aboutsummaryrefslogtreecommitdiff
path: root/nxcomp/src/Pipe.cpp
blob: 4fa149412afe89aaa2a077c02e134a3aeec5b4d5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
/**************************************************************************/
/*                                                                        */
/* Copyright (c) 2001, 2011 NoMachine (http://www.nomachine.com)          */
/* Copyright (c) 2008-2014 Oleksandr Shneyder <o.shneyder@phoca-gmbh.de>  */
/* Copyright (c) 2014-2016 Ulrich Sibiller <uli42@gmx.de>                 */
/* Copyright (c) 2014-2016 Mihai Moldovan <ionic@ionic.de>                */
/* Copyright (c) 2011-2016 Mike Gabriel <mike.gabriel@das-netzwerkteam.de>*/
/* Copyright (c) 2015-2016 Qindel Group (http://www.qindel.com)           */
/*                                                                        */
/* NXCOMP, NX protocol compression and NX extensions to this software     */
/* are copyright of the aforementioned persons and companies.             */
/*                                                                        */
/* Redistribution and use of the present software is allowed according    */
/* to terms specified in the file LICENSE.nxcomp which comes in the       */
/* source distribution.                                                   */
/*                                                                        */
/* All rights reserved.                                                   */
/*                                                                        */
/* NOTE: This software has received contributions from various other      */
/* contributors, only the core maintainers and supporters are listed as   */
/* copyright holders. Please contact us, if you feel you should be listed */
/* as copyright holder, as well.                                          */
/*                                                                        */
/**************************************************************************/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <pwd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <grp.h>

#include "Pipe.h"
#include "Misc.h"
#include "Fork.h"

//
// Set the verbosity level.
//

#define PANIC
#define WARNING
#undef  TEST
#undef  DEBUG

extern void RegisterChild(int child);

static int Psplit(const char *command, char *parameters[], int limit);

//
// These are slightly modified versions of popen(3) and pclose(3)
// that don't rely on a shell to be available on the system, so
// that they can also work on Windows. As an additional benefit,
// these functions give up all privileges before running the com-
// mand. Code is taken from the X distribution and, in turn, is
// based on libc from FreeBSD 2.2.
//

static struct pid
{
  struct pid *next;
  FILE *fp;
  int self;

} *pidlist;

//
// A very unsofisticated attempt to parse the command line and
// split each parameter in distinct strings. This is not going
// to work when dealing with parameters containing spaces, even
// if they are enclosed in quotes.
// 

int Psplit(const char *command, char *parameters[], int limit)
{
  char *line;
  char *value;

  int number;

  //
  // Preapare the list of parameters.
  //

  for (number = 0; number < limit; number++)
  {
    parameters[number] = NULL;
  }

  //
  // Copy the command to get rid of the
  // const qualifier.
  //

  line = new char[strlen(command) + 1];

  if (line == NULL)
  {
    goto PsplitError;
  }

  strcpy(line, command);

  number = 0;

  value = strtok(line, " ");

  while (value != NULL && number < limit)
  {
    #ifdef DEBUG
    *logofs << "Psplit: Got parameter '" << value
            << "'.\n" << logofs_flush;
    #endif

    parameters[number] = new char[strlen(value) + 1];

    if (parameters[number] == NULL)
    {
      goto PsplitError;
    }

    strcpy(parameters[number], value);

    number++;

    //
    // If this is the first parameter, then
    // copy it in the second position and
    // use it as the name of the command.
    //

    if (number == 1)
    {
      parameters[number] = new char[strlen(value) + 1];

      if (parameters[number] == NULL)
      {
        goto PsplitError;
      }

      strcpy(parameters[number], value);

      number++;
    }

    value = strtok(NULL, " ");
  }

  //
  // Needs at least to have the command itself and
  // the first argument, being again the name of
  // the command.
  //

  if (number < 2)
  {
    goto PsplitError;
  }

  return number;

PsplitError:

  #ifdef PANIC
  *logofs << "Psplit: PANIC! Can't split command line '"
          << command << "'.\n" << logofs_flush;
  #endif

  cerr << "Error" << ": Can't split command line '"
       << command << "'.\n";

  delete [] line;

  return -1;
}

FILE *Popen(char * const parameters[], const char *type)
{
  FILE *iop;

  struct pid *cur;
  int pdes[2], pid;

  if (parameters == NULL || type == NULL)
  {
    return NULL;
  }

  if ((*type != 'r' && *type != 'w') || type[1])
  {
    return NULL;
  }

  if ((cur = (struct pid *) malloc(sizeof(struct pid))) == NULL)
  {
    return NULL;
  }

  if (pipe(pdes) < 0)
  {
    free(cur);

    return NULL;
  }

  //
  // Block all signals until command is exited.
  // We need to gather information about the
  // child in Pclose().
  //

  DisableSignals();

  switch (pid = Fork())
  {
    case -1:
    {
      //
      // Error.
      //

      #ifdef PANIC
      *logofs << "Popen: PANIC! Function fork failed. "
              << "Error is " << EGET() << " '" << ESTR()
              << "'.\n" << logofs_flush;
      #endif

      cerr << "Error" << ": Function fork failed. "
           << "Error is " << EGET() << " '" << ESTR()
           << "'.\n";

      close(pdes[0]);
      close(pdes[1]);

      free(cur);

      return NULL;
    }
    case 0:
    {
      //
      // Child.
      //

      struct passwd *pwent = getpwuid(getuid());
      if (pwent) initgroups(pwent->pw_name,getgid());
      if (setgid(getgid()) == -1)
      {
        _exit(127);
      }
      if (setuid(getuid()) == -1)
      {
        _exit(127);
      }

      if (*type == 'r')
      {
        if (pdes[1] != 1)
        {
          //
          // Set up stdout.
          //

          dup2(pdes[1], 1);
          close(pdes[1]);
        }

        close(pdes[0]);
      }
      else
      {
        if (pdes[0] != 0)
        {
          //
          // Set up stdin.
          //

          dup2(pdes[0], 0);
          close(pdes[0]);
        }

        close(pdes[1]);
      }

      execvp(parameters[0], parameters + 1);

      exit(127);
    }
  }

  //
  // Parent. Save data about the child.
  //

  RegisterChild(pid);

  if (*type == 'r')
  {
    iop = fdopen(pdes[0], type);

    close(pdes[1]);
  }
  else
  {
    iop = fdopen(pdes[1], type);

    close(pdes[0]);
  }

  cur -> fp = iop;
  cur -> self = pid;
  cur -> next = pidlist;

  pidlist = cur;

  #ifdef TEST
  *logofs << "Popen: Executing ";

  for (int i = 0; i < 256 && parameters[i] != NULL; i++)
  {
    *logofs << "[" << parameters[i] << "]";
  }

  *logofs << " with descriptor " << fileno(iop)
          << ".\n" << logofs_flush;
  #endif

  return iop;
}

FILE *Popen(const char *command, const char *type)
{
  char *parameters[256];

  if (Psplit(command, parameters, 256) > 0)
  {
    FILE *file = Popen(parameters, type);

    for (int i = 0; i < 256; i++)
    {
      delete [] parameters[i];
    }

    return file;
  }
  else
  {
    #ifdef PANIC
    *logofs << "Popen: PANIC! Failed to parse command '"
            << command << "'.\n" << logofs_flush;
    #endif

    cerr << "Error" << ": Failed to parse command '"
         << command << "'.\n";

    return NULL;
  }
}

int Pclose(FILE *iop)
{
  struct pid *cur, *last;

  int pstat;
  int pid;

  #ifdef TEST
  *logofs << "Pclose: Closing command with output "
          << "on descriptor " << fileno(iop) << ".\n"
          << logofs_flush;
  #endif

  fclose((FILE *) iop);

  for (last = NULL, cur = pidlist; cur; last = cur, cur = cur -> next)
  {
    if (cur -> fp == iop)
    {
      break;
    }
  }

  if (cur == NULL)
  {
    #ifdef PANIC
    *logofs << "Pclose: PANIC! Failed to find the process "
            << "for descriptor " << fileno(iop) << ".\n"
            << logofs_flush;
    #endif

    cerr << "Error" << ": Failed to find the process "
         << "for descriptor " << fileno(iop) << ".\n";

    return -1;
  }

  do
  {
    #ifdef TEST
    *logofs << "Pclose: Going to wait for process "
            << "with pid '" << cur -> self << "'.\n"
            << logofs_flush;
    #endif

    pid = waitpid(cur -> self, &pstat, 0);
  }
  while (pid == -1 && errno == EINTR);

  if (last == NULL)
  {
    pidlist = cur -> next;
  }
  else
  {
    last -> next = cur -> next;
  }

  free(cur);

  //
  // Child has finished and we called the
  // waitpid(). We can enable signals again.
  //

  EnableSignals();

  return (pid == -1 ? -1 : pstat);
}