1 /* pb_decode.c -- decode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
6 /* The warn_unused_result attribute appeared first in gcc-3.4.0 */
7 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
10 /* Verify that we remember to check all return values for proper error propagation */
11 #define checkreturn __attribute__((warn_unused_result))
14 #define NANOPB_INTERNALS
16 #include "pb_decode.h"
19 typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn;
21 /* --- Function pointers to field decoders ---
22 * Order in the array must match pb_action_t LTYPE numbering.
24 static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = {
39 bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
41 if (stream->bytes_left < count)
44 if (!stream->callback(stream, buf, count))
47 stream->bytes_left -= count;
51 static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
53 uint8_t *source = (uint8_t*)stream->state;
56 memcpy(buf, source, count);
58 stream->state = source + count;
62 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
65 stream.callback = &buf_read;
67 stream.bytes_left = bufsize;
75 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
78 bool status = pb_decode_varint(stream, &temp);
79 *dest = (uint32_t)temp;
83 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
89 while (bitpos < 64 && pb_read(stream, &byte, 1))
91 *dest |= (uint64_t)(byte & 0x7F) << bitpos;
101 bool checkreturn pb_skip_varint(pb_istream_t *stream)
106 if (!pb_read(stream, &byte, 1))
108 } while (byte & 0x80);
112 bool checkreturn pb_skip_string(pb_istream_t *stream)
115 if (!pb_decode_varint32(stream, &length))
118 return pb_read(stream, NULL, length);
121 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
125 *wire_type = (pb_wire_type_t) 0;
128 if (!pb_decode_varint32(stream, &temp))
130 if (stream->bytes_left == 0)
138 *eof = true; /* Special feature: allow 0-terminated messages. */
143 *wire_type = (pb_wire_type_t)(temp & 7);
147 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
151 case PB_WT_VARINT: return pb_skip_varint(stream);
152 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
153 case PB_WT_STRING: return pb_skip_string(stream);
154 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
155 default: return false;
159 /* Read a raw value to buffer, for the purpose of passing it to callback as
160 * a substream. Size is maximum size on call, and actual size on return.
162 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
164 size_t max_size = *size;
172 if (*size > max_size) return false;
173 if (!pb_read(stream, buf, 1)) return false;
174 } while (*buf++ & 0x80);
179 return pb_read(stream, buf, 8);
183 return pb_read(stream, buf, 4);
185 default: return false;
189 /* Decode string length from stream and return a substream with limited length. */
190 static bool substream_callback(pb_istream_t *stream, uint8_t *buf, size_t count)
192 pb_istream_t *parent = (pb_istream_t*)stream->state;
193 return pb_read(parent, buf, count);
196 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
199 if (!pb_decode_varint32(stream, &size))
202 if (stream->bytes_left < size)
205 substream->callback = &substream_callback;
206 substream->state = stream;
207 substream->bytes_left = size;
212 /* Iterator for pb_field_t list */
214 const pb_field_t *start; /* Start of the pb_field_t array */
215 const pb_field_t *current; /* Current position of the iterator */
216 int field_index; /* Zero-based index of the field. */
217 int required_field_index; /* Zero-based index that counts only the required fields */
218 void *dest_struct; /* Pointer to the destination structure to decode to */
219 void *pData; /* Pointer where to store current field value */
220 void *pSize; /* Pointer where to store the size of current array field */
221 } pb_field_iterator_t;
223 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
225 iter->start = iter->current = fields;
226 iter->field_index = 0;
227 iter->required_field_index = 0;
228 iter->pData = (char*)dest_struct + iter->current->data_offset;
229 iter->pSize = (char*)iter->pData + iter->current->size_offset;
230 iter->dest_struct = dest_struct;
233 static bool pb_field_next(pb_field_iterator_t *iter)
235 bool notwrapped = true;
236 size_t prev_size = iter->current->data_size;
238 if (PB_HTYPE(iter->current->type) == PB_HTYPE_ARRAY)
239 prev_size *= iter->current->array_size;
241 if (PB_HTYPE(iter->current->type) == PB_HTYPE_REQUIRED)
242 iter->required_field_index++;
246 if (iter->current->tag == 0)
248 iter->current = iter->start;
249 iter->field_index = 0;
250 iter->required_field_index = 0;
251 iter->pData = iter->dest_struct;
256 iter->pData = (char*)iter->pData + prev_size + iter->current->data_offset;
257 iter->pSize = (char*)iter->pData + iter->current->size_offset;
261 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
263 int start = iter->field_index;
266 if (iter->current->tag == tag)
269 } while (iter->field_index != start);
274 /*************************
275 * Decode a single field *
276 *************************/
278 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
280 pb_decoder_t func = PB_DECODERS[PB_LTYPE(iter->current->type)];
282 switch (PB_HTYPE(iter->current->type))
284 case PB_HTYPE_REQUIRED:
285 return func(stream, iter->current, iter->pData);
287 case PB_HTYPE_OPTIONAL:
288 *(bool*)iter->pSize = true;
289 return func(stream, iter->current, iter->pData);
292 if (wire_type == PB_WT_STRING
293 && PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE)
296 size_t *size = (size_t*)iter->pSize;
297 pb_istream_t substream;
298 if (!pb_make_string_substream(stream, &substream))
301 while (substream.bytes_left && *size < iter->current->array_size)
303 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
304 if (!func(&substream, iter->current, pItem))
308 return (substream.bytes_left == 0);
313 size_t *size = (size_t*)iter->pSize;
314 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
315 if (*size >= iter->current->array_size)
319 return func(stream, iter->current, pItem);
322 case PB_HTYPE_CALLBACK:
324 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
326 if (pCallback->funcs.decode == NULL)
327 return pb_skip_field(stream, wire_type);
329 if (wire_type == PB_WT_STRING)
331 pb_istream_t substream;
333 if (!pb_make_string_substream(stream, &substream))
336 while (substream.bytes_left)
338 if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
346 /* Copy the single scalar value to stack.
347 * This is required so that we can limit the stream length,
348 * which in turn allows to use same callback for packed and
349 * not-packed fields. */
350 pb_istream_t substream;
352 size_t size = sizeof(buffer);
354 if (!read_raw_value(stream, wire_type, buffer, &size))
356 substream = pb_istream_from_buffer(buffer, size);
358 return pCallback->funcs.decode(&substream, iter->current, pCallback->arg);
367 /* Initialize message fields to default values, recursively */
368 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
370 pb_field_iterator_t iter;
371 pb_field_init(&iter, fields, dest_struct);
373 /* Initialize size/has fields and apply default values */
376 if (iter.current->tag == 0)
379 /* Initialize the size field for optional/repeated fields to 0. */
380 if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL)
382 *(bool*)iter.pSize = false;
384 else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY)
386 *(size_t*)iter.pSize = 0;
387 continue; /* Array is empty, no need to initialize contents */
390 /* Initialize field contents to default value */
391 if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK)
393 continue; /* Don't overwrite callback */
395 else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
397 pb_message_set_to_defaults((const pb_field_t *) iter.current->ptr, iter.pData);
399 else if (iter.current->ptr != NULL)
401 memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
405 memset(iter.pData, 0, iter.current->data_size);
407 } while (pb_field_next(&iter));
410 /*********************
411 * Decode all fields *
412 *********************/
414 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
416 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
417 pb_field_iterator_t iter;
419 pb_message_set_to_defaults(fields, dest_struct);
421 pb_field_init(&iter, fields, dest_struct);
423 while (stream->bytes_left)
426 pb_wire_type_t wire_type;
429 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
437 if (!pb_field_find(&iter, tag))
439 /* No match found, skip data */
440 if (!pb_skip_field(stream, wire_type))
445 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED
446 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
448 fields_seen[iter.required_field_index >> 3] |= 1 << (iter.required_field_index & 7);
451 if (!decode_field(stream, wire_type, &iter))
455 /* Check that all required fields were present. */
456 pb_field_init(&iter, fields, dest_struct);
458 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED &&
459 iter.required_field_index < PB_MAX_REQUIRED_FIELDS &&
460 !(fields_seen[iter.required_field_index >> 3] & (1 << (iter.required_field_index & 7))))
464 } while (pb_field_next(&iter));
471 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
474 if (!pb_decode_varint(stream, &value))
478 *dest = ~(value >> 1);
485 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
487 #ifdef __BIG_ENDIAN__
488 uint8_t *bytes = (uint8_t*)dest;
491 if (!pb_read(stream, lebytes, 4))
494 bytes[0] = lebytes[3];
495 bytes[1] = lebytes[2];
496 bytes[2] = lebytes[1];
497 bytes[3] = lebytes[0];
500 return pb_read(stream, (uint8_t*)dest, 4);
504 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
506 #ifdef __BIG_ENDIAN__
507 uint8_t *bytes = (uint8_t*)dest;
510 if (!pb_read(stream, lebytes, 8))
513 bytes[0] = lebytes[7];
514 bytes[1] = lebytes[6];
515 bytes[2] = lebytes[5];
516 bytes[3] = lebytes[4];
517 bytes[4] = lebytes[3];
518 bytes[5] = lebytes[2];
519 bytes[6] = lebytes[1];
520 bytes[7] = lebytes[0];
523 return pb_read(stream, (uint8_t*)dest, 8);
527 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
530 bool status = pb_decode_varint(stream, &value);
532 switch (field->data_size)
534 case 1: *(uint8_t*)dest = value; break;
535 case 2: *(uint16_t*)dest = value; break;
536 case 4: *(uint32_t*)dest = value; break;
537 case 8: *(uint64_t*)dest = value; break;
538 default: return false;
544 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
547 bool status = pb_decode_svarint(stream, &value);
549 switch (field->data_size)
551 case 4: *(int32_t*)dest = value; break;
552 case 8: *(int64_t*)dest = value; break;
553 default: return false;
559 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
562 return pb_decode_fixed32(stream, dest);
565 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
568 return pb_decode_fixed64(stream, dest);
571 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
573 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
576 if (!pb_decode_varint32(stream, &temp))
580 /* Check length, noting the space taken by the size_t header. */
581 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
584 return pb_read(stream, x->bytes, x->size);
587 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
591 if (!pb_decode_varint32(stream, &size))
594 /* Check length, noting the null terminator */
595 if (size + 1 > field->data_size)
598 status = pb_read(stream, (uint8_t*)dest, size);
599 *((uint8_t*)dest + size) = 0;
603 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
605 pb_istream_t substream;
607 if (!pb_make_string_substream(stream, &substream))
610 if (field->ptr == NULL)
613 return pb_decode(&substream, (pb_field_t*)field->ptr, dest);