aboutsummaryrefslogtreecommitdiff
path: root/msvc-common/msvc-filter.cxx
blob: ae1a3ff43eedecefd488794efc0acadaffa70c70 (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
// file      : msvc-common/msvc-filter.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2018 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#include <sys/time.h>   // timeval
#include <sys/select.h>

#include <ios>           // ios_base::failure
#include <string>
#include <cstring>       // strchr()
#include <ostream>
#include <utility>       // move()
#include <iostream>
#include <algorithm>     // max()
#include <system_error>
#include <unordered_map>

#include <libbutl/path.mxx>     // path::traits::realize()
#include <libbutl/utility.mxx>  // alpha(), throw_generic_error()
#include <libbutl/process.mxx>
#include <libbutl/fdstream.mxx>

#include <msvc-common/version.hxx>

using namespace std;
using namespace butl;

// Cached mapping of Windows paths to the corresponding POSIX paths.
//
static unordered_map<string, string> path_cache;

inline static bool
path_separator (char c)
{
  return c == '\\' || c == '/';
}

// Replace absolute Windows paths encountered in the line with their POSIX
// representation. Write the result followed by a newline to the stream. Throw
// ostream::failure on IO failures, system_error on others.
//
static void
filter (const char* s, size_t n, ostream& os)
{
  // Strip the terminating 0xOD character if present.
  //
  if (n > 0 && s[n - 1] == '\r')
    --n;

  // Translate absolute Windows paths back to POSIX. The hard part here is to
  // determing the end of the path. For example, the error location has the
  // 'X:\...\foo(10):' form. However, we cannot assume that '(' ends the path;
  // remember 'Program Files (x86)'.
  //
  // To sidestep this whole mess we are going to use this trick: instead of
  // translating the whole path we will only translate its directory part,
  // that is, the longest part that still ends with the directory
  // separator. We will also still recognize ':' and '\'' as path terminators
  // as well as space if it is the first character in the component.
  //
  // We also pass the path through realpath in order to get the actual path
  // rather than Wine's dosdevices links.
  //
  const char* b (s);
  const char* e (s + n);

  for (;;)
  {
    const char* p (b);

    // Line tail should be at least 3 characters long to contain an absolute
    // Windows path.
    //
    bool no_path (e - b < 3);

    if (!no_path)
    {
      // An absolute path must begin with [A-Za-z]:[\/] (like C:\).
      //
      const char* pe (e - 3);

      for (; p != pe; ++p)
      {
        if (alpha (p[0]) && p[1] == ':' && path_separator (p[2]))
          break;
      }

      no_path = p == pe;
    }

    // Bail out if we reached the end of the line with no path found.
    //
    if (no_path)
    {
      os.write (b, e - b);
      os.put ('\n');
      break;
    }

    os.write (b, p - b); // Print characters that preceed the path.

    b = p;                  // Beginnig of the path.
    const char* pe (p + 3); // End of the last path component.

    for (p = pe; p != e; ++p)
    {
      char c (*p);
      if (c == ':' || c == '\'' || (p == pe && c == ' '))
        break;

      if (path_separator (c))
        pe = p + 1;
    }

    // Convert the Windows directory path to POSIX. First check if the mapping
    // is already cached.
    //
    string d (b, pe - b);
    auto i (path_cache.find (d));

    b = pe;

    if (i == path_cache.end ())
    {
      const char* args[] = {"winepath", "-u", d.c_str (), nullptr};

      // Redirect stderr to /dev/null not to mess the output (read more in
      // main()).
      //
      process pr (args, 0, -1, -2);
      ifdstream is (move (pr.in_ofd));

      string pd;
      getline (is, pd);
      is.close ();

      // It's unknown what can cause winepath to fail. At least not a
      // non-existent path. Anyway will consider it fatal.
      //
      if (!pr.wait ())
        throw_generic_error (ECHILD);

      try
      {
        path::traits::realize (pd);

        assert (!pd.empty ());

        // Restore the trailing slash.
        //
        if (pd.back () != '/')
          pd += '/';

      }
      catch (const invalid_path&)
      {
        // The path doesn't exist. Let's keep it as provided by winepath.
      }

      i = path_cache.emplace (move (d), move (pd)).first;
    }

    os.write (i->second.c_str (), i->second.size ());
  }
}

int
main (int argc, char* argv[])
try
{
  auto print_usage = [argv]()
  {
    cerr << "usage: " << argv[0]
         << " <diag> <wine-path> <program-path> [arguments]" << endl;
  };

  if (argc < 2)
  {
    cerr << "error: diag stream file descriptor expected" << endl;
    print_usage ();
    return 1;
  }

  string d (argv[1]);
  if (d != "1" && d != "2")
  {
    cerr << "error: invalid diag stream file descriptor" << endl;
    print_usage ();
    return 1;
  }

  size_t diag (stoi (d));

  if (argc < 3)
  {
    cerr << "error: wine path expected" << endl;
    print_usage ();
    return 1;
  }

  if (argc < 4)
  {
    cerr << "error: program path expected" << endl;
    print_usage ();
    return 1;
  }

  // After arguments are validated we will not be printing error messages on
  // failures not to mess the filtered output of the child Windows process.
  // Note that in the case of a failure the text from STDERR can be treated by
  // the calling process as a build tool diagnostics so our message most
  // likelly would be misinterpreted.
  //
  // The reason we still print error message on the arguments parsing failure
  // is that it is likely to be a program misuse rather than runtime error.
  //

  // If diag is 1 then both stdout and stderr of the child process are read and
  // filtered (achieved by redirecting stdout to stderr). Otherwise the data
  // read from child stdout is proxied to own stdout (sounds redundant but
  // prevents Windows process from writing to /dev/null directly which is known
  // to be super slow). The filtered data is written to the diag file
  // descriptor.
  //
  process pr (const_cast <const char**> (&argv[2]), 0, diag == 1 ? 2 : -1, -1);

  // Stream to filter from.
  //
  ifdstream isf (move (pr.in_efd), fdstream_mode::non_blocking);

  // Stream to proxy from.
  //
  ifdstream isp (
    diag == 1 ? nullfd : move (pr.in_ofd), fdstream_mode::non_blocking);

  ostream& osf (diag == 1 ? cout : cerr);     // Stream to filter to.
  ostream* osp (diag == 1 ? nullptr : &cout); // Stream to proxy to.

  // The presense of proxy input and output streams must be correlated.
  //
  assert (isp.is_open () == (osp != nullptr));

  // Will be using ostream::write() solely, so badbit is the only one which
  // needs to be set.
  //
  osf.exceptions (ostream::badbit);

  if (osp != nullptr)
    osp->exceptions (ostream::badbit);

  const size_t nbuf (8192);
  char buf[nbuf + 1]; // Reserve one extra for terminating '\0'.

  bool terminated (false); // Required for Wine bug workaround (see below).
  string line; // Incomplete line.

  while (isf.is_open () || isp.is_open ())
  {
    // Use timeout to workaround the wineserver bug: sometimes the file
    // descriptor that corresponds to the redirected STDERR of a Windows
    // process is not closed when that process is terminated. So if STDERR is
    // redirected to a pipe (as in our case) the reading peer does not receive
    // EOF and hangs forever. We will consider the no-data 100 ms period for an
    // exited process to represent such a situation.
    //
    // Note that it is wineserver who owns the corresponding file descriptor
    // not a wine process which runs the Windows program.
    //
    // Note also that some implementations of select() can modify the timeout
    // value so it is essential to reinitialize it prior to every select()
    // call.
    //
    timeval timeout {0, 100000};

    fd_set rd;
    FD_ZERO (&rd);

    if (isf.is_open ())
      FD_SET (isf.fd (), &rd);

    if (isp.is_open ())
      FD_SET (isp.fd (), &rd);

    int r (select (max (isf.fd (), isp.fd ()) + 1,
                   &rd,
                   nullptr,
                   nullptr,
                   &timeout));

    if (r == -1)
    {
      if (errno == EINTR)
        continue;

      throw_generic_error (errno);
    }

    // Timeout occured. Apply wineserver bug workaround if required.
    //
    bool status;
    if (r == 0 && pr.try_wait (status))
    {
      if (!status)
        // Handle the child failure outside the loop.
        //
        break;

      // Presumably end of the data reached.
      //
      if (!terminated)
      {
        // We don't know when the process exited. It possibly wasn't writing
        // to the output for quite a long time before terminating a nanosecond
        // ago. But let's wait for another timeout to be sure that the process
        // has terminated a long (enough) time ago.
        //
        terminated = true;
        continue;
      }

      break;
    }

    // Proxy the data if requested.
    //
    if (isp.is_open () && FD_ISSET (isp.fd (), &rd))
    {
      for (;;)
      {
        // The only leagal way to read from non-blocking ifdstream.
        //
        streamsize n (isp.readsome (buf, nbuf));

        if (isp.eof ())
        {
          // End of the data to be proxied reached.
          //
          isp.close ();
          break;
        }

        if (n == 0)
          break; // No data available, try later.

        assert (osp != nullptr);
        osp->write (buf, n);
      }
    }

    // Read & filter.
    //
    if (isf.is_open () && FD_ISSET (isf.fd (), &rd))
    {
      for (;;)
      {
        // The only leagal way to read from non-blocking ifdstream.
        //
        streamsize n (isf.readsome (buf, nbuf));

        if (isf.eof ())
        {
          // End of the data to be filtered reached.
          //
          isf.close ();
          break;
        }

        if (n == 0)
          break; // No data available, try later.

        // Filter buffer content line by line. Concatenate the line with an
        // incomplete one if produced on the previous iteration. Save the last
        // line if incomplete (not terminated with '\n').
        //
        buf[n] = '\0';
        const char* b (buf);

        for (;;)
        {
          const char* le (strchr (b, '\n'));

          if (le == nullptr)
          {
            line += b;
            break;
          }

          if (!line.empty ())
          {
            line.append (b, le - b);
            filter (line.c_str (), line.size (), osf);
            line.clear ();
          }
          else
            filter (b, le - b, osf);

          b = le + 1; // Skip the newline character.
        }
      }
    }
  }

  if (!line.empty ())
    filter (line.c_str (), line.size (), osf);

  isf.close ();
  isp.close ();

  // Passing through the exact child process exit status on failure tends to be
  // a bit hairy as involves handling the situation when the process is
  // terminated with a signal and so exit code is unavailable. Lets implement
  // when really required.
  //
  return pr.wait () ? 0 : 1;
}
catch (const ios_base::failure&)
{
  return 1;
}
// Also handles process_error exception (derived from system_error).
//
catch (const system_error&)
{
  return 1;
}