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 static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
41 uint8_t *source = (uint8_t*)stream->state;
42 stream->state = source + count;
53 bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
55 #ifndef PB_BUFFER_ONLY
56 if (buf == NULL && stream->callback != buf_read)
58 /* Skip input bytes */
62 if (!pb_read(stream, tmp, 16))
68 return pb_read(stream, tmp, count);
72 if (stream->bytes_left < count)
73 PB_RETURN_ERROR(stream, "end-of-stream");
75 #ifndef PB_BUFFER_ONLY
76 if (!stream->callback(stream, buf, count))
77 PB_RETURN_ERROR(stream, "io error");
79 if (!buf_read(stream, buf, count))
83 stream->bytes_left -= count;
87 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
91 stream.callback = NULL;
93 stream.callback = &buf_read;
96 stream.bytes_left = bufsize;
103 /********************
105 ********************/
107 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
112 if (!pb_read(stream, &byte, 1))
117 /* Quick case, 1 byte value */
124 result = byte & 0x7F;
129 PB_RETURN_ERROR(stream, "varint overflow");
131 if (!pb_read(stream, &byte, 1))
134 result |= (uint32_t)(byte & 0x7F) << bitpos;
135 bitpos = (uint8_t)(bitpos + 7);
136 } while (byte & 0x80);
143 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
152 PB_RETURN_ERROR(stream, "varint overflow");
154 if (!pb_read(stream, &byte, 1))
157 result |= (uint64_t)(byte & 0x7F) << bitpos;
158 bitpos = (uint8_t)(bitpos + 7);
159 } while (byte & 0x80);
165 bool checkreturn pb_skip_varint(pb_istream_t *stream)
170 if (!pb_read(stream, &byte, 1))
172 } while (byte & 0x80);
176 bool checkreturn pb_skip_string(pb_istream_t *stream)
179 if (!pb_decode_varint32(stream, &length))
182 return pb_read(stream, NULL, length);
185 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
189 *wire_type = (pb_wire_type_t) 0;
192 if (!pb_decode_varint32(stream, &temp))
194 if (stream->bytes_left == 0)
202 *eof = true; /* Special feature: allow 0-terminated messages. */
207 *wire_type = (pb_wire_type_t)(temp & 7);
211 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
215 case PB_WT_VARINT: return pb_skip_varint(stream);
216 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
217 case PB_WT_STRING: return pb_skip_string(stream);
218 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
219 default: PB_RETURN_ERROR(stream, "invalid wire_type");
223 /* Read a raw value to buffer, for the purpose of passing it to callback as
224 * a substream. Size is maximum size on call, and actual size on return.
226 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
228 size_t max_size = *size;
236 if (*size > max_size) return false;
237 if (!pb_read(stream, buf, 1)) return false;
238 } while (*buf++ & 0x80);
243 return pb_read(stream, buf, 8);
247 return pb_read(stream, buf, 4);
249 default: PB_RETURN_ERROR(stream, "invalid wire_type");
253 /* Decode string length from stream and return a substream with limited length.
254 * Remember to close the substream using pb_close_string_substream().
256 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
259 if (!pb_decode_varint32(stream, &size))
262 *substream = *stream;
263 if (substream->bytes_left < size)
264 PB_RETURN_ERROR(stream, "parent stream too short");
266 substream->bytes_left = size;
267 stream->bytes_left -= size;
271 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
273 stream->state = substream->state;
276 stream->errmsg = substream->errmsg;
280 /* Iterator for pb_field_t list */
282 const pb_field_t *start; /* Start of the pb_field_t array */
283 const pb_field_t *pos; /* Current position of the iterator */
284 unsigned field_index; /* Zero-based index of the field. */
285 unsigned required_field_index; /* Zero-based index that counts only the required fields */
286 void *dest_struct; /* Pointer to the destination structure to decode to */
287 void *pData; /* Pointer where to store current field value */
288 void *pSize; /* Pointer where to store the size of current array field */
289 } pb_field_iterator_t;
291 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
293 iter->start = iter->pos = fields;
294 iter->field_index = 0;
295 iter->required_field_index = 0;
296 iter->pData = (char*)dest_struct + iter->pos->data_offset;
297 iter->pSize = (char*)iter->pData + iter->pos->size_offset;
298 iter->dest_struct = dest_struct;
301 static bool pb_field_next(pb_field_iterator_t *iter)
303 bool notwrapped = true;
304 size_t prev_size = iter->pos->data_size;
306 if (PB_ATYPE(iter->pos->type) == PB_ATYPE_STATIC &&
307 PB_HTYPE(iter->pos->type) == PB_HTYPE_REPEATED)
309 prev_size *= iter->pos->array_size;
312 if (PB_HTYPE(iter->pos->type) == PB_HTYPE_REQUIRED)
313 iter->required_field_index++;
315 if (iter->pos->tag == 0)
316 return false; /* Only happens with empty message types */
320 if (iter->pos->tag == 0)
322 iter->pos = iter->start;
323 iter->field_index = 0;
324 iter->required_field_index = 0;
325 iter->pData = iter->dest_struct;
330 iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
331 iter->pSize = (char*)iter->pData + iter->pos->size_offset;
335 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
337 unsigned start = iter->field_index;
340 if (iter->pos->tag == tag)
343 } while (iter->field_index != start);
348 /*************************
349 * Decode a single field *
350 *************************/
352 static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
357 type = iter->pos->type;
358 func = PB_DECODERS[PB_LTYPE(type)];
360 switch (PB_HTYPE(type))
362 case PB_HTYPE_REQUIRED:
363 return func(stream, iter->pos, iter->pData);
365 case PB_HTYPE_OPTIONAL:
366 *(bool*)iter->pSize = true;
367 return func(stream, iter->pos, iter->pData);
369 case PB_HTYPE_REPEATED:
370 if (wire_type == PB_WT_STRING
371 && PB_LTYPE(type) <= PB_LTYPE_LAST_PACKABLE)
375 size_t *size = (size_t*)iter->pSize;
376 pb_istream_t substream;
377 if (!pb_make_string_substream(stream, &substream))
380 while (substream.bytes_left && *size < iter->pos->array_size)
382 void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
383 if (!func(&substream, iter->pos, pItem))
390 pb_close_string_substream(stream, &substream);
392 if (substream.bytes_left != 0)
393 PB_RETURN_ERROR(stream, "array overflow");
400 size_t *size = (size_t*)iter->pSize;
401 void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
402 if (*size >= iter->pos->array_size)
403 PB_RETURN_ERROR(stream, "array overflow");
406 return func(stream, iter->pos, pItem);
410 PB_RETURN_ERROR(stream, "invalid field type");
414 static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
416 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
418 if (pCallback->funcs.decode == NULL)
419 return pb_skip_field(stream, wire_type);
421 if (wire_type == PB_WT_STRING)
423 pb_istream_t substream;
425 if (!pb_make_string_substream(stream, &substream))
428 while (substream.bytes_left)
430 if (!pCallback->funcs.decode(&substream, iter->pos, pCallback->arg))
431 PB_RETURN_ERROR(stream, "callback failed");
434 pb_close_string_substream(stream, &substream);
439 /* Copy the single scalar value to stack.
440 * This is required so that we can limit the stream length,
441 * which in turn allows to use same callback for packed and
442 * not-packed fields. */
443 pb_istream_t substream;
445 size_t size = sizeof(buffer);
447 if (!read_raw_value(stream, wire_type, buffer, &size))
449 substream = pb_istream_from_buffer(buffer, size);
451 return pCallback->funcs.decode(&substream, iter->pos, pCallback->arg);
455 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
457 switch (PB_ATYPE(iter->pos->type))
459 case PB_ATYPE_STATIC:
460 return decode_static_field(stream, wire_type, iter);
462 case PB_ATYPE_CALLBACK:
463 return decode_callback_field(stream, wire_type, iter);
466 PB_RETURN_ERROR(stream, "invalid field type");
470 /* Initialize message fields to default values, recursively */
471 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
473 pb_field_iterator_t iter;
474 pb_field_init(&iter, fields, dest_struct);
476 /* Initialize size/has fields and apply default values */
480 type = iter.pos->type;
482 if (iter.pos->tag == 0)
485 if (PB_ATYPE(type) == PB_ATYPE_STATIC)
487 /* Initialize the size field for optional/repeated fields to 0. */
488 if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL)
490 *(bool*)iter.pSize = false;
492 else if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
494 *(size_t*)iter.pSize = 0;
495 continue; /* Array is empty, no need to initialize contents */
498 /* Initialize field contents to default value */
499 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_SUBMESSAGE)
501 pb_message_set_to_defaults((const pb_field_t *) iter.pos->ptr, iter.pData);
503 else if (iter.pos->ptr != NULL)
505 memcpy(iter.pData, iter.pos->ptr, iter.pos->data_size);
509 memset(iter.pData, 0, iter.pos->data_size);
512 else if (PB_ATYPE(type) == PB_ATYPE_CALLBACK)
514 continue; /* Don't overwrite callback */
516 } while (pb_field_next(&iter));
519 /*********************
520 * Decode all fields *
521 *********************/
523 bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
525 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
526 pb_field_iterator_t iter;
528 pb_field_init(&iter, fields, dest_struct);
530 while (stream->bytes_left)
533 pb_wire_type_t wire_type;
536 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
544 if (!pb_field_find(&iter, tag))
546 /* No match found, skip data */
547 if (!pb_skip_field(stream, wire_type))
552 if (PB_HTYPE(iter.pos->type) == PB_HTYPE_REQUIRED
553 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
555 fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
558 if (!decode_field(stream, wire_type, &iter))
562 /* Check that all required fields were present. */
564 /* First figure out the number of required fields by
565 * seeking to the end of the field array. Usually we
566 * are already close to end after decoding.
568 unsigned req_field_count;
572 req_field_count = iter.required_field_index;
573 last_type = iter.pos->type;
574 } while (pb_field_next(&iter));
576 /* Fixup if last field was also required. */
577 if (PB_HTYPE(last_type) == PB_HTYPE_REQUIRED && iter.pos->tag)
580 /* Check the whole bytes */
581 for (i = 0; i < (req_field_count >> 3); i++)
583 if (fields_seen[i] != 0xFF)
584 PB_RETURN_ERROR(stream, "missing required field");
587 /* Check the remaining bits */
588 if (fields_seen[req_field_count >> 3] != (0xFF >> (8 - (req_field_count & 7))))
589 PB_RETURN_ERROR(stream, "missing required field");
595 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
597 pb_message_set_to_defaults(fields, dest_struct);
598 return pb_decode_noinit(stream, fields, dest_struct);
603 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
606 if (!pb_decode_varint(stream, &value))
610 *dest = (int64_t)(~(value >> 1));
612 *dest = (int64_t)(value >> 1);
617 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
619 #ifdef __BIG_ENDIAN__
620 uint8_t *bytes = (uint8_t*)dest;
623 if (!pb_read(stream, lebytes, 4))
626 bytes[0] = lebytes[3];
627 bytes[1] = lebytes[2];
628 bytes[2] = lebytes[1];
629 bytes[3] = lebytes[0];
632 return pb_read(stream, (uint8_t*)dest, 4);
636 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
638 #ifdef __BIG_ENDIAN__
639 uint8_t *bytes = (uint8_t*)dest;
642 if (!pb_read(stream, lebytes, 8))
645 bytes[0] = lebytes[7];
646 bytes[1] = lebytes[6];
647 bytes[2] = lebytes[5];
648 bytes[3] = lebytes[4];
649 bytes[4] = lebytes[3];
650 bytes[5] = lebytes[2];
651 bytes[6] = lebytes[1];
652 bytes[7] = lebytes[0];
655 return pb_read(stream, (uint8_t*)dest, 8);
659 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
662 bool status = pb_decode_varint(stream, &value);
664 switch (field->data_size)
666 case 1: *(uint8_t*)dest = (uint8_t)value; break;
667 case 2: *(uint16_t*)dest = (uint16_t)value; break;
668 case 4: *(uint32_t*)dest = (uint32_t)value; break;
669 case 8: *(uint64_t*)dest = value; break;
670 default: PB_RETURN_ERROR(stream, "invalid data_size");
676 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
679 bool status = pb_decode_svarint(stream, &value);
681 switch (field->data_size)
683 case 4: *(int32_t*)dest = (int32_t)value; break;
684 case 8: *(int64_t*)dest = value; break;
685 default: PB_RETURN_ERROR(stream, "invalid data_size");
691 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
694 return pb_decode_fixed32(stream, dest);
697 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
700 return pb_decode_fixed64(stream, dest);
703 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
705 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
708 if (!pb_decode_varint32(stream, &temp))
712 /* Check length, noting the space taken by the size_t header. */
713 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
714 PB_RETURN_ERROR(stream, "bytes overflow");
716 return pb_read(stream, x->bytes, x->size);
719 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
723 if (!pb_decode_varint32(stream, &size))
726 /* Check length, noting the null terminator */
727 if (size + 1 > field->data_size)
728 PB_RETURN_ERROR(stream, "string overflow");
730 status = pb_read(stream, (uint8_t*)dest, size);
731 *((uint8_t*)dest + size) = 0;
735 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
738 pb_istream_t substream;
739 const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
741 if (!pb_make_string_substream(stream, &substream))
744 if (field->ptr == NULL)
745 PB_RETURN_ERROR(stream, "invalid field descriptor");
747 /* New array entries need to be initialized, while required and optional
748 * submessages have already been initialized in the top-level pb_decode. */
749 if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
750 status = pb_decode(&substream, submsg_fields, dest);
752 status = pb_decode_noinit(&substream, submsg_fields, dest);
754 pb_close_string_substream(stream, &substream);