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"
18 typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn;
20 /* --- Function pointers to field decoders ---
21 * Order in the array must match pb_action_t LTYPE numbering.
23 static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = {
38 static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
40 uint8_t *source = (uint8_t*)stream->state;
41 stream->state = source + count;
52 bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
54 #ifndef PB_BUFFER_ONLY
55 if (buf == NULL && stream->callback != buf_read)
57 /* Skip input bytes */
61 if (!pb_read(stream, tmp, 16))
67 return pb_read(stream, tmp, count);
71 if (stream->bytes_left < count)
72 PB_RETURN_ERROR(stream, "end-of-stream");
74 #ifndef PB_BUFFER_ONLY
75 if (!stream->callback(stream, buf, count))
76 PB_RETURN_ERROR(stream, "io error");
78 if (!buf_read(stream, buf, count))
82 stream->bytes_left -= count;
86 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
90 stream.callback = NULL;
92 stream.callback = &buf_read;
95 stream.bytes_left = bufsize;
102 /********************
104 ********************/
106 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
111 if (!pb_read(stream, &byte, 1))
116 /* Quick case, 1 byte value */
123 result = byte & 0x7F;
128 PB_RETURN_ERROR(stream, "varint overflow");
130 if (!pb_read(stream, &byte, 1))
133 result |= (uint32_t)(byte & 0x7F) << bitpos;
134 bitpos = (uint8_t)(bitpos + 7);
135 } while (byte & 0x80);
142 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
151 PB_RETURN_ERROR(stream, "varint overflow");
153 if (!pb_read(stream, &byte, 1))
156 result |= (uint64_t)(byte & 0x7F) << bitpos;
157 bitpos = (uint8_t)(bitpos + 7);
158 } while (byte & 0x80);
164 bool checkreturn pb_skip_varint(pb_istream_t *stream)
169 if (!pb_read(stream, &byte, 1))
171 } while (byte & 0x80);
175 bool checkreturn pb_skip_string(pb_istream_t *stream)
178 if (!pb_decode_varint32(stream, &length))
181 return pb_read(stream, NULL, length);
184 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
188 *wire_type = (pb_wire_type_t) 0;
191 if (!pb_decode_varint32(stream, &temp))
193 if (stream->bytes_left == 0)
201 *eof = true; /* Special feature: allow 0-terminated messages. */
206 *wire_type = (pb_wire_type_t)(temp & 7);
210 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
214 case PB_WT_VARINT: return pb_skip_varint(stream);
215 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
216 case PB_WT_STRING: return pb_skip_string(stream);
217 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
218 default: PB_RETURN_ERROR(stream, "invalid wire_type");
222 /* Read a raw value to buffer, for the purpose of passing it to callback as
223 * a substream. Size is maximum size on call, and actual size on return.
225 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
227 size_t max_size = *size;
235 if (*size > max_size) return false;
236 if (!pb_read(stream, buf, 1)) return false;
237 } while (*buf++ & 0x80);
242 return pb_read(stream, buf, 8);
246 return pb_read(stream, buf, 4);
248 default: PB_RETURN_ERROR(stream, "invalid wire_type");
252 /* Decode string length from stream and return a substream with limited length.
253 * Remember to close the substream using pb_close_string_substream().
255 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
258 if (!pb_decode_varint32(stream, &size))
261 *substream = *stream;
262 if (substream->bytes_left < size)
263 PB_RETURN_ERROR(stream, "parent stream too short");
265 substream->bytes_left = size;
266 stream->bytes_left -= size;
270 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
272 stream->state = substream->state;
275 stream->errmsg = substream->errmsg;
279 /* Iterator for pb_field_t list */
281 const pb_field_t *start; /* Start of the pb_field_t array */
282 const pb_field_t *pos; /* Current position of the iterator */
283 unsigned field_index; /* Zero-based index of the field. */
284 unsigned required_field_index; /* Zero-based index that counts only the required fields */
285 void *dest_struct; /* Pointer to the destination structure to decode to */
286 void *pData; /* Pointer where to store current field value */
287 void *pSize; /* Pointer where to store the size of current array field */
288 } pb_field_iterator_t;
290 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
292 iter->start = iter->pos = fields;
293 iter->field_index = 0;
294 iter->required_field_index = 0;
295 iter->pData = (char*)dest_struct + iter->pos->data_offset;
296 iter->pSize = (char*)iter->pData + iter->pos->size_offset;
297 iter->dest_struct = dest_struct;
300 static bool pb_field_next(pb_field_iterator_t *iter)
302 bool notwrapped = true;
303 size_t prev_size = iter->pos->data_size;
305 if (PB_ATYPE(iter->pos->type) == PB_ATYPE_STATIC &&
306 PB_HTYPE(iter->pos->type) == PB_HTYPE_REPEATED)
308 prev_size *= iter->pos->array_size;
311 if (PB_HTYPE(iter->pos->type) == PB_HTYPE_REQUIRED)
312 iter->required_field_index++;
314 if (iter->pos->tag == 0)
315 return false; /* Only happens with empty message types */
319 if (iter->pos->tag == 0)
321 iter->pos = iter->start;
322 iter->field_index = 0;
323 iter->required_field_index = 0;
324 iter->pData = iter->dest_struct;
329 iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
330 iter->pSize = (char*)iter->pData + iter->pos->size_offset;
334 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
336 unsigned start = iter->field_index;
339 if (iter->pos->tag == tag)
342 } while (iter->field_index != start);
347 /*************************
348 * Decode a single field *
349 *************************/
351 static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
356 type = iter->pos->type;
357 func = PB_DECODERS[PB_LTYPE(type)];
359 switch (PB_HTYPE(type))
361 case PB_HTYPE_REQUIRED:
362 return func(stream, iter->pos, iter->pData);
364 case PB_HTYPE_OPTIONAL:
365 *(bool*)iter->pSize = true;
366 return func(stream, iter->pos, iter->pData);
368 case PB_HTYPE_REPEATED:
369 if (wire_type == PB_WT_STRING
370 && PB_LTYPE(type) <= PB_LTYPE_LAST_PACKABLE)
374 size_t *size = (size_t*)iter->pSize;
375 pb_istream_t substream;
376 if (!pb_make_string_substream(stream, &substream))
379 while (substream.bytes_left && *size < iter->pos->array_size)
381 void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
382 if (!func(&substream, iter->pos, pItem))
389 pb_close_string_substream(stream, &substream);
391 if (substream.bytes_left != 0)
392 PB_RETURN_ERROR(stream, "array overflow");
399 size_t *size = (size_t*)iter->pSize;
400 void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
401 if (*size >= iter->pos->array_size)
402 PB_RETURN_ERROR(stream, "array overflow");
405 return func(stream, iter->pos, pItem);
409 PB_RETURN_ERROR(stream, "invalid field type");
413 static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
415 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
417 #ifdef PB_OLD_CALLBACK_STYLE
418 void *arg = pCallback->arg;
420 void **arg = &(pCallback->arg);
423 if (pCallback->funcs.decode == NULL)
424 return pb_skip_field(stream, wire_type);
426 if (wire_type == PB_WT_STRING)
428 pb_istream_t substream;
430 if (!pb_make_string_substream(stream, &substream))
435 if (!pCallback->funcs.decode(&substream, iter->pos, arg))
436 PB_RETURN_ERROR(stream, "callback failed");
437 } while (substream.bytes_left);
439 pb_close_string_substream(stream, &substream);
444 /* Copy the single scalar value to stack.
445 * This is required so that we can limit the stream length,
446 * which in turn allows to use same callback for packed and
447 * not-packed fields. */
448 pb_istream_t substream;
450 size_t size = sizeof(buffer);
452 if (!read_raw_value(stream, wire_type, buffer, &size))
454 substream = pb_istream_from_buffer(buffer, size);
456 return pCallback->funcs.decode(&substream, iter->pos, arg);
460 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
462 switch (PB_ATYPE(iter->pos->type))
464 case PB_ATYPE_STATIC:
465 return decode_static_field(stream, wire_type, iter);
467 case PB_ATYPE_CALLBACK:
468 return decode_callback_field(stream, wire_type, iter);
471 PB_RETURN_ERROR(stream, "invalid field type");
475 /* Initialize message fields to default values, recursively */
476 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
478 pb_field_iterator_t iter;
479 pb_field_init(&iter, fields, dest_struct);
481 /* Initialize size/has fields and apply default values */
485 type = iter.pos->type;
487 if (iter.pos->tag == 0)
490 if (PB_ATYPE(type) == PB_ATYPE_STATIC)
492 /* Initialize the size field for optional/repeated fields to 0. */
493 if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL)
495 *(bool*)iter.pSize = false;
497 else if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
499 *(size_t*)iter.pSize = 0;
500 continue; /* Array is empty, no need to initialize contents */
503 /* Initialize field contents to default value */
504 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_SUBMESSAGE)
506 pb_message_set_to_defaults((const pb_field_t *) iter.pos->ptr, iter.pData);
508 else if (iter.pos->ptr != NULL)
510 memcpy(iter.pData, iter.pos->ptr, iter.pos->data_size);
514 memset(iter.pData, 0, iter.pos->data_size);
517 else if (PB_ATYPE(type) == PB_ATYPE_CALLBACK)
519 continue; /* Don't overwrite callback */
521 } while (pb_field_next(&iter));
524 /*********************
525 * Decode all fields *
526 *********************/
528 bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
530 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
531 pb_field_iterator_t iter;
533 pb_field_init(&iter, fields, dest_struct);
535 while (stream->bytes_left)
538 pb_wire_type_t wire_type;
541 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
549 if (!pb_field_find(&iter, tag))
551 /* No match found, skip data */
552 if (!pb_skip_field(stream, wire_type))
557 if (PB_HTYPE(iter.pos->type) == PB_HTYPE_REQUIRED
558 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
560 fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
563 if (!decode_field(stream, wire_type, &iter))
567 /* Check that all required fields were present. */
569 /* First figure out the number of required fields by
570 * seeking to the end of the field array. Usually we
571 * are already close to end after decoding.
573 unsigned req_field_count;
577 req_field_count = iter.required_field_index;
578 last_type = iter.pos->type;
579 } while (pb_field_next(&iter));
581 /* Fixup if last field was also required. */
582 if (PB_HTYPE(last_type) == PB_HTYPE_REQUIRED && iter.pos->tag)
585 /* Check the whole bytes */
586 for (i = 0; i < (req_field_count >> 3); i++)
588 if (fields_seen[i] != 0xFF)
589 PB_RETURN_ERROR(stream, "missing required field");
592 /* Check the remaining bits */
593 if (fields_seen[req_field_count >> 3] != (0xFF >> (8 - (req_field_count & 7))))
594 PB_RETURN_ERROR(stream, "missing required field");
600 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
602 pb_message_set_to_defaults(fields, dest_struct);
603 return pb_decode_noinit(stream, fields, dest_struct);
606 bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
608 pb_istream_t substream;
611 if (!pb_make_string_substream(stream, &substream))
614 status = pb_decode(&substream, fields, dest_struct);
615 pb_close_string_substream(stream, &substream);
621 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
624 if (!pb_decode_varint(stream, &value))
628 *dest = (int64_t)(~(value >> 1));
630 *dest = (int64_t)(value >> 1);
635 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
637 #ifdef __BIG_ENDIAN__
638 uint8_t *bytes = (uint8_t*)dest;
641 if (!pb_read(stream, lebytes, 4))
644 bytes[0] = lebytes[3];
645 bytes[1] = lebytes[2];
646 bytes[2] = lebytes[1];
647 bytes[3] = lebytes[0];
650 return pb_read(stream, (uint8_t*)dest, 4);
654 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
656 #ifdef __BIG_ENDIAN__
657 uint8_t *bytes = (uint8_t*)dest;
660 if (!pb_read(stream, lebytes, 8))
663 bytes[0] = lebytes[7];
664 bytes[1] = lebytes[6];
665 bytes[2] = lebytes[5];
666 bytes[3] = lebytes[4];
667 bytes[4] = lebytes[3];
668 bytes[5] = lebytes[2];
669 bytes[6] = lebytes[1];
670 bytes[7] = lebytes[0];
673 return pb_read(stream, (uint8_t*)dest, 8);
677 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
680 if (!pb_decode_varint(stream, &value))
683 switch (field->data_size)
685 case 1: *(uint8_t*)dest = (uint8_t)value; break;
686 case 2: *(uint16_t*)dest = (uint16_t)value; break;
687 case 4: *(uint32_t*)dest = (uint32_t)value; break;
688 case 8: *(uint64_t*)dest = value; break;
689 default: PB_RETURN_ERROR(stream, "invalid data_size");
695 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
698 if (!pb_decode_svarint(stream, &value))
701 switch (field->data_size)
703 case 4: *(int32_t*)dest = (int32_t)value; break;
704 case 8: *(int64_t*)dest = value; break;
705 default: PB_RETURN_ERROR(stream, "invalid data_size");
711 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
714 return pb_decode_fixed32(stream, dest);
717 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
720 return pb_decode_fixed64(stream, dest);
723 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
725 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
728 if (!pb_decode_varint32(stream, &temp))
732 /* Check length, noting the space taken by the size_t header. */
733 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
734 PB_RETURN_ERROR(stream, "bytes overflow");
736 return pb_read(stream, x->bytes, x->size);
739 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
743 if (!pb_decode_varint32(stream, &size))
746 /* Check length, noting the null terminator */
747 if (size + 1 > field->data_size)
748 PB_RETURN_ERROR(stream, "string overflow");
750 status = pb_read(stream, (uint8_t*)dest, size);
751 *((uint8_t*)dest + size) = 0;
755 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
758 pb_istream_t substream;
759 const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
761 if (!pb_make_string_substream(stream, &substream))
764 if (field->ptr == NULL)
765 PB_RETURN_ERROR(stream, "invalid field descriptor");
767 /* New array entries need to be initialized, while required and optional
768 * submessages have already been initialized in the top-level pb_decode. */
769 if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
770 status = pb_decode(&substream, submsg_fields, dest);
772 status = pb_decode_noinit(&substream, submsg_fields, dest);
774 pb_close_string_substream(stream, &substream);