Coverage Report

Created: 2025-08-28 06:26

/proc/self/cwd/pw_protobuf/stream_decoder.cc
Line
Count
Source (jump to first uncovered line)
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// Copyright 2021 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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//     https://www.apache.org/licenses/LICENSE-2.0
8
//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
13
// the License.
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15
#include "pw_protobuf/stream_decoder.h"
16
17
#include <algorithm>
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#include <cstdint>
19
#include <cstring>
20
#include <limits>
21
#include <optional>
22
23
#include "pw_assert/assert.h"
24
#include "pw_assert/check.h"
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#include "pw_bytes/bit.h"
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#include "pw_containers/vector.h"
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#include "pw_function/function.h"
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#include "pw_protobuf/encoder.h"
29
#include "pw_protobuf/internal/codegen.h"
30
#include "pw_protobuf/wire_format.h"
31
#include "pw_span/span.h"
32
#include "pw_status/status.h"
33
#include "pw_status/status_with_size.h"
34
#include "pw_status/try.h"
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#include "pw_string/string.h"
36
#include "pw_varint/stream.h"
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#include "pw_varint/varint.h"
38
39
namespace pw::protobuf {
40
41
using internal::VarintType;
42
43
0
Status StreamDecoder::BytesReader::DoSeek(ptrdiff_t offset, Whence origin) {
44
0
  PW_TRY(status_);
45
0
  if (!decoder_.reader_.seekable()) {
46
0
    return Status::Unimplemented();
47
0
  }
48
49
0
  ptrdiff_t absolute_position = std::numeric_limits<ptrdiff_t>::min();
50
51
  // Convert from the position within the bytes field to the position within the
52
  // proto stream.
53
0
  switch (origin) {
54
0
    case Whence::kBeginning:
55
0
      absolute_position = start_offset_ + offset;
56
0
      break;
57
58
0
    case Whence::kCurrent:
59
0
      absolute_position = decoder_.position_ + offset;
60
0
      break;
61
62
0
    case Whence::kEnd:
63
0
      absolute_position = end_offset_ + offset;
64
0
      break;
65
0
  }
66
67
0
  if (absolute_position < 0) {
68
0
    return Status::InvalidArgument();
69
0
  }
70
71
0
  if (static_cast<size_t>(absolute_position) < start_offset_ ||
72
0
      static_cast<size_t>(absolute_position) > end_offset_) {
73
0
    return Status::OutOfRange();
74
0
  }
75
76
0
  PW_TRY(decoder_.reader_.Seek(absolute_position, Whence::kBeginning));
77
0
  decoder_.position_ = absolute_position;
78
0
  return OkStatus();
79
0
}
80
81
0
StatusWithSize StreamDecoder::BytesReader::DoRead(ByteSpan destination) {
82
0
  if (!status_.ok()) {
83
0
    return StatusWithSize(status_, 0);
84
0
  }
85
86
0
  if (decoder_.position_ >= end_offset_ || decoder_.position_ < start_offset_) {
87
0
    return StatusWithSize::OutOfRange();
88
0
  }
89
90
  // Bound the read buffer to the size of the bytes field.
91
0
  size_t max_length = end_offset_ - decoder_.position_;
92
0
  if (destination.size() > max_length) {
93
0
    destination = destination.first(max_length);
94
0
  }
95
96
0
  Result<ByteSpan> result = decoder_.reader_.Read(destination);
97
0
  if (!result.ok()) {
98
0
    return StatusWithSize(result.status(), 0);
99
0
  }
100
101
0
  decoder_.position_ += result.value().size();
102
0
  return StatusWithSize(result.value().size());
103
0
}
104
105
5.56k
StreamDecoder::~StreamDecoder() {
106
5.56k
  if (parent_ != nullptr) {
107
3.23k
    parent_->CloseNestedDecoder(*this);
108
3.23k
  } else if (stream_bounds_.high < std::numeric_limits<size_t>::max()) {
109
0
    if (status_.ok()) {
110
      // Advance the stream to the end of the bounds.
111
0
      PW_CHECK(Advance(stream_bounds_.high).ok());
112
0
    }
113
0
  }
114
5.56k
}
115
116
14.7k
Status StreamDecoder::Next() {
117
14.7k
  PW_CHECK(!nested_reader_open_,
118
14.7k
           "Cannot use parent decoder while a nested one is open");
119
120
14.7k
  PW_TRY(status_);
121
122
14.7k
  if (!field_consumed_) {
123
0
    PW_TRY(SkipField());
124
0
  }
125
126
14.7k
  if (position_ >= stream_bounds_.high ||
127
14.7k
      reader_.ConservativeReadLimit() == 0) {
128
1.68k
    return Status::OutOfRange();
129
1.68k
  }
130
131
13.0k
  status_ = ReadFieldKey();
132
13.0k
  return status_;
133
14.7k
}
134
135
0
StreamDecoder::BytesReader StreamDecoder::GetBytesReader() {
136
0
  Status status = CheckOkToRead(WireType::kDelimited);
137
138
0
  if (reader_.ConservativeReadLimit() < delimited_field_size_) {
139
0
    status.Update(Status::DataLoss());
140
0
  }
141
142
0
  nested_reader_open_ = true;
143
144
0
  if (!status.ok()) {
145
0
    return BytesReader(*this, status);
146
0
  }
147
148
0
  size_t low = position_;
149
0
  size_t high = low + delimited_field_size_;
150
151
0
  return BytesReader(*this, low, high);
152
0
}
153
154
3.23k
StreamDecoder StreamDecoder::GetNestedDecoder() {
155
3.23k
  Status status = CheckOkToRead(WireType::kDelimited);
156
157
3.23k
  if (reader_.ConservativeReadLimit() < delimited_field_size_) {
158
4
    status.Update(Status::DataLoss());
159
4
  }
160
161
3.23k
  nested_reader_open_ = true;
162
163
3.23k
  if (!status.ok()) {
164
21
    return StreamDecoder(reader_, this, status);
165
21
  }
166
167
3.21k
  size_t low = position_;
168
3.21k
  size_t high = low + delimited_field_size_;
169
170
3.21k
  return StreamDecoder(reader_, this, low, high);
171
3.23k
}
172
173
3.15k
Status StreamDecoder::Advance(size_t end_position) {
174
3.15k
  if (reader_.seekable()) {
175
3.15k
    PW_TRY(reader_.Seek(end_position - position_, stream::Stream::kCurrent));
176
3.15k
    position_ = end_position;
177
3.15k
    return OkStatus();
178
3.15k
  }
179
180
0
  while (position_ < end_position) {
181
0
    std::byte b;
182
0
    PW_TRY(reader_.Read(span(&b, 1)));
183
0
    position_++;
184
0
  }
185
0
  return OkStatus();
186
0
}
187
188
0
void StreamDecoder::CloseBytesReader(BytesReader& reader) {
189
0
  status_ = reader.status_;
190
0
  if (status_.ok()) {
191
    // Advance the stream to the end of the bytes field.
192
    // The BytesReader already updated our position_ field as bytes were read.
193
0
    PW_CHECK(Advance(reader.end_offset_).ok());
194
0
  }
195
196
0
  field_consumed_ = true;
197
0
  nested_reader_open_ = false;
198
0
}
199
200
3.23k
void StreamDecoder::CloseNestedDecoder(StreamDecoder& nested) {
201
3.23k
  PW_CHECK_PTR_EQ(nested.parent_, this);
202
203
3.23k
  nested.nested_reader_open_ = true;
204
3.23k
  nested.parent_ = nullptr;
205
206
3.23k
  status_ = nested.status_;
207
3.23k
  position_ = nested.position_;
208
3.23k
  if (status_.ok()) {
209
    // Advance the stream to the end of the nested message field.
210
3.15k
    PW_CHECK(Advance(nested.stream_bounds_.high).ok());
211
3.15k
  }
212
213
3.23k
  field_consumed_ = true;
214
3.23k
  nested_reader_open_ = false;
215
3.23k
}
216
217
13.0k
Status StreamDecoder::ReadFieldKey() {
218
13.0k
  PW_DCHECK(field_consumed_);
219
220
13.0k
  uint64_t varint = 0;
221
13.0k
  PW_TRY_ASSIGN(size_t bytes_read,
222
12.9k
                varint::Read(reader_, &varint, RemainingBytes()));
223
12.9k
  position_ += bytes_read;
224
225
12.9k
  if (!FieldKey::IsValidKey(varint)) {
226
132
    return Status::DataLoss();
227
132
  }
228
229
12.8k
  PW_DCHECK(varint <= std::numeric_limits<uint32_t>::max());
230
12.8k
  current_field_ = FieldKey(static_cast<uint32_t>(varint));
231
232
12.8k
  if (current_field_.wire_type() == WireType::kDelimited) {
233
    // Read the length varint of length-delimited fields immediately to simplify
234
    // later processing of the field.
235
8.71k
    StatusWithSize sws = varint::Read(reader_, &varint, RemainingBytes());
236
8.71k
    position_ += sws.size();
237
8.71k
    if (sws.IsOutOfRange()) {
238
      // Out of range indicates the end of the stream. As a value is expected
239
      // here, report it as a data loss and terminate the decode operation.
240
28
      return Status::DataLoss();
241
28
    }
242
8.68k
    if (!sws.ok()) {
243
3
      return sws.status();
244
3
    }
245
246
8.68k
    if (varint > std::numeric_limits<uint32_t>::max()) {
247
65
      return Status::DataLoss();
248
65
    }
249
250
8.62k
    delimited_field_size_ = varint;
251
8.62k
    delimited_field_offset_ = position_;
252
8.62k
  }
253
254
12.7k
  field_consumed_ = false;
255
12.7k
  return OkStatus();
256
12.8k
}
257
258
0
Result<StreamDecoder::Bounds> StreamDecoder::GetLengthDelimitedPayloadBounds() {
259
0
  PW_TRY(CheckOkToRead(WireType::kDelimited));
260
0
  return StreamDecoder::Bounds{delimited_field_offset_,
261
0
                               delimited_field_size_ + delimited_field_offset_};
262
0
}
263
264
// Consumes the current protobuf field, advancing the stream to the key of the
265
// next field (if one exists).
266
0
Status StreamDecoder::SkipField() {
267
0
  PW_DCHECK(!field_consumed_);
268
269
0
  size_t bytes_to_skip = 0;
270
0
  uint64_t value = 0;
271
272
0
  switch (current_field_.wire_type()) {
273
0
    case WireType::kVarint: {
274
      // Consume the varint field; nothing more to skip afterward.
275
0
      PW_TRY_ASSIGN(size_t bytes_read,
276
0
                    varint::Read(reader_, &value, RemainingBytes()));
277
0
      position_ += bytes_read;
278
0
      break;
279
0
    }
280
0
    case WireType::kDelimited:
281
0
      bytes_to_skip = delimited_field_size_;
282
0
      break;
283
284
0
    case WireType::kFixed32:
285
0
      bytes_to_skip = sizeof(uint32_t);
286
0
      break;
287
288
0
    case WireType::kFixed64:
289
0
      bytes_to_skip = sizeof(uint64_t);
290
0
      break;
291
0
  }
292
293
0
  if (bytes_to_skip > 0) {
294
    // Check if the stream has the field available. If not, report it as a
295
    // DATA_LOSS since the proto is invalid (as opposed to OUT_OF_BOUNDS if we
296
    // just tried to seek beyond the end).
297
0
    if (reader_.ConservativeReadLimit() < bytes_to_skip) {
298
0
      status_ = Status::DataLoss();
299
0
      return status_;
300
0
    }
301
302
0
    if (RemainingBytes() < bytes_to_skip) {
303
0
      status_ = Status::DataLoss();
304
0
      return status_;
305
0
    }
306
307
0
    PW_TRY(Advance(position_ + bytes_to_skip));
308
0
  }
309
310
0
  field_consumed_ = true;
311
0
  return OkStatus();
312
0
}
313
314
Status StreamDecoder::ReadVarintField(span<std::byte> out,
315
2.40k
                                      VarintType decode_type) {
316
2.40k
  PW_CHECK(out.size() == sizeof(bool) || out.size() == sizeof(uint32_t) ||
317
2.40k
               out.size() == sizeof(uint64_t),
318
2.40k
           "Protobuf varints must only be used with bool, int32_t, uint32_t, "
319
2.40k
           "int64_t, or uint64_t");
320
2.40k
  PW_TRY(CheckOkToRead(WireType::kVarint));
321
322
2.35k
  const StatusWithSize sws = ReadOneVarint(out, decode_type);
323
2.35k
  if (sws.status() != Status::DataLoss())
324
2.07k
    field_consumed_ = true;
325
2.35k
  return sws.status();
326
2.40k
}
327
328
StatusWithSize StreamDecoder::ReadOneVarint(span<std::byte> out,
329
12.3k
                                            VarintType decode_type) {
330
12.3k
  uint64_t value;
331
12.3k
  StatusWithSize sws = varint::Read(reader_, &value, RemainingBytes());
332
12.3k
  position_ += sws.size();
333
12.3k
  if (sws.IsOutOfRange()) {
334
    // Out of range indicates the end of the stream. As a value is expected
335
    // here, report it as a data loss and terminate the decode operation.
336
51
    status_ = Status::DataLoss();
337
51
    return StatusWithSize(status_, sws.size());
338
51
  }
339
12.2k
  if (!sws.ok()) {
340
403
    return sws;
341
403
  }
342
343
11.8k
  if (out.size() == sizeof(uint64_t)) {
344
8.05k
    if (decode_type == VarintType::kUnsigned) {
345
3.43k
      std::memcpy(out.data(), &value, out.size());
346
4.61k
    } else {
347
4.61k
      const int64_t signed_value = decode_type == VarintType::kZigZag
348
4.61k
                                       ? varint::ZigZagDecode(value)
349
4.61k
                                       : static_cast<int64_t>(value);
350
4.61k
      std::memcpy(out.data(), &signed_value, out.size());
351
4.61k
    }
352
8.05k
  } else if (out.size() == sizeof(uint32_t)) {
353
3.79k
    if (decode_type == VarintType::kUnsigned) {
354
1.59k
      if (value > std::numeric_limits<uint32_t>::max()) {
355
85
        return StatusWithSize(Status::FailedPrecondition(), sws.size());
356
85
      }
357
1.50k
      std::memcpy(out.data(), &value, out.size());
358
2.20k
    } else {
359
2.20k
      const int64_t signed_value = decode_type == VarintType::kZigZag
360
2.20k
                                       ? varint::ZigZagDecode(value)
361
2.20k
                                       : static_cast<int64_t>(value);
362
2.20k
      if (signed_value > std::numeric_limits<int32_t>::max() ||
363
2.20k
          signed_value < std::numeric_limits<int32_t>::min()) {
364
105
        return StatusWithSize(Status::FailedPrecondition(), sws.size());
365
105
      }
366
2.09k
      std::memcpy(out.data(), &signed_value, out.size());
367
2.09k
    }
368
3.79k
  } else if (out.size() == sizeof(bool)) {
369
0
    PW_CHECK(decode_type == VarintType::kUnsigned,
370
0
             "Protobuf bool can never be signed");
371
0
    std::memcpy(out.data(), &value, out.size());
372
0
  }
373
374
11.6k
  return sws;
375
11.8k
}
376
377
1.65k
Status StreamDecoder::ReadFixedField(span<std::byte> out) {
378
1.65k
  WireType expected_wire_type =
379
1.65k
      out.size() == sizeof(uint32_t) ? WireType::kFixed32 : WireType::kFixed64;
380
1.65k
  PW_TRY(CheckOkToRead(expected_wire_type));
381
382
1.62k
  if (reader_.ConservativeReadLimit() < out.size()) {
383
16
    status_ = Status::DataLoss();
384
16
    return status_;
385
16
  }
386
387
1.60k
  if (RemainingBytes() < out.size()) {
388
6
    status_ = Status::DataLoss();
389
6
    return status_;
390
6
  }
391
392
1.59k
  PW_TRY(reader_.Read(out));
393
1.59k
  position_ += out.size();
394
1.59k
  field_consumed_ = true;
395
396
1.59k
  if (endian::native != endian::little) {
397
0
    std::reverse(out.begin(), out.end());
398
0
  }
399
400
1.59k
  return OkStatus();
401
1.59k
}
402
403
1.01k
StatusWithSize StreamDecoder::ReadDelimitedField(span<std::byte> out) {
404
1.01k
  if (Status status = CheckOkToRead(WireType::kDelimited); !status.ok()) {
405
7
    return StatusWithSize(status, 0);
406
7
  }
407
408
1.01k
  if (reader_.ConservativeReadLimit() < delimited_field_size_) {
409
40
    status_ = Status::DataLoss();
410
40
    return StatusWithSize(status_, 0);
411
40
  }
412
413
972
  if (out.size() < delimited_field_size_) {
414
    // Value can't fit into the provided buffer. Don't advance the cursor so
415
    // that the field can be re-read with a larger buffer or through the stream
416
    // API.
417
33
    return StatusWithSize::ResourceExhausted();
418
33
  }
419
420
939
  Result<ByteSpan> result = reader_.Read(out.first(delimited_field_size_));
421
939
  if (!result.ok()) {
422
51
    return StatusWithSize(result.status(), 0);
423
51
  }
424
425
888
  position_ += result.value().size();
426
888
  field_consumed_ = true;
427
888
  return StatusWithSize(result.value().size());
428
939
}
429
430
StatusWithSize StreamDecoder::ReadPackedFixedField(span<std::byte> out,
431
2.19k
                                                   size_t elem_size) {
432
2.19k
  if (Status status = CheckOkToRead(WireType::kDelimited); !status.ok()) {
433
32
    return StatusWithSize(status, 0);
434
32
  }
435
436
2.16k
  if (reader_.ConservativeReadLimit() < delimited_field_size_) {
437
39
    status_ = Status::DataLoss();
438
39
    return StatusWithSize(status_, 0);
439
39
  }
440
441
2.12k
  if (out.size() < delimited_field_size_) {
442
    // Value can't fit into the provided buffer. Don't advance the cursor so
443
    // that the field can be re-read with a larger buffer or through the stream
444
    // API.
445
62
    return StatusWithSize::ResourceExhausted();
446
62
  }
447
448
2.06k
  Result<ByteSpan> result = reader_.Read(out.first(delimited_field_size_));
449
2.06k
  if (!result.ok()) {
450
138
    return StatusWithSize(result.status(), 0);
451
138
  }
452
453
1.92k
  position_ += result.value().size();
454
1.92k
  field_consumed_ = true;
455
456
  // Decode little-endian serialized packed fields.
457
1.92k
  if (endian::native != endian::little) {
458
0
    for (auto out_start = out.begin(); out_start != out.end();
459
0
         out_start += elem_size) {
460
0
      std::reverse(out_start, out_start + elem_size);
461
0
    }
462
0
  }
463
464
1.92k
  return StatusWithSize(result.value().size() / elem_size);
465
2.06k
}
466
467
StatusWithSize StreamDecoder::ReadPackedVarintField(span<std::byte> out,
468
                                                    size_t elem_size,
469
2.26k
                                                    VarintType decode_type) {
470
2.26k
  PW_CHECK(elem_size == sizeof(bool) || elem_size == sizeof(uint32_t) ||
471
2.26k
               elem_size == sizeof(uint64_t),
472
2.26k
           "Protobuf varints must only be used with bool, int32_t, uint32_t, "
473
2.26k
           "int64_t, or uint64_t");
474
475
2.26k
  if (Status status = CheckOkToRead(WireType::kDelimited); !status.ok()) {
476
52
    return StatusWithSize(status, 0);
477
52
  }
478
479
2.21k
  if (reader_.ConservativeReadLimit() < delimited_field_size_) {
480
41
    status_ = Status::DataLoss();
481
41
    return StatusWithSize(status_, 0);
482
41
  }
483
484
2.16k
  size_t bytes_read = 0;
485
2.16k
  size_t number_out = 0;
486
11.7k
  while (bytes_read < delimited_field_size_ && !out.empty()) {
487
9.94k
    const StatusWithSize sws = ReadOneVarint(out.first(elem_size), decode_type);
488
9.94k
    if (!sws.ok()) {
489
361
      return StatusWithSize(sws.status(), number_out);
490
361
    }
491
492
9.58k
    bytes_read += sws.size();
493
9.58k
    out = out.subspan(elem_size);
494
9.58k
    ++number_out;
495
9.58k
  }
496
497
1.80k
  if (bytes_read < delimited_field_size_) {
498
12
    return StatusWithSize(Status::ResourceExhausted(), number_out);
499
12
  }
500
501
1.79k
  field_consumed_ = true;
502
1.79k
  return StatusWithSize(OkStatus(), number_out);
503
1.80k
}
504
505
12.7k
Status StreamDecoder::CheckOkToRead(WireType type) {
506
12.7k
  PW_CHECK(!nested_reader_open_,
507
12.7k
           "Cannot read from a decoder while a nested decoder is open");
508
12.7k
  PW_CHECK(!field_consumed_,
509
12.7k
           "Attempting to read from protobuf decoder without first calling "
510
12.7k
           "Next()");
511
512
  // Attempting to read the wrong type is typically a programmer error;
513
  // however, it could also occur due to data corruption. As we don't want to
514
  // crash on bad data, return NOT_FOUND here to distinguish it from other
515
  // corruption cases.
516
12.7k
  if (current_field_.wire_type() != type) {
517
185
    status_ = Status::NotFound();
518
185
  }
519
520
12.7k
  return status_;
521
12.7k
}
522
523
Status StreamDecoder::Read(span<std::byte> message,
524
0
                           span<const internal::MessageField> table) {
525
0
  PW_TRY(status_);
526
527
0
  while (Next().ok()) {
528
    // Find the field in the table,
529
    // TODO: b/234876102 - Finding the field can be made more efficient.
530
0
    const auto field =
531
0
        std::find(table.begin(), table.end(), current_field_.field_number());
532
0
    if (field == table.end()) {
533
      // If the field is not found, skip to the next one.
534
      // TODO: b/234873295 - Provide a way to allow the caller to inspect
535
      // unknown fields, and serialize them back out later.
536
0
      continue;
537
0
    }
538
539
    // Calculate the span of bytes corresponding to the structure field to
540
    // output into.
541
0
    const auto out =
542
0
        message.subspan(field->field_offset(), field->field_size());
543
0
    PW_CHECK(out.begin() >= message.begin() && out.end() <= message.end());
544
545
    // If the field is using callbacks, interpret the output field accordingly
546
    // and allow the caller to provide custom handling.
547
0
    if (field->callback_type() == internal::CallbackType::kSingleField) {
548
0
      const Callback<StreamEncoder, StreamDecoder>* callback =
549
0
          reinterpret_cast<const Callback<StreamEncoder, StreamDecoder>*>(
550
0
              out.data());
551
0
      PW_TRY(callback->Decode(*this));
552
0
      continue;
553
0
    }
554
0
    if (field->callback_type() == internal::CallbackType::kOneOfGroup) {
555
0
      const OneOf<StreamEncoder, StreamDecoder>* callback =
556
0
          reinterpret_cast<const OneOf<StreamEncoder, StreamDecoder>*>(
557
0
              out.data());
558
0
      PW_TRY(callback->Decode(
559
0
          static_cast<NullFields>(current_field_.field_number()), *this));
560
0
      continue;
561
0
    }
562
563
    // Switch on the expected wire type of the field, not the actual, to ensure
564
    // the remote encoder doesn't influence our decoding unexpectedly.
565
0
    switch (field->wire_type()) {
566
0
      case WireType::kFixed64:
567
0
      case WireType::kFixed32: {
568
        // Fixed fields call ReadFixedField() for singular case, and either
569
        // ReadPackedFixedField() or ReadRepeatedFixedField() for repeated
570
        // fields.
571
0
        PW_CHECK(field->elem_size() == (field->wire_type() == WireType::kFixed32
572
0
                                            ? sizeof(uint32_t)
573
0
                                            : sizeof(uint64_t)),
574
0
                 "Mismatched message field type and size");
575
0
        if (field->is_fixed_size()) {
576
0
          PW_CHECK(field->is_repeated(), "Non-repeated fixed size field");
577
0
          PW_TRY(ReadPackedFixedField(out, field->elem_size()));
578
0
        } else if (field->is_repeated()) {
579
          // The struct member for this field is a vector of a type
580
          // corresponding to the field element size. Cast to the correct
581
          // vector type so we're not performing type aliasing (except for
582
          // unsigned vs signed which is explicitly allowed).
583
0
          if (field->elem_size() == sizeof(uint64_t)) {
584
0
            auto* vector = reinterpret_cast<pw::Vector<uint64_t>*>(out.data());
585
0
            PW_TRY(ReadRepeatedFixedField(*vector));
586
0
          } else if (field->elem_size() == sizeof(uint32_t)) {
587
0
            auto* vector = reinterpret_cast<pw::Vector<uint32_t>*>(out.data());
588
0
            PW_TRY(ReadRepeatedFixedField(*vector));
589
0
          }
590
0
        } else if (field->is_optional()) {
591
          // The struct member for this field is a std::optional of a type
592
          // corresponding to the field element size. Cast to the correct
593
          // optional type so we're not performing type aliasing (except for
594
          // unsigned vs signed which is explicitly allowed), and assign through
595
          // a temporary.
596
0
          if (field->elem_size() == sizeof(uint64_t)) {
597
0
            uint64_t value = 0;
598
0
            PW_TRY(ReadFixedField(as_writable_bytes(span(&value, 1))));
599
0
            auto* optional =
600
0
                reinterpret_cast<std::optional<uint64_t>*>(out.data());
601
0
            *optional = value;
602
0
          } else if (field->elem_size() == sizeof(uint32_t)) {
603
0
            uint32_t value = 0;
604
0
            PW_TRY(ReadFixedField(as_writable_bytes(span(&value, 1))));
605
0
            auto* optional =
606
0
                reinterpret_cast<std::optional<uint32_t>*>(out.data());
607
0
            *optional = value;
608
0
          }
609
0
        } else {
610
0
          PW_CHECK(out.size() == field->elem_size(),
611
0
                   "Mismatched message field type and size");
612
0
          PW_TRY(ReadFixedField(out));
613
0
        }
614
0
        break;
615
0
      }
616
0
      case WireType::kVarint: {
617
        // Varint fields call ReadVarintField() for singular case, and either
618
        // ReadPackedVarintField() or ReadRepeatedVarintField() for repeated
619
        // fields.
620
0
        PW_CHECK(field->elem_size() == sizeof(uint64_t) ||
621
0
                     field->elem_size() == sizeof(uint32_t) ||
622
0
                     field->elem_size() == sizeof(bool),
623
0
                 "Mismatched message field type and size");
624
0
        if (field->is_fixed_size()) {
625
0
          PW_CHECK(field->is_repeated(), "Non-repeated fixed size field");
626
0
          PW_TRY(ReadPackedVarintField(
627
0
              out, field->elem_size(), field->varint_type()));
628
0
        } else if (field->is_repeated()) {
629
          // The struct member for this field is a vector of a type
630
          // corresponding to the field element size. Cast to the correct
631
          // vector type so we're not performing type aliasing (except for
632
          // unsigned vs signed which is explicitly allowed).
633
0
          if (field->elem_size() == sizeof(uint64_t)) {
634
0
            auto* vector = reinterpret_cast<pw::Vector<uint64_t>*>(out.data());
635
0
            PW_TRY(ReadRepeatedVarintField(*vector, field->varint_type()));
636
0
          } else if (field->elem_size() == sizeof(uint32_t)) {
637
0
            auto* vector = reinterpret_cast<pw::Vector<uint32_t>*>(out.data());
638
0
            PW_TRY(ReadRepeatedVarintField(*vector, field->varint_type()));
639
0
          } else if (field->elem_size() == sizeof(bool)) {
640
0
            auto* vector = reinterpret_cast<pw::Vector<bool>*>(out.data());
641
0
            PW_TRY(ReadRepeatedVarintField(*vector, field->varint_type()));
642
0
          }
643
0
        } else if (field->is_optional()) {
644
          // The struct member for this field is a std::optional of a type
645
          // corresponding to the field element size. Cast to the correct
646
          // optional type so we're not performing type aliasing (except for
647
          // unsigned vs signed which is explicitly allowed), and assign through
648
          // a temporary.
649
0
          if (field->elem_size() == sizeof(uint64_t)) {
650
0
            uint64_t value = 0;
651
0
            PW_TRY(ReadVarintField(as_writable_bytes(span(&value, 1)),
652
0
                                   field->varint_type()));
653
0
            auto* optional =
654
0
                reinterpret_cast<std::optional<uint64_t>*>(out.data());
655
0
            *optional = value;
656
0
          } else if (field->elem_size() == sizeof(uint32_t)) {
657
0
            uint32_t value = 0;
658
0
            PW_TRY(ReadVarintField(as_writable_bytes(span(&value, 1)),
659
0
                                   field->varint_type()));
660
0
            auto* optional =
661
0
                reinterpret_cast<std::optional<uint32_t>*>(out.data());
662
0
            *optional = value;
663
0
          } else if (field->elem_size() == sizeof(bool)) {
664
0
            bool value = false;
665
0
            PW_TRY(ReadVarintField(as_writable_bytes(span(&value, 1)),
666
0
                                   field->varint_type()));
667
0
            auto* optional = reinterpret_cast<std::optional<bool>*>(out.data());
668
0
            *optional = value;
669
0
          }
670
0
        } else {
671
0
          PW_CHECK(out.size() == field->elem_size(),
672
0
                   "Mismatched message field type and size");
673
0
          PW_TRY(ReadVarintField(out, field->varint_type()));
674
0
        }
675
0
        break;
676
0
      }
677
0
      case WireType::kDelimited: {
678
        // Delimited fields are always a singular case because of the inability
679
        // to cast to a generic vector with an element of a certain size (we
680
        // always need a type).
681
0
        PW_CHECK(!field->is_repeated(),
682
0
                 "Repeated delimited messages always require a callback");
683
0
        if (field->nested_message_fields()) {
684
          // Nested Message. Struct member is an embedded struct for the
685
          // nested field. Obtain a nested decoder and recursively call Read()
686
          // using the fields table pointer from this field.
687
0
          auto nested_decoder = GetNestedDecoder();
688
0
          PW_TRY(nested_decoder.Read(out, *field->nested_message_fields()));
689
0
        } else if (field->is_fixed_size()) {
690
          // Fixed-length bytes field. Struct member is a std::array<std::byte>.
691
          // Call ReadDelimitedField() to populate it from the stream.
692
0
          PW_CHECK(field->elem_size() == sizeof(std::byte),
693
0
                   "Mismatched message field type and size");
694
0
          PW_TRY(ReadDelimitedField(out));
695
0
        } else {
696
          // bytes or string field with a maximum size. The struct member is
697
          // pw::Vector<std::byte> for bytes or pw::InlineString<> for string.
698
0
          PW_CHECK(field->elem_size() == sizeof(std::byte),
699
0
                   "Mismatched message field type and size");
700
0
          if (field->is_string()) {
701
0
            PW_TRY(ReadStringOrBytesField<pw::InlineString<>>(out.data()));
702
0
          } else {
703
0
            PW_TRY(ReadStringOrBytesField<pw::Vector<std::byte>>(out.data()));
704
0
          }
705
0
        }
706
0
        break;
707
0
      }
708
0
    }
709
0
  }
710
711
  // Reaching the end of the encoded protobuf is not an error.
712
0
  if (status_ == Status::OutOfRange()) {
713
0
    return OkStatus();
714
0
  }
715
716
0
  return status_;
717
0
}
718
719
}  // namespace pw::protobuf