2 * PLink - a command-line (stdin/stdout) variant of PuTTY.
15 #include <sys/ioctl.h>
17 #ifndef HAVE_NO_SYS_SELECT_H
18 #include <sys/select.h>
21 #define PUTTY_DO_GLOBALS /* actually _define_ globals */
26 #define MAX_STDIN_BACKLOG 4096
30 static struct termios orig_termios;
32 void fatalbox(char *p, ...)
37 fprintf(stderr, "FATAL ERROR: ");
39 vfprintf(stderr, p, ap);
49 void modalfatalbox(char *p, ...)
54 fprintf(stderr, "FATAL ERROR: ");
56 vfprintf(stderr, p, ap);
66 void connection_fatal(void *frontend, char *p, ...)
71 fprintf(stderr, "FATAL ERROR: ");
73 vfprintf(stderr, p, ap);
83 void cmdline_error(char *p, ...)
88 fprintf(stderr, "plink: ");
90 vfprintf(stderr, p, ap);
97 static int local_tty = FALSE; /* do we have a local tty? */
100 static void *backhandle;
104 * Default settings that are specific to pterm.
106 char *platform_default_s(const char *name)
108 if (!strcmp(name, "TermType"))
109 return dupstr(getenv("TERM"));
110 if (!strcmp(name, "UserName"))
111 return get_username();
112 if (!strcmp(name, "SerialLine"))
113 return dupstr("/dev/ttyS0");
117 int platform_default_i(const char *name, int def)
119 if (!strcmp(name, "TermWidth") ||
120 !strcmp(name, "TermHeight")) {
122 if (ioctl(STDIN_FILENO, TIOCGWINSZ, (void *)&size) >= 0)
123 return (!strcmp(name, "TermWidth") ? size.ws_col : size.ws_row);
128 FontSpec platform_default_fontspec(const char *name)
135 Filename platform_default_filename(const char *name)
138 if (!strcmp(name, "LogFileName"))
139 strcpy(ret.path, "putty.log");
145 char *x_get_default(const char *key)
147 return NULL; /* this is a stub */
149 int term_ldisc(Terminal *term, int mode)
153 void ldisc_update(void *frontend, int echo, int edit)
155 /* Update stdin read mode to reflect changes in line discipline. */
158 if (!local_tty) return;
163 mode.c_lflag |= ECHO;
165 mode.c_lflag &= ~ECHO;
168 mode.c_iflag |= ICRNL;
169 mode.c_lflag |= ISIG | ICANON;
170 mode.c_oflag |= OPOST;
172 mode.c_iflag &= ~ICRNL;
173 mode.c_lflag &= ~(ISIG | ICANON);
174 mode.c_oflag &= ~OPOST;
175 /* Solaris sets these to unhelpful values */
177 mode.c_cc[VTIME] = 0;
178 /* FIXME: perhaps what we do with IXON/IXOFF should be an
179 * argument to ldisc_update(), to allow implementation of SSH-2
180 * "xon-xoff" and Rlogin's equivalent? */
181 mode.c_iflag &= ~IXON;
182 mode.c_iflag &= ~IXOFF;
185 * Mark parity errors and (more important) BREAK on input. This
186 * is more complex than it need be because POSIX-2001 suggests
187 * that escaping of valid 0xff in the input stream is dependent on
188 * IGNPAR being clear even though marking of BREAK isn't. NetBSD
189 * 2.0 goes one worse and makes it dependent on INPCK too. We
190 * deal with this by forcing these flags into a useful state and
191 * then faking the state in which we found them in from_tty() if
192 * we get passed a parity or framing error.
194 mode.c_iflag = (mode.c_iflag | INPCK | PARMRK) & ~IGNPAR;
196 tcsetattr(STDIN_FILENO, TCSANOW, &mode);
199 /* Helper function to extract a special character from a termios. */
200 static char *get_ttychar(struct termios *t, int index)
202 cc_t c = t->c_cc[index];
203 #if defined(_POSIX_VDISABLE)
204 if (c == _POSIX_VDISABLE)
205 return dupprintf("");
207 return dupprintf("^<%d>", c);
210 char *get_ttymode(void *frontend, const char *mode)
213 * Propagate appropriate terminal modes from the local terminal,
216 if (!local_tty) return NULL;
218 #define GET_CHAR(ourname, uxname) \
220 if (strcmp(mode, ourname) == 0) \
221 return get_ttychar(&orig_termios, uxname); \
223 #define GET_BOOL(ourname, uxname, uxmemb, transform) \
225 if (strcmp(mode, ourname) == 0) { \
226 int b = (orig_termios.uxmemb & uxname) != 0; \
228 return dupprintf("%d", b); \
233 * Modes that want to be the same on all terminal devices involved.
235 /* All the special characters supported by SSH */
237 GET_CHAR("INTR", VINTR);
240 GET_CHAR("QUIT", VQUIT);
243 GET_CHAR("ERASE", VERASE);
246 GET_CHAR("KILL", VKILL);
249 GET_CHAR("EOF", VEOF);
252 GET_CHAR("EOL", VEOL);
255 GET_CHAR("EOL2", VEOL2);
258 GET_CHAR("START", VSTART);
261 GET_CHAR("STOP", VSTOP);
264 GET_CHAR("SUSP", VSUSP);
267 GET_CHAR("DSUSP", VDSUSP);
269 #if defined(VREPRINT)
270 GET_CHAR("REPRINT", VREPRINT);
273 GET_CHAR("WERASE", VWERASE);
276 GET_CHAR("LNEXT", VLNEXT);
279 GET_CHAR("FLUSH", VFLUSH);
282 GET_CHAR("SWTCH", VSWTCH);
285 GET_CHAR("STATUS", VSTATUS);
287 #if defined(VDISCARD)
288 GET_CHAR("DISCARD", VDISCARD);
290 /* Modes that "configure" other major modes. These should probably be
291 * considered as user preferences. */
292 /* Configuration of ICANON */
294 GET_BOOL("ECHOK", ECHOK, c_lflag, );
297 GET_BOOL("ECHOKE", ECHOKE, c_lflag, );
300 GET_BOOL("ECHOE", ECHOE, c_lflag, );
303 GET_BOOL("ECHONL", ECHONL, c_lflag, );
306 GET_BOOL("XCASE", XCASE, c_lflag, );
308 /* Configuration of ECHO */
310 GET_BOOL("ECHOCTL", ECHOCTL, c_lflag, );
312 /* Configuration of IXON/IXOFF */
314 GET_BOOL("IXANY", IXANY, c_iflag, );
316 /* Configuration of OPOST */
318 GET_BOOL("OLCUC", OLCUC, c_oflag, );
321 GET_BOOL("ONLCR", ONLCR, c_oflag, );
324 GET_BOOL("OCRNL", OCRNL, c_oflag, );
327 GET_BOOL("ONOCR", ONOCR, c_oflag, );
330 GET_BOOL("ONLRET", ONLRET, c_oflag, );
334 * Modes that want to be set in only one place, and that we have
338 GET_BOOL("ISIG", ISIG, c_lflag, );
341 GET_BOOL("ICANON", ICANON, c_lflag, );
344 GET_BOOL("ECHO", ECHO, c_lflag, );
347 GET_BOOL("IXON", IXON, c_iflag, );
350 GET_BOOL("IXOFF", IXOFF, c_iflag, );
353 GET_BOOL("OPOST", OPOST, c_oflag, );
357 * We do not propagate the following modes:
358 * - Parity/serial settings, which are a local affair and don't
359 * make sense propagated over SSH's 8-bit byte-stream.
360 * IGNPAR PARMRK INPCK CS7 CS8 PARENB PARODD
361 * - Things that want to be enabled in one place that we don't
366 * - Things I don't know what to do with. (FIXME)
367 * ISTRIP IMAXBEL NOFLSH TOSTOP IEXTEN
374 /* Fall through to here for unrecognised names, or ones that are
375 * unsupported on this platform */
379 void cleanup_termios(void)
382 tcsetattr(STDIN_FILENO, TCSANOW, &orig_termios);
385 bufchain stdout_data, stderr_data;
387 int try_output(int is_stderr)
389 bufchain *chain = (is_stderr ? &stderr_data : &stdout_data);
390 int fd = (is_stderr ? STDERR_FILENO : STDOUT_FILENO);
392 int sendlen, ret, fl;
394 if (bufchain_size(chain) == 0)
395 return bufchain_size(&stdout_data) + bufchain_size(&stderr_data);
397 fl = fcntl(fd, F_GETFL);
398 if (fl != -1 && !(fl & O_NONBLOCK))
399 fcntl(fd, F_SETFL, fl | O_NONBLOCK);
401 bufchain_prefix(chain, &senddata, &sendlen);
402 ret = write(fd, senddata, sendlen);
404 bufchain_consume(chain, ret);
405 } while (ret == sendlen && bufchain_size(chain) != 0);
406 if (fl != -1 && !(fl & O_NONBLOCK))
407 fcntl(fd, F_SETFL, fl);
408 if (ret < 0 && errno != EAGAIN) {
409 perror(is_stderr ? "stderr: write" : "stdout: write");
412 return bufchain_size(&stdout_data) + bufchain_size(&stderr_data);
415 int from_backend(void *frontend_handle, int is_stderr,
416 const char *data, int len)
419 bufchain_add(&stderr_data, data, len);
420 return try_output(TRUE);
422 bufchain_add(&stdout_data, data, len);
423 return try_output(FALSE);
427 int from_backend_untrusted(void *frontend_handle, const char *data, int len)
430 * No "untrusted" output should get here (the way the code is
431 * currently, it's all diverted by FLAG_STDERR).
433 assert(!"Unexpected call to from_backend_untrusted()");
434 return 0; /* not reached */
437 int get_userpass_input(prompts_t *p, unsigned char *in, int inlen)
440 ret = cmdline_get_passwd_input(p, in, inlen);
442 ret = console_get_userpass_input(p, in, inlen);
447 * Handle data from a local tty in PARMRK format.
449 static void from_tty(void *vbuf, unsigned len)
451 char *p, *q, *end, *buf = vbuf;
452 static enum {NORMAL, FF, FF00} state = NORMAL;
454 p = buf; end = buf + len;
462 q = memchr(p, '\xff', end - p);
463 if (q == NULL) q = end;
464 back->send(backhandle, p, q - p);
470 back->send(backhandle, p, 1);
473 } else if (*p == '\0') {
480 back->special(backhandle, TS_BRK);
483 * Pretend that PARMRK wasn't set. This involves
484 * faking what INPCK and IGNPAR would have done if
485 * we hadn't overridden them. Unfortunately, we
486 * can't do this entirely correctly because INPCK
487 * distinguishes between framing and parity
488 * errors, but PARMRK format represents both in
489 * the same way. We assume that parity errors are
490 * more common than framing errors, and hence
491 * treat all input errors as being subject to
494 if (orig_termios.c_iflag & INPCK) {
495 /* If IGNPAR is set, we throw away the character. */
496 if (!(orig_termios.c_iflag & IGNPAR)) {
497 /* PE/FE get passed on as NUL. */
499 back->send(backhandle, p, 1);
502 /* INPCK not set. Assume we got a parity error. */
503 back->send(backhandle, p, 1);
514 void sigwinch(int signum)
516 write(signalpipe[1], "x", 1);
520 * In Plink our selects are synchronous, so these functions are
523 int uxsel_input_add(int fd, int rwx) { return 0; }
524 void uxsel_input_remove(int id) { }
527 * Short description of parameters.
529 static void usage(void)
531 printf("PuTTY Link: command-line connection utility\n");
533 printf("Usage: plink [options] [user@]host [command]\n");
534 printf(" (\"host\" can also be a PuTTY saved session name)\n");
535 printf("Options:\n");
536 printf(" -V print version information and exit\n");
537 printf(" -pgpfp print PGP key fingerprints and exit\n");
538 printf(" -v show verbose messages\n");
539 printf(" -load sessname Load settings from saved session\n");
540 printf(" -ssh -telnet -rlogin -raw\n");
541 printf(" force use of a particular protocol\n");
542 printf(" -P port connect to specified port\n");
543 printf(" -l user connect with specified username\n");
544 printf(" -batch disable all interactive prompts\n");
545 printf("The following options only apply to SSH connections:\n");
546 printf(" -pw passw login with specified password\n");
547 printf(" -D [listen-IP:]listen-port\n");
548 printf(" Dynamic SOCKS-based port forwarding\n");
549 printf(" -L [listen-IP:]listen-port:host:port\n");
550 printf(" Forward local port to remote address\n");
551 printf(" -R [listen-IP:]listen-port:host:port\n");
552 printf(" Forward remote port to local address\n");
553 printf(" -X -x enable / disable X11 forwarding\n");
554 printf(" -A -a enable / disable agent forwarding\n");
555 printf(" -t -T enable / disable pty allocation\n");
556 printf(" -1 -2 force use of particular protocol version\n");
557 printf(" -4 -6 force use of IPv4 or IPv6\n");
558 printf(" -C enable compression\n");
559 printf(" -i key private key file for authentication\n");
560 printf(" -noagent disable use of Pageant\n");
561 printf(" -agent enable use of Pageant\n");
562 printf(" -m file read remote command(s) from file\n");
563 printf(" -s remote command is an SSH subsystem (SSH-2 only)\n");
564 printf(" -N don't start a shell/command (SSH-2 only)\n");
565 printf(" -nc host:port\n");
566 printf(" open tunnel in place of session (SSH-2 only)\n");
570 static void version(void)
572 printf("plink: %s\n", ver);
576 int main(int argc, char **argv)
582 int i, fdcount, fdsize, fdstate;
586 int use_subsystem = 0;
591 fdcount = fdsize = 0;
593 * Initialise port and protocol to sensible defaults. (These
594 * will be overridden by more or less anything.)
596 default_protocol = PROT_SSH;
599 flags = FLAG_STDERR | FLAG_STDERR_TTY;
603 * Process the command line.
605 do_defaults(NULL, &cfg);
606 loaded_session = FALSE;
607 default_protocol = cfg.protocol;
608 default_port = cfg.port;
612 * Override the default protocol if PLINK_PROTOCOL is set.
614 char *p = getenv("PLINK_PROTOCOL");
616 const Backend *b = backend_from_name(p);
618 default_protocol = cfg.protocol = b->protocol;
619 default_port = cfg.port = b->default_port;
626 int ret = cmdline_process_param(p, (argc > 1 ? argv[1] : NULL),
630 "plink: option \"%s\" requires an argument\n", p);
632 } else if (ret == 2) {
634 } else if (ret == 1) {
636 } else if (!strcmp(p, "-batch")) {
637 console_batch_mode = 1;
638 } else if (!strcmp(p, "-s")) {
639 /* Save status to write to cfg later. */
641 } else if (!strcmp(p, "-V")) {
643 } else if (!strcmp(p, "-pgpfp")) {
646 } else if (!strcmp(p, "-o")) {
649 "plink: option \"-o\" requires an argument\n");
653 provide_xrm_string(*++argv);
656 fprintf(stderr, "plink: unknown option \"%s\"\n", p);
660 if (!cfg_launchable(&cfg)) {
664 * If the hostname starts with "telnet:", set the
665 * protocol to Telnet and process the string as a
668 if (!strncmp(q, "telnet:", 7)) {
672 if (q[0] == '/' && q[1] == '/')
674 cfg.protocol = PROT_TELNET;
676 while (*p && *p != ':' && *p != '/')
685 strncpy(cfg.host, q, sizeof(cfg.host) - 1);
686 cfg.host[sizeof(cfg.host) - 1] = '\0';
688 char *r, *user, *host;
690 * Before we process the [user@]host string, we
691 * first check for the presence of a protocol
692 * prefix (a protocol name followed by ",").
698 b = backend_from_name(p);
700 default_protocol = cfg.protocol = b->protocol;
701 portnumber = b->default_port;
707 * A nonzero length string followed by an @ is treated
708 * as a username. (We discount an _initial_ @.) The
709 * rest of the string (or the whole string if no @)
710 * is treated as a session name and/or hostname.
714 p++, r = NULL; /* discount initial @ */
719 user = NULL, host = p;
723 * Now attempt to load a saved session with the
724 * same name as the hostname.
728 do_defaults(host, &cfg2);
729 if (loaded_session || !cfg_launchable(&cfg2)) {
730 /* No settings for this host; use defaults */
731 /* (or session was already loaded with -load) */
732 strncpy(cfg.host, host, sizeof(cfg.host) - 1);
733 cfg.host[sizeof(cfg.host) - 1] = '\0';
734 cfg.port = default_port;
741 /* Patch in specified username. */
742 strncpy(cfg.username, user,
743 sizeof(cfg.username) - 1);
744 cfg.username[sizeof(cfg.username) - 1] = '\0';
751 cmdlen = cmdsize = 0;
756 if (cmdlen >= cmdsize) {
757 cmdsize = cmdlen + 512;
758 command = sresize(command, cmdsize, char);
760 command[cmdlen++]=*p++;
762 if (cmdlen >= cmdsize) {
763 cmdsize = cmdlen + 512;
764 command = sresize(command, cmdsize, char);
766 command[cmdlen++]=' '; /* always add trailing space */
767 if (--argc) p = *++argv;
769 if (cmdlen) command[--cmdlen]='\0';
770 /* change trailing blank to NUL */
771 cfg.remote_cmd_ptr = command;
772 cfg.remote_cmd_ptr2 = NULL;
773 cfg.nopty = TRUE; /* command => no terminal */
775 break; /* done with cmdline */
783 if (!cfg_launchable(&cfg)) {
788 * Trim leading whitespace off the hostname if it's there.
791 int space = strspn(cfg.host, " \t");
792 memmove(cfg.host, cfg.host+space, 1+strlen(cfg.host)-space);
795 /* See if host is of the form user@host */
796 if (cfg.host[0] != '\0') {
797 char *atsign = strrchr(cfg.host, '@');
798 /* Make sure we're not overflowing the user field */
800 if (atsign - cfg.host < sizeof cfg.username) {
801 strncpy(cfg.username, cfg.host, atsign - cfg.host);
802 cfg.username[atsign - cfg.host] = '\0';
804 memmove(cfg.host, atsign + 1, 1 + strlen(atsign + 1));
809 * Perform command-line overrides on session configuration.
811 cmdline_run_saved(&cfg);
814 * Apply subsystem status.
817 cfg.ssh_subsys = TRUE;
820 * Trim a colon suffix off the hostname if it's there.
822 cfg.host[strcspn(cfg.host, ":")] = '\0';
825 * Remove any remaining whitespace from the hostname.
829 while (cfg.host[p2] != '\0') {
830 if (cfg.host[p2] != ' ' && cfg.host[p2] != '\t') {
831 cfg.host[p1] = cfg.host[p2];
839 if (!cfg.remote_cmd_ptr && !*cfg.remote_cmd && !*cfg.ssh_nc_host)
840 flags |= FLAG_INTERACTIVE;
843 * Select protocol. This is farmed out into a table in a
844 * separate file to enable an ssh-free variant.
846 back = backend_from_proto(cfg.protocol);
849 "Internal fault: Unsupported protocol found\n");
856 if (portnumber != -1)
857 cfg.port = portnumber;
860 * Set up the pipe we'll use to tell us about SIGWINCH.
862 if (pipe(signalpipe) < 0) {
866 putty_signal(SIGWINCH, sigwinch);
872 * Unix Plink doesn't provide any way to add forwardings after the
873 * connection is set up, so if there are none now, we can safely set
876 if (cfg.protocol == PROT_SSH && !cfg.x11_forward && !cfg.agentfwd &&
877 cfg.portfwd[0] == '\0' && cfg.portfwd[1] == '\0')
878 cfg.ssh_simple = TRUE;
880 * Start up the connection.
882 logctx = log_init(NULL, &cfg);
883 console_provide_logctx(logctx);
887 /* nodelay is only useful if stdin is a terminal device */
888 int nodelay = cfg.tcp_nodelay && isatty(0);
890 error = back->init(NULL, &backhandle, &cfg, cfg.host, cfg.port,
891 &realhost, nodelay, cfg.tcp_keepalives);
893 fprintf(stderr, "Unable to open connection:\n%s\n", error);
896 back->provide_logctx(backhandle, logctx);
897 ldisc = ldisc_create(&cfg, NULL, back, backhandle, NULL);
903 * Set up the initial console mode. We don't care if this call
904 * fails, because we know we aren't necessarily running in a
907 local_tty = (tcgetattr(STDIN_FILENO, &orig_termios) == 0);
908 atexit(cleanup_termios);
909 ldisc_update(NULL, 1, 1);
911 now = GETTICKCOUNT();
914 fd_set rset, wset, xset;
924 FD_SET_MAX(signalpipe[0], maxfd, rset);
926 if (connopen && !sending &&
927 back->connected(backhandle) &&
928 back->sendok(backhandle) &&
929 back->sendbuffer(backhandle) < MAX_STDIN_BACKLOG) {
930 /* If we're OK to send, then try to read from stdin. */
931 FD_SET_MAX(STDIN_FILENO, maxfd, rset);
934 if (bufchain_size(&stdout_data) > 0) {
935 /* If we have data for stdout, try to write to stdout. */
936 FD_SET_MAX(STDOUT_FILENO, maxfd, wset);
939 if (bufchain_size(&stderr_data) > 0) {
940 /* If we have data for stderr, try to write to stderr. */
941 FD_SET_MAX(STDERR_FILENO, maxfd, wset);
944 /* Count the currently active fds. */
946 for (fd = first_fd(&fdstate, &rwx); fd >= 0;
947 fd = next_fd(&fdstate, &rwx)) i++;
949 /* Expand the fdlist buffer if necessary. */
952 fdlist = sresize(fdlist, fdsize, int);
956 * Add all currently open fds to the select sets, and store
957 * them in fdlist as well.
960 for (fd = first_fd(&fdstate, &rwx); fd >= 0;
961 fd = next_fd(&fdstate, &rwx)) {
962 fdlist[fdcount++] = fd;
964 FD_SET_MAX(fd, maxfd, rset);
966 FD_SET_MAX(fd, maxfd, wset);
968 FD_SET_MAX(fd, maxfd, xset);
973 struct timeval tv, *ptv;
975 if (run_timers(now, &next)) {
976 ticks = next - GETTICKCOUNT();
977 if (ticks < 0) ticks = 0; /* just in case */
978 tv.tv_sec = ticks / 1000;
979 tv.tv_usec = ticks % 1000 * 1000;
984 ret = select(maxfd, &rset, &wset, &xset, ptv);
988 long newnow = GETTICKCOUNT();
990 * Check to see whether the system clock has
991 * changed massively during the select.
993 if (newnow - now < 0 || newnow - now > next - now) {
995 * If so, look at the elapsed time in the
996 * select and use it to compute a new
999 long othernow = now + tv.tv_sec * 1000 + tv.tv_usec / 1000;
1000 /* So we'd like GETTICKCOUNT to have returned othernow,
1001 * but instead it return newnow. Hence ... */
1002 tickcount_offset += othernow - newnow;
1008 } while (ret < 0 && errno == EINTR);
1015 for (i = 0; i < fdcount; i++) {
1018 * We must process exceptional notifications before
1019 * ordinary readability ones, or we may go straight
1020 * past the urgent marker.
1022 if (FD_ISSET(fd, &xset))
1023 select_result(fd, 4);
1024 if (FD_ISSET(fd, &rset))
1025 select_result(fd, 1);
1026 if (FD_ISSET(fd, &wset))
1027 select_result(fd, 2);
1030 if (FD_ISSET(signalpipe[0], &rset)) {
1032 struct winsize size;
1033 read(signalpipe[0], c, 1); /* ignore its value; it'll be `x' */
1034 if (ioctl(0, TIOCGWINSZ, (void *)&size) >= 0)
1035 back->size(backhandle, size.ws_col, size.ws_row);
1038 if (FD_ISSET(STDIN_FILENO, &rset)) {
1042 if (connopen && back->connected(backhandle)) {
1043 ret = read(STDIN_FILENO, buf, sizeof(buf));
1045 perror("stdin: read");
1047 } else if (ret == 0) {
1048 back->special(backhandle, TS_EOF);
1049 sending = FALSE; /* send nothing further after this */
1054 back->send(backhandle, buf, ret);
1059 if (FD_ISSET(STDOUT_FILENO, &wset)) {
1060 back->unthrottle(backhandle, try_output(FALSE));
1063 if (FD_ISSET(STDERR_FILENO, &wset)) {
1064 back->unthrottle(backhandle, try_output(TRUE));
1067 if ((!connopen || !back->connected(backhandle)) &&
1068 bufchain_size(&stdout_data) == 0 &&
1069 bufchain_size(&stderr_data) == 0)
1070 break; /* we closed the connection */
1072 exitcode = back->exitcode(backhandle);
1074 fprintf(stderr, "Remote process exit code unavailable\n");
1075 exitcode = 1; /* this is an error condition */
1077 cleanup_exit(exitcode);
1078 return exitcode; /* shouldn't happen, but placates gcc */