nt/cmdproxy.c

   1 /* Proxy shell designed for use with Emacs on Windows 95 and NT.
   2    Copyright (C) 1997 Free Software Foundation, Inc.
   3
   4    Accepts subset of Unix sh(1) command-line options, for compatability
   5    with elisp code written for Unix.  When possible, executes external
   6    programs directly (a common use of /bin/sh by Emacs), otherwise
   7    invokes the user-specified command processor to handle built-in shell
   8    commands, batch files and interactive mode.
   9
  10    The main function is simply to process the "-c string" option in the
  11    way /bin/sh does, since the standard Windows command shells use the
  12    convention that everything after "/c" (the Windows equivalent of
  13    "-c") is the input string.
  14
  15 This file is part of GNU Emacs.
  16
  17 GNU Emacs is free software; you can redistribute it and/or modify
  18 it under the terms of the GNU General Public License as published by
  19 the Free Software Foundation; either version 2, or (at your option)
  20 any later version.
  21
  22 GNU Emacs is distributed in the hope that it will be useful,
  23 but WITHOUT ANY WARRANTY; without even the implied warranty of
  24 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25 GNU General Public License for more details.
  26
  27 You should have received a copy of the GNU General Public License
  28 along with GNU Emacs; see the file COPYING.  If not, write to
  29 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  30 Boston, MA 02111-1307, USA.  */
  31
  32 #include <windows.h>
  33
  34 #include <stdarg.h>  /* va_args */
  35 #include <malloc.h>  /* alloca */
  36 #include <stdlib.h>  /* getenv */
  37 #include <string.h>  /* strlen */
  38
  39
  40 /*******  Mock C library routines  *********************************/
  41
  42 /* These routines are used primarily to minimize the executable size.  */
  43
  44 #define stdin  GetStdHandle (STD_INPUT_HANDLE)
  45 #define stdout GetStdHandle (STD_OUTPUT_HANDLE)
  46 #define stderr GetStdHandle (STD_ERROR_HANDLE)
  47
  48 int
  49 vfprintf(HANDLE hnd, char * msg, va_list args)
  50 {
  51   DWORD bytes_written;
  52   char buf[1024];
  53
  54   wvsprintf (buf, msg, args);
  55   return WriteFile (hnd, buf, strlen (buf), &bytes_written, NULL);
  56 }
  57
  58 int
  59 fprintf(HANDLE hnd, char * msg, ...)
  60 {
  61   va_list args;
  62   int rc;
  63
  64   va_start (args, msg);
  65   rc = vfprintf (hnd, msg, args);
  66   va_end (args);
  67
  68   return rc;
  69 }
  70
  71 int
  72 printf(char * msg, ...)
  73 {
  74   va_list args;
  75   int rc;
  76
  77   va_start (args, msg);
  78   rc = vfprintf (stdout, msg, args);
  79   va_end (args);
  80
  81   return rc;
  82 }
  83
  84 void
  85 fail (char * msg, ...)
  86 {
  87   va_list args;
  88
  89   va_start (args, msg);
  90   vfprintf (stderr, msg, args);
  91   va_end (args);
  92
  93   exit (-1);
  94 }
  95
  96 void
  97 warn (char * msg, ...)
  98 {
  99   va_list args;
 100
 101   va_start (args, msg);
 102   vfprintf (stderr, msg, args);
 103   va_end (args);
 104 }
 105
 106 /******************************************************************/
 107
 108 char *
 109 canon_filename (char *fname)
 110 {
 111   char *p = fname;
 112
 113   while (*p)
 114     {
 115       if (*p == '/')
 116         *p = '\\';
 117       p++;
 118     }
 119
 120   return fname;
 121 }
 122
 123 char *
 124 skip_space (char *str)
 125 {
 126   while (isspace (*str)) str++;
 127   return str;
 128 }
 129
 130 char *
 131 skip_nonspace (char *str)
 132 {
 133   while (*str && !isspace (*str)) str++;
 134   return str;
 135 }
 136
 137 int escape_char = '\\';
 138
 139 /* Get next token from input, advancing pointer.  */
 140 int
 141 get_next_token (char * buf, char ** pSrc)
 142 {
 143   char * p = *pSrc;
 144   char * o = buf;
 145
 146   p = skip_space (p);
 147   if (*p == '"')
 148     {
 149       int escape_char_run = 0;
 150
 151       /* Go through src until an ending quote is found, unescaping
 152          quotes along the way.  If the escape char is not quote, then do
 153          special handling of multiple escape chars preceding a quote
 154          char (ie. the reverse of what Emacs does to escape quotes).  */
 155       p++;
 156       while (1)
 157         {
 158           if (p[0] == escape_char && escape_char != '"')
 159             {
 160               escape_char_run++;
 161               continue;
 162             }
 163           else if (p[0] == '"')
 164             {
 165               while (escape_char_run > 1)
 166                 {
 167                   *o++ = escape_char;
 168                   escape_char_run -= 2;
 169                 }
 170
 171               if (escape_char_run > 0)
 172                 {
 173                   /* escaped quote */
 174                   *o++ = *p++;
 175                   escape_char_run = 0;
 176                 }
 177               else if (p[1] == escape_char && escape_char == '"')
 178                 {
 179                   /* quote escaped by doubling */
 180                   *o++ = *p;
 181                   p += 2;
 182                 }
 183               else
 184                 {
 185                   /* The ending quote.  */
 186                   *o = '\0';
 187                   /* Leave input pointer after token.  */
 188                   p++;
 189                   break;
 190                 }
 191             }
 192           else if (p[0] == '\0')
 193             {
 194               /* End of string, but no ending quote found.  We might want to
 195                  flag this as an error, but for now will consider the end as
 196                  the end of the token.  */
 197               *o = '\0';
 198               break;
 199             }
 200           else
 201             {
 202               *o++ = *p++;
 203             }
 204         }
 205     }
 206   else
 207     {
 208       /* Next token is delimited by whitespace.  */
 209       char * p1 = skip_nonspace (p);
 210       memcpy (o, p, p1 - p);
 211       o += (p1 - p);
 212       *o = '\0';
 213       p = p1;
 214     }
 215
 216   *pSrc = p;
 217
 218   return o - buf;
 219 }
 220
 221 /* Search for EXEC file in DIR.  If EXEC does not have an extension,
 222    DIR is searched for EXEC with the standard extensions appended.  */
 223 int
 224 search_dir (char *dir, char *exec, int bufsize, char *buffer)
 225 {
 226   char *exts[] = {".bat", ".cmd", ".exe", ".com"};
 227   int n_exts = sizeof (exts) / sizeof (char *);
 228   char *dummy;
 229   int i, rc;
 230
 231   /* Search the directory for the program.  */
 232   for (i = 0; i < n_exts; i++)
 233     {
 234       rc = SearchPath (dir, exec, exts[i], bufsize, buffer, &dummy);
 235       if (rc > 0)
 236         return rc;
 237     }
 238
 239   return 0;
 240 }
 241
 242 /* Return the absolute name of executable file PROG, including
 243    any file extensions.  If an absolute name for PROG cannot be found,
 244    return NULL.  */
 245 char *
 246 make_absolute (char *prog)
 247 {
 248   char absname[MAX_PATH];
 249   char dir[MAX_PATH];
 250   char curdir[MAX_PATH];
 251   char *p, *fname;
 252   char *path;
 253   int i;
 254
 255   /* At least partial absolute path specified; search there.  */
 256   if ((isalpha (prog[0]) && prog[1] == ':') ||
 257       (prog[0] == '\\'))
 258     {
 259       /* Split the directory from the filename.  */
 260       fname = strrchr (prog, '\\');
 261       if (!fname)
 262         /* Only a drive specifier is given.  */
 263         fname = prog + 2;
 264       strncpy (dir, prog, fname - prog);
 265       dir[fname - prog] = '\0';
 266
 267       /* Search the directory for the program.  */
 268       if (search_dir (dir, prog, MAX_PATH, absname) > 0)
 269         return strdup (absname);
 270       else
 271         return NULL;
 272     }
 273
 274   if (GetCurrentDirectory (MAX_PATH, curdir) <= 0)
 275     return NULL;
 276
 277   /* Relative path; search in current dir. */
 278   if (strpbrk (prog, "\\"))
 279     {
 280       if (search_dir (curdir, prog, MAX_PATH, absname) > 0)
 281         return strdup (absname);
 282       else
 283         return NULL;
 284     }
 285
 286   /* Just filename; search current directory then PATH.  */
 287   path = alloca (strlen (getenv ("PATH")) + strlen (curdir) + 2);
 288   strcpy (path, curdir);
 289   strcat (path, ";");
 290   strcat (path, getenv ("PATH"));
 291
 292   while (*path)
 293     {
 294       /* Get next directory from path.  */
 295       p = path;
 296       while (*p && *p != ';') p++;
 297       strncpy (dir, path, p - path);
 298       dir[p - path] = '\0';
 299
 300       /* Search the directory for the program.  */
 301       if (search_dir (dir, prog, MAX_PATH, absname) > 0)
 302         return strdup (absname);
 303
 304       /* Move to the next directory.  */
 305       path = p + 1;
 306     }
 307
 308   return NULL;
 309 }
 310
 311 /*****************************************************************/
 312
 313 #if 0
 314 char ** _argv;
 315 int     _argc;
 316
 317 /* Parse commandline into argv array, allowing proper quoting of args.  */
 318 void
 319 setup_argv (void)
 320 {
 321   char * cmdline = GetCommandLine ();
 322   int arg_bytes = 0;
 323
 324
 325 }
 326 #endif
 327
 328 /* Information about child proc is global, to allow for automatic
 329    termination when interrupted.  At the moment, only one child process
 330    can be running at any one time.  */
 331
 332 PROCESS_INFORMATION child;
 333 int interactive = TRUE;
 334
 335 BOOL
 336 console_event_handler (DWORD event)
 337 {
 338   switch (event)
 339     {
 340     case CTRL_C_EVENT:
 341     case CTRL_BREAK_EVENT:
 342       if (!interactive)
 343         {
 344           /* Both command.com and cmd.exe have the annoying behaviour of
 345              prompting "Terminate batch job (y/n)?" when interrupted
 346              while running a batch file, even if running in
 347              non-interactive (-c) mode.  Try to make up for this
 348              deficiency by forcibly terminating the subprocess if
 349              running non-interactively.  */
 350           if (child.hProcess &&
 351               WaitForSingleObject (child.hProcess, 500) != WAIT_OBJECT_0)
 352             TerminateProcess (child.hProcess, 0);
 353           exit (STATUS_CONTROL_C_EXIT);
 354         }
 355       break;
 356
 357 #if 0
 358     default:
 359       /* CLOSE, LOGOFF and SHUTDOWN events - actually we don't get these
 360          under Windows 95.  */
 361       fail ("cmdproxy: received %d event\n", event);
 362       if (child.hProcess)
 363         TerminateProcess (child.hProcess, 0);
 364 #endif
 365     }
 366   return TRUE;
 367 }
 368
 369 /* Change from normal usage; return value indicates whether spawn
 370    succeeded or failed - program return code is returned separately.  */
 371 int
 372 spawn (char * progname, char * cmdline, int * retcode)
 373 {
 374   BOOL success = FALSE;
 375   SECURITY_ATTRIBUTES sec_attrs;
 376   STARTUPINFO start;
 377   /* In theory, passing NULL for the environment block to CreateProcess
 378      is the same as passing the value of GetEnvironmentStrings, but
 379      doing this explicitly seems to cure problems running DOS programs
 380      in some cases.  */
 381   char * envblock = GetEnvironmentStrings ();
 382
 383   sec_attrs.nLength = sizeof (sec_attrs);
 384   sec_attrs.lpSecurityDescriptor = NULL;
 385   sec_attrs.bInheritHandle = FALSE;
 386
 387   memset (&start, 0, sizeof (start));
 388   start.cb = sizeof (start);
 389
 390   if (CreateProcess (progname, cmdline, &sec_attrs, NULL, TRUE,
 391                      0, envblock, NULL, &start, &child))
 392   {
 393     success = TRUE;
 394     /* wait for completion and pass on return code */
 395     WaitForSingleObject (child.hProcess, INFINITE);
 396     if (retcode)
 397       GetExitCodeProcess (child.hProcess, (DWORD *)retcode);
 398     CloseHandle (child.hThread);
 399     CloseHandle (child.hProcess);
 400     child.hProcess = NULL;
 401   }
 402
 403   FreeEnvironmentStrings (envblock);
 404
 405   return success;
 406 }
 407
 408 /* Return size of current environment block.  */
 409 int
 410 get_env_size ()
 411 {
 412   char * start = GetEnvironmentStrings ();
 413   char * tmp = start;
 414
 415   while (tmp[0] || tmp[1])
 416     ++tmp;
 417   FreeEnvironmentStrings (start);
 418   return  tmp + 2 - start;
 419 }
 420
 421 /*******  Main program  ********************************************/
 422
 423 int
 424 main (int argc, char ** argv)
 425 {
 426   int rc;
 427   int need_shell;
 428   char * cmdline;
 429   char * progname;
 430   int envsize;
 431   char **pass_through_args;
 432   int num_pass_through_args;
 433   char modname[MAX_PATH];
 434   char path[MAX_PATH];
 435
 436
 437   interactive = TRUE;
 438
 439   SetConsoleCtrlHandler ((PHANDLER_ROUTINE) console_event_handler, TRUE);
 440
 441   /* We serve double duty: we can be called either as a proxy for the
 442      real shell (that is, because we are defined to be the user shell),
 443      or in our role as a helper application for running DOS programs.
 444      In the former case, we interpret the command line options as if we
 445      were a Unix shell, but in the latter case we simply pass our
 446      command line to CreateProcess.  We know which case we are dealing
 447      with by whether argv[0] refers to ourself or to some other program.
 448      (This relies on an arcane feature of CreateProcess, where we can
 449      specify cmdproxy as the module to run, but specify a different
 450      program in the command line - the MSVC startup code sets argv[0]
 451      from the command line.)  */
 452
 453   if (!GetModuleFileName (NULL, modname, sizeof (modname)))
 454     fail ("error: GetModuleFileName failed\n");
 455
 456   /* Although Emacs always sets argv[0] to an absolute pathname, we
 457      might get run in other ways as well, so convert argv[0] to an
 458      absolute name before comparing to the module name.  */
 459   if (!SearchPath (NULL, argv[0], ".exe", sizeof (path), path, &progname)
 460       || stricmp (modname, path) != 0)
 461     {
 462       /* We are being used as a helper to run a DOS app; just pass
 463          command line to DOS app without change.  */
 464       /* TODO: fill in progname.  */
 465       if (spawn (NULL, GetCommandLine (), &rc))
 466         return rc;
 467       fail ("Could not run %s\n", GetCommandLine ());
 468     }
 469
 470   /* Process command line.  If running interactively (-c or /c not
 471      specified) then spawn a real command shell, passing it the command
 472      line arguments.
 473
 474      If not running interactively, then attempt to execute the specified
 475      command directly.  If necessary, spawn a real shell to execute the
 476      command.
 477
 478   */
 479
 480   progname = NULL;
 481   cmdline = NULL;
 482   /* If no args, spawn real shell for interactive use.  */
 483   need_shell = TRUE;
 484   interactive = TRUE;
 485   /* Ask command.com to create an environment block with a reasonable
 486      amount of free space.  */
 487   envsize = get_env_size () + 300;
 488   pass_through_args = (char **) alloca (argc * sizeof(char *));
 489   num_pass_through_args = 0;
 490
 491   while (--argc > 0)
 492     {
 493       ++argv;
 494       /* Act on switches we recognize (mostly single letter switches,
 495          except for -e); all unrecognised switches and extra args are
 496          passed on to real shell if used (only really of benefit for
 497          interactive use, but allow for batch use as well).  Accept / as
 498          switch char for compatability with cmd.exe.  */
 499       if (((*argv)[0] == '-' || (*argv)[0] == '/') && (*argv)[1] != '\0')
 500         {
 501           if (((*argv)[1] == 'c' || (*argv)[1] == 'C') && ((*argv)[2] == '\0'))
 502             {
 503               if (--argc == 0)
 504                 fail ("error: expecting arg for %s\n", *argv);
 505               cmdline = *(++argv);
 506               interactive = FALSE;
 507             }
 508           else if (((*argv)[1] == 'i' || (*argv)[1] == 'I') && ((*argv)[2] == '\0'))
 509             {
 510               if (cmdline)
 511                 warn ("warning: %s ignored because of -c\n", *argv);
 512             }
 513           else if (((*argv)[1] == 'e' || (*argv[1] == 'E')) && ((*argv)[2] == ':'))
 514             {
 515               int requested_envsize = atoi (*argv + 3);
 516               /* Enforce a reasonable minimum size, as above.  */
 517               if (requested_envsize > envsize)
 518                 envsize = requested_envsize;
 519               /* For sanity, enforce a reasonable maximum.  */
 520               if (envsize > 32768)
 521                 envsize = 32768;
 522             }
 523           else
 524             {
 525               /* warn ("warning: unknown option %s ignored", *argv); */
 526               pass_through_args[num_pass_through_args++] = *argv;
 527             }
 528         }
 529       else
 530         break;
 531     }
 532
 533 #if 0
 534   /* I think this is probably not useful - cmd.exe ignores extra
 535      (non-switch) args in interactive mode, and they cannot be passed on
 536      when -c was given.  */
 537
 538   /* Collect any remaining args after (initial) switches.  */
 539   while (argc-- > 0)
 540     {
 541       pass_through_args[num_pass_through_args++] = *argv++;
 542     }
 543 #else
 544   /* Probably a mistake for there to be extra args; not fatal.  */
 545   if (argc > 0)
 546     warn ("warning: extra args ignored after '%s'\n", argv[-1]);
 547 #endif
 548
 549   pass_through_args[num_pass_through_args] = NULL;
 550
 551   /* If -c option, determine if we must spawn a real shell, or if we can
 552      execute the command directly ourself.  */
 553   if (cmdline)
 554     {
 555       /* If no redirection or piping, and if program can be found, then
 556          run program directly.  Otherwise invoke a real shell. */
 557
 558       static char copout_chars[] = "|<>&";
 559
 560       if (strpbrk (cmdline, copout_chars) == NULL)
 561         {
 562           char *args;
 563
 564           /* The program name is the first token of cmdline.  Since
 565              filenames cannot legally contain embedded quotes, the value
 566              of escape_char doesn't matter.  */
 567           args = cmdline;
 568           if (!get_next_token (path, &args))
 569             fail ("error: no program name specified.\n");
 570
 571           canon_filename (path);
 572           progname = make_absolute (path);
 573
 574           /* If we found the program, run it directly (if not found it
 575              might be an internal shell command, so don't fail).  */
 576           if (progname != NULL)
 577             need_shell = FALSE;
 578         }
 579     }
 580
 581  pass_to_shell:
 582   if (need_shell)
 583     {
 584       char * p;
 585       int    extra_arg_space = 0;
 586       int    run_command_dot_com;
 587
 588       progname = getenv ("COMSPEC");
 589       if (!progname)
 590         fail ("error: COMSPEC is not set\n");
 591
 592       canon_filename (progname);
 593       progname = make_absolute (progname);
 594
 595       if (progname == NULL || strchr (progname, '\\') == NULL)
 596         fail ("error: the program %s could not be found.\n", getenv ("COMSPEC"));
 597
 598       /* Need to set environment size when running command.com.  */
 599       run_command_dot_com =
 600         (stricmp (strrchr (progname, '\\'), "command.com") == 0);
 601
 602       /* Work out how much extra space is required for
 603          pass_through_args.  */
 604       for (argv = pass_through_args; *argv != NULL; ++argv)
 605         /* We don't expect to have to quote switches.  */
 606         extra_arg_space += strlen (*argv) + 2;
 607
 608       if (cmdline)
 609         {
 610           char * buf;
 611
 612           /* Convert to syntax expected by cmd.exe/command.com for
 613              running non-interactively.  Always quote program name in
 614              case path contains spaces (fortunately it can't contain
 615              quotes, since they are illegal in path names).  */
 616
 617           buf = p = alloca (strlen (progname) + extra_arg_space +
 618                             strlen (cmdline) + 16);
 619
 620           /* Quote progname in case it contains spaces.  */
 621           p += wsprintf (p, "\"%s\"", progname);
 622
 623           /* Include pass_through_args verbatim; these are just switches
 624              so should not need quoting.  */
 625           for (argv = pass_through_args; *argv != NULL; ++argv)
 626             p += wsprintf (p, " %s", *argv);
 627
 628           if (run_command_dot_com)
 629             wsprintf(p, " /e:%d /c %s", envsize, cmdline);
 630           else
 631             wsprintf(p, " /c %s", cmdline);
 632           cmdline = buf;
 633         }
 634       else
 635         {
 636           if (run_command_dot_com)
 637             {
 638               /* Provide dir arg expected by command.com when first
 639                  started interactively (the "command search path").  To
 640                  avoid potential problems with spaces in command dir
 641                  (which cannot be quoted - command.com doesn't like it),
 642                  we always use the 8.3 form.  */
 643               GetShortPathName (progname, path, sizeof (path));
 644               p = strrchr (path, '\\');
 645               /* Trailing slash is acceptable, so always leave it.  */
 646               *(++p) = '\0';
 647             }
 648           else
 649             path[0] = '\0';
 650
 651           cmdline = p = alloca (strlen (progname) + extra_arg_space +
 652                                 strlen (path) + 13);
 653
 654           /* Quote progname in case it contains spaces.  */
 655           p += wsprintf (p, "\"%s\" %s", progname, path);
 656
 657           /* Include pass_through_args verbatim; these are just switches
 658              so should not need quoting.  */
 659           for (argv = pass_through_args; *argv != NULL; ++argv)
 660             p += wsprintf (p, " %s", *argv);
 661
 662           if (run_command_dot_com)
 663             wsprintf (p, " /e:%d", envsize);
 664         }
 665     }
 666
 667   if (!progname)
 668     fail ("Internal error: program name not defined\n");
 669
 670   if (!cmdline)
 671     cmdline = progname;
 672
 673   if (spawn (progname, cmdline, &rc))
 674     return rc;
 675
 676   if (!need_shell)
 677     {
 678       need_shell = TRUE;
 679       goto pass_to_shell;
 680     }
 681
 682   fail ("Could not run %s\n", progname);
 683
 684   return 0;
 685 }