NIL otherwise
 */

DRIVER *unix_valid (char *name)
{
  int fd;
  DRIVER *ret = NIL;
  char *t,file[MAILTMPLEN];
  struct stat sbuf;
  time_t tp[2];
  errno = EINVAL;		/* assume invalid argument */
				/* must be non-empty file */
  if ((t = dummy_file (file,name)) && !stat (t,&sbuf)) {
    if (!sbuf.st_size)errno = 0;/* empty file */
    else if ((fd = open (file,O_RDONLY,NIL)) >= 0) {
				/* OK if mailbox format good */
      if (unix_isvalid_fd (fd)) ret = &unixdriver;
      else errno = -1;		/* invalid format */
      close (fd);		/* close the file */
				/* \Marked status? */
      if ((sbuf.st_ctime > sbuf.st_atime) || (sbuf.st_mtime > sbuf.st_atime)) {
	tp[0] = sbuf.st_atime;	/* yes, preserve atime and mtime */
	tp[1] = sbuf.st_mtime;
	utime (file,tp);	/* set the times */
      }
    }
  }
  return ret;			/* return what we should */
}

/* UNIX mail test for valid mailbox
 * Accepts: file descriptor
 *	    scratch buffer
 * Returns: T if valid, NIL otherwise
 */

long unix_isvalid_fd (int fd)
{
  int zn;
  int ret = NIL;
  char tmp[MAILTMPLEN],*s,*t,c = '\n';
  memset (tmp,'\0',MAILTMPLEN);
  if (read (fd,tmp,MAILTMPLEN-1) >= 0) {
    for (s = tmp; (*s == '\r') || (*s == '\n') || (*s == ' ') || (*s == '\t');)
      c = *s++;
    if (c == '\n') VALID (s,t,ret,zn);
  }
  return ret;			/* return what we should */
}


/* UNIX manipulate driver parameters
 * Accepts: function code
 *	    function-dependent value
 * Returns: function-dependent return value
 */

void *unix_parameters (long function,void *value)
{
  void *ret = NIL;
  switch ((int) function) {
  case GET_INBOXPATH:
    if (value) ret = dummy_file ((char *) value,"INBOX");
    break;
  case SET_FROMWIDGET:
    unix_fromwidget = (long) value;
  case GET_FROMWIDGET:
    ret = (void *) unix_fromwidget;
    break;
  }
  return ret;
}

/* UNIX mail scan mailboxes
 * Accepts: mail stream
 *	    reference
 *	    pattern to search
 *	    string to scan
 */

void unix_scan (MAILSTREAM *stream,char *ref,char *pat,char *contents)
{
  if (stream) dummy_scan (NIL,ref,pat,contents);
}


/* UNIX mail list mailboxes
 * Accepts: mail stream
 *	    reference
 *	    pattern to search
 */

void unix_list (MAILSTREAM *stream,char *ref,char *pat)
{
  if (stream) dummy_list (NIL,ref,pat);
}


/* UNIX mail list subscribed mailboxes
 * Accepts: mail stream
 *	    reference
 *	    pattern to search
 */

void unix_lsub (MAILSTREAM *stream,char *ref,char *pat)
{
  if (stream) dummy_lsub (NIL,ref,pat);
}

/* UNIX mail create mailbox
 * Accepts: MAIL stream
 *	    mailbox name to create
 * Returns: T on success, NIL on failure
 */

long unix_create (MAILSTREAM *stream,char *mailbox)
{
  char *s,mbx[MAILTMPLEN],tmp[MAILTMPLEN];
  long ret = NIL;
  int i,fd;
  time_t ti = time (0);
  if (!(s = dummy_file (mbx,mailbox))) {
    sprintf (tmp,"Can't create %.80s: invalid name",mailbox);
    MM_LOG (tmp,ERROR);
  }
				/* create underlying file */
  else if (dummy_create_path (stream,s,get_dir_protection (mailbox))) {
				/* done if dir-only or whiner */
    if (((s = strrchr (s,'/')) && !s[1]) ||
	mail_parameters (NIL,GET_USERHASNOLIFE,NIL)) ret = T;
    else if ((fd = open (mbx,O_WRONLY,
		    (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL))) < 0) {
      sprintf (tmp,"Can't reopen mailbox node %.80s: %s",mbx,strerror (errno));
      MM_LOG (tmp,ERROR);
      unlink (mbx);		/* delete the file */
    }
    else {			/* initialize header */
      memset (tmp,'\0',MAILTMPLEN);
      sprintf (tmp,"From %s %sDate: ",pseudo_from,ctime (&ti));
      rfc822_fixed_date (s = tmp + strlen (tmp));
				/* write the pseudo-header */
      sprintf (s += strlen (s),
	       "\nFrom: %s <%s@%s>\nSubject: %s\nX-IMAP: %010lu 0000000000",
	       pseudo_name,pseudo_from,mylocalhost (),pseudo_subject,
	       (unsigned long) ti);
      for (i = 0; i < NUSERFLAGS; ++i) if (default_user_flag (i))
	sprintf (s += strlen (s)," %s",default_user_flag (i));
      sprintf (s += strlen (s),"\nStatus: RO\n\n%s\n\n",pseudo_msg);
      if (write (fd,tmp,strlen (tmp)) > 0) ret = T;
      else {
	sprintf (tmp,"Can't initialize mailbox node %.80s: %s",mbx,
		 strerror (errno));
	MM_LOG (tmp,ERROR);
	unlink (mbx);		/* delete the file */
      }
      close (fd);		/* close file */
    }
  }
				/* set proper protections */
  return ret ? set_mbx_protections (mailbox,mbx) : NIL;
}

/* UNIX mail delete mailbox
 * Accepts: MAIL stream
 *	    mailbox name to delete
 * Returns: T on success, NIL on failure
 */

long unix_delete (MAILSTREAM *stream,char *mailbox)
{
  return unix_rename (stream,mailbox,NIL);
}


/* UNIX mail rename mailbox
 * Accepts: MAIL stream
 *	    old mailbox name
 *	    new mailbox name (or NIL for delete)
 * Returns: T on success, NIL on failure
 */

long unix_rename (MAILSTREAM *stream,char *old,char *newname)
{
  long ret = NIL;
  char c,*s = NIL;
  char tmp[MAILTMPLEN],file[MAILTMPLEN],lock[MAILTMPLEN];
  DOTLOCK lockx;
  int fd,ld;
  long i;
  struct stat sbuf;
  MM_CRITICAL (stream);		/* get the c-client lock */
  if (!dummy_file (file,old) ||
      (newname && (!((s = mailboxfile (tmp,newname)) && *s) ||
		   ((s = strrchr (tmp,'/')) && !s[1])))){
    if(newname)
	sprintf (tmp, "Can't rename mailbox %.80s to %.80s: invalid name",
	     old,newname);
    else
	sprintf (tmp, "Can't delete mailbox %.80s: invalid name",old);
				/* lock out other c-clients */
  } else if ((ld = lockname (lock,file,LOCK_EX|LOCK_NB,&i)) < 0)
    sprintf (tmp,"Mailbox %.80s is in use by another process",old);

  else {
    if ((fd = unix_lock (file,O_RDWR,
			 (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL),
			 &lockx,LOCK_EX)) < 0)
      sprintf (tmp,"Can't lock mailbox %.80s: %s",old,strerror (errno));
    else {
      if (newname) {		/* want rename? */
				/* found superior to destination name? */
	if ((s = strrchr (s,'/')) != NULL) {
	  c = *++s;		/* remember first character of inferior */
	  *s = '\0';		/* tie off to get just superior */
				/* name doesn't exist, create it */
	  if ((stat (tmp,&sbuf) || ((sbuf.st_mode & S_IFMT) != S_IFDIR)) &&
	      !dummy_create_path (stream,tmp,get_dir_protection (newname))) {
	    unix_unlock (fd,NIL,&lockx);
	    unix_unlock (ld,NIL,NIL);
	    unlink (lock);
	    MM_NOCRITICAL (stream);
	    return ret;		/* return success or failure */
	  }
	  *s = c;		/* restore full name */
	}
	if (rename (file,tmp))
	  sprintf (tmp,"Can't rename mailbox %.80s to %.80s: %s",old,newname,
		   strerror (errno));
	else ret = T;		/* set success */
      }
      else if (unlink (file))
	sprintf (tmp,"Can't delete mailbox %.80s: %s",old,strerror (errno));
      else ret = T;		/* set success */
      unix_unlock (fd,NIL,&lockx);
    }
    unix_unlock (ld,NIL,NIL);	/* flush the lock */
    unlink (lock);
  }
  MM_NOCRITICAL (stream);	/* no longer critical */
  if (!ret) MM_LOG (tmp,ERROR);	/* log error */
  return ret;			/* return success or failure */
}

/* UNIX mail open
 * Accepts: Stream to open
 * Returns: Stream on success, NIL on failure
 */

MAILSTREAM *unix_open (MAILSTREAM *stream)
{
  long i;
  int fd;
  char tmp[MAILTMPLEN];
  DOTLOCK lock;
  long retry;
				/* return prototype for OP_PROTOTYPE call */
  if (!stream) return user_flags (&unixproto);
  retry = stream->silent ? 1 : KODRETRY;
  if (stream->local) fatal ("unix recycle stream");
  stream->local = memset (fs_get (sizeof (UNIXLOCAL)),0,sizeof (UNIXLOCAL));
				/* note if an INBOX or not */
  stream->inbox = !compare_cstring (stream->mailbox,"INBOX");
				/* canonicalize the stream mailbox name */
  if (!dummy_file (tmp,stream->mailbox)) {
    sprintf (tmp,"Can't open - invalid name: %.80s",stream->mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  }
				/* flush old name */
  fs_give ((void **) &stream->mailbox);
				/* save canonical name */
  stream->mailbox = cpystr (tmp);
  LOCAL->fd = LOCAL->ld = -1;	/* no file or state locking yet */
  LOCAL->buf = (char *) fs_get (CHUNKSIZE);
  LOCAL->buflen = CHUNKSIZE - 1;
  LOCAL->text.data = (unsigned char *) fs_get (CHUNKSIZE);
  LOCAL->text.size = CHUNKSIZE - 1;
  LOCAL->linebuf = (char *) fs_get (CHUNKSIZE);
  LOCAL->linebuflen = CHUNKSIZE - 1;
  stream->sequence++;		/* bump sequence number */

				/* make lock for read/write access */
  if (!stream->rdonly) while (retry) {
				/* try to lock file */
    if ((fd = lockname (tmp,stream->mailbox,LOCK_EX|LOCK_NB,&i)) < 0) {
				/* suppressing kiss-of-death? */
      if (stream->nokod) retry = 0;
				/* no, first time through? */
      else if (retry-- == KODRETRY) {
				/* learned other guy's PID and can signal? */
	if (i && !kill ((int) i,SIGUSR2)) {
	  sprintf (tmp,"Trying to get mailbox lock from process %ld",i);
	  MM_LOG (tmp,WARN);
	}
	else retry = 0;		/* give up */
      }
      if (!stream->silent) {	/* nothing if silent stream */
	if (retry) sleep (1);	/* wait a second before trying again */
	else MM_LOG ("Mailbox is open by another process, access is readonly",
		     WARN);
      }
    }
    else {			/* got the lock, nobody else can alter state */
      LOCAL->ld = fd;		/* note lock's fd and name */
      LOCAL->lname = cpystr (tmp);
				/* make sure mode OK (don't use fchmod()) */
      chmod (LOCAL->lname,(long) mail_parameters (NIL,GET_LOCKPROTECTION,NIL));
      if (stream->silent) i = 0;/* silent streams won't accept KOD */
      else {			/* note our PID in the lock */
	sprintf (tmp,"%d",getpid ());
	write (fd,tmp,(i = strlen (tmp))+1);
      }
      ftruncate (fd,i);		/* make sure tied off */
      fsync (fd);		/* make sure it's available */
      retry = 0;		/* no more need to try */
    }
  }

				/* parse mailbox */
  stream->nmsgs = stream->recent = 0;
				/* will we be able to get write access? */
  if ((LOCAL->ld >= 0) && access (stream->mailbox,W_OK) && (errno == EACCES)) {
    MM_LOG ("Can't get write access to mailbox, access is readonly",WARN);
    flock (LOCAL->ld,LOCK_UN);	/* release the lock */
    close (LOCAL->ld);		/* close the lock file */
    LOCAL->ld = -1;		/* no more lock fd */
    unlink (LOCAL->lname);	/* delete it */
  }
				/* reset UID validity */
  stream->uid_validity = stream->uid_last = 0;
  if (stream->silent && !stream->rdonly && (LOCAL->ld < 0))
    unix_abort (stream);	/* abort if can't get RW silent stream */
				/* parse mailbox */
  else if (unix_parse (stream,&lock,LOCK_SH)) {
    unix_unlock (LOCAL->fd,stream,&lock);
    mail_unlock (stream);
    MM_NOCRITICAL (stream);	/* done with critical */
  }
  if (!LOCAL) return NIL;	/* failure if stream died */
				/* make sure upper level knows readonly */
  stream->rdonly = (LOCAL->ld < 0);
				/* notify about empty mailbox */
  if (!(stream->nmsgs || stream->silent)) MM_LOG ("Mailbox is empty",NIL);
  if (!stream->rdonly) {	/* flags stick if readwrite */
    stream->perm_seen = stream->perm_deleted =
      stream->perm_flagged = stream->perm_answered = stream->perm_draft = T;
    if (!stream->uid_nosticky) {/* users with lives get permanent keywords */
      stream->perm_user_flags = 0xffffffff;
				/* and maybe can create them too! */
      stream->kwd_create = stream->user_flags[NUSERFLAGS-1] ? NIL : T;
    }
  }
  return stream;		/* return stream alive to caller */
}


/* UNIX mail close
 * Accepts: MAIL stream
 *	    close options
 */

void unix_close (MAILSTREAM *stream,long options)
{
  int silent = stream->silent;
  stream->silent = T;		/* go silent */
				/* expunge if requested */
  if (options & CL_EXPUNGE) unix_expunge (stream,NIL,NIL);
				/* else dump final checkpoint */
  else if (LOCAL->dirty) unix_check (stream);
  stream->silent = silent;	/* restore old silence state */
  unix_abort (stream);		/* now punt the file and local data */
}

/* UNIX mail fetch message header
 * Accepts: MAIL stream
 *	    message # to fetch
 *	    pointer to returned header text length
 *	    option flags
 * Returns: message header in RFC822 format
 */


STRINGLIST XIMAPbase = {{"X-IMAPbase", 10}, NIL};
STRINGLIST XIMAP     = {{"X-IMAP", 6}, &XIMAPbase};
STRINGLIST XUID      = {{"X-UID", 5}, &XIMAP};
STRINGLIST XKeywords = {{"X-Keywords", 10}, &XUID};
STRINGLIST XStatus   = {{"X-Status", 8}, &XKeywords};
STRINGLIST Status    = {{"Status", 6}, &XStatus};

static STRINGLIST *unix_hlines = &Status;

char *unix_header (MAILSTREAM *stream,unsigned long msgno,
		   unsigned long *length,long flags)
{
  MESSAGECACHE *elt;
  unsigned char *s,*t,*tl;
  *length = 0;			/* default to empty */
  if (flags & FT_UID) return "";/* UID call "impossible" */
  elt = mail_elt (stream,msgno);/* get cache */
				/* go to header position */
  lseek (LOCAL->fd,elt->private.special.offset +
	 elt->private.msg.header.offset,L_SET);

  if (flags & FT_INTERNAL) {	/* initial data OK? */
    if (elt->private.msg.header.text.size > LOCAL->buflen) {
      fs_give ((void **) &LOCAL->buf);
      LOCAL->buf = (char *) fs_get ((LOCAL->buflen =
				     elt->private.msg.header.text.size) + 1);
    }
				/* read message */
    read (LOCAL->fd,LOCAL->buf,elt->private.msg.header.text.size);
				/* got text, tie off string */
    LOCAL->buf[*length = elt->private.msg.header.text.size] = '\0';
				/* squeeze out CRs (in case from PC) */
    for (s = t = LOCAL->buf,tl = LOCAL->buf + *length; t < tl; t++)
      if (*t != '\r') *s++ = *t;
    *s = '\0';
    *length = s - LOCAL->buf;	/* adjust length */
  }
  else {			/* need to make a CRLF version */
    read (LOCAL->fd,s = (char *) fs_get (elt->private.msg.header.text.size+1),
	  elt->private.msg.header.text.size);
				/* tie off string, and convert to CRLF */
    s[elt->private.msg.header.text.size] = '\0';
    *length = strcrlfcpy (&LOCAL->buf,&LOCAL->buflen,s,
			  elt->private.msg.header.text.size);
    fs_give ((void **) &s);	/* free readin buffer */
				/* squeeze out spurious CRs */
    for (s = t = LOCAL->buf,tl = LOCAL->buf + *length; t < tl; t++)
      if ((*t != '\r') || (t[1] == '\n')) *s++ = *t;
    *s = '\0';
    *length = s - LOCAL->buf;	/* adjust length */
  }
  *length = mail_filter (LOCAL->buf,*length,unix_hlines,FT_NOT);
  return (char *) LOCAL->buf;	/* return processed copy */
}

/* UNIX mail fetch message text
 * Accepts: MAIL stream
 *	    message # to fetch
 *	    pointer to returned stringstruct
 *	    option flags
 * Returns: T on success, NIL if failure
 */

long unix_text (MAILSTREAM *stream,unsigned long msgno,STRING *bs,long flags)
{
  char *s;
  unsigned long i;
  MESSAGECACHE *elt;
				/* UID call "impossible" */
  if (flags & FT_UID) return NIL;
  elt = mail_elt (stream,msgno);/* get cache element */
				/* if message not seen */
  if (!(flags & FT_PEEK) && !elt->seen) {
				/* mark message seen and dirty */
    elt->seen = elt->private.dirty = LOCAL->dirty = T;
    MM_FLAGS (stream,msgno);
  }
  s = unix_text_work (stream,elt,&i,flags);
  INIT (bs,mail_string,s,i);	/* set up stringstruct */
  return T;			/* success */
}

/* UNIX mail fetch message text worker routine
 * Accepts: MAIL stream
 *	    message cache element
 *	    pointer to returned header text length
 *	    option flags
 */

char *unix_text_work (MAILSTREAM *stream,MESSAGECACHE *elt,
		      unsigned long *length,long flags)
{
  FDDATA d;
  STRING bs;
  unsigned char c,*s,*t,*tl,tmp[CHUNKSIZE];
				/* go to text position */
  lseek (LOCAL->fd,elt->private.special.offset +
	 elt->private.msg.text.offset,L_SET);
  if (flags & FT_INTERNAL) {	/* initial data OK? */
    if (elt->private.msg.text.text.size > LOCAL->buflen) {
      fs_give ((void **) &LOCAL->buf);
      LOCAL->buf = (char *) fs_get ((LOCAL->buflen =
				     elt->private.msg.text.text.size) + 1);
    }
				/* read message */
    read (LOCAL->fd,LOCAL->buf,elt->private.msg.text.text.size);
				/* got text, tie off string */
    LOCAL->buf[*length = elt->private.msg.text.text.size] = '\0';
				/* squeeze out CRs (in case from PC) */
    for (s = t = LOCAL->buf,tl = LOCAL->buf + *length; t < tl; t++)
      if (*t != '\r') *s++ = *t;
    *s = '\0';
    *length = s - LOCAL->buf;	/* adjust length */
    return (char *) LOCAL->buf;
  }

				/* have it cached already? */
  if (elt->private.uid != LOCAL->uid) {
				/* not cached, cache it now */
    LOCAL->uid = elt->private.uid;
				/* is buffer big enough? */
    if (elt->rfc822_size > LOCAL->text.size) {
      /* excessively conservative, but the right thing is too hard to do */
      fs_give ((void **) &LOCAL->text.data);
      LOCAL->text.data = (unsigned char *)
	fs_get ((LOCAL->text.size = elt->rfc822_size) + 1);
    }
    d.fd = LOCAL->fd;		/* yes, set up file descriptor */
    d.pos = elt->private.special.offset + elt->private.msg.text.offset;
    d.chunk = tmp;		/* initial buffer chunk */
    d.chunksize = CHUNKSIZE;	/* file chunk size */
    INIT (&bs,fd_string,&d,elt->private.msg.text.text.size);
    for (s = (char *) LOCAL->text.data; SIZE (&bs);) switch (c = SNX (&bs)) {
    case '\r':			/* carriage return seen */
      break;
    case '\n':
      *s++ = '\r';		/* insert a CR */
    default:
      *s++ = c;			/* copy characters */
    }
    *s = '\0';			/* tie off buffer */
				/* calculate length of cached data */
    LOCAL->textlen = s - LOCAL->text.data;
  }
  *length = LOCAL->textlen;	/* return from cache */
  return (char *) LOCAL->text.data;
}

/* UNIX per-message modify flag
 * Accepts: MAIL stream
 *	    message cache element
 */

void unix_flagmsg (MAILSTREAM *stream,MESSAGECACHE *elt)
{
				/* only after finishing */
  if (elt->valid) elt->private.dirty = LOCAL->dirty = T;
}


/* UNIX mail ping mailbox
 * Accepts: MAIL stream
 * Returns: T if stream alive, else NIL
 */

long unix_ping (MAILSTREAM *stream)
{
  DOTLOCK lock;
  struct stat sbuf;
  long reparse;
				/* big no-op if not readwrite */
  if (LOCAL && (LOCAL->ld >= 0) && !stream->lock) {
    if (stream->rdonly) {	/* does he want to give up readwrite? */
				/* checkpoint if we changed something */
      if (LOCAL->dirty) unix_check (stream);
      flock (LOCAL->ld,LOCK_UN);/* release readwrite lock */
      close (LOCAL->ld);	/* close the readwrite lock file */
      LOCAL->ld = -1;		/* no more readwrite lock fd */
      unlink (LOCAL->lname);	/* delete the readwrite lock file */
    }
    else {			/* see if need to reparse */
      if (!(reparse = (long) mail_parameters (NIL,GET_NETFSSTATBUG,NIL))) {
				/* get current mailbox size */
	if (LOCAL->fd >= 0) fstat (LOCAL->fd,&sbuf);
	else if (stat (stream->mailbox,&sbuf)) {
	  sprintf (LOCAL->buf,"Mailbox stat failed, aborted: %s",
		   strerror (errno));
	  MM_LOG (LOCAL->buf,ERROR);
	  unix_abort (stream);
	  return NIL;
	}
	reparse = (sbuf.st_size != LOCAL->filesize);
      }
				/* parse if mailbox changed */
      if ((LOCAL->ddirty || reparse) && unix_parse (stream,&lock,LOCK_EX)) {
				/* force checkpoint if double-dirty */
	if (LOCAL->ddirty) unix_rewrite (stream,NIL,&lock,NIL);
				/* unlock mailbox */
	else unix_unlock (LOCAL->fd,stream,&lock);
	mail_unlock (stream);	/* and stream */
	MM_NOCRITICAL (stream);	/* done with critical */
      }
    }
  }
  return LOCAL ? LONGT : NIL;	/* return if still alive */
}

/* UNIX mail check mailbox
 * Accepts: MAIL stream
 */

void unix_check (MAILSTREAM *stream)
{
  DOTLOCK lock;
				/* parse and lock mailbox */
  if (LOCAL && (LOCAL->ld >= 0) && !stream->lock &&
      unix_parse (stream,&lock,LOCK_EX)) {
				/* any unsaved changes? */
    if (LOCAL->dirty && unix_rewrite (stream,NIL,&lock,NIL)) {
      if (!stream->silent) MM_LOG ("Checkpoint completed",NIL);
    }
				/* no checkpoint needed, just unlock */
    else unix_unlock (LOCAL->fd,stream,&lock);
    mail_unlock (stream);	/* unlock the stream */
    MM_NOCRITICAL (stream);	/* done with critical */
  }
}


/* UNIX mail expunge mailbox
 * Accepts: MAIL stream
 *	    sequence to expunge if non-NIL
 *	    expunge options
 * Returns: T, always
 */

long unix_expunge (MAILSTREAM *stream,char *sequence,long options)
{
  long ret;
  unsigned long i;
  DOTLOCK lock;
  char *msg = NIL;
				/* parse and lock mailbox */
  if ((ret = (sequence ? ((options & EX_UID) ?
			 mail_uid_sequence (stream,sequence) :
			 mail_sequence (stream,sequence)) : LONGT) != 0L) &&
      LOCAL && (LOCAL->ld >= 0) && !stream->lock &&
      unix_parse (stream,&lock,LOCK_EX)) {
				/* check expunged messages if not dirty */
    for (i = 1; !LOCAL->dirty && (i <= stream->nmsgs); i++) {
      MESSAGECACHE *elt = mail_elt (stream,i);
      if (mail_elt (stream,i)->deleted) LOCAL->dirty = T;
    }
    if (!LOCAL->dirty) {	/* not dirty and no expunged messages */
      unix_unlock (LOCAL->fd,stream,&lock);
      msg = "No messages deleted, so no update needed";
    }
    else if (unix_rewrite (stream,&i,&lock,sequence ? LONGT : NIL)) {
      if (i) sprintf (msg = LOCAL->buf,"Expunged %lu messages",i);
      else msg = "Mailbox checkpointed, but no messages expunged";
    }
				/* rewrite failed */
    else unix_unlock (LOCAL->fd,stream,&lock);
    mail_unlock (stream);	/* unlock the stream */
    MM_NOCRITICAL (stream);	/* done with critical */
    if (msg && !stream->silent) MM_LOG (msg,NIL);
  }
  else if (!stream->silent) MM_LOG("Expunge ignored on readonly mailbox",WARN);
  return ret;
}

/* UNIX mail copy message(s)
 * Accepts: MAIL stream
 *	    sequence
 *	    destination mailbox
 *	    copy options
 * Returns: T if copy successful, else NIL
 */

long unix_copy (MAILSTREAM *stream,char *sequence,char *mailbox,long options)
{
  struct stat sbuf;
  int fd;
  char *s,file[MAILTMPLEN];
  DOTLOCK lock;
  time_t tp[2];
  unsigned long i,j;
  MESSAGECACHE *elt;
  long ret = T;
  mailproxycopy_t pc =
    (mailproxycopy_t) mail_parameters (stream,GET_MAILPROXYCOPY,NIL);
  copyuid_t cu = (copyuid_t) (mail_parameters (NIL,GET_USERHASNOLIFE,NIL) ?
			      NIL : mail_parameters (NIL,GET_COPYUID,NIL));
  SEARCHSET *source = cu ? mail_newsearchset () : NIL;
  SEARCHSET *dest = cu ? mail_newsearchset () : NIL;
  MAILSTREAM *tstream = NIL;
  DRIVER *d;
  for (d = (DRIVER *) mail_parameters (NIL,GET_DRIVERS,NIL);
       (d && strcmp (d->name,"mbox") && !(d->flags & DR_DISABLE));
       d = d->next);		/* see if mbox driver active */
  if (!((options & CP_UID) ? mail_uid_sequence (stream,sequence) :
	mail_sequence (stream,sequence))) return NIL;
				/* make sure destination is valid */
  if (!((d && mbox_valid (mailbox) && (mailbox = "mbox")) ||
	unix_valid (mailbox) || !errno))
    switch (errno) {
    case ENOENT:		/* no such file? */
      if (compare_cstring (mailbox,"INBOX")) {
	MM_NOTIFY (stream,"[TRYCREATE] Must create mailbox before copy",NIL);
	return NIL;
      }
      if (pc) return (*pc) (stream,sequence,mailbox,options);
      unix_create (NIL,"INBOX");/* create empty INBOX */
    case EACCES:		/* file protected */
      sprintf (LOCAL->buf,"Can't access destination: %.80s",mailbox);
      MM_LOG (LOCAL->buf,ERROR);
      return NIL;
    case EINVAL:
      if (pc) return (*pc) (stream,sequence,mailbox,options);
      sprintf (LOCAL->buf,"Invalid UNIX-format mailbox name: %.80s",mailbox);
      MM_LOG (LOCAL->buf,ERROR);
      return NIL;
    default:
      if (pc) return (*pc) (stream,sequence,mailbox,options);
      sprintf (LOCAL->buf,"Not a UNIX-format mailbox: %.80s",mailbox);
      MM_LOG (LOCAL->buf,ERROR);
      return NIL;
    }

				/* try to open readwrite for UIDPLUS */
  if (cu && (tstream = mail_open_work (&unixdriver,NIL,mailbox,
				 OP_SILENT|OP_NOKOD)) && tstream->rdonly)
    tstream = mail_close (tstream);
  if (cu && !tstream) {		/* wanted a COPYUID? */
    sprintf (LOCAL->buf,"Unable to write-open mailbox for COPYUID: %.80s",
	     mailbox);
    MM_LOG (LOCAL->buf,WARN);
    cu = NIL;			/* don't try to do COPYUID */
  }
  LOCAL->buf[0] = '\0';
  MM_CRITICAL (stream);		/* go critical */
  if ((fd = unix_lock (dummy_file (file,mailbox),O_WRONLY|O_APPEND,
		       (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL),
		       &lock,LOCK_EX)) < 0) {
    MM_NOCRITICAL (stream);	/* done with critical */
    sprintf (LOCAL->buf,"Can't open destination mailbox: %s",strerror (errno));
    MM_LOG (LOCAL->buf,ERROR);/* log the error */
    return NIL;			/* failed */
  }
  fstat (fd,&sbuf);		/* get current file size */
				/* write all requested messages to mailbox */
  for (i = 1; ret && (i <= stream->nmsgs); i++)
    if ((elt = mail_elt (stream,i))->sequence) {
      lseek (LOCAL->fd,elt->private.special.offset,L_SET);
      read (LOCAL->fd,LOCAL->buf,elt->private.special.text.size);
      if (write (fd,LOCAL->buf,elt->private.special.text.size) < 0) ret = NIL;
      else {			/* internal header succeeded */
	s = unix_header (stream,i,&j,FT_INTERNAL);
				/* header size, sans trailing newline */
	if (j && (s[j - 2] == '\n')) j--;
	if (write (fd,s,j) < 0) ret = NIL;
	else {			/* message header succeeded */
	  j = tstream ?		/* write UIDPLUS data if have readwrite */
	    unix_xstatus (stream,LOCAL->buf,elt,++(tstream->uid_last),LONGT) :
	    unix_xstatus (stream,LOCAL->buf,elt,NIL,NIL);
	  if (write (fd,LOCAL->buf,j) < 0) ret = NIL;
	  else {		/* message status succeeded */
	    s = unix_text_work (stream,elt,&j,FT_INTERNAL);
	    if ((write (fd,s,j) < 0) || (write (fd,"\n",1) < 0)) ret = NIL;
	    else if (cu) {	/* need to pass back new UID? */
	      mail_append_set (source,mail_uid (stream,i));
	      mail_append_set (dest,tstream->uid_last);
	    }
	  }
	}
      }
    }

  if (!ret || fsync (fd)) {	/* force out the update */
    sprintf (LOCAL->buf,"Message copy failed: %s",strerror (errno));
    ftruncate (fd,sbuf.st_size);
    ret = NIL;
  }
				/* force UIDVALIDITY assignment now */
  if (tstream && !tstream->uid_validity) tstream->uid_validity = time (0);
				/* return sets if doing COPYUID */
  if (cu && ret) (*cu) (stream,mailbox,tstream->uid_validity,source,dest);
  else {			/* flush any sets we may have built */
    mail_free_searchset (&source);
    mail_free_searchset (&dest);
  }
  tp[1] = time (0);		/* set mtime to now */
  if (ret) tp[0] = tp[1] - 1;	/* set atime to now-1 if successful copy */
  else tp[0] =			/* else preserve \Marked status */
	 ((sbuf.st_ctime > sbuf.st_atime) || (sbuf.st_mtime > sbuf.st_atime)) ?
	 sbuf.st_atime : tp[1];
  utime (file,tp);		/* set the times */
  unix_unlock (fd,NIL,&lock);	/* unlock and close mailbox */
  if (tstream) {		/* update last UID if we can */
    UNIXLOCAL *local = (UNIXLOCAL *) tstream->local;
    local->dirty = T;		/* do a rewrite */
    local->appending = T;	/* but not at the cost of marking as old */
    tstream = mail_close (tstream);
  }
				/* log the error */
  if (!ret) MM_LOG (LOCAL->buf,ERROR);
				/* delete if requested message */
  else if (options & CP_MOVE) for (i = 1; i <= stream->nmsgs; i++)
    if ((elt = mail_elt (stream,i))->sequence)
      elt->deleted = elt->private.dirty = LOCAL->dirty = T;
  MM_NOCRITICAL (stream);	/* release critical */
  return ret;
}

/* UNIX mail append message from stringstruct
 * Accepts: MAIL stream
 *	    destination mailbox
 *	    append callback
 *	    data for callback
 * Returns: T if append successful, else NIL
 */

#define BUFLEN 8*MAILTMPLEN

long unix_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data)
{
  struct stat sbuf;
  int fd;
  unsigned long i;
  char *flags,*date,buf[BUFLEN],tmp[MAILTMPLEN],file[MAILTMPLEN];
  time_t tp[2];
  FILE *sf,*df;
  MESSAGECACHE elt;
  DOTLOCK lock;
  STRING *message;
  unsigned long uidlocation = 0;
  appenduid_t au = (appenduid_t)
    (mail_parameters (NIL,GET_USERHASNOLIFE,NIL) ? NIL :
     mail_parameters (NIL,GET_APPENDUID,NIL));
  SEARCHSET *dst = au ? mail_newsearchset () : NIL;
  long ret = LONGT;
  MAILSTREAM *tstream = NIL;
  if (!stream) {		/* stream specified? */
    stream = &unixproto;	/* no, default stream to prototype */
    for (i = 0; i < NUSERFLAGS && stream->user_flags[i]; ++i)
      fs_give ((void **) &stream->user_flags[i]);
  }
  if (!unix_valid (mailbox)) switch (errno) {
  case ENOENT:			/* no such file? */
    if (compare_cstring (mailbox,"INBOX")) {
      MM_NOTIFY (stream,"[TRYCREATE] Must create mailbox before append",NIL);
      return NIL;
    }
    unix_create (NIL,"INBOX");	/* create empty INBOX */
  case 0:			/* merely empty file? */
    tstream = stream;
    break;
  case EACCES:			/* file protected */
    sprintf (tmp,"Can't access destination: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  case EINVAL:
    sprintf (tmp,"Invalid UNIX-format mailbox name: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  default:
    sprintf (tmp,"Not a UNIX-format mailbox: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  }
				/* get sniffing stream for keywords */
  else if (!(tstream = mail_open (NIL,mailbox,
				  OP_READONLY|OP_SILENT|OP_NOKOD|OP_SNIFF))) {
    sprintf (tmp,"Unable to examine mailbox for APPEND: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  }

				/* get first message */
  if (!MM_APPEND (af) (tstream,data,&flags,&date,&message)) return NIL;
  if (!(sf = tmpfile ())) {	/* must have scratch file */
    sprintf (tmp,".%lx.%lx",(unsigned long) time (0),(unsigned long)getpid ());
    if (!stat (tmp,&sbuf) || !(sf = fopen (tmp,"wb+"))) {
      sprintf (tmp,"Unable to create scratch file: %.80s",strerror (errno));
      MM_LOG (tmp,ERROR);
      return NIL;
    }
    unlink (tmp);
  }
  do {				/* parse date */
    if (!date) rfc822_date (date = tmp);
    if (!mail_parse_date (&elt,date)) {
      sprintf (tmp,"Bad date in append: %.80s",date);
      MM_LOG (tmp,ERROR);
    }
    else {			/* user wants to suppress time zones? */
      if (mail_parameters (NIL,GET_NOTIMEZONES,NIL)) {
	time_t when = mail_longdate (&elt);
	date = ctime (&when);	/* use traditional date */
      }
				/* use POSIX-style date */
      else date = mail_cdate (tmp,&elt);
      if (!SIZE (message)) MM_LOG ("Append of zero-length message",ERROR);
      else if (!unix_collect_msg (tstream,sf,flags,date,message)) {
	sprintf (tmp,"Error writing scratch file: %.80s",strerror (errno));
	MM_LOG (tmp,ERROR);
      }
				/* get next message */
      else if (MM_APPEND (af) (tstream,data,&flags,&date,&message)) continue;
    }
    fclose (sf);		/* punt scratch file */
    return NIL;			/* give up */
  } while (message);		/* until no more messages */
  if (fflush (sf)) {
    sprintf (tmp,"Error finishing scratch file: %.80s",strerror (errno));
    MM_LOG (tmp,ERROR);
    fclose (sf);		/* punt scratch file */
    return NIL;			/* give up */
  }
  i = ftell (sf);		/* size of scratch file */
				/* close sniffing stream */
  if (tstream != stream) tstream = mail_close (tstream);

  MM_CRITICAL (stream);		/* go critical */
				/* try to open readwrite for UIDPLUS */
  if ((tstream = mail_open_work (&unixdriver,NIL,mailbox,
				 OP_SILENT|OP_NOKOD)) && tstream->rdonly)
    tstream = mail_close (tstream);
  if (au && !tstream) {		/* wanted an APPENDUID? */
    sprintf (tmp,"Unable to re-open mailbox for APPENDUID: %.80s",mailbox);
    MM_LOG (tmp,WARN);
    au = NIL;
  }
  if (((fd = unix_lock (dummy_file (file,mailbox),O_WRONLY|O_APPEND,
		       (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL),
			&lock,LOCK_EX)) < 0) ||
      !(df = fdopen (fd,"ab"))) {
    MM_NOCRITICAL (stream);	/* done with critical */
    sprintf (tmp,"Can't open append mailbox: %s",strerror (errno));
    MM_LOG (tmp,ERROR);
    return NIL;
  }
  fstat (fd,&sbuf);		/* get current file size */
  rewind (sf);
  tp[1] = time (0);		/* set mtime to now */
				/* write all messages */
  if (!unix_append_msgs (tstream,sf,df,au ? dst : NIL) ||
      (fflush (df) == EOF) || fsync (fd)) {
    sprintf (buf,"Message append failed: %s",strerror (errno));
    MM_LOG (buf,ERROR);
    ftruncate (fd,sbuf.st_size);
    tp[0] =			/* preserve \Marked status */
      ((sbuf.st_ctime > sbuf.st_atime) || (sbuf.st_mtime > sbuf.st_atime)) ?
      sbuf.st_atime : tp[1];
    ret = NIL;			/* return error */
  }
  else tp[0] = tp[1] - 1;	/* set atime to now-1 if successful copy */
  utime (file,tp);		/* set the times */
  fclose (sf);			/* done with scratch file */
				/* force UIDVALIDITY assignment now */
  if (tstream && !tstream->uid_validity) tstream->uid_validity = time (0);
				/* return sets if doing APPENDUID */
  if (au && ret) (*au) (mailbox,tstream->uid_validity,dst);
  else mail_free_searchset (&dst);
  unix_unlock (fd,NIL,&lock);	/* unlock and close mailbox */
  fclose (df);			/* note that unix_unlock() released the fd */
  if (tstream) {		/* update last UID if we can */
    UNIXLOCAL *local = (UNIXLOCAL *) tstream->local;
    local->dirty = T;		/* do a rewrite */
    local->appending = T;	/* but not at the cost of marking as old */
    tstream = mail_close (tstream);
  }
  MM_NOCRITICAL (stream);	/* release critical */
  return ret;
}

/* Collect and write single message to append scratch file
 * Accepts: MAIL stream
 *	    scratch file
 *	    flags
 *	    date
 *	    message stringstruct
 * Returns: NIL if write error, else T
 */

int unix_collect_msg (MAILSTREAM *stream,FILE *sf,char *flags,char *date,
		     STRING *msg)
{
  unsigned char *s,*t;
  unsigned long uf;
  long f = mail_parse_flags (stream,flags,&uf);
				/* write metadata, note date ends with NL */
  if (fprintf (sf,"%ld %lu %s",f,SIZE (msg) + 1,date) < 0) return NIL;
  while (uf)			/* write user flags */    
    if ((s = stream->user_flags[find_rightmost_bit (&uf)]) &&
	(fprintf (sf," %s",s) < 0)) return NIL;
  if (putc ('\n',sf) == EOF) return NIL;
  while (SIZE (msg)) {		/* copy text to scratch file */
    for (s = (unsigned char *) msg->curpos, t = s + msg->cursize; s < t; ++s)
      if (!*s) *s = 0x80;	/* disallow NUL */
				/* write buffered text */
    if (fwrite (msg->curpos,1,msg->cursize,sf) == msg->cursize)
      SETPOS (msg,GETPOS (msg) + msg->cursize);
    else return NIL;		/* failed */
  }
				/* write trailing newline and return */
  return (putc ('\n',sf) == EOF) ? NIL : T;
}

/* Append messages from scratch file to mailbox
 * Accepts: MAIL stream
 *	    source file
 *	    destination file
 *	    uidset to update if non-NIL
 * Returns: T if success, NIL if failure
 */

int unix_append_msgs (MAILSTREAM *stream,FILE *sf,FILE *df,SEARCHSET *set)
{
  int ti,zn,c;
  long f;
  unsigned long i,j;
  char *x,tmp[MAILTMPLEN];
  int hdrp = T;
				/* get message metadata line */
  while (fgets (tmp,MAILTMPLEN,sf)) {
    if (!(isdigit (tmp[0]) && strchr (tmp,'\n'))) return NIL;
    f = strtol (tmp,&x,10);	/* get flags */
    if (!((*x++ == ' ') && isdigit (*x))) return NIL;
    i = strtoul (x,&x,10);	/* get message size */
    if ((*x++ != ' ') ||	/* build initial header */
	(fprintf (df,"From %s@%s %sStatus: ",myusername(),mylocalhost(),x)<0)||
	(f&fSEEN && (putc ('R',df) == EOF)) ||
	(fputs ("\nX-Status: ",df) == EOF) ||
	(f&fDELETED && (putc ('D',df) == EOF)) ||
	(f&fFLAGGED && (putc ('F',df) == EOF)) ||
	(f&fANSWERED && (putc ('A',df) == EOF)) ||
	(f&fDRAFT && (putc ('T',df) == EOF)) ||
	(fputs ("\nX-Keywords:",df) == EOF)) return NIL;
				/* copy keywords */
    while ((c = getc (sf)) != '\n') switch (c) {
    case EOF:
      return NIL;
    default:
      if (putc (c,df) == EOF) return NIL;
    }
    if ((putc ('\n',df) == EOF) ||
	(set && (fprintf (df,"X-UID: %lu\n",++(stream->uid_last)) < 0)))
      return NIL;

    for (c = '\n'; i && fgets (tmp,MAILTMPLEN,sf); c = tmp[j-1]) {
				/* get read line length */
      if (i < (j = strlen (tmp))) fatal ("unix_append_msgs overrun");
      i -= j;			/* number of bytes left */
				/* squish out CRs (note also copies NUL) */
      for (x = tmp; (x = strchr (x,'\r')) != NULL; --j) memmove (x,x+1,j-(x-tmp));
      if (!j) continue;		/* do nothing if line emptied */
				/* start of line? */
      if (c == '\n') switch (tmp[0]) {
      case 'F':			/* possible "From " (case counts here) */
	if ((j > 4) && (tmp[0] == 'F') && (tmp[1] == 'r') && (tmp[2] == 'o') &&
	    (tmp[3] == 'm') && (tmp[4] == ' ')) {
	  if (!unix_fromwidget) {
	    VALID (tmp,x,ti,zn);/* conditional, only write widget if */
	    if (!ti) break;	/*  it looks like a valid header */
	  }			/* write the widget */
	  if (putc ('>',df) == EOF) return NIL;
	}
	break;
      case 'S': case 's':	/* possible "Status:" */
	if (hdrp && (j > 6) && ((tmp[1] == 't') || (tmp[1] == 'T')) &&
	    ((tmp[2] == 'a') || (tmp[2] == 'A')) &&
	    ((tmp[3] == 't') || (tmp[3] == 'T')) &&
	    ((tmp[4] == 'u') || (tmp[4] == 'U')) &&
	    ((tmp[5] == 's') || (tmp[5] == 'S')) && (tmp[6] == ':') &&
	    (fputs ("X-Original-",df) == EOF)) return NIL;
	break;
      case 'X': case 'x':	/* possible X-??? header */
	if (hdrp && (tmp[1] == '-') &&
				/* possible X-UID: */
	    (((j > 5) && ((tmp[2] == 'U') || (tmp[2] == 'u')) &&
	      ((tmp[3] == 'I') || (tmp[3] == 'i')) &&
	      ((tmp[4] == 'D') || (tmp[4] == 'd')) && (tmp[5] == ':')) ||
				/* possible X-IMAP: */
	     ((j > 6) && ((tmp[2] == 'I') || (tmp[2] == 'i')) &&
	      ((tmp[3] == 'M') || (tmp[3] == 'm')) &&
	      ((tmp[4] == 'A') || (tmp[4] == 'a')) &&
	      ((tmp[5] == 'P') || (tmp[5] == 'p')) &&
	      ((tmp[6] == ':') ||
				/* or X-IMAPbase: */
	       ((j > 10) && ((tmp[6] == 'b') || (tmp[6] == 'B')) &&
		((tmp[7] == 'a') || (tmp[7] == 'A')) &&
		((tmp[8] == 's') || (tmp[8] == 'S')) &&
		((tmp[9] == 'e') || (tmp[9] == 'E')) && (tmp[10] == ':')))) ||
				/* possible X-Status: */
	     ((j > 8) && ((tmp[2] == 'S') || (tmp[2] == 's')) &&
	      ((tmp[3] == 't') || (tmp[3] == 'T')) &&
	      ((tmp[4] == 'a') || (tmp[4] == 'A')) &&
	      ((tmp[5] == 't') || (tmp[5] == 'T')) &&
	      ((tmp[6] == 'u') || (tmp[6] == 'U')) &&
	      ((tmp[7] == 's') || (tmp[7] == 'S')) && (tmp[8] == ':')) ||
				/* possible X-Keywords: */
	     ((j > 10) && ((tmp[2] == 'K') || (tmp[2] == 'k')) &&
	      ((tmp[3] == 'e') || (tmp[3] == 'E')) &&
	      ((tmp[4] == 'y') || (tmp[4] == 'Y')) &&
	      ((tmp[5] == 'w') || (tmp[5] == 'W')) &&
	      ((tmp[6] == 'o') || (tmp[6] == 'O')) &&
	      ((tmp[7] == 'r') || (tmp[7] == 'R')) &&
	      ((tmp[8] == 'd') || (tmp[8] == 'D')) &&
	      ((tmp[9] == 's') || (tmp[9] == 'S')) && (tmp[10] == ':'))) &&
	    (fputs ("X-Original-",df) == EOF)) return NIL;
      case '\n':		/* blank line */
	hdrp = NIL;
	break;
      default:			/* nothing to do */
	break;
      }
				/* just write the line */
      if (fwrite (tmp,1,j,df) != j) return NIL;
    }
    if (i) return NIL;		/* didn't read entire message */
				/* update set */
    if (stream) mail_append_set (set,stream->uid_last);
  }
  return T;
}

/* Internal routines */


/* UNIX mail abort stream
 * Accepts: MAIL stream
 */

void unix_abort (MAILSTREAM *stream)
{
  if (LOCAL) {			/* only if a file is open */
    if (LOCAL->fd >= 0) close (LOCAL->fd);
    if (LOCAL->ld >= 0) {	/* have a mailbox lock? */
      flock (LOCAL->ld,LOCK_UN);/* yes, release the lock */
      close (LOCAL->ld);	/* close the lock file */
      unlink (LOCAL->lname);	/* and delete it */
    }
    if (LOCAL->lname) fs_give ((void **) &LOCAL->lname);
				/* free local text buffers */
    if (LOCAL->buf) fs_give ((void **) &LOCAL->buf);
    if (LOCAL->text.data) fs_give ((void **) &LOCAL->text.data);
    if (LOCAL->linebuf) fs_give ((void **) &LOCAL->linebuf);
    if (LOCAL->line) fs_give ((void **) &LOCAL->line);
				/* nuke the local data */
    fs_give ((void **) &stream->local);
    stream->dtb = NIL;		/* log out the DTB */
  }
}

/* UNIX open and lock mailbox
 * Accepts: file name to open/lock
 *	    file open mode
 *	    destination buffer for lock file name
 *	    type of locking operation (LOCK_SH or LOCK_EX)
 */

int unix_lock (char *file,int flags,int mode,DOTLOCK *lock,int op)
{
  int fd;
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
  (*bn) (BLOCK_FILELOCK,NIL);
				/* try locking the easy way */
  if (dotlock_lock (file,lock,-1)) {
				/* got dotlock file, easy open */
    if ((fd = open (file,flags,mode)) >= 0) flock (fd,op);
    else dotlock_unlock (lock);	/* open failed, free the dotlock */
  }
				/* no dot lock file, open file now */
  else if ((fd = open (file,flags,mode)) >= 0) {
				/* try paranoid way to make a dot lock file */
    if (dotlock_lock (file,lock,fd)) {
      close (fd);		/* get fresh fd in case of timing race */
      if ((fd = open (file,flags,mode)) >= 0) flock (fd,op);
				/* open failed, free the dotlock */
      else dotlock_unlock (lock);
    }
    else flock (fd,op);		/* paranoid way failed, just flock() it */
  }
  (*bn) (BLOCK_NONE,NIL);
  return fd;
}

/* UNIX unlock and close mailbox
 * Accepts: file descriptor
 *	    (optional) mailbox stream to check atime/mtime
 *	    (optional) lock file name
 */

void unix_unlock (int fd,MAILSTREAM *stream,DOTLOCK *lock)
{
  if (stream) {			/* need to muck with times? */
    struct stat sbuf;
    time_t tp[2];
    time_t now = time (0);
    fstat (fd,&sbuf);		/* get file times */
    if (LOCAL->ld >= 0) {	/* yes, readwrite session? */
      tp[0] = now;		/* set atime to now */
				/* set mtime to (now - 1) if necessary */
      tp[1] = (now > sbuf.st_mtime) ? sbuf.st_mtime : now - 1;
    }
    else if (stream->recent) {	/* readonly with recent messages */
      if ((sbuf.st_atime >= sbuf.st_mtime) ||
	  (sbuf.st_atime >= sbuf.st_ctime))
				/* keep past mtime, whack back atime */
	tp[0] = (tp[1] = (sbuf.st_mtime < now) ? sbuf.st_mtime : now) - 1;
      else now = 0;		/* no time change needed */
    }
				/* readonly with no recent messages */
    else if ((sbuf.st_atime < sbuf.st_mtime) ||
	     (sbuf.st_atime < sbuf.st_ctime)) {
      tp[0] = now;		/* set atime to now */
				/* set mtime to (now - 1) if necessary */
      tp[1] = (now > sbuf.st_mtime) ? sbuf.st_mtime : now - 1;
    }
    else now = 0;		/* no time change needed */
				/* set the times, note change */
    if (now && !utime (stream->mailbox,tp)) LOCAL->filetime = tp[1];
  }
  flock (fd,LOCK_UN);		/* release flock'ers */
  if (!stream) close (fd);	/* close the file if no stream */
  dotlock_unlock (lock);	/* flush the lock file if any */
}

/* UNIX mail parse and lock mailbox
 * Accepts: MAIL stream
 *	    space to write lock file name
 *	    type of locking operation
 * Returns: T if parse OK, critical & mailbox is locked shared; NIL if failure
 */

int unix_parse (MAILSTREAM *stream,DOTLOCK *lock,int op)
{
  int zn;
  unsigned long i,j,k,m;
  unsigned char c,*s,*t,*u,tmp[MAILTMPLEN],date[30];
  int ti = 0,retain = T;
  unsigned long nmsgs = stream->nmsgs;
  unsigned long prevuid = nmsgs ? mail_elt (stream,nmsgs)->private.uid : 0;
  unsigned long recent = stream->recent;
  unsigned long oldnmsgs = stream->nmsgs;
  short silent = stream->silent;
  short pseudoseen = NIL;
  struct stat sbuf;
  STRING bs;
  FDDATA d;
  MESSAGECACHE *elt;
  mail_lock (stream);		/* guard against recursion or pingers */
				/* toss out previous descriptor */
  if (LOCAL->fd >= 0) close (LOCAL->fd);
  MM_CRITICAL (stream);		/* open and lock mailbox (shared OK) */
  if ((LOCAL->fd = unix_lock (stream->mailbox,(LOCAL->ld >= 0) ?
			      O_RDWR : O_RDONLY,
			      (long)mail_parameters(NIL,GET_MBXPROTECTION,NIL),
			      lock,op)) < 0) {
    sprintf (tmp,"Mailbox open failed, aborted: %s",strerror (errno));
    MM_LOG (tmp,ERROR);
    unix_abort (stream);
    mail_unlock (stream);
    MM_NOCRITICAL (stream);	/* done with critical */
    return NIL;
  }
  fstat (LOCAL->fd,&sbuf);	/* get status */
				/* validate change in size */
  if (sbuf.st_size < LOCAL->filesize) {
    sprintf (tmp,"Mailbox shrank from %lu to %lu bytes, aborted",
	     (unsigned long) LOCAL->filesize,(unsigned long) sbuf.st_size);
    MM_LOG (tmp,ERROR);		/* this is pretty bad */
    unix_unlock (LOCAL->fd,stream,lock);
    unix_abort (stream);
    mail_unlock (stream);
    MM_NOCRITICAL (stream);	/* done with critical */
    return NIL;
  }

				/* new data? */
  else if ((i = sbuf.st_size - LOCAL->filesize) != 0L) {
    d.fd = LOCAL->fd;		/* yes, set up file descriptor */
    d.pos = LOCAL->filesize;	/* get to that position in the file */
    d.chunk = LOCAL->buf;	/* initial buffer chunk */
    d.chunksize = CHUNKSIZE;	/* file chunk size */
    INIT (&bs,fd_string,&d,i);	/* initialize stringstruct */
				/* skip leading whitespace for broken MTAs */
    while (((c = CHR (&bs)) == '\n') || (c == '\r') ||
	   (c == ' ') || (c == '\t')) SNX (&bs);
    if (SIZE (&bs)) {		/* read new data */
				/* remember internal header position */
      j = LOCAL->filesize + GETPOS (&bs);
      s = unix_mbxline (stream,&bs,&i);
      t = NIL,zn = 0;
      if (i) VALID (s,t,ti,zn);	/* see if valid From line */
      if (!ti) {		/* someone pulled the rug from under us */
	sprintf (tmp,"Unexpected changes to mailbox (try restarting): %.20s",
		 (char *) s);
	MM_LOG (tmp,ERROR);
	unix_unlock (LOCAL->fd,stream,lock);
	unix_abort (stream);
	mail_unlock (stream);
				/* done with critical */
	MM_NOCRITICAL (stream);
	return NIL;
      }
      stream->silent = T;	/* quell main program new message events */
      do {			/* found a message */
				/* instantiate first new message */
	mail_exists (stream,++nmsgs);
	(elt = mail_elt (stream,nmsgs))->valid = T;
	recent++;		/* assume recent by default */
	elt->recent = T;
				/* note position/size of internal header */
	elt->private.special.offset = j;
	elt->private.msg.header.offset = elt->private.special.text.size = i;

				/* generate plausible IMAPish date string */
	date[2] = date[6] = date[20] = '-'; date[11] = ' ';
	date[14] = date[17] = ':';
				/* dd */
	date[0] = t[ti - 2]; date[1] = t[ti - 1];
				/* mmm */
	date[3] = t[ti - 6]; date[4] = t[ti - 5]; date[5] = t[ti - 4];
				/* hh */
	date[12] = t[ti + 1]; date[13] = t[ti + 2];
				/* mm */
	date[15] = t[ti + 4]; date[16] = t[ti + 5];
	if (t[ti += 6] == ':') {/* ss */
	  date[18] = t[++ti]; date[19] = t[++ti];
	  ti++;			/* move to space */
	}
	else date[18] = date[19] = '0';
				/* yy -- advance over timezone if necessary */
	if (zn == ti) ti += (((t[zn+1] == '+') || (t[zn+1] == '-')) ? 6 : 4);
	date[7] = t[ti + 1]; date[8] = t[ti + 2];
	date[9] = t[ti + 3]; date[10] = t[ti + 4];
				/* zzz */
	t = zn ? (t + zn + 1) : (unsigned char *) "LCL";
	date[21] = *t++; date[22] = *t++; date[23] = *t++;
	if ((date[21] != '+') && (date[21] != '-')) date[24] = '\0';
	else {			/* numeric time zone */
	  date[24] = *t++; date[25] = *t++;
	  date[26] = '\0'; date[20] = ' ';
	}
				/* set internal date */
	if (!mail_parse_date (elt,date)) {
	  sprintf (tmp,"Unable to parse internal date: %s",(char *) date);
	  MM_LOG (tmp,WARN);
	}

	do {			/* look for message body */
	  s = t = unix_mbxline (stream,&bs,&i);
	  if (i) switch (*s) {	/* check header lines */
	  case 'X':		/* possible X-???: line */
	    if (s[1] == '-') {	/* must be immediately followed by hyphen */
				/* X-Status: becomes Status: in S case */
	      if (s[2] == 'S' && s[3] == 't' && s[4] == 'a' && s[5] == 't' &&
		  s[6] == 'u' && s[7] == 's' && s[8] == ':') s += 2;
				/* possible X-Keywords */
	      else if (s[2] == 'K' && s[3] == 'e' && s[4] == 'y' &&
		       s[5] == 'w' && s[6] == 'o' && s[7] == 'r' &&
		       s[8] == 'd' && s[9] == 's' && s[10] == ':') {
		SIZEDTEXT uf;
		retain = NIL;	/* don't retain continuation */
		s += 11;	/* flush leading whitespace */
		while (*s && (*s != '\n') && ((*s != '\r') || (s[1] != '\n'))){
		  while (*s == ' ') s++;
				/* find end of keyword */
		  if (!(u = strpbrk (s," \n\r"))) u = s + strlen (s);
				/* got a keyword? */
		  if ((k = (u - s)) && (k <= MAXUSERFLAG)) {
		    uf.data = (unsigned char *) s;
		    uf.size = k;
		    for (j = 0; (j < NUSERFLAGS) && stream->user_flags[j]; ++j)
		      if (!compare_csizedtext (stream->user_flags[j],&uf)) {
			elt->user_flags |= ((long) 1) << j;
			break;
		      }
 		  }
		  s = u;	/* advance to next keyword */
		}
		break;
	      }

				/* possible X-IMAP */
	      else if ((s[2] == 'I') && (s[3] == 'M') && (s[4] == 'A') &&
		       (s[5] == 'P') && ((m = (s[6] == ':')) ||
					 ((s[6] == 'b') && (s[7] == 'a') &&
					  (s[8] == 's') && (s[9] == 'e') &&
					  (s[10] == ':')))) {
		retain = NIL;	/* don't retain continuation */
		if ((nmsgs == 1) && !stream->uid_validity) {
				/* advance to data */
		  s += m ? 7 : 11;
				/* flush whitespace */
		  while (*s == ' ') s++;
		  j = 0;	/* slurp UID validity */
				/* found a digit? */
		  while (isdigit (*s)) {
		    j *= 10;	/* yes, add it in */
		    j += *s++ - '0';
		  }
				/* flush whitespace */
		  while (*s == ' ') s++;
				/* must have valid UID validity and UID last */
		  if (j && isdigit (*s)) {
				/* pseudo-header seen if X-IMAP */
		    if (m) pseudoseen = LOCAL->pseudo = T;
				/* save UID validity */
		    stream->uid_validity = j;
		    j = 0;	/* slurp UID last */
		    while (isdigit (*s)) {
		      j *= 10;	/* yes, add it in */
		      j += *s++ - '0';
		    }
				/* save UID last */
		    stream->uid_last = j;
				/* process keywords */
		    for (j = 0; (*s != '\n') && ((*s != '\r')||(s[1] != '\n'));
			 s = u,j++) {
				/* flush leading whitespace */
		      while (*s == ' ') s++;
		      u = strpbrk (s," \n\r");
				/* got a keyword? */
		      if ((j < NUSERFLAGS) && (k = (u - s)) &&
			  (k <= MAXUSERFLAG)) {
			if (stream->user_flags[j])
			  fs_give ((void **) &stream->user_flags[j]);
			stream->user_flags[j] = (char *) fs_get (k + 1);
			strncpy (stream->user_flags[j],s,k);
			stream->user_flags[j][k] = '\0';
		      }
		    }
		  }
		}
		break;
	      }

				/* possible X-UID */
	      else if (s[2] == 'U' && s[3] == 'I' && s[4] == 'D' &&
		       s[5] == ':') {
		retain = NIL;	/* don't retain continuation */
				/* only believe if have a UID validity */
		if (stream->uid_validity && ((nmsgs > 1) || !pseudoseen)) {
		  s += 6;	/* advance to UID value */
				/* flush whitespace */
		  while (*s == ' ') s++;
		  j = 0;
				/* found a digit? */
		  while (isdigit (*s)) {
		    j *= 10;	/* yes, add it in */
		    j += *s++ - '0';
		  }
				/* flush remainder of line */
		  while (*s != '\n') s++;
				/* make sure not duplicated */
		  if (elt->private.uid)
		    sprintf (tmp,"Message %lu UID %lu already has UID %lu",
			     pseudoseen ? elt->msgno - 1 : elt->msgno,
			     j,elt->private.uid);
				/* make sure UID doesn't go backwards */
		  else if (j <= prevuid)
		    sprintf (tmp,"Message %lu UID %lu less than %lu",
			     pseudoseen ? elt->msgno - 1 : elt->msgno,
			     j,prevuid + 1);
#if 0	/* this is currently broken by UIDPLUS */
				/* or skip by mailbox's recorded last */
		  else if (j > stream->uid_last)
		    sprintf (tmp,"Message %lu UID %lu greater than last %lu",
			     pseudoseen ? elt->msgno - 1 : elt->msgno,
			     j,stream->uid_last);
#endif
		  else {	/* normal UID case */
		    prevuid = elt->private.uid = j;
#if 1	/* temporary kludge for UIDPLUS */
		    if (prevuid > stream->uid_last) {
		      stream->uid_last = prevuid;
		      LOCAL->ddirty = LOCAL->dirty = T;
		    }		    
#endif
		    break;	/* exit this cruft */
		  }
		  MM_LOG (tmp,WARN);
				/* invalidate UID validity */
		  stream->uid_validity = 0;
		  elt->private.uid = 0;
		}
		break;
	      }
	    }
				/* otherwise fall into S case */

	  case 'S':		/* possible Status: line */
	    if (s[0] == 'S' && s[1] == 't' && s[2] == 'a' && s[3] == 't' &&
		s[4] == 'u' && s[5] == 's' && s[6] == ':') {
	      retain = NIL;	/* don't retain continuation */
	      s += 6;		/* advance to status flags */
	      do switch (*s++) {/* parse flags */
	      case 'R':		/* message read */
		elt->seen = T;
		break;
	      case 'O':		/* message old */
		if (elt->recent) {
		  elt->recent = NIL;
		  recent--;	/* it really wasn't recent */
		}
		break;
	      case 'D':		/* message deleted */
		elt->deleted = T;
		break;
	      case 'F':		/* message flagged */
		elt->flagged = T;
		break;
	      case 'A':		/* message answered */
		elt->answered = T;
		break;
	      case 'T':		/* message is a draft */
		elt->draft = T;
		break;
	      default:		/* some other crap */
		break;
	      } while (*s && (*s != '\n') && ((*s != '\r') || (s[1] != '\n')));
	      break;		/* all done */
	    }
				/* otherwise fall into default case */

	  default:		/* ordinary header line */
	    if ((*s == 'S') || (*s == 's') ||
		(((*s == 'X') || (*s == 'x')) && (s[1] == '-'))) {
	      unsigned char *e,*v;
				/* must match what mail_filter() does */
	      for (u = s,v = tmp,e = u + min (i,MAILTMPLEN - 1);
		   (u < e) && ((c = (*u ? *u : (*u = ' '))) != ':') &&
		   ((c > ' ') || ((c != ' ') && (c != '\t') &&
				  (c != '\r') && (c != '\n')));
		   *v++ = *u++);
	      *v = '\0';	/* tie off */
				/* matches internal header? */
	      if (!compare_cstring (tmp,"STATUS") ||
		  !compare_cstring (tmp,"X-STATUS") ||
		  !compare_cstring (tmp,"X-KEYWORDS") ||
		  !compare_cstring (tmp,"X-UID") ||
		  !compare_cstring (tmp,"X-IMAP") ||
		  !compare_cstring (tmp,"X-IMAPBASE")) {
		char err[MAILTMPLEN];
		sprintf (err,"Discarding bogus %.20s header in message %lu",
			 (char *) tmp,elt->msgno);
		MM_LOG (err,WARN);
		retain = NIL;	/* don't retain continuation */
		break;		/* different case or something */
	      }
	    }
				/* retain or non-continuation? */
	    if (retain || ((*s != ' ') && (*s != '\t'))) {
	      retain = T;	/* retaining continuation now */
				/* line length in LF format newline */
	      for (j = k = 0; j < i; ++j) if (s[j] != '\r') ++k;
				/* "internal" header size */
	      elt->private.spare.data += k;
				/* message size */
	      elt->rfc822_size += k + 1;
	    }
	    else {
	      char err[MAILTMPLEN];
	      sprintf (err,"Discarding bogus continuation in msg %lu: %.80s",
		      elt->msgno,(char *) s);
	      if ((u = strpbrk (err,"\r\n")) != NULL) *u = '\0';
	      MM_LOG (err,WARN);
	      break;		/* different case or something */
	    }
	    break;
	  }
	} while (i && (*t != '\n') && ((*t != '\r') || (t[1] != '\n')));
				/* "internal" header sans trailing newline */
	if (i) elt->private.spare.data--;
				/* assign a UID if none found */
	if (((nmsgs > 1) || !pseudoseen) && !elt->private.uid) {
	  prevuid = elt->private.uid = ++stream->uid_last;
	  elt->private.dirty = T;
	  LOCAL->ddirty = T;	/* force update */
	}
	else elt->private.dirty = elt->recent;

				/* note size of header, location of text */
	elt->private.msg.header.text.size = 
	  (elt->private.msg.text.offset =
	   (LOCAL->filesize + GETPOS (&bs)) - elt->private.special.offset) -
	     elt->private.special.text.size;
	k = m = 0;		/* no previous line size yet */
				/* note current position */
	j = LOCAL->filesize + GETPOS (&bs);
	if (i) do {		/* look for next message */
	  s = unix_mbxline (stream,&bs,&i);
	  if (i) {		/* got new data? */
	    VALID (s,t,ti,zn);	/* yes, parse line */
	    if (!ti) {		/* not a header line, add it to message */
	      elt->rfc822_size += i;
	      for (j = 0; j < i; ++j) switch (s[j]) {
	      case '\r':	/* squeeze out CRs */
		elt->rfc822_size -= 1;
		break;
	      case '\n':	/* LF becomes CRLF */
		elt->rfc822_size += 1;
		break;
	      default:
		break;
	      }
	      if ((i == 1) && (*s == '\n')) {
		k = 2;
		m = 1;
	      }
	      else if ((i == 2) && (*s == '\r') && (s[1] == '\n'))
		k = m = 2;
	      else k = m = 0;	/* file does not end with newline! */
				/* update current position */
	      j = LOCAL->filesize + GETPOS (&bs);
	    }
	  }
	} while (i && !ti);	/* until found a header */
	elt->private.msg.text.text.size = j -
	  (elt->private.special.offset + elt->private.msg.text.offset);
				/* flush ending blank line */
	elt->private.msg.text.text.size -= m;
	elt->rfc822_size -= k;
				/* until end of buffer */
      } while (!stream->sniff && i);
      if (pseudoseen) {		/* flush pseudo-message if present */
				/* decrement recent count */
	if (mail_elt (stream,1)->recent) recent--;
				/* and the exists count */
	mail_exists (stream,nmsgs--);
	mail_expunged(stream,1);/* fake an expunge of that message */
      }
				/* need to start a new UID validity? */
      if (!stream->uid_validity) {
	stream->uid_validity = time (0);
				/* in case a whiner with no life */
	if (mail_parameters (NIL,GET_USERHASNOLIFE,NIL))
	  stream->uid_nosticky = T;
	else if (nmsgs) {	/* don't bother if empty file */
				/* make dirty to restart UID epoch */
	  LOCAL->ddirty = LOCAL->dirty = T;
				/* need to rewrite msg 1 if not pseudo */
	  if (!LOCAL->pseudo) mail_elt (stream,1)->private.dirty = T;
	  MM_LOG ("Assigning new unique identifiers to all messages",NIL);
	}
      }
      stream->nmsgs = oldnmsgs;	/* whack it back down */
      stream->silent = silent;	/* restore old silent setting */
				/* notify upper level of new mailbox sizes */
      mail_exists (stream,nmsgs);
      mail_recent (stream,recent);
				/* mark dirty so O flags are set */
      if (recent) LOCAL->dirty = T;
    }
  }
				/* no change, don't babble if never got time */
  else if (LOCAL->filetime && LOCAL->filetime != sbuf.st_mtime)
    MM_LOG ("New mailbox modification time but apparently no changes",WARN);
				/* update parsed file size and time */
  LOCAL->filesize = sbuf.st_size;
  LOCAL->filetime = sbuf.st_mtime;
  return T;			/* return the winnage */
}

/* UNIX read line from mailbox
 * Accepts: mail stream
 *	    stringstruct
 *	    pointer to line size
 * Returns: pointer to input line
 */

char *unix_mbxline (MAILSTREAM *stream,STRING *bs,unsigned long *size)
{
  unsigned long i,j,k,m;
  char *s,*t,*te;
  char *ret = "";
				/* flush old buffer */
  if (LOCAL->line) fs_give ((void **) &LOCAL->line);
				/* if buffer needs refreshing */
  if (!bs->cursize) SETPOS (bs,GETPOS (bs));
  if (SIZE (bs)) {		/* find newline */
				/* end of fast scan */
    te = (t = (s = bs->curpos) + bs->cursize) - 12;
    while (s < te) if ((*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
		       (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
		       (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
		       (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n')) {
      --s;			/* back up */
      break;			/* exit loop */
    }
				/* final character-at-a-time scan */
    while ((s < t) && (*s != '\n')) ++s;
				/* difficult case if line spans buffer */
    if ((i = s - bs->curpos) == bs->cursize) {
				/* have space in line buffer? */
      if (i > LOCAL->linebuflen) {
	fs_give ((void **) &LOCAL->linebuf);
	LOCAL->linebuf = (char *) fs_get (LOCAL->linebuflen = i);
      }
				/* remember what we have so far */
      memcpy (LOCAL->linebuf,bs->curpos,i);
				/* load next buffer */
      SETPOS (bs,k = GETPOS (bs) + i);
				/* end of fast scan */
      te = (t = (s = bs->curpos) + bs->cursize) - 12;
				/* fast scan in overlap buffer */
      while (s < te) if ((*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
			 (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
			 (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
			 (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n')) {
	--s;			/* back up */
	break;			/* exit loop */
      }

				/* final character-at-a-time scan */
      while ((s < t) && (*s != '\n')) ++s;
				/* huge line? */
      if ((j = s - bs->curpos) == bs->cursize) {
	SETPOS (bs,GETPOS (bs) + j);
				/* look for end of line (s-l-o-w!!) */
	for (m = SIZE (bs); m && (SNX (bs) != '\n'); --m,++j);
	SETPOS (bs,k);		/* go back to where it started */
      }
				/* got size of data, make buffer for return */
      ret = LOCAL->line = (char *) fs_get (i + j + 2);
				/* copy first chunk */
      memcpy (ret,LOCAL->linebuf,i);
      while (j) {		/* copy remainder */
	if (!bs->cursize) SETPOS (bs,GETPOS (bs));
	memcpy (ret + i,bs->curpos,k = min (j,bs->cursize));
	i += k;			/* account for this much read in */
	j -= k;
	bs->curpos += k;	/* increment new position */
	bs->cursize -= k;	/* eat that many bytes */
      }
      if (!bs->cursize) SETPOS (bs,GETPOS (bs));
				/* read newline at end */
      if (SIZE (bs)) ret[i++] = SNX (bs);
      ret[i] = '\0';		/* makes debugging easier */
    }
    else {			/* this is easy */
      ret = bs->curpos;		/* string it at this position */
      bs->curpos += ++i;	/* increment new position */
      bs->cursize -= i;		/* eat that many bytes */
    }
    *size = i;			/* return that to user */
  }
  else *size = 0;		/* end of data, return empty */
  return ret;
}

/* UNIX make pseudo-header
 * Accepts: MAIL stream
 *	    buffer to write pseudo-header
 * Returns: length of pseudo-header
 */

unsigned long unix_pseudo (MAILSTREAM *stream,char *hdr)
{
  int i;
  char *s,tmp[MAILTMPLEN];
  time_t now = time (0);
  rfc822_fixed_date (tmp);
  sprintf (hdr,"From %s %.24s\nDate: %s\nFrom: %s <%s@%.80s>\nSubject: %s\nMessage-ID: <%lu@%.80s>\nX-IMAP: %010lu %010lu",
	   pseudo_from,ctime (&now),
	   tmp,pseudo_name,pseudo_from,mylocalhost (),pseudo_subject,
	   (unsigned long) now,mylocalhost (),stream->uid_validity,
	   stream->uid_last);
  for (s = hdr + strlen (hdr),i = 0; i < NUSERFLAGS; ++i)
    if (stream->user_flags[i])
      sprintf (s += strlen (s)," %s",stream->user_flags[i]);
  sprintf (s += strlen (s),"\nStatus: RO\n\n%s\n\n",pseudo_msg);
  return strlen (hdr);		/* return header length */
}

/* UNIX make status string
 * Accepts: MAIL stream
 *	    destination string to write
 *	    message cache entry
 *	    UID to write if non-zero (else use elt->private.uid)
 *	    non-zero flag to write UID (.LT. 0 to write UID base info too)
 * Returns: length of string
 */

unsigned long unix_xstatus (MAILSTREAM *stream,char *status,MESSAGECACHE *elt,
			    unsigned long uid,long flag)
{
  char *t,stack[64];
  char *s = status;
  unsigned long n;
  int pad = 50;
  int sticky = uid ? T : !stream->uid_nosticky;
  /* This used to use sprintf(), but thanks to certain cretinous C libraries
     with horribly slow implementations of sprintf() I had to change it to this
     mess.  At least it should be fast. */
  if ((flag < 0) && sticky) {	/* need to write X-IMAPbase: header? */
    *s++ = 'X'; *s++ = '-'; *s++ = 'I'; *s++ = 'M'; *s++ = 'A'; *s++ = 'P';
    *s++ = 'b'; *s++ = 'a'; *s++ = 's'; *s++ = 'e'; *s++ = ':'; *s++ = ' ';
    t = stack;
    n = stream->uid_validity;	/* push UID validity digits on the stack */
    do *t++ = (char) (n % 10) + '0';
    while (n /= 10);
				/* pop UID validity digits from stack */
    while (t > stack) *s++ = *--t;
    *s++ = ' ';
    n = stream->uid_last;	/* push UID last digits on the stack */
    do *t++ = (char) (n % 10) + '0';
    while (n /= 10);
				/* pop UID last digits from stack */
    while (t > stack) *s++ = *--t;
    for (n = 0; n < NUSERFLAGS; ++n) if ((t = stream->user_flags[n]) != NULL)
      for (*s++ = ' '; *t; *s++ = *t++);
    *s++ = '\n';
    pad += 30;			/* increased padding if have IMAPbase */
  }
  *s++ = 'S'; *s++ = 't'; *s++ = 'a'; *s++ = 't'; *s++ = 'u'; *s++ = 's';
  *s++ = ':'; *s++ = ' ';
  if (elt->seen) *s++ = 'R';
				/* only write O if have a UID */
  if (flag && (!elt->recent || !LOCAL->appending)) *s++ = 'O';
  *s++ = '\n';
  *s++ = 'X'; *s++ = '-'; *s++ = 'S'; *s++ = 't'; *s++ = 'a'; *s++ = 't';
  *s++ = 'u'; *s++ = 's'; *s++ = ':'; *s++ = ' ';
  if (elt->deleted) *s++ = 'D';
  if (elt->flagged) *s++ = 'F';
  if (elt->answered) *s++ = 'A';
  if (elt->draft) *s++ = 'T';
  *s++ = '\n';

  if (sticky) {			/* only do this if UIDs sticky */
    *s++ = 'X'; *s++ = '-'; *s++ = 'K'; *s++ = 'e'; *s++ = 'y'; *s++ = 'w';
    *s++ = 'o'; *s++ = 'r'; *s++ = 'd'; *s++ = 's'; *s++ = ':';
    if ((n = elt->user_flags) != 0L) do {
      *s++ = ' ';
      for (t = stream->user_flags[find_rightmost_bit (&n)]; *t; *s++ = *t++);
    } while (n);
    n = s - status;		/* get size of stuff so far */
				/* pad X-Keywords to make size constant */
    if (n < pad) for (n = pad - n; n > 0; --n) *s++ = ' ';
    *s++ = '\n';
    if (flag) {			/* want to include UID? */
      t = stack;
				/* push UID digits on the stack */
      n = uid ? uid : elt->private.uid;
      do *t++ = (char) (n % 10) + '0';
      while (n /= 10);
      *s++ = 'X'; *s++ = '-'; *s++ = 'U'; *s++ = 'I'; *s++ = 'D'; *s++ = ':';
      *s++ = ' ';
				/* pop UID from stack */
      while (t > stack) *s++ = *--t;
      *s++ = '\n';
    }
  }
  *s++ = '\n'; *s = '\0';	/* end of extended message status */
  return s - status;		/* return size of resulting string */
}

/* Rewrite mailbox file
 * Accepts: MAIL stream, must be critical and locked
 *	    return pointer to number of expunged messages if want expunge
 *	    lock file name
 *	    expunge sequence, not deleted flag
 * Returns: T if success and mailbox unlocked, NIL if failure
 */

#define OVERFLOWBUFLEN 8192	/* initial overflow buffer length */

long unix_rewrite (MAILSTREAM *stream,unsigned long *nexp,DOTLOCK *lock,
		   long flags)
{
  MESSAGECACHE *elt;
  UNIXFILE f;
  char *s;
  time_t tp[2];
  long ret,flag;
  unsigned long i,j;
  unsigned long recent = stream->recent;
  unsigned long size = LOCAL->pseudo ? unix_pseudo (stream,LOCAL->buf) : 0;
  if (nexp) *nexp = 0;		/* initially nothing expunged */
				/* calculate size of mailbox after rewrite */
  for (i = 1,flag = LOCAL->pseudo ? 1 : -1; i <= stream->nmsgs; i++) {
    elt = mail_elt (stream,i);	/* get cache */
    if (!(nexp && elt->deleted && (flags ? elt->sequence : T))) {
				/* add RFC822 size of this message */
      size += elt->private.special.text.size + elt->private.spare.data +
	unix_xstatus (stream,LOCAL->buf,elt,NIL,flag) +
	  elt->private.msg.text.text.size + 1;
      flag = 1;			/* only count X-IMAPbase once */
    }
  }
				/* no messages, has a life, and no pseudo */
  if (!size && !mail_parameters (NIL,GET_USERHASNOLIFE,NIL)) {
    LOCAL->pseudo = T;		/* so make a pseudo-message now */
    size = unix_pseudo (stream,LOCAL->buf);
  }
				/* extend the file as necessary */
  if ((ret = unix_extend (stream,size)) != 0L) {
    /* Set up buffered I/O file structure
     * curpos	current position being written through buffering
     * filepos	current position being written physically to the disk
     * bufpos	current position being written in the buffer
     * protect	current maximum position that can be written to the disk
     *		before buffering is forced
     * The code tries to buffer so that that disk is written in multiples of
     * OVERBLOWBUFLEN bytes.
     */
    f.stream = stream;		/* note mail stream */
    f.curpos = f.filepos = 0;	/* start of file */
    f.protect = stream->nmsgs ?	/* initial protection pointer */
    mail_elt (stream,1)->private.special.offset : 8192;
    f.bufpos = f.buf = (char *) fs_get (f.buflen = OVERFLOWBUFLEN);

    if (LOCAL->pseudo)		/* update pseudo-header */
      unix_write (&f,LOCAL->buf,unix_pseudo (stream,LOCAL->buf));
				/* loop through all messages */
    for (i = 1,flag = LOCAL->pseudo ? 1 : -1; i <= stream->nmsgs;) {
      elt = mail_elt (stream,i);/* get cache */
				/* expunge this message? */
      if (nexp && elt->deleted && (flags ? elt->sequence : T)) {
				/* one less recent message */
	if (elt->recent) --recent;
	mail_expunged(stream,i);/* notify upper levels */
	++*nexp;		/* count up one more expunged message */
      }
      else {			/* preserve this message */
	i++;			/* advance to next message */
	if ((flag < 0) ||	/* need to rewrite message? */
	    elt->private.dirty || (f.curpos != elt->private.special.offset) ||
	    (elt->private.msg.header.text.size !=
	     (elt->private.spare.data +
	      unix_xstatus (stream,LOCAL->buf,elt,NIL,flag)))) {
	  unsigned long newoffset = f.curpos;
				/* yes, seek to internal header */
	  lseek (LOCAL->fd,elt->private.special.offset,L_SET);
	  read (LOCAL->fd,LOCAL->buf,elt->private.special.text.size);
				/* see if need to squeeze out a CR */
	  if (LOCAL->buf[elt->private.special.text.size - 2] == '\r') {
	    LOCAL->buf[--elt->private.special.text.size - 1] = '\n';
	    --size;		/* squeezed out a CR from PC */
	  }
				/* protection pointer moves to RFC822 header */
	  f.protect = elt->private.special.offset +
	    elt->private.msg.header.offset;
				/* write internal header */
	  unix_write (&f,LOCAL->buf,elt->private.special.text.size);
				/* get RFC822 header */
	  s = unix_header (stream,elt->msgno,&j,FT_INTERNAL);
				/* in case this got decremented */
	  elt->private.msg.header.offset = elt->private.special.text.size;
				/* header size, sans trailing newline */
	  if ((j < 2) || (s[j - 2] == '\n')) j--;
				/* this can happen if CRs were squeezed */
	  if (j < elt->private.spare.data) {
				/* so fix up counts */
	    size -= elt->private.spare.data - j;
	    elt->private.spare.data = j;
	  }
	  else if (j != elt->private.spare.data)
	    fatal ("header size inconsistent");
				/* protection pointer moves to RFC822 text */
	  f.protect = elt->private.special.offset +
	    elt->private.msg.text.offset;
	  unix_write (&f,s,j);	/* write RFC822 header */
				/* write status and UID */
	  unix_write (&f,LOCAL->buf,
		      j = unix_xstatus (stream,LOCAL->buf,elt,NIL,flag));
	  flag = 1;		/* only write X-IMAPbase once */
				/* new file header size */
	  elt->private.msg.header.text.size = elt->private.spare.data + j;

				/* did text move? */
	  if (f.curpos != f.protect) {
				/* get message text */
	    s = unix_text_work (stream,elt,&j,FT_INTERNAL);
				/* this can happen if CRs were squeezed */
	    if (j < elt->private.msg.text.text.size) {
				/* so fix up counts */
	      size -= elt->private.msg.text.text.size - j;
	      elt->private.msg.text.text.size = j;
	    }
				/* can't happen it says here */
	    else if (j > elt->private.msg.text.text.size)
	      fatal ("text size inconsistent");
				/* new text offset, status/UID may change it */
	    elt->private.msg.text.offset = f.curpos - newoffset;
				/* protection pointer moves to next message */
	    f.protect = (i <= stream->nmsgs) ?
	      mail_elt (stream,i)->private.special.offset : (f.curpos + j + 1);
	    unix_write (&f,s,j);/* write text */
				/* write trailing newline */
	    unix_write (&f,"\n",1);
	  }
	  else {		/* tie off header and status */
	    unix_write (&f,NIL,NIL);
				/* protection pointer moves to next message */
	    f.protect = (i <= stream->nmsgs) ?
	      mail_elt (stream,i)->private.special.offset : size;
				/* locate end of message text */
	    j = f.filepos + elt->private.msg.text.text.size;
				/* trailing newline already there? */
	    if (f.protect == (j + 1)) f.curpos = f.filepos = f.protect;
	    else {		/* trailing newline missing, write it */
	      f.curpos = f.filepos = j;
	      unix_write (&f,"\n",1);
	    }
	  }
				/* new internal header offset */
	  elt->private.special.offset = newoffset;
	  elt->private.dirty =NIL;/* message is now clean */
	}
	else {			/* no need to rewrite this message */
				/* tie off previous message if needed */
	  unix_write (&f,NIL,NIL);
				/* protection pointer moves to next message */
	  f.protect = (i <= stream->nmsgs) ?
	    mail_elt (stream,i)->private.special.offset : size;
				/* locate end of message text */
	  j = f.filepos + elt->private.special.text.size +
	    elt->private.msg.header.text.size +
	      elt->private.msg.text.text.size;
				/* trailing newline already there? */
	  if (f.protect == (j + 1)) f.curpos = f.filepos = f.protect;
	  else {		/* trailing newline missing, write it */
	    f.curpos = f.filepos = j;
	    unix_write (&f,"\n",1);
	  }
	}
      }
    }

    unix_write (&f,NIL,NIL);	/* tie off final message */
    if (size != f.filepos) fatal ("file size inconsistent");
    fs_give ((void **) &f.buf);	/* free buffer */
				/* make sure tied off */
    ftruncate (LOCAL->fd,LOCAL->filesize = size);
    fsync (LOCAL->fd);		/* make sure the updates take */
    if (size && (flag < 0)) fatal ("lost UID base information");
				/* no longer dirty */
    LOCAL->ddirty = LOCAL->dirty = NIL;
  				/* notify upper level of new mailbox sizes */
    mail_exists (stream,stream->nmsgs);
    mail_recent (stream,recent);
				/* set atime to now, mtime a second earlier */
    tp[1] = (tp[0] = time (0)) - 1;
				/* set the times, note change */
    if (!utime (stream->mailbox,tp)) LOCAL->filetime = tp[1];
    close (LOCAL->fd);		/* close and reopen file */
    if ((LOCAL->fd = open (stream->mailbox,O_RDWR,
			   (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL)))
	< 0) {
      sprintf (LOCAL->buf,"Mailbox open failed, aborted: %s",strerror (errno));
      MM_LOG (LOCAL->buf,ERROR);
      unix_abort (stream);
    }
    dotlock_unlock (lock);	/* flush the lock file */
  }
  return ret;			/* return state from algorithm */
}

/* Extend UNIX mailbox file
 * Accepts: MAIL stream
 *	    new desired size
 * Return: T if success, else NIL
 */

long unix_extend (MAILSTREAM *stream,unsigned long size)
{
  unsigned long i = (size > LOCAL->filesize) ? size - LOCAL->filesize : 0;
  if (i) {			/* does the mailbox need to grow? */
    if (i > LOCAL->buflen) {	/* make sure have enough space */
				/* this user won the lottery all right */
      fs_give ((void **) &LOCAL->buf);
      LOCAL->buf = (char *) fs_get ((LOCAL->buflen = i) + 1);
    }
    memset (LOCAL->buf,'\0',i);	/* get a block of nulls */
    while (T) {			/* until write successful or punt */
      lseek (LOCAL->fd,LOCAL->filesize,L_SET);
      if ((write (LOCAL->fd,LOCAL->buf,i) >= 0) && !fsync (LOCAL->fd)) break;
      else {
	long e = errno;		/* note error before doing ftruncate */
	ftruncate (LOCAL->fd,LOCAL->filesize);
	if (MM_DISKERROR (stream,e,NIL)) {
	  fsync (LOCAL->fd);	/* user chose to punt */
	  sprintf (LOCAL->buf,"Unable to extend mailbox: %s",strerror (e));
	  if (!stream->silent) MM_LOG (LOCAL->buf,ERROR);
	  return NIL;
	}
      }
    }
  }
  return LONGT;
}

/* Write data to buffered file
 * Accepts: buffered file pointer
 *	    file data or NIL to indicate "flush buffer"
 *	    date size (ignored for "flush buffer")
 * Does not return until success
 */

void unix_write (UNIXFILE *f,char *buf,unsigned long size)
{
  unsigned long i,j,k;
  if (buf) {			/* doing buffered write? */
    i = f->bufpos - f->buf;	/* yes, get size of current buffer data */
				/* yes, have space in current buffer chunk? */
    if ((j = i ? ((f->buflen - i) % OVERFLOWBUFLEN) : f->buflen) != 0L) {
				/* yes, fill up buffer as much as we can */
      memcpy (f->bufpos,buf,k = min (j,size));
      f->bufpos += k;		/* new buffer position */
      f->curpos += k;		/* new current position */
      if (j -= k) return;	/* all done if still have buffer free space */
      buf += k;			/* full, get new unwritten data pointer */
      size -= k;		/* new data size */
      i += k;			/* new buffer data size */
    }
    /* This chunk of the buffer is full.  See if can make some space by
     * writing to the disk, if there's enough unprotected space to do so.
     * Try to fill out any unaligned chunk, along with any subsequent full
     * chunks that will fit in unprotected space.
     */
				/* any unprotected space we can write to? */
    if ((j = min (i,f->protect - f->filepos)) != 0L) {
				/* yes, filepos not at chunk boundary? */
      if ((k = f->filepos % OVERFLOWBUFLEN) && ((k = OVERFLOWBUFLEN - k) < j))
	j -= k;			/* yes, and can write out partial chunk */
      else k = 0;		/* no partial chunk to write */
				/* if at least a chunk free, write that too */
      if (j > OVERFLOWBUFLEN) k += j - (j % OVERFLOWBUFLEN);
      if (k) {			/* write data if there is anything we can */
	unix_phys_write (f,f->buf,k);
				/* slide buffer */
	if (i -= k) memmove (f->buf,f->buf + k,i);
	f->bufpos = f->buf + i;	/* new end of buffer */
      }
    }

    /* Have flushed the buffer as best as possible.  All done if no more
     * data to write.  Otherwise, if the buffer is empty AND if the unwritten
     * data is larger than a chunk AND the unprotected space is also larger
     * than a chunk, then write as many chunks as we can directly from the
     * data.  Buffer the rest, expanding the buffer as needed.
     */
    if (size) {			/* have more data that we need to buffer? */
				/* can write any of it to disk instead? */
      if ((f->bufpos == f->buf) && 
	  ((j = min (f->protect - f->filepos,size)) > OVERFLOWBUFLEN)) {
				/* write as much as we can right now */
	unix_phys_write (f,buf,j -= (j % OVERFLOWBUFLEN));
	buf += j;		/* new data pointer */
	size -= j;		/* new data size */
	f->curpos += j;		/* advance current pointer */
      }
      if (size) {		/* still have data that we need to buffer? */
				/* yes, need to expand the buffer? */
	if ((i = ((f->bufpos + size) - f->buf)) > f->buflen) {
				/* note current position in buffer */
	  j = f->bufpos - f->buf;
	  i += OVERFLOWBUFLEN;	/* yes, grow another chunk */
	  fs_resize ((void **) &f->buf,f->buflen = i - (i % OVERFLOWBUFLEN));
				/* in case buffer relocated */
	  f->bufpos = f->buf + j;
	}
				/* buffer remaining data */
	memcpy (f->bufpos,buf,size);
	f->bufpos += size;	/* new end of buffer */
	f->curpos += size;	/* advance current pointer */
      }
    }
  }
  else {			/* flush buffer to disk */
    unix_phys_write (f,f->buf,i = f->bufpos - f->buf);
    f->bufpos = f->buf;		/* reset buffer */
				/* update positions */
    f->curpos = f->protect = f->filepos;
  }
}

/* Physical disk write
 * Accepts: buffered file pointer
 *	    buffer address
 *	    buffer size
 * Does not return until success
 */

void unix_phys_write (UNIXFILE *f,char *buf,size_t size)
{
  MAILSTREAM *stream = f->stream;
				/* write data at desired position */
  while (size && ((lseek (LOCAL->fd,f->filepos,L_SET) < 0) ||
		  (write (LOCAL->fd,buf,size) < 0))) {
    int e;
    char tmp[MAILTMPLEN];
    sprintf (tmp,"Unable to write to mailbox: %s",strerror (e = errno));
    MM_LOG (tmp,ERROR);
    MM_DISKERROR (NIL,e,T);	/* serious problem, must retry */
  }
  f->filepos += size;		/* update file position */
}

/* MBOX mail routines */


/* Driver dispatch used by MAIL */

DRIVER mboxdriver = {
  "mbox",			/* driver name */
				/* driver flags */
  DR_LOCAL|DR_MAIL|DR_LOCKING|DR_NONEWMAILRONLY,
  (DRIVER *) NIL,		/* next driver */
  mbox_valid,			/* mailbox is valid for us */
  unix_parameters,		/* manipulate parameters */
  unix_scan,			/* scan mailboxes */
  unix_list,			/* find mailboxes */
  unix_lsub,			/* find subscribed mailboxes */
  NIL,				/* subscribe to mailbox */
  NIL,				/* unsubscribe from mailbox */
  mbox_create,			/* create mailbox */
  mbox_delete,			/* delete mailbox */
  mbox_rename,			/* rename mailbox */
  mbox_status,			/* status of mailbox */
  mbox_open,			/* open mailbox */
  unix_close,			/* close mailbox */
  NIL,				/* fetch message "fast" attributes */
  NIL,				/* fetch message flags */
  NIL,				/* fetch overview */
  NIL,				/* fetch message structure */
  unix_header,			/* fetch message header */
  unix_text,			/* fetch message body */
  NIL,				/* fetch partial message text */
  NIL,				/* unique identifier */
  NIL,				/* message number */
  NIL,				/* modify flags */
  unix_flagmsg,			/* per-message modify flags */
  NIL,				/* search for message based on criteria */
  NIL,				/* sort messages */
  NIL,				/* thread messages */
  mbox_ping,			/* ping mailbox to see if still alive */
  mbox_check,			/* check for new messages */
  mbox_expunge,			/* expunge deleted messages */
  unix_copy,			/* copy messages to another mailbox */
  mbox_append,			/* append string message to mailbox */
  NIL				/* garbage collect stream */
};

				/* prototype stream */
MAILSTREAM mboxproto = {&mboxdriver};

/* MBOX mail validate mailbox
 * Accepts: mailbox name
 * Returns: our driver if name is valid, NIL otherwise
 */

DRIVER *mbox_valid (char *name)
{
				/* only INBOX, mbox must exist */
  if (!compare_cstring (name,"INBOX") && (unix_valid ("mbox") || !errno) &&
      (unix_valid (sysinbox()) || !errno || (errno == ENOENT)))
    return &mboxdriver;
  return NIL;			/* can't win (yet, anyway) */
}

/* MBOX mail create mailbox
 * Accepts: MAIL stream
 *	    mailbox name to create
 * Returns: T on success, NIL on failure
 */

long mbox_create (MAILSTREAM *stream,char *mailbox)
{
  char tmp[MAILTMPLEN];
  if (!compare_cstring (mailbox,"INBOX")) return unix_create (NIL,"mbox");
  sprintf (tmp,"Can't create non-INBOX name as mbox: %.80s",mailbox);
  MM_LOG (tmp,ERROR);
  return NIL;
}


/* MBOX mail delete mailbox
 * Accepts: MAIL stream
 *	    mailbox name to delete
 * Returns: T on success, NIL on failure
 */

long mbox_delete (MAILSTREAM *stream,char *mailbox)
{
  return mbox_rename (stream,mailbox,NIL);
}


/* MBOX mail rename mailbox
 * Accepts: MAIL stream
 *	    old mailbox name
 *	    new mailbox name (or NIL for delete)
 * Returns: T on success, NIL on failure
 */

long mbox_rename (MAILSTREAM *stream,char *old,char *newname)
{
  char tmp[MAILTMPLEN];
  long ret = unix_rename (stream,"~/mbox",newname);
				/* recreate file if renamed INBOX */
  if (ret) unix_create (NIL,"mbox");
  else MM_LOG (tmp,ERROR);	/* log error */
  return ret;			/* return success */
}

/* MBOX Mail status
 * Accepts: mail stream
 *	    mailbox name
 *	    status flags
 * Returns: T on success, NIL on failure
 */

long mbox_status (MAILSTREAM *stream,char *mbx,long flags)
{
  MAILSTATUS status;
  unsigned long i;
  MAILSTREAM *tstream = NIL;
  MAILSTREAM *systream = NIL;
				/* make temporary stream (unless this mbx) */
  if (!stream && !(stream = tstream =
		   mail_open (NIL,mbx,OP_READONLY|OP_SILENT))) return NIL;
  status.flags = flags;		/* return status values */
  status.messages = stream->nmsgs;
  status.recent = stream->recent;
  if (flags & SA_UNSEEN)	/* must search to get unseen messages */
    for (i = 1,status.unseen = 0; i <= stream->nmsgs; i++)
      if (!mail_elt (stream,i)->seen) status.unseen++;
  status.uidnext = stream->uid_last + 1;
  status.uidvalidity = stream->uid_validity;
  if (!status.recent &&		/* calculate post-snarf results */
      (systream = mail_open (NIL,sysinbox (),OP_READONLY|OP_SILENT))) {
    status.messages += systream->nmsgs;
    status.recent += systream->recent;
    if (flags & SA_UNSEEN)	/* must search to get unseen messages */
      for (i = 1; i <= systream->nmsgs; i++)
	if (!mail_elt (systream,i)->seen) status.unseen++;
				/* kludge but probably good enough */
    status.uidnext += systream->nmsgs;
  }
  MM_STATUS(stream,mbx,&status);/* pass status to main program */
  if (tstream) mail_close (tstream);
  if (systream) mail_close (systream);
  return T;			/* success */
}

/* MBOX mail open
 * Accepts: stream to open
 * Returns: stream on success, NIL on failure
 */

MAILSTREAM *mbox_open (MAILSTREAM *stream)
{
  unsigned long i = 1;
  unsigned long recent = 0;
				/* return prototype for OP_PROTOTYPE call */
  if (!stream) return &mboxproto;
				/* change mailbox file name */
  fs_give ((void **) &stream->mailbox);
  stream->mailbox = cpystr ("mbox");
				/* open mailbox, snarf new mail */
  if (!(unix_open (stream) && mbox_ping (stream))) return NIL;
  stream->inbox = T;		/* mark that this is an INBOX */
				/* notify upper level of mailbox sizes */
  mail_exists (stream,stream->nmsgs);
  while (i <= stream->nmsgs) if (mail_elt (stream,i++)->recent) ++recent;
  mail_recent (stream,recent);	/* including recent messages */
  return stream;
}

/* MBOX mail ping mailbox
 * Accepts: MAIL stream
 * Returns: T if stream alive, else NIL
 * No-op for readonly files, since read/writer can expunge it from under us!
 */

static int snarfed = 0;		/* number of snarfs */

long mbox_ping (MAILSTREAM *stream)
{
  int sfd;
  unsigned long size;
  struct stat sbuf;
  char *s;
  DOTLOCK lock,lockx;
				/* time to try snarf and sysinbox non-empty? */
  if (LOCAL && !stream->rdonly && !stream->lock &&
      (time (0) >= (LOCAL->lastsnarf +
		    (long) mail_parameters (NIL,GET_SNARFINTERVAL,NIL))) &&
      !stat (sysinbox (),&sbuf) && sbuf.st_size) {
    MM_CRITICAL (stream);	/* yes, go critical */
				/* open and lock sysinbox */
    if ((sfd = unix_lock (sysinbox (),O_RDWR,
			  (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL),
			  &lockx,LOCK_EX)) >= 0) {
				/* locked sysinbox in good format? */
      if (fstat (sfd,&sbuf) || !(size = sbuf.st_size) ||
	  !unix_isvalid_fd (sfd)) {
	sprintf (LOCAL->buf,"Mail drop %s is not in standard Unix format",
		 sysinbox ());
	MM_LOG (LOCAL->buf,ERROR);
      }
				/* sysinbox good, parse and excl-lock mbox */
      else if (unix_parse (stream,&lock,LOCK_EX)) {
	lseek (sfd,0,L_SET);	/* read entire sysinbox into memory */
	read (sfd,s = (char *) fs_get (size + 1),size);
	s[size] = '\0';		/* tie it off */
				/* append to end of mbox */
	lseek (LOCAL->fd,LOCAL->filesize,L_SET);

				/* copy to mbox */
	if ((write (LOCAL->fd,s,size) < 0) || fsync (LOCAL->fd)) {
	  sprintf (LOCAL->buf,"New mail move failed: %s",strerror (errno));
	  MM_LOG (LOCAL->buf,WARN);
				/* revert mbox to previous size */
	  ftruncate (LOCAL->fd,LOCAL->filesize);
	}
				/* sysinbox better not have changed */
	else if (fstat (sfd,&sbuf) || (size != sbuf.st_size)) {
	  sprintf (LOCAL->buf,"Mail drop %s lock failure, old=%lu now=%lu",
		   sysinbox (),size,(unsigned long) sbuf.st_size);
	  MM_LOG (LOCAL->buf,ERROR);
				/* revert mbox to previous size */
	  ftruncate (LOCAL->fd,LOCAL->filesize);
	  /* Believe it or not, a Singaporean government system actually had
	   * symlinks from /var/mail/user to ~user/mbox.  To compound this
	   * error, they used an SVR4 system; BSD and OSF locks would have
	   * prevented it but not SVR4 locks.
	   */
	  if (!fstat (sfd,&sbuf) && (size == sbuf.st_size))
	    syslog (LOG_ALERT,"File %s and %s are the same file!",
		    sysinbox (),stream->mailbox);
	}
	else {			/* data copied OK */
	  ftruncate (sfd,0);	/* truncate sysinbox to zero bytes */
	  if (!snarfed++) {	/* have we snarfed before? */
				/* syslog if server, else user log */
	    sprintf (LOCAL->buf,"Moved %lu bytes of new mail to %s from %s",
		     size,stream->mailbox,sysinbox ());
	    if (strcmp ((char *) mail_parameters (NIL,GET_SERVICENAME,NIL),
			"unknown"))
	      syslog (LOG_INFO,"%s host= %s",LOCAL->buf,tcp_clienthost ());
	    else MM_LOG (LOCAL->buf,WARN);
	  }
	}
				/* done with sysinbox text */
	fs_give ((void **) &s);
				/* all done with mbox */
	unix_unlock (LOCAL->fd,stream,&lock);
	mail_unlock (stream);	/* unlock the stream */
	MM_NOCRITICAL (stream);	/* done with critical */
      }
				/* all done with sysinbox */
      unix_unlock (sfd,NIL,&lockx);
    }
    MM_NOCRITICAL (stream);	/* done with critical */
    LOCAL->lastsnarf = time (0);/* note time of last snarf */
  }
  return unix_ping (stream);	/* do the unix routine now */
}

/* MBOX mail check mailbox
 * Accepts: MAIL stream
 */

void mbox_check (MAILSTREAM *stream)
{
				/* do local ping, then do unix routine */
  if (mbox_ping (stream)) unix_check (stream);
}


/* MBOX mail expunge mailbox
 * Accepts: MAIL stream
 *	    sequence to expunge if non-NIL
 *	    expunge options
 * Returns: T, always
 */

long mbox_expunge (MAILSTREAM *stream,char *sequence,long options)
{
  long ret = unix_expunge (stream,sequence,options);
  mbox_ping (stream);		/* do local ping */
  return ret;
}


/* MBOX mail append message from stringstruct
 * Accepts: MAIL stream
 *	    destination mailbox
 *	    append callback
 *	    data for callback
 * Returns: T if append successful, else NIL
 */

long mbox_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data)
{
  char tmp[MAILTMPLEN];
  if (mbox_valid (mailbox)) return unix_append (stream,"mbox",af,data);
  sprintf (tmp,"Can't append to that name: %.80s",mailbox);
  MM_LOG (tmp,ERROR);
  return NIL;
}