/* movemail foo bar -- move file foo to file bar,
   locking file foo the way /bin/mail respects.
   Copyright (C) 1986 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.

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

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/*
 * Modified January, 1986 by Michael R. Gretzinger (Project Athena)
 *
 * Added POP (Post Office Protocol) service.  When compiled -DPOP
 * movemail will accept input filename arguments of the form
 * "po:username".  This will cause movemail to open a connection to
 * a pop server running on $MAILHOST (environment variable).  Movemail
 * must be setuid to root in order to work with POP.
 * 
 * New module: popmail.c
 * Modified routines:
 *	main - added code within #ifdef MAIL_USE_POP; added setuid(getuid())
 *		after POP code. 
 * New routines in movemail.c:
 *	get_errmsg - return pointer to system error message
 *
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <errno.h>
#include <unistd.h>
#define NO_SHORTNAMES   /* Tell config not to load remap.h */
#include "../src/config.h"

#ifdef USG
#include <fcntl.h>
#include <unistd.h>
#ifndef F_OK
#define F_OK 0
#define X_OK 1
#define W_OK 2
#define R_OK 4
#endif
#endif /* USG */

#ifdef XENIX
#include <sys/locking.h>
#endif

/* Cancel substitutions made by config.h for Emacs.  */
#undef open
#undef read
#undef write
#undef close

char *concat ();
extern int errno;

/* Nonzero means this is name of a lock file to delete on fatal error.  */
char *delete_lockname;

main (argc, argv)
     int argc;
     char **argv;
{
  char *inname, *outname;
  int indesc, outdesc;
  char buf[1024];
  int nread;

#ifndef MAIL_USE_FLOCK
  struct stat st;
  long now;
  int tem;
  char *lockname, *p;
  char tempname[40];
  int desc;
#endif /* not MAIL_USE_FLOCK */

  delete_lockname = 0;

  if (argc < 3)
    fatal ("two arguments required");

  inname = argv[1];
  outname = argv[2];

  /* Check access to output file.  */
  if (access (outname, F_OK) == 0 && access (outname, W_OK) != 0)
    pfatal_with_name (outname);

  /* Also check that outname's directory is writeable to the real uid.  */
  {
    char *buf = (char *) malloc (strlen (outname) + 1);
    char *p, q;
    strcpy (buf, outname);
    p = buf + strlen (buf);
    while (p > buf && p[-1] != '/')
      *--p = 0;
    if (p == buf)
      *p++ = '.';
    if (access (buf, W_OK) != 0)
      pfatal_with_name (buf);
    free (buf);
  }

#ifdef MAIL_USE_POP
  if (!bcmp (inname, "po:", 3))
    {
      int status; char *user;

      user = (char *) rindex (inname, ':') + 1;
      status = popmail (user, outname);
      exit (status);
    }

  setuid (getuid());
#endif /* MAIL_USE_POP */

  /* Check access to input file.  */
  if (access (inname, R_OK | W_OK) != 0)
    pfatal_with_name (inname);

#ifndef MAIL_USE_FLOCK
  /* Use a lock file named /usr/spool/mail/$USER.lock:
     If it exists, the mail file is locked.  */
  lockname = concat (inname, ".lock", "");
  strcpy (tempname, inname);
  p = tempname + strlen (tempname);
  while (p != tempname && p[-1] != '/')
    p--;
  *p = 0;
  strcpy (p, "EXXXXXX");
  mktemp (tempname);
  (void) unlink (tempname);

  while (1)
    {
      /* Create the lock file, but not under the lock file name.  */
      /* Give up if cannot do that.  */
      desc = open (tempname, O_WRONLY | O_CREAT, 0666);
      if (desc < 0)
        pfatal_with_name (concat ("temporary file \"", tempname, "\""));
      close (desc);

      tem = link (tempname, lockname);
      (void) unlink (tempname);
      if (tem >= 0)
	break;
      sleep (1);

      /* If lock file is a minute old, unlock it.  */
      if (stat (lockname, &st) >= 0)
	{
	  now = time (0);
	  if (st.st_ctime < now - 60)
	    (void) unlink (lockname);
	}
    }

  delete_lockname = lockname;
#endif /* not MAIL_USE_FLOCK */

#ifdef MAIL_USE_FLOCK
  indesc = open (inname, O_RDWR);
#else /* if not MAIL_USE_FLOCK */
  indesc = open (inname, O_RDONLY);
#endif /* not MAIL_USE_FLOCK */
  if (indesc < 0)
    pfatal_with_name (inname);

#if defined(BSD) || defined(XENIX)
  /* In case movemail is setuid to root, make sure the user can
     read the output file.  */
  /* This is desirable for all systems
     but I don't want to assume all have the umask system call */
  umask (umask (0) & 0333);
#endif /* BSD or Xenix */
  outdesc = open (outname, O_WRONLY | O_CREAT | O_EXCL, 0666);
  if (outdesc < 0)
    pfatal_with_name (outname);
#ifdef MAIL_USE_FLOCK
#ifdef XENIX
  if (locking (indesc, LK_RLCK, 0L) < 0) pfatal_with_name (inname);
#else
  flock (indesc, LOCK_EX);
#endif
#endif /* MAIL_USE_FLOCK */

  while (1)
    {
      nread = read (indesc, buf, sizeof buf);
      if (nread != write (outdesc, buf, nread))
	{
	  int saved_errno = errno;
	  (void) unlink (outname);
	  errno = saved_errno;
	  pfatal_with_name (outname);
	}
      if (nread < sizeof buf)
	break;
    }

#ifdef BSD
  fsync (outdesc);
#endif

  /* Check to make sure no errors before we zap the inbox.  */
  if (close (outdesc) != 0)
    {
      int saved_errno = errno;
      (void) unlink (outname);
      errno = saved_errno;
      pfatal_with_name (outname);
  }

#ifdef MAIL_USE_FLOCK
#if defined(STRIDE) || defined(XENIX)
  /* Stride, xenix have file locking, but no ftruncate.  This mess will do. */
  (void) close (open (inname, O_CREAT | O_TRUNC | O_RDWR, 0666));
#else
  (void) ftruncate (indesc, (off_t)0);
#endif /* STRIDE or XENIX */
#endif /* MAIL_USE_FLOCK */
  close (indesc);

#ifndef MAIL_USE_FLOCK
  /* Delete the input file; if we can't, at least get rid of its contents.  */
  if (unlink (inname) < 0)
    if (errno != ENOENT)
      creat (inname, 0666);
  (void) unlink (lockname);
#endif /* not MAIL_USE_FLOCK */
  exit (0);
}

/* Print error message and exit.  */

fatal (s1, s2)
     char *s1, *s2;
{
  if (delete_lockname)
    unlink (delete_lockname);
  error (s1, s2);
  exit (1);
}

/* Print error message.  `s1' is printf control string, `s2' is arg for it. */

error (s1, s2, s3)
     char *s1, *s2, *s3;
{
  printf ("movemail: ");
  printf (s1, s2, s3);
  printf ("\n");
}

pfatal_with_name (name)
     char *name;
{
  extern int errno, sys_nerr;
  extern char *sys_errlist[];
  char *s;

  if (errno < sys_nerr)
    s = concat ("", sys_errlist[errno], " for %s");
  else
    s = "cannot open %s";
  fatal (s, name);
}

/* Return a newly-allocated string whose contents concatenate those of s1, s2, s3.  */

char *
concat (s1, s2, s3)
     char *s1, *s2, *s3;
{
  int len1 = strlen (s1), len2 = strlen (s2), len3 = strlen (s3);
  char *result = (char *) xmalloc (len1 + len2 + len3 + 1);

  strcpy (result, s1);
  strcpy (result + len1, s2);
  strcpy (result + len1 + len2, s3);
  *(result + len1 + len2 + len3) = 0;

  return result;
}

/* Like malloc but get fatal error if memory is exhausted.  */

int
xmalloc (size)
     int size;
{
  int result = malloc (size);
  if (!result)
    fatal ("virtual memory exhausted", 0);
  return result;
}

/* This is the guts of the interface to the Post Office Protocol.  */

#ifdef MAIL_USE_POP

#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>

#ifdef USG
#include <fcntl.h>
/* Cancel substitutions made by config.h for Emacs.  */
#undef open
#undef read
#undef write
#undef close
#endif /* USG */

#define NOTOK (-1)
#define OK 0
#define DONE 1

char *progname;
FILE *sfi;
FILE *sfo;
char Errmsg[80];

static int debug = 0;

popmail(user, outfile)
char *user;
char *outfile;
{
    char *host;
    int nmsgs, nbytes;
    char response[128];
    register int i;
    int mbfi;
    FILE *mbf;
    char *getenv();
    int mbx_write();
    char *get_errmsg();

    host = getenv("MAILHOST");
    if (host == NULL) {
	fatal("no MAILHOST defined");
    }

    if (pop_init(host) == NOTOK) {
	error(Errmsg);
	return(1);
    }

    if (getline(response, sizeof response, sfi) != OK) {
	error(response);
	return(1);
    }

    if (pop_command("USER %s", user) == NOTOK || 
	pop_command("RPOP %s", user) == NOTOK) {
	error(Errmsg);
	pop_command("QUIT");
	return(1);
    }

    if (pop_stat(&nmsgs, &nbytes) == NOTOK) {
	error(Errmsg);
	pop_command("QUIT");
	return(1);
    }

    if (!nmsgs)
      {
	pop_command("QUIT");
	return(0);
      }

    mbfi = open (outfile, O_WRONLY | O_CREAT | O_EXCL, 0666);
    if (mbfi < 0)
      {
	pop_command("QUIT");
	error("Error in open: %s, %s", get_errmsg(), outfile);
	return(1);
      }
    fchown(mbfi, getuid(), -1);

    if ((mbf = fdopen(mbfi, "w")) == NULL)
      {
	pop_command("QUIT");
	error("Error in fdopen: %s", get_errmsg());
	close(mbfi);
	unlink(outfile);
	return(1);
      }

    for (i = 1; i <= nmsgs; i++) {
	mbx_delimit_begin(mbf);
	if (pop_retr(i, mbx_write, mbf) != OK) {
	    error(Errmsg);
	    pop_command("QUIT");
	    close(mbfi);
	    return(1);
	}
	mbx_delimit_end(mbf);
	fflush(mbf);
    }

    for (i = 1; i <= nmsgs; i++) {
	if (pop_command("DELE %d", i) == NOTOK) {
	    error(Errmsg);
	    pop_command("QUIT");
	    close(mbfi);
	    return(1);
	}
    }

    pop_command("QUIT");
    close(mbfi);
    return(0);
}

pop_init(host)
char *host;
{
    register struct hostent *hp;
    register struct servent *sp;
    int lport = IPPORT_RESERVED - 1;
    struct sockaddr_in sin;
    register int s;
    char *get_errmsg();

    hp = gethostbyname(host);
    if (hp == NULL) {
	sprintf(Errmsg, "MAILHOST unknown: %s", host);
	return(NOTOK);
    }

    sp = getservbyname("pop", "tcp");
    if (sp == 0) {
	strcpy(Errmsg, "tcp/pop: unknown service");
	return(NOTOK);
    }

    sin.sin_family = hp->h_addrtype;
    bcopy(hp->h_addr, (char *)&sin.sin_addr, hp->h_length);
    sin.sin_port = sp->s_port;
    s = rresvport(&lport);
    if (s < 0) {
	sprintf(Errmsg, "error creating socket: %s", get_errmsg());
	return(NOTOK);
    }

    if (connect(s, (char *)&sin, sizeof sin) < 0) {
	sprintf(Errmsg, "error during connect: %s", get_errmsg());
	close(s);
	return(NOTOK);
    }

    sfi = fdopen(s, "r");
    sfo = fdopen(s, "w");
    if (sfi == NULL || sfo == NULL) {
	sprintf(Errmsg, "error in fdopen: %s", get_errmsg());
	close(s);
	return(NOTOK);
    }

    return(OK);
}

pop_command(fmt, a, b, c, d)
char *fmt;
{
    char buf[128];
    char errmsg[64];

    sprintf(buf, fmt, a, b, c, d);

    if (debug) fprintf(stderr, "---> %s\n", buf);
    if (putline(buf, Errmsg, sfo) == NOTOK) return(NOTOK);

    if (getline(buf, sizeof buf, sfi) != OK) {
	strcpy(Errmsg, buf);
	return(NOTOK);
    }

    if (debug) fprintf(stderr, "<--- %s\n", buf);
    if (*buf != '+') {
	strcpy(Errmsg, buf);
	return(NOTOK);
    } else {
	return(OK);
    }
}

    
pop_stat(nmsgs, nbytes)
int *nmsgs, *nbytes;
{
    char buf[128];

    if (debug) fprintf(stderr, "---> STAT\n");
    if (putline("STAT", Errmsg, sfo) == NOTOK) return(NOTOK);

    if (getline(buf, sizeof buf, sfi) != OK) {
	strcpy(Errmsg, buf);
	return(NOTOK);
    }

    if (debug) fprintf(stderr, "<--- %s\n", buf);
    if (*buf != '+') {
	strcpy(Errmsg, buf);
	return(NOTOK);
    } else {
	sscanf(buf, "+OK %d %d", nmsgs, nbytes);
	return(OK);
    }
}

pop_retr(msgno, action, arg)
int (*action)();
{
    char buf[128];

    sprintf(buf, "RETR %d", msgno);
    if (debug) fprintf(stderr, "%s\n", buf);
    if (putline(buf, Errmsg, sfo) == NOTOK) return(NOTOK);

    if (getline(buf, sizeof buf, sfi) != OK) {
	strcpy(Errmsg, buf);
	return(NOTOK);
    }

    while (1) {
	switch (multiline(buf, sizeof buf, sfi)) {
	case OK:
	    (*action)(buf, arg);
	    break;
	case DONE:
	    return (OK);
	case NOTOK:
	    strcpy(Errmsg, buf);
	    return (NOTOK);
	}
    }
}

getline(buf, n, f)
char *buf;
register int n;
FILE *f;
{
    register char *p;
    int c;

    p = buf;
    while (--n > 0 && (c = fgetc(f)) != EOF)
      if ((*p++ = c) == '\n') break;

    if (ferror(f)) {
	strcpy(buf, "error on connection");
	return (NOTOK);
    }

    if (c == EOF && p == buf) {
	strcpy(buf, "connection closed by foreign host");
	return (DONE);
    }

    *p = NULL;
    if (*--p == '\n') *p = NULL;
    if (*--p == '\r') *p = NULL;
    return(OK);
}

multiline(buf, n, f)
char *buf;
register int n;
FILE *f;
{
    if (getline(buf, n, f) != OK) return (NOTOK);
    if (*buf == '.') {
	if (*(buf+1) == NULL) {
	    return (DONE);
	} else {
	    strcpy(buf, buf+1);
	}
    }
    return(OK);
}

char *
get_errmsg()
{
    extern int errno, sys_nerr;
    extern char *sys_errlist[];
    char *s;

    if (errno < sys_nerr)
      s = sys_errlist[errno];
    else
      s = "unknown error";
    return(s);
}

putline(buf, err, f)
char *buf;
char *err;
FILE *f;
{
    fprintf(f, "%s\r\n", buf);
    fflush(f);
    if (ferror(f)) {
	strcpy(err, "lost connection");
	return(NOTOK);
    }
    return(OK);
}

mbx_write(line, mbf)
char *line;
FILE *mbf;
{
    fputs(line, mbf);
    fputc(0x0a, mbf);
}

mbx_delimit_begin(mbf)
FILE *mbf;
{
    fputs("\f\n0, unseen,,\n", mbf);
}

mbx_delimit_end(mbf)
FILE *mbf;
{
    putc('\037', mbf);
}

#endif /* MAIL_USE_POP */