mdw@git.distorted.org.uk Git - sw-tools/blob - src/sw_rsh.c

   1 /* -*-c-*-
   2  *
   3  * $Id: sw_rsh.c,v 1.6 1999/09/24 13:15:57 mdw Exp $
   4  *
   5  * Run remote commands
   6  *
   7  * (c) 1999 EBI
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of sw-tools.
  13  *
  14  * sw-tools is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * sw-tools is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with sw-tools; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: sw_rsh.c,v $
  32  * Revision 1.6  1999/09/24 13:15:57  mdw
  33  * Remove unnecessary assumptions about structure layouts.  (The `pkhead'
  34  * structure is no more.)
  35  *
  36  * Revision 1.5  1999/06/24 16:02:22  mdw
  37  * Fix signal handling some more.
  38  *
  39  * Revision 1.4  1999/06/24 15:51:17  mdw
  40  * Fix signal handlers so they don't corrupt `errno'.
  41  *
  42  * Revision 1.3  1999/06/18 18:58:54  mdw
  43  * Signal handling fixes.
  44  *
  45  * Revision 1.2  1999/06/02 17:03:29  mdw
  46  * Fix use of `octet' now that mLib includes `bits.h' (as of version 1.3.5
  47  * release).  Also use the mLib load and store macros rather than doing it
  48  * by hand.
  49  *
  50  * Revision 1.1.1.1  1999/06/02  16:53:34  mdw
  51  * Initial import.
  52  *
  53  */
  54
  55 /*----- Header files ------------------------------------------------------*/
  56
  57 #include "config.h"
  58
  59 #include <ctype.h>
  60 #include <errno.h>
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <string.h>
  66
  67 #include <sys/types.h>
  68 #include <sys/time.h>
  69 #include <fcntl.h>
  70 #include <unistd.h>
  71
  72 #include <sys/socket.h>
  73 #include <sys/wait.h>
  74
  75 #ifndef DECL_ENVIRON
  76   extern char **environ;
  77 #endif
  78
  79 #include <mLib/alloc.h>
  80 #include <mLib/bits.h>
  81 #include <mLib/dstr.h>
  82 #include <mLib/exc.h>
  83 #include <mLib/mdwopt.h>
  84 #include <mLib/quis.h>
  85 #include <mLib/report.h>
  86 #include <mLib/sym.h>
  87
  88 #define RCMD_LINK 0
  89 #include "sw_arch.h"
  90 #include "sw_build.h"
  91 #include "sw_env.h"
  92 #include "sw_rsh.h"
  93
  94 /*----- Data structures ---------------------------------------------------*/
  95
  96 #define PKHEADSZ 3
  97
  98 /*----- Static variables --------------------------------------------------*/
  99
 100 static int handler = 0;
 101 static rcmd *rcmds = RCMD_LINK;
 102
 103 /*----- Packet interface --------------------------------------------------*/
 104
 105 /* --- @pksend@ --- *
 106  *
 107  * Arguments:   @sw_remote@ = pointer to the remote block
 108  *              @int type@ = packet type to send
 109  *              @const void *p@ = pointer to packet data
 110  *              @size_t sz@ = size of data to send
 111  *
 112  * Returns:     Zero if it worked, nonzero otherwise.
 113  *
 114  * Use:         Sends a data packet.  If the type is `data', then `sz' may be
 115  *              arbitrarily large and is divided into small eenough chunks.
 116  *              Otherwise it's an error to send a packet that's too big.
 117  */
 118
 119 int pksend(sw_remote *r, int type, const void *p, size_t sz)
 120 {
 121   octet h[PKHEADSZ];
 122   const char *q = p;
 123   size_t chunk;
 124
 125   /* --- Sort out error conditions --- */
 126
 127   if (sz > PKMAX && type != PKTYPE_DATA) {
 128     errno = E2BIG;
 129     return (-1);
 130   }
 131
 132   /* --- Main output loop --- */
 133
 134   h[2] = type;
 135   do {
 136
 137     /* --- Set up the packet header --- */
 138
 139     chunk = (sz > PKMAX ? PKMAX : sz);
 140     STORE16(h, chunk);
 141
 142     /* --- Write the packet header --- */
 143
 144   try_again:
 145     if (write(r->fdout, &h, PKHEADSZ) < PKHEADSZ) {
 146       if (errno == EINTR)
 147         goto try_again;
 148       return (-1);
 149     }
 150
 151     /* --- Write the payload, if there is one --- *
 152      *
 153      * Maybe the OS won't want to bite it all off in one go.
 154      */
 155
 156     while (chunk) {
 157       ssize_t n = write(r->fdout, q, chunk);
 158       if (n < 0 && errno != EINTR)
 159         return (-1);
 160       if (n > 0) {
 161         q += n;
 162         chunk -= n;
 163         sz -= n;
 164       }
 165     }
 166   } while (sz);
 167
 168   /* --- Done --- */
 169
 170   return (0);
 171 }
 172
 173 /* --- @pkrecv@ --- *
 174  *
 175  * Arguments:   @sw_remote *r@ = remote block
 176  *
 177  * Returns:     Packet type received, or @-1@ for an error.
 178  *
 179  * Use:         Receives a packet from the remote host.  The packet data is
 180  *              placed in the block's buffer, the block's packet length is
 181  *              diddled appropriately.
 182  */
 183
 184 int pkrecv(sw_remote *r)
 185 {
 186   octet h[PKHEADSZ];
 187   size_t sz;
 188   char *p;
 189   ssize_t n;
 190
 191   /* --- Read the packet header --- */
 192
 193   sz = PKHEADSZ;
 194   p = (char *)&h;
 195   while (sz) {
 196     n = read(r->fdin, p, sz);
 197     if (n < 0 && errno != EINTR)
 198       return (-1);
 199     if (n == 0)
 200       return (PKTYPE_EOF);
 201     if (n > 0) {
 202       p += n;
 203       sz -= n;
 204     }
 205   }
 206
 207   /* --- Hack for error messages --- *
 208    *
 209    * If it doesn't look like a valid packet, read a `chunk' and pretend it's
 210    * data.  This isn't too bad, because all the packet types are control
 211    * codes, and are unlikely to be in a textual message.
 212    *
 213    * Normally what happens here is that something sitting before the `sw'
 214    * program fails, reports a plain textual error, and exits.  Grabbing the
 215    * `last gasp' like this, then, traps that error message and allows
 216    * something to report it.  The rest ought to be completely silent, so I
 217    * get an `unexpected eof' and then drop everything.
 218    *
 219    * This is certainly better than the behaviour otherwise, which is an
 220    * @E2BIG@ message reported when the packet size is really ASCII
 221    * characters.
 222    */
 223
 224   if (h[2] >= PKTYPE_BOGUS) {
 225     memcpy(r->buf, &h, PKHEADSZ);
 226     n = read(r->fdin, r->buf + PKHEADSZ, sizeof(r->buf) - PKHEADSZ);
 227     if (n < 0)
 228       return (-1);
 229     r->sz = n + PKHEADSZ;
 230     return (PKTYPE_DATA);
 231   }
 232
 233   /* --- Sort out what's going on --- */
 234
 235   sz = LOAD16(h);
 236   r->sz = sz;
 237   if (!sz)
 238     return (h[2]);
 239   if (sz > PKMAX) {
 240     errno = E2BIG;
 241     return (-1);
 242   }
 243
 244   /* --- Read the packet payload --- */
 245
 246   p = r->buf;
 247   while (sz) {
 248     n = read(r->fdin, p, sz);
 249     if (n < 0 && errno != EINTR)
 250       return (-1);
 251     if (n == 0)
 252       return (PKTYPE_EOF);
 253     if (n > 0) {
 254       p += n;
 255       sz -= n;
 256     }
 257   }
 258
 259   return (h[2]);
 260 }
 261
 262 /*----- Error reporting and exit statuses --------------------------------*/
 263
 264 /* --- @swexit@ --- *
 265  *
 266  * Arguments:   @sw_remote *r@ = remote context
 267  *              @int status@ = exit status to return
 268  *
 269  * Returns:     Doesn't.
 270  *
 271  * Use:         Reports the exit status via packet protocol and quits.
 272  */
 273
 274 void swexit(sw_remote *r, int status)
 275 {
 276   unsigned char s = status;
 277   pksend(r, PKTYPE_STATUS, &s, 1);
 278   _exit(status);
 279 }
 280
 281 /* --- @swsignal@ --- *
 282  *
 283  * Arguments:   @sw_remote *r@ = remote context
 284  *              @int sig@ = signal ocurrence to return
 285  *
 286  * Returns:     Doesn't.
 287  *
 288  * Use:         Reports a signalled-to-death status via packet protocol and
 289  *              quits.
 290  */
 291
 292 void swsignal(sw_remote *r, int sig)
 293 {
 294 #if defined(HAVE_STRSIGNAL)
 295   char *s = strsignal(sig);
 296 #elif defined(HAVE__SYS_SIGLIST)
 297   char *s = _sys_siglist[sig];
 298 #else
 299   char s[16];
 300   sprintf(s, "signal %i", sig);
 301 #endif
 302
 303   pksend(r, PKTYPE_STATUS, s, strlen(s) + 1);
 304   _exit(127);
 305 }
 306
 307 /* --- @swwait@ --- *
 308  *
 309  * Arguments:   @sw_remote *r@ = remote context
 310  *              @int status@ = status answer from @wait@(2)
 311  *
 312  * Returns:     Doesn't.
 313  *
 314  * Use:         Reports a child's demise appropriately, and quits.
 315  */
 316
 317 void swwait(sw_remote *r, int status)
 318 {
 319   if (WIFEXITED(status))
 320     swexit(r, WEXITSTATUS(status));
 321   else if (WIFSIGNALED(status))
 322     swsignal(r, WTERMSIG(status));
 323   else
 324     swexit(r, 126);
 325 }
 326
 327 /* --- @swvprintf@ --- *
 328  *
 329  * Arguments:   @sw_remote *r@ = remote context
 330  *              @const char *format@ = format string
 331  *              @va_list ap@ = things to format
 332  *
 333  * Returns:     ---
 334  *
 335  * Use:         Writes a string to the remote end.  This is the low-level bit
 336  *              of @swprintf@.
 337  */
 338
 339 void swvprintf(sw_remote *r, const char *format, va_list ap)
 340 {
 341   dstr d = DSTR_INIT;
 342   dstr_vputf(&d, format, ap);
 343   pksend(r, PKTYPE_DATA, d.buf, d.len);
 344   dstr_destroy(&d);
 345 }
 346
 347 /* --- @swprintf@ --- *
 348  *
 349  * Arguments:   @sw_remote *r@ = remote context
 350  *              @const char *format@ = format string
 351  *              @...@ = other arguments
 352  *
 353  * Returns:     ---
 354  *
 355  * Use:         Writes a string to the remote end.
 356  */
 357
 358 void swprintf(sw_remote *r, const char *format, ...)
 359 {
 360   va_list ap;
 361   va_start(ap, format);
 362   swvprintf(r, format, ap);
 363   va_end(ap);
 364 }
 365
 366 /* --- @swdie@ --- *
 367  *
 368  * Arguments:   @sw_remote *r@ = remote context
 369  *              @int status@ = exit status to report
 370  *              @const char *format@ = format string to fill in
 371  *              @...@ = other arguments
 372  *
 373  * Returns:     Doesn't.
 374  *
 375  * Use:         Reports a message and quits.
 376  */
 377
 378 void swdie(sw_remote *r, int status, const char *format, ...)
 379 {
 380   va_list ap;
 381   dstr d = DSTR_INIT;
 382
 383   va_start(ap, format);
 384   dstr_putf(&d, "%s [remote]: ", QUIS);
 385   dstr_vputf(&d, format, ap);
 386   dstr_putc(&d, '\n');
 387   dstr_putz(&d);
 388   va_end(ap);
 389   pksend(r, PKTYPE_DATA, d.buf, d.len);
 390   dstr_destroy(&d);
 391   swexit(r, status);
 392 }
 393
 394 /*----- Command handling and dispatch -------------------------------------*/
 395
 396 /* --- @remote@ --- *
 397  *
 398  * Arguments:   @sw_remote *r@ = pointer to remote block
 399  *              @const char *cmd@ = command to run
 400  *              @char *argv[]@ = argument array
 401  *              @char *env[]@ = environment variables
 402  *
 403  * Returns:     Doesn't.  Reports an exit status through packet protocol and
 404  *              quits.
 405  *
 406  * Use:         Dispatches a remote command.  At this point, the two code
 407  *              paths for local and remote invokation have joined again.
 408  */
 409
 410 static void remote(sw_remote *r, const char *cmd, char *argv[], char *env[])
 411 {
 412   struct rcmd *p, *chosen = 0;
 413   size_t sz = strlen(cmd);
 414
 415   /* --- Make sure that I can get the exit status of children --- */
 416
 417   signal(SIGCHLD, SIG_DFL);
 418
 419   /* --- Fix up the environment --- */
 420
 421   {
 422     sym_table t;
 423     sym_create(&t);
 424     env_import(&t, env);
 425     if (env != environ) {
 426       free(env);
 427       env_import(&t, environ);
 428     }
 429     env_put(&t, "SW_ARCH", ARCH);
 430     env_file(&t, DATADIR "/sw-env");
 431     env = env_export(&t);
 432   }
 433
 434   /* --- Dispatch to the command handler --- */
 435
 436   for (p = rcmds; p; p = p->next) {
 437     if (strncmp(cmd, p->name, sz) == 0) {
 438       if (p->name[sz] == 0) {
 439         chosen = p;
 440         break;
 441       } else if (chosen)
 442         swdie(r, 1, "ambiguous remote command name `%s'", cmd);
 443       else
 444         chosen = p;
 445     }
 446   }
 447   if (!chosen)
 448     swdie(r, 1, "unknown remote command name `%s'", cmd);
 449   chosen->rcmd(r, argv, env);
 450 }
 451
 452 /*----- Remote invocation -------------------------------------------------*/
 453
 454 /* --- @sendargv@ --- *
 455  *
 456  * Arguments:   @sw_remote *r@ = pointer to the remote context
 457  *              @int type@ = packet type to send with
 458  *              @char *v[]@ = pointer to the array to send
 459  *
 460  * Returns:     Zero if OK, nonzero if it failed.
 461  *
 462  * Use:         Sends something @argv@-shaped; i.e., an array of strings
 463  *              terminated by a null pointer.
 464  */
 465
 466 static int sendargv(sw_remote *r, int type, char *v[])
 467 {
 468   dstr d = DSTR_INIT;
 469   int e;
 470
 471   while (*v) {
 472     dstr_puts(&d, *v);
 473     d.len++;                            /* Make the null `real' */
 474     v++;
 475   }
 476   e = pksend(r, type, d.buf, d.len);
 477   dstr_destroy(&d);
 478   return (e);
 479 }
 480
 481 /* --- @snarfargv@ --- *
 482  *
 483  * Arguments:   @const char *buf@ = pointer to buffer
 484  *              @size_t sz@ = size of buffer
 485  *
 486  * Returns:     Pointer to argument array (allocated with @malloc@).
 487  *
 488  * Use:         Snarfs the null-terminated strings in the buffer and returns
 489  *              an array of them.  The whole lot, strings and array, is
 490  *              returned in one big chunk allocated from the heap.  Note that
 491  *              this means it's OK to throw the initial buffer away.
 492  */
 493
 494 static char **snarfargv(const char *buf, size_t sz)
 495 {
 496   /* --- Initial setup --- */
 497
 498   const char *p, *lim;
 499   char *q;
 500   size_t c;
 501   char **v, **w;
 502
 503   /* --- Pass one: count the number of arguments --- */
 504
 505   c = 0;
 506   p = buf;
 507   lim = p + sz;
 508   while (p < lim) {
 509     c++;
 510     while (*p) {
 511       p++;
 512       if (p >= lim)
 513         goto done_pass1;
 514     }
 515     p++;
 516   }
 517 done_pass1:
 518
 519   /* --- Allocate memory for everything --- */
 520
 521   v = xmalloc((c + 1) * sizeof(char *) + sz + 1);
 522   q = (char *)(v + c + 1);
 523   memcpy(q, buf, sz);
 524
 525   /* --- Pass two: set up the arrays --- */
 526
 527   lim = q + sz;
 528   w = v;
 529   while (q < lim) {
 530     *w++ = q;
 531     while (*q) {
 532       q++;
 533       if (q >= lim)
 534         goto done_pass2;
 535     }
 536     q++;
 537   }
 538 done_pass2:
 539   *w++ = 0;
 540   *q++ = 0;
 541
 542   /* --- Done --- */
 543
 544   return (v);
 545 }
 546
 547 /* --- @swrsh_remote@ --- *
 548  *
 549  * Arguments:   @const char *cmd@ = the command to perform
 550  *
 551  * Returns:     Doesn't.  Reports an exit status through packet protocol and
 552  *              quits.
 553  *
 554  * Use:         Handles the remote end of a remote job invokation.
 555  */
 556
 557 void swrsh_remote(const char *cmd)
 558 {
 559   sw_remote r;
 560   static char *dummy = 0;
 561   char **argv = 0;
 562   char **env = 0;
 563   char *dir = 0;
 564   r.fdin = 0;
 565   r.fdout = 1;
 566
 567  /* --- Read packets from the remote host --- */
 568
 569   for (;;) {
 570     int t = pkrecv(&r);
 571     switch (t) {
 572       case -1:
 573         swdie(&r, 1, "error reading packet: %s", strerror(errno));
 574         break;
 575       case PKTYPE_EOF:
 576         goto done;
 577       case PKTYPE_ARGS:
 578         if (argv)
 579           free(argv);
 580         argv = snarfargv(r.buf, r.sz);
 581         break;
 582       case PKTYPE_ENV:
 583         if (env)
 584           free(env);
 585         env = snarfargv(r.buf, r.sz);
 586         break;
 587       case PKTYPE_DIR:
 588         if (dir)
 589           free(dir);
 590         r.buf[r.sz] = 0;
 591         dir = xstrdup(r.buf);
 592         break;
 593       case PKTYPE_GO:
 594         goto done;
 595       case PKTYPE_DATA:
 596       case PKTYPE_STATUS:
 597         swdie(&r, 1, "internal error: unexpected packet");
 598         break;
 599     }
 600   }
 601
 602   /* --- Sort out any missing arguments --- */
 603
 604 done:
 605   if (!argv)
 606     argv = &dummy;
 607   if (!env)
 608     env = &dummy;
 609   if (dir)
 610     chdir(dir);
 611
 612   /* --- Run the command --- */
 613
 614   TRY
 615     remote(&r, cmd, argv, env);
 616   CATCH switch (exc_type) {
 617     case EXC_NOMEM: {
 618       static char msg[] = "\nsw [remote]: not enough memory\n";
 619       pksend(&r, PKTYPE_DATA, msg, sizeof(msg) - 1);
 620       swexit(&r, 1);
 621     } break;
 622     default:
 623       swdie(&r, 1, "uncaught exception, type = %lx", exc_type);
 624   } END_TRY;
 625 }
 626
 627 /*----- Starting remote jobs ----------------------------------------------*/
 628
 629 /* --- @sigchld@ --- *
 630  *
 631  * Arguments:   @int sig@ = the signal number
 632  *
 633  * Returns:     ---
 634  *
 635  * Use:         Catches @SIGCHLD@ and reaps any children that have lost.
 636  */
 637
 638 static void sigchld(int sig)
 639 {
 640   int e = errno;
 641 #ifdef DEBUG_SIGCHLD
 642   int status;
 643   while (waitpid(-1, &status, WNOHANG) > 0) {
 644     if (WIFEXITED(status)) {
 645       fprintf(stderr, "reap child with exit status %i\n",
 646               WEXITSTATUS(status));
 647     } else if (WIFSIGNALED(status)) {
 648       fprintf(stderr, "reap child killed by signal %s\n",
 649               strsignal(WTERMSIG(status)));
 650     } else
 651       fprintf(stderr, "reaped bizarre child which is still alive\n");
 652   }
 653 #else
 654   while (waitpid(-1, 0, WNOHANG) > 0)
 655     ;
 656 #endif
 657   errno = e;
 658 }
 659
 660 /* --- @swrsh@ --- *
 661  *
 662  * Arguments:   @sw_remote *r@ = remote process block to look after
 663  *              @const char *host@ = host to run on (0 for this one)
 664  *              @const char *cmd@ = remote command to run
 665  *              @char *argv[]@ = arguments to pass on
 666  *
 667  * Returns:     Zero if it worked, nonzero if not.
 668  *
 669  * Use:         Runs a command on a remote host.  The argument array is
 670  *              mangled to come out OK at the far end.  The environment and
 671  *              current directory are also passed along, and pop out the
 672  *              other end unmolested.
 673  */
 674
 675 int swrsh(sw_remote *r, const char *host, const char *cmd, char *argv[])
 676 {
 677   int sk[2];
 678   pid_t kid;
 679
 680   /* --- Get a socket pair for communicating with the other end --- */
 681
 682   if (socketpair(PF_UNIX, SOCK_STREAM, 0, sk))
 683     goto tidy_0;
 684
 685   /* --- Set up a signal handler --- */
 686
 687   if (!handler) {
 688     struct sigaction sa;
 689     sa.sa_handler = sigchld;
 690     sa.sa_flags = SA_NOCLDSTOP;
 691 #ifdef SA_RESTART
 692     sa.sa_flags |= SA_RESTART;
 693 #endif
 694     sigemptyset(&sa.sa_mask);
 695     sigaction(SIGCHLD, &sa, 0);
 696     handler = 1;
 697   }
 698
 699   /* --- Fork off a child to cope with stuff --- */
 700
 701   kid = fork();
 702   if (kid < 0)
 703     goto tidy_1;
 704
 705   /* --- Handle the child process --- *
 706    *
 707    * If this is a local job, then just loop around inside to handle the
 708    * `remote' command.  Otherwise crank up `rsh' and pass the command over to
 709    * a remote copy of myself.
 710    *
 711    * (Why do I need a separate process for local jobs?  I don't really, but
 712    * it makes everything much simpler when running multiple jobs at the same
 713    * time.)
 714    */
 715
 716   if (kid == 0) {
 717     close(sk[0]);
 718
 719     /* --- Child end of a local job --- */
 720
 721     signal(SIGINT, SIG_DFL);
 722     signal(SIGQUIT, SIG_DFL);
 723
 724     if (!host) {
 725       r->fdin = r->fdout = sk[1];
 726       remote(r, cmd, argv, environ);
 727     }
 728
 729     /* --- Local child end of a remote job --- */
 730
 731     else {
 732       const char *rsh;
 733       dup2(sk[1], 0);
 734       dup2(sk[1], 1);
 735       dup2(sk[1], 2);
 736       if (sk[1] > 2)
 737         close(sk[1]);
 738       rsh = getenv("SW_RSH");
 739       if (!rsh)
 740         rsh = RSH;
 741       execlp(rsh, rsh, host, PATH_SW, "--remote", cmd, (char *)0);
 742     }
 743
 744     /* --- I don't expect either to come back --- */
 745
 746     _exit(1);
 747   }
 748
 749   /* --- Local sort out of what to do --- *
 750    *
 751    * Either way, I've now got a socket tied to something which speaks my
 752    * communication protocol.  However, if this is a local job, then I can get
 753    * going right away; otherwise, I've got to transmit various bits of
 754    * information over the protocol.
 755    */
 756
 757   r->fdin = r->fdout = sk[0];
 758   close(sk[1]);
 759
 760   if (host) {
 761     char buf[PKMAX];
 762     if (!getcwd(buf, sizeof(buf)))
 763       goto tidy_1;
 764     sendargv(r, PKTYPE_ARGS, argv);
 765     sendargv(r, PKTYPE_ENV, environ);
 766     pksend(r, PKTYPE_DIR, buf, strlen(buf) + 1);
 767     pksend(r, PKTYPE_GO, 0, 0);
 768   }
 769
 770   /* --- Ready to rock'n'roll --- */
 771
 772   r->sz = 0;
 773   return (0);
 774
 775   /* --- Tidy up if it failed --- */
 776
 777 tidy_1:
 778   close(sk[0]);
 779   close(sk[1]);
 780 tidy_0:
 781   return (-1);
 782 }
 783
 784 /*----- Subcommands -------------------------------------------------------*/
 785
 786 /* --- @swrsh_rsh@ --- */
 787
 788 void rsw_rsh(sw_remote *r, char *argv[], char *env[])
 789 {
 790   pid_t kid, k;
 791   int pfd[2];
 792   int status;
 793
 794   /* --- Create a pipe --- */
 795
 796   if (pipe(pfd))
 797     swdie(r, 1, "couldn't create pipe: %s", strerror(errno));
 798
 799   /* --- Start the child process up --- */
 800
 801   kid = fork();
 802   if (kid < 0)
 803     swdie(r, 1, "fork failed: %s", strerror(errno));
 804   else if (kid == 0) {
 805     int fd;
 806
 807     /* --- Use my new environment --- */
 808
 809     environ = env; /* Yuk. */
 810
 811     /* --- Fiddle with pipe file descriptors --- */
 812
 813     close(pfd[0]);
 814     dup2(pfd[1], 1);
 815     dup2(pfd[1], 2);
 816     if (pfd[1] > 2)
 817       close(pfd[1]);
 818
 819     /* --- Make sure it doesn't get any input --- */
 820
 821     close(0);
 822     fd = open("/dev/null", O_RDONLY);
 823     if (fd != 0) {
 824       dup2(fd, 0);
 825       close(fd);
 826     }
 827
 828     /* --- Run the program --- */
 829
 830     execvp(argv[0], argv);
 831     die(1, "couldn't exec `%s': %s", argv[0], strerror(errno));
 832   }
 833
 834   /* --- Read the data from the pipe until it closes --- */
 835
 836   close(pfd[1]);
 837   for (;;) {
 838     ssize_t n = read(pfd[0], r->buf, sizeof(r->buf));
 839     if (n < 0)
 840       swdie(r, 1, "read error: %s", strerror(errno));
 841     else if (!n)
 842       break;
 843     else
 844       pksend(r, PKTYPE_DATA, r->buf, n);
 845   }
 846   close(pfd[0]);
 847
 848   /* --- Finally, reap the exit status and pass it on --- */
 849
 850   for (;;) {
 851     k = wait(&status);
 852     if (k == kid)
 853       break;
 854     if (k < 0)
 855       swdie(r, 1, "error reaping child: %s", strerror(errno));
 856   }
 857   swwait(r, status);
 858 }
 859
 860 /* --- @sw_rsh@ --- */
 861
 862 int sw_rsh(int argc, char *argv[])
 863 {
 864   sw_remote r;
 865   char *h;
 866   int status = 1;
 867
 868   /* --- Check the arguments --- */
 869
 870   if (argc < 3)
 871     die(1, "Usage: rsh HOST|ARCH COMMAND [ARGS...]");
 872
 873   /* --- Translate architecture names into hostnames --- */
 874
 875   if (strcmp(argv[1], "-") == 0)
 876     h = 0;
 877   else {
 878     archent *a = arch_lookup(argv[1], 0);
 879     if (!a)
 880       h = argv[1];
 881     else if (a->flags & archFlag_home)
 882       h = 0;
 883     else
 884       h = a->host;
 885   }
 886
 887   /* --- Start the remote process --- */
 888
 889   if (swrsh(&r, h, "rsh", argv + 2))
 890     die(1, "remote shell failed: %s", strerror(errno));
 891
 892   /* --- Cope with packets from the remote process --- */
 893
 894   fflush(stdout);
 895   for (;;) {
 896     int t = pkrecv(&r);
 897     switch (t) {
 898       case -1:
 899         die(1, "error reading packet: %s", strerror(errno));
 900       case PKTYPE_DATA:
 901         write(STDOUT_FILENO, r.buf, r.sz);
 902         break;
 903       case PKTYPE_STATUS:
 904         r.buf[r.sz] = 0;
 905         if (r.sz > 1) {
 906           status = 127;
 907           moan("command exited due to signal: %s", r.buf);
 908         } else {
 909           status = r.buf[0];
 910             moan("command exited with status %i", r.buf[0]);
 911         }
 912         goto done;
 913       case PKTYPE_EOF:
 914         moan("command exited unexpectedly");
 915         goto done;
 916       default:
 917         die(1, "unexpected packet type");
 918     }
 919   }
 920
 921   /* --- Finished --- */
 922
 923 done:
 924   close(r.fdin);
 925   return (status);
 926 }
 927
 928 /*----- That's all, folks -------------------------------------------------*/