lib-src/movemail.c

   1 /* movemail foo bar -- move file foo to file bar,
   2    locking file foo the way /bin/mail respects.
   3    Copyright (C) 1986, 1992 Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 1, or (at your option)
  10 any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 /* Important notice: defining MAIL_USE_FLOCK *will cause loss of mail*
  22    if you do it on a system that does not normally use flock as its way of
  23    interlocking access to inbox files.  The setting of MAIL_USE_FLOCK
  24    *must agree* with the system's own conventions.
  25    It is not a choice that is up to you.
  26
  27    So, if your system uses lock files rather than flock, then the only way
  28    you can get proper operation is to enable movemail to write lockfiles there.
  29    This means you must either give that directory access modes
  30    that permit everyone to write lockfiles in it, or you must make movemail
  31    a setuid or setgid program.  */
  32
  33 /*
  34  * Modified January, 1986 by Michael R. Gretzinger (Project Athena)
  35  *
  36  * Added POP (Post Office Protocol) service.  When compiled -DPOP
  37  * movemail will accept input filename arguments of the form
  38  * "po:username".  This will cause movemail to open a connection to
  39  * a pop server running on $MAILHOST (environment variable).  Movemail
  40  * must be setuid to root in order to work with POP.
  41  *
  42  * New module: popmail.c
  43  * Modified routines:
  44  *      main - added code within #ifdef MAIL_USE_POP; added setuid (getuid ())
  45  *              after POP code.
  46  * New routines in movemail.c:
  47  *      get_errmsg - return pointer to system error message
  48  *
  49  */
  50
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53 #include <sys/file.h>
  54 #include <errno.h>
  55 #define NO_SHORTNAMES   /* Tell config not to load remap.h */
  56 #include "../src/config.h"
  57
  58 #ifdef USG
  59 #include <fcntl.h>
  60 #include <unistd.h>
  61 #ifndef F_OK
  62 #define F_OK 0
  63 #define X_OK 1
  64 #define W_OK 2
  65 #define R_OK 4
  66 #endif
  67 #endif /* USG */
  68
  69 #ifdef XENIX
  70 #include <sys/locking.h>
  71 #endif
  72
  73 #ifdef MAIL_USE_MMDF
  74 extern int lk_open (), lk_close ();
  75 #endif
  76
  77 /* Cancel substitutions made by config.h for Emacs.  */
  78 #undef open
  79 #undef read
  80 #undef write
  81 #undef close
  82
  83 char *malloc ();
  84 char *strcpy ();
  85 char *concat ();
  86 char *xmalloc ();
  87 #ifndef errno
  88 extern int errno;
  89 #endif
  90
  91 /* Nonzero means this is name of a lock file to delete on fatal error.  */
  92 char *delete_lockname;
  93
  94 main (argc, argv)
  95      int argc;
  96      char **argv;
  97 {
  98   char *inname, *outname;
  99   int indesc, outdesc;
 100   int nread;
 101
 102 #ifndef MAIL_USE_FLOCK
 103   struct stat st;
 104   long now;
 105   int tem;
 106   char *lockname, *p;
 107   char *tempname;
 108   int desc;
 109 #endif /* not MAIL_USE_FLOCK */
 110
 111   delete_lockname = 0;
 112
 113   if (argc < 3)
 114     fatal ("two arguments required");
 115
 116   inname = argv[1];
 117   outname = argv[2];
 118
 119 #ifdef MAIL_USE_MMDF
 120   mmdf_init (argv[0]);
 121 #endif
 122
 123   /* Check access to output file.  */
 124   if (access (outname, F_OK) == 0 && access (outname, W_OK) != 0)
 125     pfatal_with_name (outname);
 126
 127   /* Also check that outname's directory is writeable to the real uid.  */
 128   {
 129     char *buf = (char *) malloc (strlen (outname) + 1);
 130     char *p, q;
 131     strcpy (buf, outname);
 132     p = buf + strlen (buf);
 133     while (p > buf && p[-1] != '/')
 134       *--p = 0;
 135     if (p == buf)
 136       *p++ = '.';
 137     if (access (buf, W_OK) != 0)
 138       pfatal_with_name (buf);
 139     free (buf);
 140   }
 141
 142 #ifdef MAIL_USE_POP
 143   if (!bcmp (inname, "po:", 3))
 144     {
 145       int status; char *user;
 146
 147       user = (char *) rindex (inname, ':') + 1;
 148       status = popmail (user, outname);
 149       exit (status);
 150     }
 151
 152   setuid (getuid ());
 153 #endif /* MAIL_USE_POP */
 154
 155   /* Check access to input file.  */
 156   if (access (inname, R_OK | W_OK) != 0)
 157     pfatal_with_name (inname);
 158
 159 #ifndef MAIL_USE_MMDF
 160 #ifndef MAIL_USE_FLOCK
 161   /* Use a lock file named /usr/spool/mail/$USER.lock:
 162      If it exists, the mail file is locked.  */
 163   /* Note: this locking mechanism is *required* by the mailer
 164      (on systems which use it) to prevent loss of mail.
 165
 166      On systems that use a lock file, extracting the mail without locking
 167      WILL occasionally cause loss of mail due to timing errors!
 168
 169      So, if creation of the lock file fails
 170      due to access permission on /usr/spool/mail,
 171      you simply MUST change the permission
 172      and/or make movemail a setgid program
 173      so it can create lock files properly.
 174
 175      You might also wish to verify that your system is one
 176      which uses lock files for this purpose.  Some systems use other methods.
 177
 178      If your system uses the `flock' system call for mail locking,
 179      define MAIL_USE_FLOCK in config.h or the s-*.h file
 180      and recompile movemail.  If the s- file for your system
 181      should define MAIL_USE_FLOCK but does not, send a bug report
 182      to bug-gnu-emacs@prep.ai.mit.edu so we can fix it.  */
 183
 184   lockname = concat (inname, ".lock", "");
 185   tempname = strcpy (xmalloc (strlen (inname)+1), inname);
 186   p = tempname + strlen (tempname);
 187   while (p != tempname && p[-1] != '/')
 188     p--;
 189   *p = 0;
 190   strcpy (p, "EXXXXXX");
 191   mktemp (tempname);
 192   unlink (tempname);
 193
 194   while (1)
 195     {
 196       /* Create the lock file, but not under the lock file name.  */
 197       /* Give up if cannot do that.  */
 198       desc = open (tempname, O_WRONLY | O_CREAT, 0666);
 199       if (desc < 0)
 200         pfatal_with_name ("lock file--see source file etc/movemail.c");
 201       close (desc);
 202
 203       tem = link (tempname, lockname);
 204       unlink (tempname);
 205       if (tem >= 0)
 206         break;
 207       sleep (1);
 208
 209       /* If lock file is a minute old, unlock it.  */
 210       if (stat (lockname, &st) >= 0)
 211         {
 212           now = time (0);
 213           if (st.st_ctime < now - 60)
 214             unlink (lockname);
 215         }
 216     }
 217
 218   delete_lockname = lockname;
 219 #endif /* not MAIL_USE_FLOCK */
 220
 221 #ifdef MAIL_USE_FLOCK
 222   indesc = open (inname, O_RDWR);
 223 #else /* if not MAIL_USE_FLOCK */
 224   indesc = open (inname, O_RDONLY);
 225 #endif /* not MAIL_USE_FLOCK */
 226 #else /* MAIL_USE_MMDF */
 227   indesc = lk_open (inname, O_RDONLY, 0, 0, 10);
 228 #endif /* MAIL_USE_MMDF */
 229
 230   if (indesc < 0)
 231     pfatal_with_name (inname);
 232
 233 #if defined (BSD) || defined (XENIX)
 234   /* In case movemail is setuid to root, make sure the user can
 235      read the output file.  */
 236   /* This is desirable for all systems
 237      but I don't want to assume all have the umask system call */
 238   umask (umask (0) & 0333);
 239 #endif /* BSD or Xenix */
 240   outdesc = open (outname, O_WRONLY | O_CREAT | O_EXCL, 0666);
 241   if (outdesc < 0)
 242     pfatal_with_name (outname);
 243 #ifdef MAIL_USE_FLOCK
 244 #ifdef XENIX
 245   if (locking (indesc, LK_RLCK, 0L) < 0) pfatal_with_name (inname);
 246 #else
 247   if (flock (indesc, LOCK_EX) < 0) pfatal_with_name (inname);
 248 #endif
 249 #endif /* MAIL_USE_FLOCK */
 250
 251   {
 252     char buf[1024];
 253
 254     while (1)
 255       {
 256         nread = read (indesc, buf, sizeof buf);
 257         if (nread != write (outdesc, buf, nread))
 258           {
 259             int saved_errno = errno;
 260             unlink (outname);
 261             errno = saved_errno;
 262             pfatal_with_name (outname);
 263           }
 264         if (nread < sizeof buf)
 265           break;
 266       }
 267   }
 268
 269 #ifdef BSD
 270   if (fsync (outdesc) < 0)
 271     pfatal_and_delete (outname);
 272 #endif
 273
 274   /* Check to make sure no errors before we zap the inbox.  */
 275   if (close (outdesc) != 0)
 276     pfatal_and_delete (outname);
 277
 278 #ifdef MAIL_USE_FLOCK
 279 #if defined (STRIDE) || defined (XENIX)
 280   /* Stride, xenix have file locking, but no ftruncate.  This mess will do. */
 281   close (open (inname, O_CREAT | O_TRUNC | O_RDWR, 0666));
 282 #else
 283   ftruncate (indesc, 0L);
 284 #endif /* STRIDE or XENIX */
 285 #endif /* MAIL_USE_FLOCK */
 286
 287 #ifdef MAIL_USE_MMDF
 288   lk_close (indesc, 0, 0, 0);
 289 #else
 290   close (indesc);
 291 #endif
 292
 293 #ifndef MAIL_USE_FLOCK
 294   /* Delete the input file; if we can't, at least get rid of its contents.  */
 295 #ifdef MAIL_UNLINK_SPOOL
 296   /* This is generally bad to do, because it destroys the permissions
 297      that were set on the file.  Better to just empty the file.  */
 298   if (unlink (inname) < 0 && errno != ENOENT)
 299 #endif /* MAIL_UNLINK_SPOOL */
 300     creat (inname, 0600);
 301 #ifndef MAIL_USE_MMDF
 302   unlink (lockname);
 303 #endif /* not MAIL_USE_MMDF */
 304 #endif /* not MAIL_USE_FLOCK */
 305   exit (0);
 306 }
 307 \f
 308 /* Print error message and exit.  */
 309
 310 fatal (s1, s2)
 311      char *s1, *s2;
 312 {
 313   if (delete_lockname)
 314     unlink (delete_lockname);
 315   error (s1, s2);
 316   exit (1);
 317 }
 318
 319 /* Print error message.  `s1' is printf control string, `s2' is arg for it. */
 320
 321 error (s1, s2, s3)
 322      char *s1, *s2, *s3;
 323 {
 324   printf ("movemail: ");
 325   printf (s1, s2, s3);
 326   printf ("\n");
 327 }
 328
 329 pfatal_with_name (name)
 330      char *name;
 331 {
 332   extern int errno, sys_nerr;
 333   extern char *sys_errlist[];
 334   char *s;
 335
 336   if (errno < sys_nerr)
 337     s = concat ("", sys_errlist[errno], " for %s");
 338   else
 339     s = "cannot open %s";
 340   fatal (s, name);
 341 }
 342
 343 pfatal_and_delete (name)
 344      char *name;
 345 {
 346   extern int errno, sys_nerr;
 347   extern char *sys_errlist[];
 348   char *s;
 349
 350   if (errno < sys_nerr)
 351     s = concat ("", sys_errlist[errno], " for %s");
 352   else
 353     s = "cannot open %s";
 354
 355   unlink (name);
 356   fatal (s, name);
 357 }
 358
 359 /* Return a newly-allocated string whose contents concatenate those of s1, s2, s3.  */
 360
 361 char *
 362 concat (s1, s2, s3)
 363      char *s1, *s2, *s3;
 364 {
 365   int len1 = strlen (s1), len2 = strlen (s2), len3 = strlen (s3);
 366   char *result = (char *) xmalloc (len1 + len2 + len3 + 1);
 367
 368   strcpy (result, s1);
 369   strcpy (result + len1, s2);
 370   strcpy (result + len1 + len2, s3);
 371   *(result + len1 + len2 + len3) = 0;
 372
 373   return result;
 374 }
 375
 376 /* Like malloc but get fatal error if memory is exhausted.  */
 377
 378 char *
 379 xmalloc (size)
 380      unsigned size;
 381 {
 382   char *result = malloc (size);
 383   if (!result)
 384     fatal ("virtual memory exhausted", 0);
 385   return result;
 386 }
 387 \f
 388 /* This is the guts of the interface to the Post Office Protocol.  */
 389
 390 #ifdef MAIL_USE_POP
 391
 392 #include <sys/socket.h>
 393 #include <netinet/in.h>
 394 #include <netdb.h>
 395 #include <stdio.h>
 396 #include <pwd.h>
 397
 398 #ifdef USG
 399 #include <fcntl.h>
 400 /* Cancel substitutions made by config.h for Emacs.  */
 401 #undef open
 402 #undef read
 403 #undef write
 404 #undef close
 405 #endif /* USG */
 406
 407 #define NOTOK (-1)
 408 #define OK 0
 409 #define DONE 1
 410
 411 char *progname;
 412 FILE *sfi;
 413 FILE *sfo;
 414 char Errmsg[80];
 415
 416 static int debug = 0;
 417
 418 char *get_errmsg ();
 419 char *getenv ();
 420 int mbx_write ();
 421
 422 popmail (user, outfile)
 423      char *user;
 424      char *outfile;
 425 {
 426   char *host;
 427   int nmsgs, nbytes;
 428   char response[128];
 429   register int i;
 430   int mbfi;
 431   FILE *mbf;
 432   struct passwd *pw = (struct passwd *) getpwuid (getuid ());
 433   if (pw == NULL)
 434     fatal ("cannot determine user name");
 435
 436   host = getenv ("MAILHOST");
 437   if (host == NULL)
 438     {
 439       fatal ("no MAILHOST defined");
 440     }
 441
 442   if (pop_init (host) == NOTOK)
 443     {
 444       fatal (Errmsg);
 445     }
 446
 447   if (getline (response, sizeof response, sfi) != OK)
 448     {
 449       fatal (response);
 450     }
 451
 452   if (pop_command ("USER %s", user) == NOTOK
 453       || pop_command ("RPOP %s", pw->pw_name) == NOTOK)
 454     {
 455       pop_command ("QUIT");
 456       fatal (Errmsg);
 457     }
 458
 459   if (pop_stat (&nmsgs, &nbytes) == NOTOK)
 460     {
 461       pop_command ("QUIT");
 462       fatal (Errmsg);
 463     }
 464
 465   if (!nmsgs)
 466     {
 467       pop_command ("QUIT");
 468       return 0;
 469     }
 470
 471   mbfi = open (outfile, O_WRONLY | O_CREAT | O_EXCL, 0666);
 472   if (mbfi < 0)
 473     {
 474       pop_command ("QUIT");
 475       pfatal_and_delete (outfile);
 476     }
 477   fchown (mbfi, getuid (), -1);
 478
 479   if ((mbf = fdopen (mbfi, "w")) == NULL)
 480     {
 481       pop_command ("QUIT");
 482       pfatal_and_delete (outfile);
 483     }
 484
 485   for (i = 1; i <= nmsgs; i++)
 486     {
 487       mbx_delimit_begin (mbf);
 488       if (pop_retr (i, mbx_write, mbf) != OK)
 489         {
 490           pop_command ("QUIT");
 491           close (mbfi);
 492           unlink (outfile);
 493           fatal (Errmsg);
 494         }
 495       mbx_delimit_end (mbf);
 496       fflush (mbf);
 497     }
 498
 499   if (fsync (mbfi) < 0)
 500     {
 501       pop_command ("QUIT");
 502       pfatal_and_delete (outfile);
 503     }
 504
 505   if (close (mbfi) == -1)
 506     {
 507       pop_command ("QUIT");
 508       pfatal_and_delete (outfile);
 509     }
 510
 511   for (i = 1; i <= nmsgs; i++)
 512     {
 513       if (pop_command ("DELE %d", i) == NOTOK)
 514         {
 515           /* Better to ignore this failure.  */
 516         }
 517     }
 518
 519   pop_command ("QUIT");
 520   return (0);
 521 }
 522
 523 pop_init (host)
 524      char *host;
 525 {
 526   register struct hostent *hp;
 527   register struct servent *sp;
 528   int lport = IPPORT_RESERVED - 1;
 529   struct sockaddr_in sin;
 530   register int s;
 531
 532   hp = gethostbyname (host);
 533   if (hp == NULL)
 534     {
 535       sprintf (Errmsg, "MAILHOST unknown: %s", host);
 536       return NOTOK;
 537     }
 538
 539   sp = getservbyname ("pop", "tcp");
 540   if (sp == 0)
 541     {
 542       strcpy (Errmsg, "tcp/pop: unknown service");
 543       return NOTOK;
 544     }
 545
 546   sin.sin_family = hp->h_addrtype;
 547   bcopy (hp->h_addr, (char *)&sin.sin_addr, hp->h_length);
 548   sin.sin_port = sp->s_port;
 549   s = rresvport (&lport);
 550   if (s < 0)
 551     {
 552       sprintf (Errmsg, "error creating socket: %s", get_errmsg ());
 553       return NOTOK;
 554     }
 555
 556   if (connect (s, (char *)&sin, sizeof sin) < 0)
 557     {
 558       sprintf (Errmsg, "error during connect: %s", get_errmsg ());
 559       close (s);
 560       return NOTOK;
 561     }
 562
 563   sfi = fdopen (s, "r");
 564   sfo = fdopen (s, "w");
 565   if (sfi == NULL || sfo == NULL)
 566     {
 567       sprintf (Errmsg, "error in fdopen: %s", get_errmsg ());
 568       close (s);
 569       return NOTOK;
 570     }
 571
 572   return OK;
 573 }
 574
 575 pop_command (fmt, a, b, c, d)
 576      char *fmt;
 577 {
 578   char buf[128];
 579   char errmsg[64];
 580
 581   sprintf (buf, fmt, a, b, c, d);
 582
 583   if (debug) fprintf (stderr, "---> %s\n", buf);
 584   if (putline (buf, Errmsg, sfo) == NOTOK) return NOTOK;
 585
 586   if (getline (buf, sizeof buf, sfi) != OK)
 587     {
 588       strcpy (Errmsg, buf);
 589       return NOTOK;
 590     }
 591
 592   if (debug)
 593     fprintf (stderr, "<--- %s\n", buf);
 594   if (*buf != '+')
 595     {
 596       strcpy (Errmsg, buf);
 597       return NOTOK;
 598     }
 599   else
 600     {
 601       return OK;
 602     }
 603 }
 604
 605
 606 pop_stat (nmsgs, nbytes)
 607      int *nmsgs, *nbytes;
 608 {
 609   char buf[128];
 610
 611   if (debug)
 612     fprintf (stderr, "---> STAT\n");
 613   if (putline ("STAT", Errmsg, sfo) == NOTOK)
 614     return NOTOK;
 615
 616   if (getline (buf, sizeof buf, sfi) != OK)
 617     {
 618       strcpy (Errmsg, buf);
 619       return NOTOK;
 620     }
 621
 622   if (debug) fprintf (stderr, "<--- %s\n", buf);
 623   if (*buf != '+')
 624     {
 625       strcpy (Errmsg, buf);
 626       return NOTOK;
 627     }
 628   else
 629     {
 630       sscanf (buf, "+OK %d %d", nmsgs, nbytes);
 631       return OK;
 632     }
 633 }
 634
 635 pop_retr (msgno, action, arg)
 636      int (*action)();
 637 {
 638   char buf[128];
 639
 640   sprintf (buf, "RETR %d", msgno);
 641   if (debug) fprintf (stderr, "%s\n", buf);
 642   if (putline (buf, Errmsg, sfo) == NOTOK) return NOTOK;
 643
 644   if (getline (buf, sizeof buf, sfi) != OK)
 645     {
 646       strcpy (Errmsg, buf);
 647       return NOTOK;
 648     }
 649
 650   while (1)
 651     {
 652       switch (multiline (buf, sizeof buf, sfi))
 653         {
 654         case OK:
 655           (*action)(buf, arg);
 656           break;
 657         case DONE:
 658           return OK;
 659         case NOTOK:
 660           strcpy (Errmsg, buf);
 661           return NOTOK;
 662         }
 663     }
 664 }
 665
 666 getline (buf, n, f)
 667      char *buf;
 668      register int n;
 669      FILE *f;
 670 {
 671   register char *p;
 672   int c;
 673
 674   p = buf;
 675   while (--n > 0 && (c = fgetc (f)) != EOF)
 676     if ((*p++ = c) == '\n') break;
 677
 678   if (ferror (f))
 679     {
 680       strcpy (buf, "error on connection");
 681       return NOTOK;
 682     }
 683
 684   if (c == EOF && p == buf)
 685     {
 686       strcpy (buf, "connection closed by foreign host");
 687       return DONE;
 688     }
 689
 690   *p = NULL;
 691   if (*--p == '\n') *p = NULL;
 692   if (*--p == '\r') *p = NULL;
 693   return OK;
 694 }
 695
 696 multiline (buf, n, f)
 697      char *buf;
 698      register int n;
 699      FILE *f;
 700 {
 701   if (getline (buf, n, f) != OK)
 702     return NOTOK;
 703   if (*buf == '.')
 704     {
 705       if (*(buf+1) == NULL)
 706         return DONE;
 707       else
 708         strcpy (buf, buf+1);
 709     }
 710   return OK;
 711 }
 712
 713 char *
 714 get_errmsg ()
 715 {
 716   extern int errno, sys_nerr;
 717   extern char *sys_errlist[];
 718   char *s;
 719
 720   if (errno < sys_nerr)
 721     s = sys_errlist[errno];
 722   else
 723     s = "unknown error";
 724   return (s);
 725 }
 726
 727 putline (buf, err, f)
 728      char *buf;
 729      char *err;
 730      FILE *f;
 731 {
 732   fprintf (f, "%s\r\n", buf);
 733   fflush (f);
 734   if (ferror (f))
 735     {
 736       strcpy (err, "lost connection");
 737       return NOTOK;
 738     }
 739   return OK;
 740 }
 741
 742 mbx_write (line, mbf)
 743      char *line;
 744      FILE *mbf;
 745 {
 746   fputs (line, mbf);
 747   fputc (0x0a, mbf);
 748 }
 749
 750 mbx_delimit_begin (mbf)
 751      FILE *mbf;
 752 {
 753   fputs ("\f\n0, unseen,,\n", mbf);
 754 }
 755
 756 mbx_delimit_end (mbf)
 757      FILE *mbf;
 758 {
 759   putc ('\037', mbf);
 760 }
 761
 762 #endif /* MAIL_USE_POP */