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 * Remember to close the substream using pb_close_string_substream().
192 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
195 if (!pb_decode_varint32(stream, &size))
198 *substream = *stream;
199 if (substream->bytes_left < size)
202 substream->bytes_left = size;
203 stream->bytes_left -= size;
207 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
209 stream->state = substream->state;
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)
297 size_t *size = (size_t*)iter->pSize;
298 pb_istream_t substream;
299 if (!pb_make_string_substream(stream, &substream))
302 while (substream.bytes_left && *size < iter->current->array_size)
304 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
305 if (!func(&substream, iter->current, pItem))
309 status = (substream.bytes_left == 0);
310 pb_close_string_substream(stream, &substream);
316 size_t *size = (size_t*)iter->pSize;
317 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
318 if (*size >= iter->current->array_size)
322 return func(stream, iter->current, pItem);
325 case PB_HTYPE_CALLBACK:
327 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
329 if (pCallback->funcs.decode == NULL)
330 return pb_skip_field(stream, wire_type);
332 if (wire_type == PB_WT_STRING)
334 pb_istream_t substream;
336 if (!pb_make_string_substream(stream, &substream))
339 while (substream.bytes_left)
341 if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
345 pb_close_string_substream(stream, &substream);
350 /* Copy the single scalar value to stack.
351 * This is required so that we can limit the stream length,
352 * which in turn allows to use same callback for packed and
353 * not-packed fields. */
354 pb_istream_t substream;
356 size_t size = sizeof(buffer);
358 if (!read_raw_value(stream, wire_type, buffer, &size))
360 substream = pb_istream_from_buffer(buffer, size);
362 return pCallback->funcs.decode(&substream, iter->current, pCallback->arg);
371 /* Initialize message fields to default values, recursively */
372 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
374 pb_field_iterator_t iter;
375 pb_field_init(&iter, fields, dest_struct);
377 /* Initialize size/has fields and apply default values */
380 if (iter.current->tag == 0)
383 /* Initialize the size field for optional/repeated fields to 0. */
384 if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL)
386 *(bool*)iter.pSize = false;
388 else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY)
390 *(size_t*)iter.pSize = 0;
391 continue; /* Array is empty, no need to initialize contents */
394 /* Initialize field contents to default value */
395 if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK)
397 continue; /* Don't overwrite callback */
399 else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
401 pb_message_set_to_defaults((const pb_field_t *) iter.current->ptr, iter.pData);
403 else if (iter.current->ptr != NULL)
405 memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
409 memset(iter.pData, 0, iter.current->data_size);
411 } while (pb_field_next(&iter));
414 /*********************
415 * Decode all fields *
416 *********************/
418 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
420 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
421 pb_field_iterator_t iter;
423 pb_message_set_to_defaults(fields, dest_struct);
425 pb_field_init(&iter, fields, dest_struct);
427 while (stream->bytes_left)
430 pb_wire_type_t wire_type;
433 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
441 if (!pb_field_find(&iter, tag))
443 /* No match found, skip data */
444 if (!pb_skip_field(stream, wire_type))
449 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED
450 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
452 fields_seen[iter.required_field_index >> 3] |= 1 << (iter.required_field_index & 7);
455 if (!decode_field(stream, wire_type, &iter))
459 /* Check that all required fields were present. */
460 pb_field_init(&iter, fields, dest_struct);
462 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED &&
463 iter.required_field_index < PB_MAX_REQUIRED_FIELDS &&
464 !(fields_seen[iter.required_field_index >> 3] & (1 << (iter.required_field_index & 7))))
468 } while (pb_field_next(&iter));
475 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
478 if (!pb_decode_varint(stream, &value))
482 *dest = ~(value >> 1);
489 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
491 #ifdef __BIG_ENDIAN__
492 uint8_t *bytes = (uint8_t*)dest;
495 if (!pb_read(stream, lebytes, 4))
498 bytes[0] = lebytes[3];
499 bytes[1] = lebytes[2];
500 bytes[2] = lebytes[1];
501 bytes[3] = lebytes[0];
504 return pb_read(stream, (uint8_t*)dest, 4);
508 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
510 #ifdef __BIG_ENDIAN__
511 uint8_t *bytes = (uint8_t*)dest;
514 if (!pb_read(stream, lebytes, 8))
517 bytes[0] = lebytes[7];
518 bytes[1] = lebytes[6];
519 bytes[2] = lebytes[5];
520 bytes[3] = lebytes[4];
521 bytes[4] = lebytes[3];
522 bytes[5] = lebytes[2];
523 bytes[6] = lebytes[1];
524 bytes[7] = lebytes[0];
527 return pb_read(stream, (uint8_t*)dest, 8);
531 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
534 bool status = pb_decode_varint(stream, &value);
536 switch (field->data_size)
538 case 1: *(uint8_t*)dest = value; break;
539 case 2: *(uint16_t*)dest = value; break;
540 case 4: *(uint32_t*)dest = value; break;
541 case 8: *(uint64_t*)dest = value; break;
542 default: return false;
548 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
551 bool status = pb_decode_svarint(stream, &value);
553 switch (field->data_size)
555 case 4: *(int32_t*)dest = value; break;
556 case 8: *(int64_t*)dest = value; break;
557 default: return false;
563 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
566 return pb_decode_fixed32(stream, dest);
569 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
572 return pb_decode_fixed64(stream, dest);
575 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
577 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
580 if (!pb_decode_varint32(stream, &temp))
584 /* Check length, noting the space taken by the size_t header. */
585 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
588 return pb_read(stream, x->bytes, x->size);
591 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
595 if (!pb_decode_varint32(stream, &size))
598 /* Check length, noting the null terminator */
599 if (size + 1 > field->data_size)
602 status = pb_read(stream, (uint8_t*)dest, size);
603 *((uint8_t*)dest + size) = 0;
607 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
610 pb_istream_t substream;
612 if (!pb_make_string_substream(stream, &substream))
615 if (field->ptr == NULL)
618 status = pb_decode(&substream, (pb_field_t*)field->ptr, dest);
619 pb_close_string_substream(stream, &substream);