git.distorted.org.uk Git - u/mdw/putty/blob - unix/uxplink.c

   1 /*
   2  * PLink - a command-line (stdin/stdout) variant of PuTTY.
   3  */
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <errno.h>
   8 #include <assert.h>
   9 #include <stdarg.h>
  10 #include <signal.h>
  11 #include <unistd.h>
  12 #include <fcntl.h>
  13 #include <termios.h>
  14 #include <pwd.h>
  15 #include <sys/ioctl.h>
  16 #include <sys/select.h>
  17
  18 #define PUTTY_DO_GLOBALS               /* actually _define_ globals */
  19 #include "putty.h"
  20 #include "storage.h"
  21 #include "tree234.h"
  22
  23 #define MAX_STDIN_BACKLOG 4096
  24
  25 void fatalbox(char *p, ...)
  26 {
  27     va_list ap;
  28     fprintf(stderr, "FATAL ERROR: ");
  29     va_start(ap, p);
  30     vfprintf(stderr, p, ap);
  31     va_end(ap);
  32     fputc('\n', stderr);
  33     cleanup_exit(1);
  34 }
  35 void modalfatalbox(char *p, ...)
  36 {
  37     va_list ap;
  38     fprintf(stderr, "FATAL ERROR: ");
  39     va_start(ap, p);
  40     vfprintf(stderr, p, ap);
  41     va_end(ap);
  42     fputc('\n', stderr);
  43     cleanup_exit(1);
  44 }
  45 void connection_fatal(void *frontend, char *p, ...)
  46 {
  47     va_list ap;
  48     fprintf(stderr, "FATAL ERROR: ");
  49     va_start(ap, p);
  50     vfprintf(stderr, p, ap);
  51     va_end(ap);
  52     fputc('\n', stderr);
  53     cleanup_exit(1);
  54 }
  55 void cmdline_error(char *p, ...)
  56 {
  57     va_list ap;
  58     fprintf(stderr, "plink: ");
  59     va_start(ap, p);
  60     vfprintf(stderr, p, ap);
  61     va_end(ap);
  62     fputc('\n', stderr);
  63     exit(1);
  64 }
  65
  66 struct termios orig_termios;
  67
  68 static Backend *back;
  69 static void *backhandle;
  70 static Config cfg;
  71
  72 /*
  73  * Default settings that are specific to pterm.
  74  */
  75 char *platform_default_s(const char *name)
  76 {
  77     if (!strcmp(name, "TermType"))
  78         return dupstr(getenv("TERM"));
  79     if (!strcmp(name, "UserName"))
  80         return get_username();
  81     return NULL;
  82 }
  83
  84 int platform_default_i(const char *name, int def)
  85 {
  86     if (!strcmp(name, "TermWidth") ||
  87         !strcmp(name, "TermHeight")) {
  88         struct winsize size;
  89         if (ioctl(0, TIOCGWINSZ, (void *)&size) >= 0)
  90             return (!strcmp(name, "TermWidth") ? size.ws_col : size.ws_row);
  91     }
  92     return def;
  93 }
  94
  95 FontSpec platform_default_fontspec(const char *name)
  96 {
  97     FontSpec ret;
  98     *ret.name = '\0';
  99     return ret;
 100 }
 101
 102 Filename platform_default_filename(const char *name)
 103 {
 104     Filename ret;
 105     if (!strcmp(name, "LogFileName"))
 106         strcpy(ret.path, "putty.log");
 107     else
 108         *ret.path = '\0';
 109     return ret;
 110 }
 111
 112 char *x_get_default(const char *key)
 113 {
 114     return NULL;                       /* this is a stub */
 115 }
 116 int term_ldisc(Terminal *term, int mode)
 117 {
 118     return FALSE;
 119 }
 120 void ldisc_update(void *frontend, int echo, int edit)
 121 {
 122     /* Update stdin read mode to reflect changes in line discipline. */
 123     struct termios mode;
 124
 125     mode = orig_termios;
 126
 127     if (echo)
 128         mode.c_lflag |= ECHO;
 129     else
 130         mode.c_lflag &= ~ECHO;
 131
 132     if (edit) {
 133         mode.c_iflag |= ICRNL;
 134         mode.c_lflag |= ISIG | ICANON;
 135     } else {
 136         mode.c_iflag &= ~ICRNL;
 137         mode.c_lflag &= ~(ISIG | ICANON);
 138         mode.c_cc[VMIN] = 1;
 139         mode.c_cc[VTIME] = 0;
 140     }
 141
 142     tcsetattr(0, TCSANOW, &mode);
 143 }
 144
 145 void cleanup_termios(void)
 146 {
 147     tcsetattr(0, TCSANOW, &orig_termios);
 148 }
 149
 150 bufchain stdout_data, stderr_data;
 151
 152 void try_output(int is_stderr)
 153 {
 154     bufchain *chain = (is_stderr ? &stderr_data : &stdout_data);
 155     int fd = (is_stderr ? 2 : 1);
 156     void *senddata;
 157     int sendlen, ret;
 158
 159     if (bufchain_size(chain) == 0)
 160         return;
 161
 162     bufchain_prefix(chain, &senddata, &sendlen);
 163     ret = write(fd, senddata, sendlen);
 164     if (ret > 0)
 165         bufchain_consume(chain, ret);
 166     else if (ret < 0) {
 167         perror(is_stderr ? "stderr: write" : "stdout: write");
 168         exit(1);
 169     }
 170 }
 171
 172 int from_backend(void *frontend_handle, int is_stderr,
 173                  const char *data, int len)
 174 {
 175     int osize, esize;
 176
 177     if (is_stderr) {
 178         bufchain_add(&stderr_data, data, len);
 179         try_output(1);
 180     } else {
 181         bufchain_add(&stdout_data, data, len);
 182         try_output(0);
 183     }
 184
 185     osize = bufchain_size(&stdout_data);
 186     esize = bufchain_size(&stderr_data);
 187
 188     return osize + esize;
 189 }
 190
 191 int signalpipe[2];
 192
 193 void sigwinch(int signum)
 194 {
 195     write(signalpipe[1], "x", 1);
 196 }
 197
 198 /*
 199  * In Plink our selects are synchronous, so these functions are
 200  * empty stubs.
 201  */
 202 int uxsel_input_add(int fd, int rwx) { return 0; }
 203 void uxsel_input_remove(int id) { }
 204
 205 /*
 206  * Short description of parameters.
 207  */
 208 static void usage(void)
 209 {
 210     printf("PuTTY Link: command-line connection utility\n");
 211     printf("%s\n", ver);
 212     printf("Usage: plink [options] [user@]host [command]\n");
 213     printf("       (\"host\" can also be a PuTTY saved session name)\n");
 214     printf("Options:\n");
 215     printf("  -V        print version information and exit\n");
 216     printf("  -pgpfp    print PGP key fingerprints and exit\n");
 217     printf("  -v        show verbose messages\n");
 218     printf("  -load sessname  Load settings from saved session\n");
 219     printf("  -ssh -telnet -rlogin -raw\n");
 220     printf("            force use of a particular protocol\n");
 221     printf("  -P port   connect to specified port\n");
 222     printf("  -l user   connect with specified username\n");
 223     printf("  -batch    disable all interactive prompts\n");
 224     printf("The following options only apply to SSH connections:\n");
 225     printf("  -pw passw login with specified password\n");
 226     printf("  -D [listen-IP:]listen-port\n");
 227     printf("            Dynamic SOCKS-based port forwarding\n");
 228     printf("  -L [listen-IP:]listen-port:host:port\n");
 229     printf("            Forward local port to remote address\n");
 230     printf("  -R [listen-IP:]listen-port:host:port\n");
 231     printf("            Forward remote port to local address\n");
 232     printf("  -X -x     enable / disable X11 forwarding\n");
 233     printf("  -A -a     enable / disable agent forwarding\n");
 234     printf("  -t -T     enable / disable pty allocation\n");
 235     printf("  -1 -2     force use of particular protocol version\n");
 236     printf("  -4 -6     force use of IPv4 or IPv6\n");
 237     printf("  -C        enable compression\n");
 238     printf("  -i key    private key file for authentication\n");
 239     printf("  -m file   read remote command(s) from file\n");
 240     printf("  -s        remote command is an SSH subsystem (SSH-2 only)\n");
 241     printf("  -N        don't start a shell/command (SSH-2 only)\n");
 242     exit(1);
 243 }
 244
 245 static void version(void)
 246 {
 247     printf("plink: %s\n", ver);
 248     exit(1);
 249 }
 250
 251 int main(int argc, char **argv)
 252 {
 253     int sending;
 254     int portnumber = -1;
 255     int *fdlist;
 256     int fd;
 257     int i, fdcount, fdsize, fdstate;
 258     int connopen;
 259     int exitcode;
 260     int errors;
 261     int use_subsystem = 0;
 262     void *ldisc, *logctx;
 263     long now;
 264
 265     ssh_get_line = console_get_line;
 266
 267     fdlist = NULL;
 268     fdcount = fdsize = 0;
 269     /*
 270      * Initialise port and protocol to sensible defaults. (These
 271      * will be overridden by more or less anything.)
 272      */
 273     default_protocol = PROT_SSH;
 274     default_port = 22;
 275
 276     flags = FLAG_STDERR;
 277     /*
 278      * Process the command line.
 279      */
 280     do_defaults(NULL, &cfg);
 281     loaded_session = FALSE;
 282     default_protocol = cfg.protocol;
 283     default_port = cfg.port;
 284     errors = 0;
 285     {
 286         /*
 287          * Override the default protocol if PLINK_PROTOCOL is set.
 288          */
 289         char *p = getenv("PLINK_PROTOCOL");
 290         int i;
 291         if (p) {
 292             for (i = 0; backends[i].backend != NULL; i++) {
 293                 if (!strcmp(backends[i].name, p)) {
 294                     default_protocol = cfg.protocol = backends[i].protocol;
 295                     default_port = cfg.port =
 296                         backends[i].backend->default_port;
 297                     break;
 298                 }
 299             }
 300         }
 301     }
 302     while (--argc) {
 303         char *p = *++argv;
 304         if (*p == '-') {
 305             int ret = cmdline_process_param(p, (argc > 1 ? argv[1] : NULL),
 306                                             1, &cfg);
 307             if (ret == -2) {
 308                 fprintf(stderr,
 309                         "plink: option \"%s\" requires an argument\n", p);
 310                 errors = 1;
 311             } else if (ret == 2) {
 312                 --argc, ++argv;
 313             } else if (ret == 1) {
 314                 continue;
 315             } else if (!strcmp(p, "-batch")) {
 316                 console_batch_mode = 1;
 317             } else if (!strcmp(p, "-s")) {
 318                 /* Save status to write to cfg later. */
 319                 use_subsystem = 1;
 320             } else if (!strcmp(p, "-V")) {
 321                 version();
 322             } else if (!strcmp(p, "-pgpfp")) {
 323                 pgp_fingerprints();
 324                 exit(1);
 325             } else if (!strcmp(p, "-o")) {
 326                 if (argc <= 1) {
 327                     fprintf(stderr,
 328                             "plink: option \"-o\" requires an argument\n");
 329                     errors = 1;
 330                 } else {
 331                     --argc;
 332                     provide_xrm_string(*++argv);
 333                 }
 334             } else {
 335                 fprintf(stderr, "plink: unknown option \"%s\"\n", p);
 336                 errors = 1;
 337             }
 338         } else if (*p) {
 339             if (!*cfg.host) {
 340                 char *q = p;
 341
 342                 do_defaults(NULL, &cfg);
 343
 344                 /*
 345                  * If the hostname starts with "telnet:", set the
 346                  * protocol to Telnet and process the string as a
 347                  * Telnet URL.
 348                  */
 349                 if (!strncmp(q, "telnet:", 7)) {
 350                     char c;
 351
 352                     q += 7;
 353                     if (q[0] == '/' && q[1] == '/')
 354                         q += 2;
 355                     cfg.protocol = PROT_TELNET;
 356                     p = q;
 357                     while (*p && *p != ':' && *p != '/')
 358                         p++;
 359                     c = *p;
 360                     if (*p)
 361                         *p++ = '\0';
 362                     if (c == ':')
 363                         cfg.port = atoi(p);
 364                     else
 365                         cfg.port = -1;
 366                     strncpy(cfg.host, q, sizeof(cfg.host) - 1);
 367                     cfg.host[sizeof(cfg.host) - 1] = '\0';
 368                 } else {
 369                     char *r, *user, *host;
 370                     /*
 371                      * Before we process the [user@]host string, we
 372                      * first check for the presence of a protocol
 373                      * prefix (a protocol name followed by ",").
 374                      */
 375                     r = strchr(p, ',');
 376                     if (r) {
 377                         int i, j;
 378                         for (i = 0; backends[i].backend != NULL; i++) {
 379                             j = strlen(backends[i].name);
 380                             if (j == r - p &&
 381                                 !memcmp(backends[i].name, p, j)) {
 382                                 default_protocol = cfg.protocol =
 383                                     backends[i].protocol;
 384                                 portnumber =
 385                                     backends[i].backend->default_port;
 386                                 p = r + 1;
 387                                 break;
 388                             }
 389                         }
 390                     }
 391
 392                     /*
 393                      * A nonzero length string followed by an @ is treated
 394                      * as a username. (We discount an _initial_ @.) The
 395                      * rest of the string (or the whole string if no @)
 396                      * is treated as a session name and/or hostname.
 397                      */
 398                     r = strrchr(p, '@');
 399                     if (r == p)
 400                         p++, r = NULL; /* discount initial @ */
 401                     if (r) {
 402                         *r++ = '\0';
 403                         user = p, host = r;
 404                     } else {
 405                         user = NULL, host = p;
 406                     }
 407
 408                     /*
 409                      * Now attempt to load a saved session with the
 410                      * same name as the hostname.
 411                      */
 412                     {
 413                         Config cfg2;
 414                         do_defaults(host, &cfg2);
 415                         if (loaded_session || cfg2.host[0] == '\0') {
 416                             /* No settings for this host; use defaults */
 417                             /* (or session was already loaded with -load) */
 418                             strncpy(cfg.host, host, sizeof(cfg.host) - 1);
 419                             cfg.host[sizeof(cfg.host) - 1] = '\0';
 420                             cfg.port = default_port;
 421                         } else {
 422                             cfg = cfg2;
 423                         }
 424                     }
 425
 426                     if (user) {
 427                         /* Patch in specified username. */
 428                         strncpy(cfg.username, user,
 429                                 sizeof(cfg.username) - 1);
 430                         cfg.username[sizeof(cfg.username) - 1] = '\0';
 431                     }
 432
 433                 }
 434             } else {
 435                 char *command;
 436                 int cmdlen, cmdsize;
 437                 cmdlen = cmdsize = 0;
 438                 command = NULL;
 439
 440                 while (argc) {
 441                     while (*p) {
 442                         if (cmdlen >= cmdsize) {
 443                             cmdsize = cmdlen + 512;
 444                             command = sresize(command, cmdsize, char);
 445                         }
 446                         command[cmdlen++]=*p++;
 447                     }
 448                     if (cmdlen >= cmdsize) {
 449                         cmdsize = cmdlen + 512;
 450                         command = sresize(command, cmdsize, char);
 451                     }
 452                     command[cmdlen++]=' '; /* always add trailing space */
 453                     if (--argc) p = *++argv;
 454                 }
 455                 if (cmdlen) command[--cmdlen]='\0';
 456                                        /* change trailing blank to NUL */
 457                 cfg.remote_cmd_ptr = command;
 458                 cfg.remote_cmd_ptr2 = NULL;
 459                 cfg.nopty = TRUE;      /* command => no terminal */
 460
 461                 break;                 /* done with cmdline */
 462             }
 463         }
 464     }
 465
 466     if (errors)
 467         return 1;
 468
 469     if (!*cfg.host) {
 470         usage();
 471     }
 472
 473     /*
 474      * Trim leading whitespace off the hostname if it's there.
 475      */
 476     {
 477         int space = strspn(cfg.host, " \t");
 478         memmove(cfg.host, cfg.host+space, 1+strlen(cfg.host)-space);
 479     }
 480
 481     /* See if host is of the form user@host */
 482     if (cfg.host[0] != '\0') {
 483         char *atsign = strrchr(cfg.host, '@');
 484         /* Make sure we're not overflowing the user field */
 485         if (atsign) {
 486             if (atsign - cfg.host < sizeof cfg.username) {
 487                 strncpy(cfg.username, cfg.host, atsign - cfg.host);
 488                 cfg.username[atsign - cfg.host] = '\0';
 489             }
 490             memmove(cfg.host, atsign + 1, 1 + strlen(atsign + 1));
 491         }
 492     }
 493
 494     /*
 495      * Perform command-line overrides on session configuration.
 496      */
 497     cmdline_run_saved(&cfg);
 498
 499     /*
 500      * Apply subsystem status.
 501      */
 502     if (use_subsystem)
 503         cfg.ssh_subsys = TRUE;
 504
 505     /*
 506      * Trim a colon suffix off the hostname if it's there.
 507      */
 508     cfg.host[strcspn(cfg.host, ":")] = '\0';
 509
 510     /*
 511      * Remove any remaining whitespace from the hostname.
 512      */
 513     {
 514         int p1 = 0, p2 = 0;
 515         while (cfg.host[p2] != '\0') {
 516             if (cfg.host[p2] != ' ' && cfg.host[p2] != '\t') {
 517                 cfg.host[p1] = cfg.host[p2];
 518                 p1++;
 519             }
 520             p2++;
 521         }
 522         cfg.host[p1] = '\0';
 523     }
 524
 525     if (!cfg.remote_cmd_ptr && !*cfg.remote_cmd)
 526         flags |= FLAG_INTERACTIVE;
 527
 528     /*
 529      * Select protocol. This is farmed out into a table in a
 530      * separate file to enable an ssh-free variant.
 531      */
 532     {
 533         int i;
 534         back = NULL;
 535         for (i = 0; backends[i].backend != NULL; i++)
 536             if (backends[i].protocol == cfg.protocol) {
 537                 back = backends[i].backend;
 538                 break;
 539             }
 540         if (back == NULL) {
 541             fprintf(stderr,
 542                     "Internal fault: Unsupported protocol found\n");
 543             return 1;
 544         }
 545     }
 546
 547     /*
 548      * Select port.
 549      */
 550     if (portnumber != -1)
 551         cfg.port = portnumber;
 552
 553     /*
 554      * Set up the pipe we'll use to tell us about SIGWINCH.
 555      */
 556     if (pipe(signalpipe) < 0) {
 557         perror("pipe");
 558         exit(1);
 559     }
 560     putty_signal(SIGWINCH, sigwinch);
 561
 562     sk_init();
 563     uxsel_init();
 564
 565     /*
 566      * Start up the connection.
 567      */
 568     logctx = log_init(NULL, &cfg);
 569     console_provide_logctx(logctx);
 570     {
 571         const char *error;
 572         char *realhost;
 573         /* nodelay is only useful if stdin is a terminal device */
 574         int nodelay = cfg.tcp_nodelay && isatty(0);
 575
 576         error = back->init(NULL, &backhandle, &cfg, cfg.host, cfg.port,
 577                            &realhost, nodelay, cfg.tcp_keepalives);
 578         if (error) {
 579             fprintf(stderr, "Unable to open connection:\n%s\n", error);
 580             return 1;
 581         }
 582         back->provide_logctx(backhandle, logctx);
 583         ldisc = ldisc_create(&cfg, NULL, back, backhandle, NULL);
 584         sfree(realhost);
 585     }
 586     connopen = 1;
 587
 588     /*
 589      * Set up the initial console mode. We don't care if this call
 590      * fails, because we know we aren't necessarily running in a
 591      * console.
 592      */
 593     tcgetattr(0, &orig_termios);
 594     atexit(cleanup_termios);
 595     ldisc_update(NULL, 1, 1);
 596     sending = FALSE;
 597     now = GETTICKCOUNT();
 598
 599     while (1) {
 600         fd_set rset, wset, xset;
 601         int maxfd;
 602         int rwx;
 603         int ret;
 604
 605         FD_ZERO(&rset);
 606         FD_ZERO(&wset);
 607         FD_ZERO(&xset);
 608         maxfd = 0;
 609
 610         FD_SET_MAX(signalpipe[0], maxfd, rset);
 611
 612         if (connopen && !sending &&
 613             back->socket(backhandle) != NULL &&
 614             back->sendok(backhandle) &&
 615             back->sendbuffer(backhandle) < MAX_STDIN_BACKLOG) {
 616             /* If we're OK to send, then try to read from stdin. */
 617             FD_SET_MAX(0, maxfd, rset);
 618         }
 619
 620         if (bufchain_size(&stdout_data) > 0) {
 621             /* If we have data for stdout, try to write to stdout. */
 622             FD_SET_MAX(1, maxfd, wset);
 623         }
 624
 625         if (bufchain_size(&stderr_data) > 0) {
 626             /* If we have data for stderr, try to write to stderr. */
 627             FD_SET_MAX(2, maxfd, wset);
 628         }
 629
 630         /* Count the currently active fds. */
 631         i = 0;
 632         for (fd = first_fd(&fdstate, &rwx); fd >= 0;
 633              fd = next_fd(&fdstate, &rwx)) i++;
 634
 635         /* Expand the fdlist buffer if necessary. */
 636         if (i > fdsize) {
 637             fdsize = i + 16;
 638             fdlist = sresize(fdlist, fdsize, int);
 639         }
 640
 641         /*
 642          * Add all currently open fds to the select sets, and store
 643          * them in fdlist as well.
 644          */
 645         fdcount = 0;
 646         for (fd = first_fd(&fdstate, &rwx); fd >= 0;
 647              fd = next_fd(&fdstate, &rwx)) {
 648             fdlist[fdcount++] = fd;
 649             if (rwx & 1)
 650                 FD_SET_MAX(fd, maxfd, rset);
 651             if (rwx & 2)
 652                 FD_SET_MAX(fd, maxfd, wset);
 653             if (rwx & 4)
 654                 FD_SET_MAX(fd, maxfd, xset);
 655         }
 656
 657         do {
 658             long next, ticks;
 659             struct timeval tv, *ptv;
 660
 661             if (run_timers(now, &next)) {
 662                 ticks = next - GETTICKCOUNT();
 663                 if (ticks < 0) ticks = 0;   /* just in case */
 664                 tv.tv_sec = ticks / 1000;
 665                 tv.tv_usec = ticks % 1000 * 1000;
 666                 ptv = &tv;
 667             } else {
 668                 ptv = NULL;
 669             }
 670             ret = select(maxfd, &rset, &wset, &xset, ptv);
 671             if (ret == 0)
 672                 now = next;
 673             else {
 674                 long newnow = GETTICKCOUNT();
 675                 /*
 676                  * Check to see whether the system clock has
 677                  * changed massively during the select.
 678                  */
 679                 if (newnow - now < 0 || newnow - now > next - now) {
 680                     /*
 681                      * If so, look at the elapsed time in the
 682                      * select and use it to compute a new
 683                      * tickcount_offset.
 684                      */
 685                     long othernow = now + tv.tv_sec * 1000 + tv.tv_usec / 1000;
 686                     /* So we'd like GETTICKCOUNT to have returned othernow,
 687                      * but instead it return newnow. Hence ... */
 688                     tickcount_offset += othernow - newnow;
 689                     now = othernow;
 690                 } else {
 691                     now = newnow;
 692                 }
 693             }
 694         } while (ret < 0 && errno == EINTR);
 695
 696         if (ret < 0) {
 697             perror("select");
 698             exit(1);
 699         }
 700
 701         for (i = 0; i < fdcount; i++) {
 702             fd = fdlist[i];
 703             /*
 704              * We must process exceptional notifications before
 705              * ordinary readability ones, or we may go straight
 706              * past the urgent marker.
 707              */
 708             if (FD_ISSET(fd, &xset))
 709                 select_result(fd, 4);
 710             if (FD_ISSET(fd, &rset))
 711                 select_result(fd, 1);
 712             if (FD_ISSET(fd, &wset))
 713                 select_result(fd, 2);
 714         }
 715
 716         if (FD_ISSET(signalpipe[0], &rset)) {
 717             char c[1];
 718             struct winsize size;
 719             read(signalpipe[0], c, 1); /* ignore its value; it'll be `x' */
 720             if (ioctl(0, TIOCGWINSZ, (void *)&size) >= 0)
 721                 back->size(backhandle, size.ws_col, size.ws_row);
 722         }
 723
 724         if (FD_ISSET(0, &rset)) {
 725             char buf[4096];
 726             int ret;
 727
 728             if (connopen && back->socket(backhandle) != NULL) {
 729                 ret = read(0, buf, sizeof(buf));
 730                 if (ret < 0) {
 731                     perror("stdin: read");
 732                     exit(1);
 733                 } else if (ret == 0) {
 734                     back->special(backhandle, TS_EOF);
 735                     sending = FALSE;   /* send nothing further after this */
 736                 } else {
 737                     back->send(backhandle, buf, ret);
 738                 }
 739             }
 740         }
 741
 742         if (FD_ISSET(1, &wset)) {
 743             try_output(0);
 744         }
 745
 746         if (FD_ISSET(2, &wset)) {
 747             try_output(1);
 748         }
 749
 750         if ((!connopen || back->socket(backhandle) == NULL) &&
 751             bufchain_size(&stdout_data) == 0 &&
 752             bufchain_size(&stderr_data) == 0)
 753             break;                     /* we closed the connection */
 754     }
 755     exitcode = back->exitcode(backhandle);
 756     if (exitcode < 0) {
 757         fprintf(stderr, "Remote process exit code unavailable\n");
 758         exitcode = 1;                  /* this is an error condition */
 759     }
 760     cleanup_exit(exitcode);
 761     return exitcode;                   /* shouldn't happen, but placates gcc */
 762 }