nt/cmdproxy.c

   1 /* Proxy shell designed for use with Emacs on Windows 95 and NT.
   2    Copyright (C) 1997, 2001, 2002, 2003, 2004, 2005,
   3       2006, 2007  Free Software Foundation, Inc.
   4
   5    Accepts subset of Unix sh(1) command-line options, for compatability
   6    with elisp code written for Unix.  When possible, executes external
   7    programs directly (a common use of /bin/sh by Emacs), otherwise
   8    invokes the user-specified command processor to handle built-in shell
   9    commands, batch files and interactive mode.
  10
  11    The main function is simply to process the "-c string" option in the
  12    way /bin/sh does, since the standard Windows command shells use the
  13    convention that everything after "/c" (the Windows equivalent of
  14    "-c") is the input string.
  15
  16 This file is part of GNU Emacs.
  17
  18 GNU Emacs is free software; you can redistribute it and/or modify
  19 it under the terms of the GNU General Public License as published by
  20 the Free Software Foundation; either version 2, or (at your option)
  21 any later version.
  22
  23 GNU Emacs is distributed in the hope that it will be useful,
  24 but WITHOUT ANY WARRANTY; without even the implied warranty of
  25 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26 GNU General Public License for more details.
  27
  28 You should have received a copy of the GNU General Public License
  29 along with GNU Emacs; see the file COPYING.  If not, write to
  30 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  31 Boston, MA 02110-1301, USA.  */
  32
  33 #include <windows.h>
  34
  35 #include <stdarg.h>  /* va_args */
  36 #include <malloc.h>  /* alloca */
  37 #include <stdlib.h>  /* getenv */
  38 #include <string.h>  /* strlen */
  39
  40
  41 /*******  Mock C library routines  *********************************/
  42
  43 /* These routines are used primarily to minimize the executable size.  */
  44
  45 #define stdin  GetStdHandle (STD_INPUT_HANDLE)
  46 #define stdout GetStdHandle (STD_OUTPUT_HANDLE)
  47 #define stderr GetStdHandle (STD_ERROR_HANDLE)
  48
  49 int
  50 vfprintf(HANDLE hnd, char * msg, va_list args)
  51 {
  52   DWORD bytes_written;
  53   char buf[1024];
  54
  55   wvsprintf (buf, msg, args);
  56   return WriteFile (hnd, buf, strlen (buf), &bytes_written, NULL);
  57 }
  58
  59 int
  60 fprintf(HANDLE hnd, char * msg, ...)
  61 {
  62   va_list args;
  63   int rc;
  64
  65   va_start (args, msg);
  66   rc = vfprintf (hnd, msg, args);
  67   va_end (args);
  68
  69   return rc;
  70 }
  71
  72 int
  73 printf(char * msg, ...)
  74 {
  75   va_list args;
  76   int rc;
  77
  78   va_start (args, msg);
  79   rc = vfprintf (stdout, msg, args);
  80   va_end (args);
  81
  82   return rc;
  83 }
  84
  85 void
  86 fail (char * msg, ...)
  87 {
  88   va_list args;
  89
  90   va_start (args, msg);
  91   vfprintf (stderr, msg, args);
  92   va_end (args);
  93
  94   exit (-1);
  95 }
  96
  97 void
  98 warn (char * msg, ...)
  99 {
 100   va_list args;
 101
 102   va_start (args, msg);
 103   vfprintf (stderr, msg, args);
 104   va_end (args);
 105 }
 106
 107 /******************************************************************/
 108
 109 char *
 110 canon_filename (char *fname)
 111 {
 112   char *p = fname;
 113
 114   while (*p)
 115     {
 116       if (*p == '/')
 117         *p = '\\';
 118       p++;
 119     }
 120
 121   return fname;
 122 }
 123
 124 char *
 125 skip_space (char *str)
 126 {
 127   while (isspace (*str)) str++;
 128   return str;
 129 }
 130
 131 char *
 132 skip_nonspace (char *str)
 133 {
 134   while (*str && !isspace (*str)) str++;
 135   return str;
 136 }
 137
 138 int escape_char = '\\';
 139
 140 /* Get next token from input, advancing pointer.  */
 141 int
 142 get_next_token (char * buf, char ** pSrc)
 143 {
 144   char * p = *pSrc;
 145   char * o = buf;
 146
 147   p = skip_space (p);
 148   if (*p == '"')
 149     {
 150       int escape_char_run = 0;
 151
 152       /* Go through src until an ending quote is found, unescaping
 153          quotes along the way.  If the escape char is not quote, then do
 154          special handling of multiple escape chars preceding a quote
 155          char (ie. the reverse of what Emacs does to escape quotes).  */
 156       p++;
 157       while (1)
 158         {
 159           if (p[0] == escape_char && escape_char != '"')
 160             {
 161               escape_char_run++;
 162               p++;
 163               continue;
 164             }
 165           else if (p[0] == '"')
 166             {
 167               while (escape_char_run > 1)
 168                 {
 169                   *o++ = escape_char;
 170                   escape_char_run -= 2;
 171                 }
 172
 173               if (escape_char_run > 0)
 174                 {
 175                   /* escaped quote */
 176                   *o++ = *p++;
 177                   escape_char_run = 0;
 178                 }
 179               else if (p[1] == escape_char && escape_char == '"')
 180                 {
 181                   /* quote escaped by doubling */
 182                   *o++ = *p;
 183                   p += 2;
 184                 }
 185               else
 186                 {
 187                   /* The ending quote.  */
 188                   *o = '\0';
 189                   /* Leave input pointer after token.  */
 190                   p++;
 191                   break;
 192                 }
 193             }
 194           else if (p[0] == '\0')
 195             {
 196               /* End of string, but no ending quote found.  We might want to
 197                  flag this as an error, but for now will consider the end as
 198                  the end of the token.  */
 199               *o = '\0';
 200               break;
 201             }
 202           else
 203             {
 204               *o++ = *p++;
 205             }
 206         }
 207     }
 208   else
 209     {
 210       /* Next token is delimited by whitespace.  */
 211       char * p1 = skip_nonspace (p);
 212       memcpy (o, p, p1 - p);
 213       o += (p1 - p);
 214       *o = '\0';
 215       p = p1;
 216     }
 217
 218   *pSrc = p;
 219
 220   return o - buf;
 221 }
 222
 223 /* Search for EXEC file in DIR.  If EXEC does not have an extension,
 224    DIR is searched for EXEC with the standard extensions appended.  */
 225 int
 226 search_dir (char *dir, char *exec, int bufsize, char *buffer)
 227 {
 228   char *exts[] = {".bat", ".cmd", ".exe", ".com"};
 229   int n_exts = sizeof (exts) / sizeof (char *);
 230   char *dummy;
 231   int i, rc;
 232
 233   /* Search the directory for the program.  */
 234   for (i = 0; i < n_exts; i++)
 235     {
 236       rc = SearchPath (dir, exec, exts[i], bufsize, buffer, &dummy);
 237       if (rc > 0)
 238         return rc;
 239     }
 240
 241   return 0;
 242 }
 243
 244 /* Return the absolute name of executable file PROG, including
 245    any file extensions.  If an absolute name for PROG cannot be found,
 246    return NULL.  */
 247 char *
 248 make_absolute (char *prog)
 249 {
 250   char absname[MAX_PATH];
 251   char dir[MAX_PATH];
 252   char curdir[MAX_PATH];
 253   char *p, *fname;
 254   char *path;
 255   int i;
 256
 257   /* At least partial absolute path specified; search there.  */
 258   if ((isalpha (prog[0]) && prog[1] == ':') ||
 259       (prog[0] == '\\'))
 260     {
 261       /* Split the directory from the filename.  */
 262       fname = strrchr (prog, '\\');
 263       if (!fname)
 264         /* Only a drive specifier is given.  */
 265         fname = prog + 2;
 266       strncpy (dir, prog, fname - prog);
 267       dir[fname - prog] = '\0';
 268
 269       /* Search the directory for the program.  */
 270       if (search_dir (dir, prog, MAX_PATH, absname) > 0)
 271         return strdup (absname);
 272       else
 273         return NULL;
 274     }
 275
 276   if (GetCurrentDirectory (MAX_PATH, curdir) <= 0)
 277     return NULL;
 278
 279   /* Relative path; search in current dir. */
 280   if (strpbrk (prog, "\\"))
 281     {
 282       if (search_dir (curdir, prog, MAX_PATH, absname) > 0)
 283         return strdup (absname);
 284       else
 285         return NULL;
 286     }
 287
 288   /* Just filename; search current directory then PATH.  */
 289   path = alloca (strlen (getenv ("PATH")) + strlen (curdir) + 2);
 290   strcpy (path, curdir);
 291   strcat (path, ";");
 292   strcat (path, getenv ("PATH"));
 293
 294   while (*path)
 295     {
 296       /* Get next directory from path.  */
 297       p = path;
 298       while (*p && *p != ';') p++;
 299       strncpy (dir, path, p - path);
 300       dir[p - path] = '\0';
 301
 302       /* Search the directory for the program.  */
 303       if (search_dir (dir, prog, MAX_PATH, absname) > 0)
 304         return strdup (absname);
 305
 306       /* Move to the next directory.  */
 307       path = p + 1;
 308     }
 309
 310   return NULL;
 311 }
 312
 313 /*****************************************************************/
 314
 315 #if 0
 316 char ** _argv;
 317 int     _argc;
 318
 319 /* Parse commandline into argv array, allowing proper quoting of args.  */
 320 void
 321 setup_argv (void)
 322 {
 323   char * cmdline = GetCommandLine ();
 324   int arg_bytes = 0;
 325
 326
 327 }
 328 #endif
 329
 330 /* Information about child proc is global, to allow for automatic
 331    termination when interrupted.  At the moment, only one child process
 332    can be running at any one time.  */
 333
 334 PROCESS_INFORMATION child;
 335 int interactive = TRUE;
 336
 337 BOOL
 338 console_event_handler (DWORD event)
 339 {
 340   switch (event)
 341     {
 342     case CTRL_C_EVENT:
 343     case CTRL_BREAK_EVENT:
 344       if (!interactive)
 345         {
 346           /* Both command.com and cmd.exe have the annoying behaviour of
 347              prompting "Terminate batch job (y/n)?" when interrupted
 348              while running a batch file, even if running in
 349              non-interactive (-c) mode.  Try to make up for this
 350              deficiency by forcibly terminating the subprocess if
 351              running non-interactively.  */
 352           if (child.hProcess &&
 353               WaitForSingleObject (child.hProcess, 500) != WAIT_OBJECT_0)
 354             TerminateProcess (child.hProcess, 0);
 355           exit (STATUS_CONTROL_C_EXIT);
 356         }
 357       break;
 358
 359 #if 0
 360     default:
 361       /* CLOSE, LOGOFF and SHUTDOWN events - actually we don't get these
 362          under Windows 95.  */
 363       fail ("cmdproxy: received %d event\n", event);
 364       if (child.hProcess)
 365         TerminateProcess (child.hProcess, 0);
 366 #endif
 367     }
 368   return TRUE;
 369 }
 370
 371 /* Change from normal usage; return value indicates whether spawn
 372    succeeded or failed - program return code is returned separately.  */
 373 int
 374 spawn (char * progname, char * cmdline, char * dir, int * retcode)
 375 {
 376   BOOL success = FALSE;
 377   SECURITY_ATTRIBUTES sec_attrs;
 378   STARTUPINFO start;
 379   /* In theory, passing NULL for the environment block to CreateProcess
 380      is the same as passing the value of GetEnvironmentStrings, but
 381      doing this explicitly seems to cure problems running DOS programs
 382      in some cases.  */
 383   char * envblock = GetEnvironmentStrings ();
 384
 385   sec_attrs.nLength = sizeof (sec_attrs);
 386   sec_attrs.lpSecurityDescriptor = NULL;
 387   sec_attrs.bInheritHandle = FALSE;
 388
 389   memset (&start, 0, sizeof (start));
 390   start.cb = sizeof (start);
 391
 392   if (CreateProcess (progname, cmdline, &sec_attrs, NULL, TRUE,
 393                      0, envblock, dir, &start, &child))
 394   {
 395     success = TRUE;
 396     /* wait for completion and pass on return code */
 397     WaitForSingleObject (child.hProcess, INFINITE);
 398     if (retcode)
 399       GetExitCodeProcess (child.hProcess, (DWORD *)retcode);
 400     CloseHandle (child.hThread);
 401     CloseHandle (child.hProcess);
 402     child.hProcess = NULL;
 403   }
 404
 405   FreeEnvironmentStrings (envblock);
 406
 407   return success;
 408 }
 409
 410 /* Return size of current environment block.  */
 411 int
 412 get_env_size ()
 413 {
 414   char * start = GetEnvironmentStrings ();
 415   char * tmp = start;
 416
 417   while (tmp[0] || tmp[1])
 418     ++tmp;
 419   FreeEnvironmentStrings (start);
 420   return  tmp + 2 - start;
 421 }
 422
 423 /*******  Main program  ********************************************/
 424
 425 int
 426 main (int argc, char ** argv)
 427 {
 428   int rc;
 429   int need_shell;
 430   char * cmdline;
 431   char * progname;
 432   int envsize;
 433   char **pass_through_args;
 434   int num_pass_through_args;
 435   char modname[MAX_PATH];
 436   char path[MAX_PATH];
 437   char dir[MAX_PATH];
 438
 439
 440   interactive = TRUE;
 441
 442   SetConsoleCtrlHandler ((PHANDLER_ROUTINE) console_event_handler, TRUE);
 443
 444   if (!GetCurrentDirectory (sizeof (dir), dir))
 445     fail ("error: GetCurrentDirectory failed\n");
 446
 447   /* We serve double duty: we can be called either as a proxy for the
 448      real shell (that is, because we are defined to be the user shell),
 449      or in our role as a helper application for running DOS programs.
 450      In the former case, we interpret the command line options as if we
 451      were a Unix shell, but in the latter case we simply pass our
 452      command line to CreateProcess.  We know which case we are dealing
 453      with by whether argv[0] refers to ourself or to some other program.
 454      (This relies on an arcane feature of CreateProcess, where we can
 455      specify cmdproxy as the module to run, but specify a different
 456      program in the command line - the MSVC startup code sets argv[0]
 457      from the command line.)  */
 458
 459   if (!GetModuleFileName (NULL, modname, sizeof (modname)))
 460     fail ("error: GetModuleFileName failed\n");
 461
 462   /* Change directory to location of .exe so startup directory can be
 463      deleted.  */
 464   progname = strrchr (modname, '\\');
 465   *progname = '\0';
 466   SetCurrentDirectory (modname);
 467   *progname = '\\';
 468
 469   /* Although Emacs always sets argv[0] to an absolute pathname, we
 470      might get run in other ways as well, so convert argv[0] to an
 471      absolute name before comparing to the module name.  Don't get
 472      caught out by mixed short and long names.  */
 473   GetShortPathName (modname, modname, sizeof (modname));
 474   path[0] = '\0';
 475   if (!SearchPath (NULL, argv[0], ".exe", sizeof (path), path, &progname)
 476       || !GetShortPathName (path, path, sizeof (path))
 477       || stricmp (modname, path) != 0)
 478     {
 479       /* We are being used as a helper to run a DOS app; just pass
 480          command line to DOS app without change.  */
 481       /* TODO: fill in progname.  */
 482       if (spawn (NULL, GetCommandLine (), dir, &rc))
 483         return rc;
 484       fail ("Could not run %s\n", GetCommandLine ());
 485     }
 486
 487   /* Process command line.  If running interactively (-c or /c not
 488      specified) then spawn a real command shell, passing it the command
 489      line arguments.
 490
 491      If not running interactively, then attempt to execute the specified
 492      command directly.  If necessary, spawn a real shell to execute the
 493      command.
 494
 495   */
 496
 497   progname = NULL;
 498   cmdline = NULL;
 499   /* If no args, spawn real shell for interactive use.  */
 500   need_shell = TRUE;
 501   interactive = TRUE;
 502   /* Ask command.com to create an environment block with a reasonable
 503      amount of free space.  */
 504   envsize = get_env_size () + 300;
 505   pass_through_args = (char **) alloca (argc * sizeof(char *));
 506   num_pass_through_args = 0;
 507
 508   while (--argc > 0)
 509     {
 510       ++argv;
 511       /* Act on switches we recognize (mostly single letter switches,
 512          except for -e); all unrecognised switches and extra args are
 513          passed on to real shell if used (only really of benefit for
 514          interactive use, but allow for batch use as well).  Accept / as
 515          switch char for compatability with cmd.exe.  */
 516       if (((*argv)[0] == '-' || (*argv)[0] == '/') && (*argv)[1] != '\0')
 517         {
 518           if (((*argv)[1] == 'c' || (*argv)[1] == 'C') && ((*argv)[2] == '\0'))
 519             {
 520               if (--argc == 0)
 521                 fail ("error: expecting arg for %s\n", *argv);
 522               cmdline = *(++argv);
 523               interactive = FALSE;
 524             }
 525           else if (((*argv)[1] == 'i' || (*argv)[1] == 'I') && ((*argv)[2] == '\0'))
 526             {
 527               if (cmdline)
 528                 warn ("warning: %s ignored because of -c\n", *argv);
 529             }
 530           else if (((*argv)[1] == 'e' || (*argv)[1] == 'E') && ((*argv)[2] == ':'))
 531             {
 532               int requested_envsize = atoi (*argv + 3);
 533               /* Enforce a reasonable minimum size, as above.  */
 534               if (requested_envsize > envsize)
 535                 envsize = requested_envsize;
 536               /* For sanity, enforce a reasonable maximum.  */
 537               if (envsize > 32768)
 538                 envsize = 32768;
 539             }
 540           else
 541             {
 542               /* warn ("warning: unknown option %s ignored", *argv); */
 543               pass_through_args[num_pass_through_args++] = *argv;
 544             }
 545         }
 546       else
 547         break;
 548     }
 549
 550 #if 0
 551   /* I think this is probably not useful - cmd.exe ignores extra
 552      (non-switch) args in interactive mode, and they cannot be passed on
 553      when -c was given.  */
 554
 555   /* Collect any remaining args after (initial) switches.  */
 556   while (argc-- > 0)
 557     {
 558       pass_through_args[num_pass_through_args++] = *argv++;
 559     }
 560 #else
 561   /* Probably a mistake for there to be extra args; not fatal.  */
 562   if (argc > 0)
 563     warn ("warning: extra args ignored after '%s'\n", argv[-1]);
 564 #endif
 565
 566   pass_through_args[num_pass_through_args] = NULL;
 567
 568   /* If -c option, determine if we must spawn a real shell, or if we can
 569      execute the command directly ourself.  */
 570   if (cmdline)
 571     {
 572       /* If no redirection or piping, and if program can be found, then
 573          run program directly.  Otherwise invoke a real shell. */
 574
 575       static char copout_chars[] = "|<>&";
 576
 577       if (strpbrk (cmdline, copout_chars) == NULL)
 578         {
 579           char *args;
 580
 581           /* The program name is the first token of cmdline.  Since
 582              filenames cannot legally contain embedded quotes, the value
 583              of escape_char doesn't matter.  */
 584           args = cmdline;
 585           if (!get_next_token (path, &args))
 586             fail ("error: no program name specified.\n");
 587
 588           canon_filename (path);
 589           progname = make_absolute (path);
 590
 591           /* If we found the program, run it directly (if not found it
 592              might be an internal shell command, so don't fail).  */
 593           if (progname != NULL)
 594             need_shell = FALSE;
 595         }
 596     }
 597
 598  pass_to_shell:
 599   if (need_shell)
 600     {
 601       char * p;
 602       int    extra_arg_space = 0;
 603       int    run_command_dot_com;
 604
 605       progname = getenv ("COMSPEC");
 606       if (!progname)
 607         fail ("error: COMSPEC is not set\n");
 608
 609       canon_filename (progname);
 610       progname = make_absolute (progname);
 611
 612       if (progname == NULL || strchr (progname, '\\') == NULL)
 613         fail ("error: the program %s could not be found.\n", getenv ("COMSPEC"));
 614
 615       /* Need to set environment size when running command.com.  */
 616       run_command_dot_com =
 617         (stricmp (strrchr (progname, '\\'), "command.com") == 0);
 618
 619       /* Work out how much extra space is required for
 620          pass_through_args.  */
 621       for (argv = pass_through_args; *argv != NULL; ++argv)
 622         /* We don't expect to have to quote switches.  */
 623         extra_arg_space += strlen (*argv) + 2;
 624
 625       if (cmdline)
 626         {
 627           char * buf;
 628
 629           /* Convert to syntax expected by cmd.exe/command.com for
 630              running non-interactively.  Always quote program name in
 631              case path contains spaces (fortunately it can't contain
 632              quotes, since they are illegal in path names).  */
 633
 634           buf = p = alloca (strlen (progname) + extra_arg_space +
 635                             strlen (cmdline) + 16);
 636
 637           /* Quote progname in case it contains spaces.  */
 638           p += wsprintf (p, "\"%s\"", progname);
 639
 640           /* Include pass_through_args verbatim; these are just switches
 641              so should not need quoting.  */
 642           for (argv = pass_through_args; *argv != NULL; ++argv)
 643             p += wsprintf (p, " %s", *argv);
 644
 645           if (run_command_dot_com)
 646             wsprintf(p, " /e:%d /c %s", envsize, cmdline);
 647           else
 648             wsprintf(p, " /c %s", cmdline);
 649           cmdline = buf;
 650         }
 651       else
 652         {
 653           if (run_command_dot_com)
 654             {
 655               /* Provide dir arg expected by command.com when first
 656                  started interactively (the "command search path").  To
 657                  avoid potential problems with spaces in command dir
 658                  (which cannot be quoted - command.com doesn't like it),
 659                  we always use the 8.3 form.  */
 660               GetShortPathName (progname, path, sizeof (path));
 661               p = strrchr (path, '\\');
 662               /* Trailing slash is acceptable, so always leave it.  */
 663               *(++p) = '\0';
 664             }
 665           else
 666             path[0] = '\0';
 667
 668           cmdline = p = alloca (strlen (progname) + extra_arg_space +
 669                                 strlen (path) + 13);
 670
 671           /* Quote progname in case it contains spaces.  */
 672           p += wsprintf (p, "\"%s\" %s", progname, path);
 673
 674           /* Include pass_through_args verbatim; these are just switches
 675              so should not need quoting.  */
 676           for (argv = pass_through_args; *argv != NULL; ++argv)
 677             p += wsprintf (p, " %s", *argv);
 678
 679           if (run_command_dot_com)
 680             wsprintf (p, " /e:%d", envsize);
 681         }
 682     }
 683
 684   if (!progname)
 685     fail ("Internal error: program name not defined\n");
 686
 687   if (!cmdline)
 688     cmdline = progname;
 689
 690   if (spawn (progname, cmdline, dir, &rc))
 691     return rc;
 692
 693   if (!need_shell)
 694     {
 695       need_shell = TRUE;
 696       goto pass_to_shell;
 697     }
 698
 699   fail ("Could not run %s\n", progname);
 700
 701   return 0;
 702 }
 703
 704 /* arch-tag: 88678d93-07ac-4e2f-ad63-d4a740ca69ac
 705    (do not change this comment) */