src/subshell.c

   1 /* Concurrent shell support for the Midnight Commander
   2    Copyright (C) 1994, 1995, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   3    2005, 2006, 2007 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or
   6    modify it under the terms of Version 2 of the GNU General Public
   7    License, as published by the Free Software Foundation.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  17  */
  18
  19 #include <config.h>
  20
  21 #ifdef HAVE_SUBSHELL_SUPPORT
  22
  23 #ifndef _GNU_SOURCE
  24 #   define _GNU_SOURCE 1
  25 #endif
  26
  27 #include <ctype.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <errno.h>
  31 #include <string.h>
  32 #include <signal.h>
  33
  34 #include <sys/types.h>
  35 #ifdef HAVE_SYS_IOCTL_H
  36 #  include <sys/ioctl.h>
  37 #endif
  38 #ifdef HAVE_TERMIOS_H
  39 #include <termios.h>
  40 #endif
  41 #include <unistd.h>
  42
  43 #ifdef HAVE_STROPTS_H
  44 #  include <stropts.h> /* For I_PUSH */
  45 #endif /* HAVE_STROPTS_H */
  46
  47 #include "global.h"
  48 #include "tty.h"        /* LINES */
  49 #include "panel.h"      /* current_panel */
  50 #include "wtools.h"     /* query_dialog() */
  51 #include "main.h"       /* do_update_prompt() */
  52 #include "cons.saver.h" /* handle_console() */
  53 #include "key.h"        /* XCTRL */
  54 #include "subshell.h"
  55
  56 #ifndef WEXITSTATUS
  57 #   define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
  58 #endif
  59
  60 #ifndef WIFEXITED
  61 #   define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
  62 #endif
  63
  64 /* tcsh closes all non-standard file descriptors, so we have to use a pipe */
  65 static char tcsh_fifo[128];
  66
  67 /* Local functions */
  68 static void init_raw_mode (void);
  69 static int feed_subshell (int how, int fail_on_error);
  70 static void synchronize (void);
  71 static int pty_open_master (char *pty_name);
  72 static int pty_open_slave (const char *pty_name);
  73 static int resize_tty (int fd);
  74
  75 #ifndef STDIN_FILENO
  76 #    define STDIN_FILENO 0
  77 #endif
  78
  79 #ifndef STDOUT_FILENO
  80 #    define STDOUT_FILENO 1
  81 #endif
  82
  83 #ifndef STDERR_FILENO
  84 #    define STDERR_FILENO 2
  85 #endif
  86
  87 /* If using a subshell for evaluating commands this is true */
  88 int use_subshell =
  89 #ifdef SUBSHELL_OPTIONAL
  90 FALSE;
  91 #else
  92 TRUE;
  93 #endif
  94
  95 /* File descriptors of the pseudoterminal used by the subshell */
  96 int subshell_pty = 0;
  97 static int subshell_pty_slave = -1;
  98
  99 /* The key for switching back to MC from the subshell */
 100 static const char subshell_switch_key = XCTRL('o') & 255;
 101
 102 /* State of the subshell:
 103  * INACTIVE: the default state; awaiting a command
 104  * ACTIVE: remain in the shell until the user hits `subshell_switch_key'
 105  * RUNNING_COMMAND: return to MC when the current command finishes */
 106 enum subshell_state_enum subshell_state;
 107
 108 /* Holds the latest prompt captured from the subshell */
 109 char *subshell_prompt = NULL;
 110
 111 /* Initial length of the buffer for the subshell's prompt */
 112 #define INITIAL_PROMPT_SIZE 10
 113
 114 /* Used by the child process to indicate failure to start the subshell */
 115 #define FORK_FAILURE 69  /* Arbitrary */
 116
 117 /* Initial length of the buffer for all I/O with the subshell */
 118 #define INITIAL_PTY_BUFFER_SIZE 100  /* Arbitrary; but keep it >= 80 */
 119
 120 /* For pipes */
 121 enum {READ=0, WRITE=1};
 122
 123 static char *pty_buffer;        /* For reading/writing on the subshell's pty */
 124 static int pty_buffer_size;     /* The buffer grows as needed */
 125 static int subshell_pipe[2];    /* To pass CWD info from the subshell to MC */
 126 static pid_t subshell_pid = 1;  /* The subshell's process ID */
 127 static char subshell_cwd[MC_MAXPATHLEN+1];  /* One extra char for final '\n' */
 128
 129 /* Subshell type (gleaned from the SHELL environment variable, if available) */
 130 static enum {BASH, TCSH, ZSH} subshell_type;
 131
 132 /* Flag to indicate whether the subshell is ready for next command */
 133 static int subshell_ready;
 134
 135 /* The following two flags can be changed by the SIGCHLD handler. This is */
 136 /* OK, because the `int' type is updated atomically on all known machines */
 137 static volatile int subshell_alive, subshell_stopped;
 138
 139 /* We store the terminal's initial mode here so that we can configure
 140    the pty similarly, and also so we can restore the real terminal to
 141    sanity if we have to exit abruptly */
 142 static struct termios shell_mode;
 143
 144 /* This is a transparent mode for the terminal where MC is running on */
 145 /* It is used when the shell is active, so that the control signals */
 146 /* are delivered to the shell pty */
 147 static struct termios raw_mode;
 148
 149 /* This counter indicates how many characters of prompt we have read */
 150 /* FIXME: try to figure out why this had to become global */
 151 static int prompt_pos;
 152
 153
 154 /*
 155  *  Write all data, even if the write() call is interrupted.
 156  */
 157 static ssize_t
 158 write_all (int fd, const void *buf, size_t count)
 159 {
 160     ssize_t ret;
 161     ssize_t written = 0;
 162     while (count > 0) {
 163         ret = write (fd, (const unsigned char *) buf + written, count);
 164         if (ret < 0) {
 165             if (errno == EINTR) {
 166                 continue;
 167             } else {
 168                 return written > 0 ? written : ret;
 169             }
 170         }
 171         count -= ret;
 172         written += ret;
 173     }
 174     return written;
 175 }
 176
 177 /*
 178  *  Prepare child process to running the shell and run it.
 179  *
 180  *  Modifies the global variables (in the child process only):
 181  *      shell_mode
 182  *
 183  *  Returns: never.
 184  */
 185 static void
 186 init_subshell_child (const char *pty_name)
 187 {
 188     const char *init_file = NULL;
 189 #ifdef HAVE_GETSID
 190     pid_t mc_sid;
 191 #endif                          /* HAVE_GETSID */
 192
 193     setsid ();                  /* Get a fresh terminal session */
 194
 195     /* Make sure that it has become our controlling terminal */
 196
 197     /* Redundant on Linux and probably most systems, but just in case: */
 198
 199 #ifdef TIOCSCTTY
 200     ioctl (subshell_pty_slave, TIOCSCTTY, 0);
 201 #endif
 202
 203     /* Configure its terminal modes and window size */
 204
 205     /* Set up the pty with the same termios flags as our own tty, plus  */
 206     /* TOSTOP, which keeps background processes from writing to the pty */
 207
 208     shell_mode.c_lflag |= TOSTOP;       /* So background writers get SIGTTOU */
 209     if (tcsetattr (subshell_pty_slave, TCSANOW, &shell_mode)) {
 210         fprintf (stderr, "Cannot set pty terminal modes: %s\r\n",
 211                  unix_error_string (errno));
 212         _exit (FORK_FAILURE);
 213     }
 214
 215     /* Set the pty's size (80x25 by default on Linux) according to the */
 216     /* size of the real terminal as calculated by ncurses, if possible */
 217     resize_tty (subshell_pty_slave);
 218
 219     /* Set up the subshell's environment and init file name */
 220
 221     /* It simplifies things to change to our home directory here, */
 222     /* and the user's startup file may do a `cd' command anyway   */
 223     chdir (home_dir);           /* FIXME? What about when we re-run the subshell? */
 224
 225 #ifdef HAVE_GETSID
 226     /* Set MC_SID to prevent running one mc from another */
 227     mc_sid = getsid (0);
 228     if (mc_sid != -1) {
 229         char sid_str[BUF_SMALL];
 230         g_snprintf (sid_str, sizeof (sid_str), "MC_SID=%ld",
 231                     (long) mc_sid);
 232         putenv (g_strdup (sid_str));
 233     }
 234 #endif                          /* HAVE_GETSID */
 235
 236     switch (subshell_type) {
 237     case BASH:
 238         init_file = ".mc/bashrc";
 239         if (access (init_file, R_OK) == -1)
 240             init_file = ".bashrc";
 241
 242         /* Make MC's special commands not show up in bash's history */
 243         putenv ("HISTCONTROL=ignorespace");
 244
 245         /* Allow alternative readline settings for MC */
 246         if (access (".mc/inputrc", R_OK) == 0)
 247             putenv ("INPUTRC=.mc/inputrc");
 248
 249         break;
 250
 251         /* TODO: Find a way to pass initfile to TCSH and ZSH */
 252     case TCSH:
 253     case ZSH:
 254         break;
 255
 256     default:
 257         fprintf (stderr, __FILE__ ": unimplemented subshell type %d\r\n",
 258                  subshell_type);
 259         _exit (FORK_FAILURE);
 260     }
 261
 262     /* Attach all our standard file descriptors to the pty */
 263
 264     /* This is done just before the fork, because stderr must still      */
 265     /* be connected to the real tty during the above error messages; */
 266     /* otherwise the user will never see them.                   */
 267
 268     dup2 (subshell_pty_slave, STDIN_FILENO);
 269     dup2 (subshell_pty_slave, STDOUT_FILENO);
 270     dup2 (subshell_pty_slave, STDERR_FILENO);
 271
 272     close (subshell_pipe[READ]);
 273     close (subshell_pty_slave);         /* These may be FD_CLOEXEC, but just in case... */
 274     /* Close master side of pty.  This is important; apart from */
 275     /* freeing up the descriptor for use in the subshell, it also       */
 276     /* means that when MC exits, the subshell will get a SIGHUP and     */
 277     /* exit too, because there will be no more descriptors pointing     */
 278     /* at the master side of the pty and so it will disappear.  */
 279     close (subshell_pty);
 280
 281     /* Execute the subshell at last */
 282
 283     switch (subshell_type) {
 284     case BASH:
 285         execl (shell, "bash", "-rcfile", init_file, (char *) NULL);
 286         break;
 287
 288     case TCSH:
 289         execl (shell, "tcsh", (char *) NULL);
 290         break;
 291
 292     case ZSH:
 293         /* Use -g to exclude cmds beginning with space from history
 294          * and -Z to use the line editor on non-interactive term */
 295         execl (shell, "zsh", "-Z", "-g", (char *) NULL);
 296
 297         break;
 298     }
 299
 300     /* If we get this far, everything failed miserably */
 301     _exit (FORK_FAILURE);
 302 }
 303
 304
 305 #ifdef HAVE_GETSID
 306 /*
 307  * Check MC_SID to prevent running one mc from another.
 308  * Return:
 309  * 0 if no parent mc in our session was found,
 310  * 1 if parent mc was found and the user wants to continue,
 311  * 2 if parent mc was found and the user wants to quit mc.
 312  */
 313 static int
 314 check_sid (void)
 315 {
 316     pid_t my_sid, old_sid;
 317     const char *sid_str;
 318     int r;
 319
 320     sid_str = getenv ("MC_SID");
 321     if (!sid_str)
 322         return 0;
 323
 324     old_sid = (pid_t) strtol (sid_str, NULL, 0);
 325     if (!old_sid)
 326         return 0;
 327
 328     my_sid = getsid (0);
 329     if (my_sid == -1)
 330         return 0;
 331
 332     /* The parent mc is in a different session, it's OK */
 333     if (old_sid != my_sid)
 334         return 0;
 335
 336     r = query_dialog (_("Warning"),
 337                       _("GNU Midnight Commander is already\n"
 338                         "running on this terminal.\n"
 339                         "Subshell support will be disabled."), D_ERROR, 2,
 340                       _("&OK"), _("&Quit"));
 341     if (r != 0) {
 342         return 2;
 343     }
 344
 345     return 1;
 346 }
 347 #endif                          /* HAVE_GETSID */
 348
 349
 350 /*
 351  *  Fork the subshell, and set up many, many things.
 352  *
 353  *  Possibly modifies the global variables:
 354  *      subshell_type, subshell_alive, subshell_stopped, subshell_pid
 355  *      use_subshell - Is set to FALSE if we can't run the subshell
 356  *      quit - Can be set to SUBSHELL_EXIT by the SIGCHLD handler
 357  */
 358
 359 void
 360 init_subshell (void)
 361 {
 362     /* This must be remembered across calls to init_subshell() */
 363     static char pty_name[BUF_SMALL];
 364     char precmd[BUF_SMALL];
 365
 366 #ifdef HAVE_GETSID
 367     switch (check_sid ()) {
 368     case 1:
 369         use_subshell = FALSE;
 370         return;
 371     case 2:
 372         use_subshell = FALSE;
 373         midnight_shutdown = 1;
 374         return;
 375     }
 376 #endif                          /* HAVE_GETSID */
 377
 378     /* Take the current (hopefully pristine) tty mode and make */
 379     /* a raw mode based on it now, before we do anything else with it */
 380     init_raw_mode ();
 381
 382     if (subshell_pty == 0) {    /* First time through */
 383         /* Find out what type of shell we have */
 384
 385         if (strstr (shell, "/zsh") || getenv ("ZSH_VERSION"))
 386             subshell_type = ZSH;
 387         else if (strstr (shell, "/tcsh"))
 388             subshell_type = TCSH;
 389         else if (strstr (shell, "/bash") || getenv ("BASH"))
 390             subshell_type = BASH;
 391         else {
 392             use_subshell = FALSE;
 393             return;
 394         }
 395
 396         /* Open a pty for talking to the subshell */
 397
 398         /* FIXME: We may need to open a fresh pty each time on SVR4 */
 399
 400         subshell_pty = pty_open_master (pty_name);
 401         if (subshell_pty == -1) {
 402             fprintf (stderr, "Cannot open master side of pty: %s\r\n",
 403                      unix_error_string (errno));
 404             use_subshell = FALSE;
 405             return;
 406         }
 407         subshell_pty_slave = pty_open_slave (pty_name);
 408         if (subshell_pty_slave == -1) {
 409             fprintf (stderr, "Cannot open slave side of pty %s: %s\r\n",
 410                      pty_name, unix_error_string (errno));
 411             use_subshell = FALSE;
 412             return;
 413         }
 414
 415         /* Initialise the pty's I/O buffer */
 416
 417         pty_buffer_size = INITIAL_PTY_BUFFER_SIZE;
 418         pty_buffer = g_malloc (pty_buffer_size);
 419
 420         /* Create a pipe for receiving the subshell's CWD */
 421
 422         if (subshell_type == TCSH) {
 423             g_snprintf (tcsh_fifo, sizeof (tcsh_fifo), "%s/mc.pipe.%d",
 424                         mc_tmpdir (), (int) getpid ());
 425             if (mkfifo (tcsh_fifo, 0600) == -1) {
 426                 fprintf (stderr, "mkfifo(%s) failed: %s\r\n", tcsh_fifo,
 427                          unix_error_string (errno));
 428                 use_subshell = FALSE;
 429                 return;
 430             }
 431
 432             /* Opening the FIFO as O_RDONLY or O_WRONLY causes deadlock */
 433
 434             if ((subshell_pipe[READ] = open (tcsh_fifo, O_RDWR)) == -1
 435                 || (subshell_pipe[WRITE] =
 436                     open (tcsh_fifo, O_RDWR)) == -1) {
 437                 fprintf (stderr, _("Cannot open named pipe %s\n"), tcsh_fifo);
 438                 perror (__FILE__": open");
 439                 use_subshell = FALSE;
 440                 return;
 441             }
 442         } else /* subshell_type is BASH or ZSH */ if (pipe (subshell_pipe)) {
 443             perror (__FILE__": couldn't create pipe");
 444             use_subshell = FALSE;
 445             return;
 446         }
 447     }
 448
 449     /* Fork the subshell */
 450
 451     subshell_alive = TRUE;
 452     subshell_stopped = FALSE;
 453     subshell_pid = fork ();
 454
 455     if (subshell_pid == -1) {
 456         fprintf (stderr, "Cannot spawn the subshell process: %s\r\n",
 457                  unix_error_string (errno));
 458         /* We exit here because, if the process table is full, the */
 459         /* other method of running user commands won't work either */
 460         exit (1);
 461     }
 462
 463     if (subshell_pid == 0) {    /* We are in the child process */
 464         init_subshell_child (pty_name);
 465     }
 466
 467     /* Set up `precmd' or equivalent for reading the subshell's CWD */
 468
 469     switch (subshell_type) {
 470     case BASH:
 471         g_snprintf (precmd, sizeof (precmd),
 472                     " PROMPT_COMMAND='pwd>&%d;kill -STOP $$'\n",
 473                     subshell_pipe[WRITE]);
 474         break;
 475
 476     case ZSH:
 477         g_snprintf (precmd, sizeof (precmd),
 478                     " precmd(){ pwd>&%d;kill -STOP $$ }\n",
 479                     subshell_pipe[WRITE]);
 480         break;
 481
 482     case TCSH:
 483         g_snprintf (precmd, sizeof (precmd),
 484                     "set echo_style=both;"
 485                     "alias precmd 'echo $cwd:q >>%s;kill -STOP $$'\n",
 486                     tcsh_fifo);
 487         break;
 488     }
 489     write_all (subshell_pty, precmd, strlen (precmd));
 490
 491     /* Wait until the subshell has started up and processed the command */
 492
 493     subshell_state = RUNNING_COMMAND;
 494     enable_interrupt_key ();
 495     if (!feed_subshell (QUIETLY, TRUE)) {
 496         use_subshell = FALSE;
 497     }
 498     disable_interrupt_key ();
 499     if (!subshell_alive)
 500         use_subshell = FALSE;   /* Subshell died instantly, so don't use it */
 501 }
 502
 503
 504 static void init_raw_mode ()
 505 {
 506     static int initialized = 0;
 507
 508     /* MC calls reset_shell_mode() in pre_exec() to set the real tty to its */
 509     /* original settings.  However, here we need to make this tty very raw, */
 510     /* so that all keyboard signals, XON/XOFF, etc. will get through to the */
 511     /* pty.  So, instead of changing the code for execute(), pre_exec(),    */
 512     /* etc, we just set up the modes we need here, before each command.     */
 513
 514     if (initialized == 0)  /* First time: initialise `raw_mode' */
 515     {
 516         tcgetattr (STDOUT_FILENO, &raw_mode);
 517         raw_mode.c_lflag &= ~ICANON;  /* Disable line-editing chars, etc.   */
 518         raw_mode.c_lflag &= ~ISIG;    /* Disable intr, quit & suspend chars */
 519         raw_mode.c_lflag &= ~ECHO;    /* Disable input echoing              */
 520         raw_mode.c_iflag &= ~IXON;    /* Pass ^S/^Q to subshell undisturbed */
 521         raw_mode.c_iflag &= ~ICRNL;   /* Don't translate CRs into LFs       */
 522         raw_mode.c_oflag &= ~OPOST;   /* Don't postprocess output           */
 523         raw_mode.c_cc[VTIME] = 0;     /* IE: wait forever, and return as    */
 524         raw_mode.c_cc[VMIN] = 1;      /* soon as a character is available   */
 525         initialized = 1;
 526     }
 527 }
 528
 529
 530 int invoke_subshell (const char *command, int how, char **new_dir)
 531 {
 532     /* Make the MC terminal transparent */
 533     tcsetattr (STDOUT_FILENO, TCSANOW, &raw_mode);
 534
 535     /* Make the subshell change to MC's working directory */
 536     if (new_dir)
 537         do_subshell_chdir (current_panel->cwd, TRUE, 1);
 538
 539     if (command == NULL)  /* The user has done "C-o" from MC */
 540     {
 541         if (subshell_state == INACTIVE)
 542         {
 543             subshell_state = ACTIVE;
 544             /* FIXME: possibly take out this hack; the user can
 545                re-play it by hitting C-hyphen a few times! */
 546             write_all (subshell_pty, " \b", 2);  /* Hack to make prompt reappear */
 547         }
 548     }
 549     else  /* MC has passed us a user command */
 550     {
 551         if (how == QUIETLY)
 552             write_all (subshell_pty, " ", 1);
 553         /* FIXME: if command is long (>8KB ?) we go comma */
 554         write_all (subshell_pty, command, strlen (command));
 555         write_all (subshell_pty, "\n", 1);
 556         subshell_state = RUNNING_COMMAND;
 557         subshell_ready = FALSE;
 558     }
 559
 560     feed_subshell (how, FALSE);
 561
 562     if (new_dir && subshell_alive && strcmp (subshell_cwd, current_panel->cwd))
 563         *new_dir = subshell_cwd;  /* Make MC change to the subshell's CWD */
 564
 565     /* Restart the subshell if it has died by SIGHUP, SIGQUIT, etc. */
 566     while (!subshell_alive && !quit && use_subshell)
 567         init_subshell ();
 568
 569     prompt_pos = 0;
 570
 571     return quit;
 572 }
 573
 574
 575 int
 576 read_subshell_prompt (void)
 577 {
 578     static int prompt_size = INITIAL_PROMPT_SIZE;
 579     int bytes = 0, i, rc = 0;
 580     struct timeval timeleft = { 0, 0 };
 581
 582     fd_set tmp;
 583     FD_ZERO (&tmp);
 584     FD_SET (subshell_pty, &tmp);
 585
 586     if (subshell_prompt == NULL) {      /* First time through */
 587         subshell_prompt = g_malloc (prompt_size);
 588         *subshell_prompt = '\0';
 589         prompt_pos = 0;
 590     }
 591
 592     while (subshell_alive
 593            && (rc =
 594                select (subshell_pty + 1, &tmp, NULL, NULL, &timeleft))) {
 595         /* Check for `select' errors */
 596         if (rc == -1) {
 597             if (errno == EINTR)
 598                 continue;
 599             else {
 600                 fprintf (stderr, "select (FD_SETSIZE, &tmp...): %s\r\n",
 601                          unix_error_string (errno));
 602                 exit (1);
 603             }
 604         }
 605
 606         bytes = read (subshell_pty, pty_buffer, pty_buffer_size);
 607
 608         /* Extract the prompt from the shell output */
 609
 610         for (i = 0; i < bytes; ++i)
 611             if (pty_buffer[i] == '\n' || pty_buffer[i] == '\r') {
 612                 prompt_pos = 0;
 613             } else {
 614                 if (!pty_buffer[i])
 615                     continue;
 616
 617                 subshell_prompt[prompt_pos++] = pty_buffer[i];
 618                 if (prompt_pos == prompt_size)
 619                     subshell_prompt =
 620                         g_realloc (subshell_prompt, prompt_size *= 2);
 621             }
 622
 623         subshell_prompt[prompt_pos] = '\0';
 624     }
 625     if (rc == 0 && bytes == 0)
 626         return FALSE;
 627     return TRUE;
 628 }
 629
 630 /* Resize given terminal using TIOCSWINSZ, return ioctl() result */
 631 static int resize_tty (int fd)
 632 {
 633 #if defined TIOCSWINSZ
 634     struct winsize tty_size;
 635
 636     tty_size.ws_row = LINES;
 637     tty_size.ws_col = COLS;
 638     tty_size.ws_xpixel = tty_size.ws_ypixel = 0;
 639
 640     return ioctl (fd, TIOCSWINSZ, &tty_size);
 641 #else
 642     return 0;
 643 #endif
 644 }
 645
 646 /* Resize subshell_pty */
 647 void resize_subshell (void)
 648 {
 649     if (use_subshell == 0)
 650         return;
 651
 652     resize_tty (subshell_pty);
 653 }
 654
 655 int
 656 exit_subshell (void)
 657 {
 658     int quit = TRUE;
 659
 660     if (subshell_state != INACTIVE && subshell_alive)
 661         quit =
 662             !query_dialog (_("Warning"),
 663                            _(" The shell is still active. Quit anyway? "),
 664                            0, 2, _("&Yes"), _("&No"));
 665
 666     if (quit) {
 667         if (subshell_type == TCSH) {
 668             if (unlink (tcsh_fifo) == -1)
 669                 fprintf (stderr, "Cannot remove named pipe %s: %s\r\n",
 670                          tcsh_fifo, unix_error_string (errno));
 671         }
 672
 673         g_free (subshell_prompt);
 674         g_free (pty_buffer);
 675         subshell_prompt = NULL;
 676         pty_buffer = NULL;
 677     }
 678
 679     return quit;
 680 }
 681
 682
 683 /*
 684  * Carefully quote directory name to allow entering any directory safely,
 685  * no matter what weird characters it may contain in its name.
 686  * NOTE: Treat directory name an untrusted data, don't allow it to cause
 687  * executing any commands in the shell.  Escape all control characters.
 688  * Use following technique:
 689  *
 690  * printf(1) with format string containing a single conversion specifier,
 691  * "b", and an argument which contains a copy of the string passed to
 692  * subshell_name_quote() with all characters, except digits and letters,
 693  * replaced by the backslash-escape sequence \0nnn, where "nnn" is the
 694  * numeric value of the character converted to octal number.
 695  *
 696  *   cd "`printf "%b" 'ABC\0nnnDEF\0nnnXYZ'`"
 697  *
 698  */
 699 static char *
 700 subshell_name_quote (const char *s)
 701 {
 702     char *ret, *d;
 703     const char quote_cmd_start[] = "\"`printf \"%b\" '";
 704     const char quote_cmd_end[] = "'`\"";
 705
 706     /* Factor 5 because we need \, 0 and 3 other digits per character. */
 707     d = ret = g_malloc (1 + (5 * strlen (s)) + (sizeof(quote_cmd_start) - 1)
 708                                 + (sizeof(quote_cmd_end) - 1));
 709     if (!d)
 710         return NULL;
 711
 712     /* Prevent interpreting leading `-' as a switch for `cd' */
 713     if (*s == '-') {
 714         *d++ = '.';
 715         *d++ = '/';
 716     }
 717
 718     /* Copy the beginning of the command to the buffer */
 719     strcpy (d, quote_cmd_start);
 720     d += sizeof(quote_cmd_start) - 1;
 721
 722     /*
 723      * Print every character except digits and letters as a backslash-escape
 724      * sequence of the form \0nnn, where "nnn" is the numeric value of the
 725      * character converted to octal number.
 726      */
 727     for (; *s; s++) {
 728         if (isalnum ((unsigned char) *s)) {
 729             *d++ = (unsigned char) *s;
 730         } else {
 731             sprintf (d, "\\0%03o", (unsigned char) *s);
 732             d += 5;
 733         }
 734     }
 735
 736     strcpy (d, quote_cmd_end);
 737
 738     return ret;
 739 }
 740
 741
 742 /* If it actually changed the directory it returns true */
 743 void
 744 do_subshell_chdir (const char *directory, int do_update, int reset_prompt)
 745 {
 746     if (!
 747         (subshell_state == INACTIVE
 748          && strcmp (subshell_cwd, current_panel->cwd))) {
 749         /* We have to repaint the subshell prompt if we read it from
 750          * the main program.  Please note that in the code after this
 751          * if, the cd command that is sent will make the subshell
 752          * repaint the prompt, so we don't have to paint it. */
 753         if (do_update)
 754             do_update_prompt ();
 755         return;
 756     }
 757
 758     /* The initial space keeps this out of the command history (in bash
 759        because we set "HISTCONTROL=ignorespace") */
 760     write_all (subshell_pty, " cd ", 4);
 761     if (*directory) {
 762         char *temp = subshell_name_quote (directory);
 763         if (temp) {
 764             write_all (subshell_pty, temp, strlen (temp));
 765             g_free (temp);
 766         } else {
 767             /* Should not happen unless the directory name is so long
 768                that we don't have memory to quote it.  */
 769             write_all (subshell_pty, ".", 1);
 770         }
 771     } else {
 772         write_all (subshell_pty, "/", 1);
 773     }
 774     write_all (subshell_pty, "\n", 1);
 775
 776     subshell_state = RUNNING_COMMAND;
 777     feed_subshell (QUIETLY, FALSE);
 778
 779     if (subshell_alive) {
 780         int bPathNotEq = strcmp (subshell_cwd, current_panel->cwd);
 781
 782         if (bPathNotEq && subshell_type == TCSH) {
 783             char rp_subshell_cwd[PATH_MAX];
 784             char rp_current_panel_cwd[PATH_MAX];
 785
 786             char *p_subshell_cwd =
 787                 mc_realpath (subshell_cwd, rp_subshell_cwd);
 788             char *p_current_panel_cwd =
 789                 mc_realpath (current_panel->cwd, rp_current_panel_cwd);
 790
 791             if (p_subshell_cwd == NULL)
 792                 p_subshell_cwd = subshell_cwd;
 793             if (p_current_panel_cwd == NULL)
 794                 p_current_panel_cwd = current_panel->cwd;
 795             bPathNotEq = strcmp (p_subshell_cwd, p_current_panel_cwd);
 796         }
 797
 798         if (bPathNotEq && strcmp (current_panel->cwd, ".")) {
 799             char *cwd = strip_password (g_strdup (current_panel->cwd), 1);
 800             fprintf (stderr, _("Warning: Cannot change to %s.\n"), cwd);
 801             g_free (cwd);
 802         }
 803     }
 804
 805     if (reset_prompt)
 806         prompt_pos = 0;
 807     update_prompt = FALSE;
 808     /* Make sure that MC never stores the CWD in a silly format */
 809     /* like /usr////lib/../bin, or the strcmp() above will fail */
 810 }
 811
 812
 813 void
 814 subshell_get_console_attributes (void)
 815 {
 816     /* Get our current terminal modes */
 817
 818     if (tcgetattr (STDOUT_FILENO, &shell_mode)) {
 819         fprintf (stderr, "Cannot get terminal settings: %s\r\n",
 820                  unix_error_string (errno));
 821         use_subshell = FALSE;
 822         return;
 823     }
 824 }
 825
 826
 827 /* Figure out whether the subshell has stopped, exited or been killed */
 828 /* Possibly modifies: `subshell_alive', `subshell_stopped' and `quit' */
 829 void
 830 sigchld_handler (int sig)
 831 {
 832     int status;
 833     pid_t pid;
 834
 835     (void) sig;
 836
 837     pid = waitpid (subshell_pid, &status, WUNTRACED | WNOHANG);
 838
 839     if (pid == subshell_pid) {
 840         /* Figure out what has happened to the subshell */
 841
 842         if (WIFSTOPPED (status)) {
 843             if (WSTOPSIG (status) == SIGSTOP) {
 844                 /* The subshell has received a SIGSTOP signal */
 845                 subshell_stopped = TRUE;
 846             } else {
 847                 /* The user has suspended the subshell.  Revive it */
 848                 kill (subshell_pid, SIGCONT);
 849             }
 850         } else {
 851             /* The subshell has either exited normally or been killed */
 852             subshell_alive = FALSE;
 853             delete_select_channel (subshell_pty);
 854             if (WIFEXITED (status) && WEXITSTATUS (status) != FORK_FAILURE)
 855                 quit |= SUBSHELL_EXIT;  /* Exited normally */
 856         }
 857     }
 858 #ifdef __linux__
 859     pid = waitpid (cons_saver_pid, &status, WUNTRACED | WNOHANG);
 860
 861     if (pid == cons_saver_pid) {
 862
 863         if (WIFSTOPPED (status))
 864             /* Someone has stopped cons.saver - restart it */
 865             kill (pid, SIGCONT);
 866         else {
 867             /* cons.saver has died - disable confole saving */
 868             handle_console (CONSOLE_DONE);
 869             console_flag = 0;
 870         }
 871
 872     }
 873 #endif                          /* __linux__ */
 874
 875     /* If we got here, some other child exited; ignore it */
 876 }
 877
 878
 879 /* Feed the subshell our keyboard input until it says it's finished */
 880 static int
 881 feed_subshell (int how, int fail_on_error)
 882 {
 883     fd_set read_set;            /* For `select' */
 884     int maxfdp;
 885     int bytes;                  /* For the return value from `read' */
 886     int i;                      /* Loop counter */
 887
 888     struct timeval wtime;       /* Maximum time we wait for the subshell */
 889     struct timeval *wptr;
 890
 891     /* we wait up to 10 seconds if fail_on_error, forever otherwise */
 892     wtime.tv_sec = 10;
 893     wtime.tv_usec = 0;
 894     wptr = fail_on_error ? &wtime : NULL;
 895
 896     while (1) {
 897         if (!subshell_alive)
 898             return FALSE;
 899
 900         /* Prepare the file-descriptor set and call `select' */
 901
 902         FD_ZERO (&read_set);
 903         FD_SET (subshell_pty, &read_set);
 904         FD_SET (subshell_pipe[READ], &read_set);
 905         maxfdp = max (subshell_pty, subshell_pipe[READ]);
 906         if (how == VISIBLY) {
 907             FD_SET (STDIN_FILENO, &read_set);
 908             maxfdp = max (maxfdp, STDIN_FILENO);
 909         }
 910
 911         if (select (maxfdp + 1, &read_set, NULL, NULL, wptr) == -1) {
 912
 913             /* Despite using SA_RESTART, we still have to check for this */
 914             if (errno == EINTR)
 915                 continue;       /* try all over again */
 916             tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
 917             fprintf (stderr, "select (FD_SETSIZE, &read_set...): %s\r\n",
 918                      unix_error_string (errno));
 919             exit (1);
 920         }
 921
 922         if (FD_ISSET (subshell_pty, &read_set))
 923             /* Read from the subshell, write to stdout */
 924
 925             /* This loop improves performance by reducing context switches
 926                by a factor of 20 or so... unfortunately, it also hangs MC
 927                randomly, because of an apparent Linux bug.  Investigate. */
 928             /* for (i=0; i<5; ++i)  * FIXME -- experimental */
 929         {
 930             bytes = read (subshell_pty, pty_buffer, pty_buffer_size);
 931
 932             /* The subshell has died */
 933             if (bytes == -1 && errno == EIO && !subshell_alive)
 934                 return FALSE;
 935
 936             if (bytes <= 0) {
 937                 tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
 938                 fprintf (stderr, "read (subshell_pty...): %s\r\n",
 939                          unix_error_string (errno));
 940                 exit (1);
 941             }
 942
 943             if (how == VISIBLY)
 944                 write_all (STDOUT_FILENO, pty_buffer, bytes);
 945         }
 946
 947         else if (FD_ISSET (subshell_pipe[READ], &read_set))
 948             /* Read the subshell's CWD and capture its prompt */
 949
 950         {
 951             bytes =
 952                 read (subshell_pipe[READ], subshell_cwd,
 953                       MC_MAXPATHLEN + 1);
 954             if (bytes <= 0) {
 955                 tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
 956                 fprintf (stderr, "read (subshell_pipe[READ]...): %s\r\n",
 957                          unix_error_string (errno));
 958                 exit (1);
 959             }
 960
 961             subshell_cwd[bytes - 1] = 0;        /* Squash the final '\n' */
 962
 963             synchronize ();
 964
 965             subshell_ready = TRUE;
 966             if (subshell_state == RUNNING_COMMAND) {
 967                 subshell_state = INACTIVE;
 968                 return 1;
 969             }
 970         }
 971
 972         else if (FD_ISSET (STDIN_FILENO, &read_set))
 973             /* Read from stdin, write to the subshell */
 974         {
 975             bytes = read (STDIN_FILENO, pty_buffer, pty_buffer_size);
 976             if (bytes <= 0) {
 977                 tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
 978                 fprintf (stderr,
 979                          "read (STDIN_FILENO, pty_buffer...): %s\r\n",
 980                          unix_error_string (errno));
 981                 exit (1);
 982             }
 983
 984             for (i = 0; i < bytes; ++i)
 985                 if (pty_buffer[i] == subshell_switch_key) {
 986                     write_all (subshell_pty, pty_buffer, i);
 987                     if (subshell_ready)
 988                         subshell_state = INACTIVE;
 989                     return TRUE;
 990                 }
 991
 992             write_all (subshell_pty, pty_buffer, bytes);
 993             subshell_ready = FALSE;
 994         } else {
 995             return FALSE;
 996         }
 997     }
 998 }
 999
1000
1001 /* Wait until the subshell dies or stops.  If it stops, make it resume.  */
1002 /* Possibly modifies the globals `subshell_alive' and `subshell_stopped' */
1003 static void synchronize (void)
1004 {
1005     sigset_t sigchld_mask, old_mask;
1006
1007     sigemptyset (&sigchld_mask);
1008     sigaddset (&sigchld_mask, SIGCHLD);
1009     sigprocmask (SIG_BLOCK, &sigchld_mask, &old_mask);
1010
1011     /*
1012      * SIGCHLD should not be blocked, but we unblock it just in case.
1013      * This is known to be useful for cygwin 1.3.12 and older.
1014      */
1015     sigdelset (&old_mask, SIGCHLD);
1016
1017     /* Wait until the subshell has stopped */
1018     while (subshell_alive && !subshell_stopped)
1019         sigsuspend (&old_mask);
1020
1021     if (subshell_state != ACTIVE) {
1022         /* Discard all remaining data from stdin to the subshell */
1023         tcflush (subshell_pty_slave, TCIFLUSH);
1024     }
1025
1026     subshell_stopped = FALSE;
1027     kill (subshell_pid, SIGCONT);
1028
1029     sigprocmask (SIG_SETMASK, &old_mask, NULL);
1030     /* We can't do any better without modifying the shell(s) */
1031 }
1032
1033 /* pty opening functions */
1034
1035 #ifdef HAVE_GRANTPT
1036
1037 /* System V version of pty_open_master */
1038
1039 static int pty_open_master (char *pty_name)
1040 {
1041     char *slave_name;
1042     int pty_master;
1043
1044 #ifdef HAVE_POSIX_OPENPT
1045     pty_master = posix_openpt(O_RDWR);
1046 #elif HAVE_GETPT
1047     /* getpt () is a GNU extension (glibc 2.1.x) */
1048     pty_master = getpt ();
1049 #elif IS_AIX
1050     strcpy (pty_name, "/dev/ptc");
1051     pty_master = open (pty_name, O_RDWR);
1052 #else
1053     strcpy (pty_name, "/dev/ptmx");
1054     pty_master = open (pty_name, O_RDWR);
1055 #endif
1056
1057     if (pty_master == -1)
1058         return -1;
1059
1060     if (grantpt (pty_master) == -1                /* Grant access to slave */
1061         || unlockpt (pty_master) == -1            /* Clear slave's lock flag */
1062         || !(slave_name = ptsname (pty_master)))  /* Get slave's name */
1063     {
1064         close (pty_master);
1065         return -1;
1066     }
1067     strcpy (pty_name, slave_name);
1068     return pty_master;
1069 }
1070
1071 /* System V version of pty_open_slave */
1072 static int
1073 pty_open_slave (const char *pty_name)
1074 {
1075     int pty_slave = open (pty_name, O_RDWR);
1076
1077     if (pty_slave == -1) {
1078         fprintf (stderr, "open (%s, O_RDWR): %s\r\n", pty_name,
1079                  unix_error_string (errno));
1080         return -1;
1081     }
1082 #if !defined(__osf__) && !defined(__linux__)
1083 #if defined (I_FIND) && defined (I_PUSH)
1084     if (!ioctl (pty_slave, I_FIND, "ptem"))
1085         if (ioctl (pty_slave, I_PUSH, "ptem") == -1) {
1086             fprintf (stderr, "ioctl (%d, I_PUSH, \"ptem\") failed: %s\r\n",
1087                      pty_slave, unix_error_string (errno));
1088             close (pty_slave);
1089             return -1;
1090         }
1091
1092     if (!ioctl (pty_slave, I_FIND, "ldterm"))
1093         if (ioctl (pty_slave, I_PUSH, "ldterm") == -1) {
1094             fprintf (stderr,
1095                      "ioctl (%d, I_PUSH, \"ldterm\") failed: %s\r\n",
1096                      pty_slave, unix_error_string (errno));
1097             close (pty_slave);
1098             return -1;
1099         }
1100 #if !defined(sgi) && !defined(__sgi)
1101     if (!ioctl (pty_slave, I_FIND, "ttcompat"))
1102         if (ioctl (pty_slave, I_PUSH, "ttcompat") == -1) {
1103             fprintf (stderr,
1104                      "ioctl (%d, I_PUSH, \"ttcompat\") failed: %s\r\n",
1105                      pty_slave, unix_error_string (errno));
1106             close (pty_slave);
1107             return -1;
1108         }
1109 #endif                          /* sgi || __sgi */
1110 #endif                          /* I_FIND && I_PUSH */
1111 #endif                          /* __osf__ || __linux__ */
1112
1113     fcntl(pty_slave, F_SETFD, FD_CLOEXEC);
1114     return pty_slave;
1115 }
1116
1117 #else /* !HAVE_GRANTPT */
1118
1119 /* BSD version of pty_open_master */
1120 static int pty_open_master (char *pty_name)
1121 {
1122     int pty_master;
1123     const char *ptr1, *ptr2;
1124
1125     strcpy (pty_name, "/dev/ptyXX");
1126     for (ptr1 = "pqrstuvwxyzPQRST"; *ptr1; ++ptr1)
1127     {
1128         pty_name [8] = *ptr1;
1129         for (ptr2 = "0123456789abcdef"; *ptr2; ++ptr2)
1130         {
1131             pty_name [9] = *ptr2;
1132
1133             /* Try to open master */
1134             if ((pty_master = open (pty_name, O_RDWR)) == -1) {
1135                 if (errno == ENOENT)  /* Different from EIO */
1136                     return -1;        /* Out of pty devices */
1137                 else
1138                     continue;         /* Try next pty device */
1139             }
1140             pty_name [5] = 't';       /* Change "pty" to "tty" */
1141             if (access (pty_name, 6)){
1142                 close (pty_master);
1143                 pty_name [5] = 'p';
1144                 continue;
1145             }
1146             return pty_master;
1147         }
1148     }
1149     return -1;  /* Ran out of pty devices */
1150 }
1151
1152 /* BSD version of pty_open_slave */
1153 static int
1154 pty_open_slave (const char *pty_name)
1155 {
1156     int pty_slave;
1157     struct group *group_info = getgrnam ("tty");
1158
1159     if (group_info != NULL) {
1160         /* The following two calls will only succeed if we are root */
1161         /* [Commented out while permissions problem is investigated] */
1162         /* chown (pty_name, getuid (), group_info->gr_gid);  FIXME */
1163         /* chmod (pty_name, S_IRUSR | S_IWUSR | S_IWGRP);   FIXME */
1164     }
1165     if ((pty_slave = open (pty_name, O_RDWR)) == -1)
1166         fprintf (stderr, "open (pty_name, O_RDWR): %s\r\n", pty_name);
1167     fcntl(pty_slave, F_SETFD, FD_CLOEXEC);
1168     return pty_slave;
1169 }
1170
1171 #endif /* !HAVE_GRANTPT */
1172 #endif /* HAVE_SUBSHELL_SUPPORT */