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 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);
70 if (stream->bytes_left < count)
71 PB_RETURN_ERROR(stream, "end-of-stream");
73 if (!stream->callback(stream, buf, count))
74 PB_RETURN_ERROR(stream, "io error");
76 stream->bytes_left -= count;
80 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
83 stream.callback = &buf_read;
85 stream.bytes_left = bufsize;
96 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
99 bool status = pb_decode_varint(stream, &temp);
100 *dest = (uint32_t)temp;
104 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
110 while (bitpos < 64 && pb_read(stream, &byte, 1))
112 *dest |= (uint64_t)(byte & 0x7F) << bitpos;
119 PB_RETURN_ERROR(stream, "varint overflow");
122 bool checkreturn pb_skip_varint(pb_istream_t *stream)
127 if (!pb_read(stream, &byte, 1))
129 } while (byte & 0x80);
133 bool checkreturn pb_skip_string(pb_istream_t *stream)
136 if (!pb_decode_varint32(stream, &length))
139 return pb_read(stream, NULL, length);
142 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
146 *wire_type = (pb_wire_type_t) 0;
149 if (!pb_decode_varint32(stream, &temp))
151 if (stream->bytes_left == 0)
159 *eof = true; /* Special feature: allow 0-terminated messages. */
164 *wire_type = (pb_wire_type_t)(temp & 7);
168 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
172 case PB_WT_VARINT: return pb_skip_varint(stream);
173 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
174 case PB_WT_STRING: return pb_skip_string(stream);
175 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
176 default: PB_RETURN_ERROR(stream, "invalid wire_type");
180 /* Read a raw value to buffer, for the purpose of passing it to callback as
181 * a substream. Size is maximum size on call, and actual size on return.
183 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
185 size_t max_size = *size;
193 if (*size > max_size) return false;
194 if (!pb_read(stream, buf, 1)) return false;
195 } while (*buf++ & 0x80);
200 return pb_read(stream, buf, 8);
204 return pb_read(stream, buf, 4);
206 default: PB_RETURN_ERROR(stream, "invalid wire_type");
210 /* Decode string length from stream and return a substream with limited length.
211 * Remember to close the substream using pb_close_string_substream().
213 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
216 if (!pb_decode_varint32(stream, &size))
219 *substream = *stream;
220 if (substream->bytes_left < size)
221 PB_RETURN_ERROR(stream, "parent stream too short");
223 substream->bytes_left = size;
224 stream->bytes_left -= size;
228 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
230 stream->state = substream->state;
233 stream->errmsg = substream->errmsg;
237 /* Iterator for pb_field_t list */
239 const pb_field_t *start; /* Start of the pb_field_t array */
240 const pb_field_t *current; /* Current position of the iterator */
241 int field_index; /* Zero-based index of the field. */
242 int required_field_index; /* Zero-based index that counts only the required fields */
243 void *dest_struct; /* Pointer to the destination structure to decode to */
244 void *pData; /* Pointer where to store current field value */
245 void *pSize; /* Pointer where to store the size of current array field */
246 } pb_field_iterator_t;
248 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
250 iter->start = iter->current = fields;
251 iter->field_index = 0;
252 iter->required_field_index = 0;
253 iter->pData = (char*)dest_struct + iter->current->data_offset;
254 iter->pSize = (char*)iter->pData + iter->current->size_offset;
255 iter->dest_struct = dest_struct;
258 static bool pb_field_next(pb_field_iterator_t *iter)
260 bool notwrapped = true;
261 size_t prev_size = iter->current->data_size;
263 if (PB_HTYPE(iter->current->type) == PB_HTYPE_ARRAY)
264 prev_size *= iter->current->array_size;
266 if (PB_HTYPE(iter->current->type) == PB_HTYPE_REQUIRED)
267 iter->required_field_index++;
271 if (iter->current->tag == 0)
273 iter->current = iter->start;
274 iter->field_index = 0;
275 iter->required_field_index = 0;
276 iter->pData = iter->dest_struct;
281 iter->pData = (char*)iter->pData + prev_size + iter->current->data_offset;
282 iter->pSize = (char*)iter->pData + iter->current->size_offset;
286 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
288 int start = iter->field_index;
291 if (iter->current->tag == tag)
294 } while (iter->field_index != start);
299 /*************************
300 * Decode a single field *
301 *************************/
303 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
305 pb_decoder_t func = PB_DECODERS[PB_LTYPE(iter->current->type)];
307 switch (PB_HTYPE(iter->current->type))
309 case PB_HTYPE_REQUIRED:
310 return func(stream, iter->current, iter->pData);
312 case PB_HTYPE_OPTIONAL:
313 *(bool*)iter->pSize = true;
314 return func(stream, iter->current, iter->pData);
317 if (wire_type == PB_WT_STRING
318 && PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE)
322 size_t *size = (size_t*)iter->pSize;
323 pb_istream_t substream;
324 if (!pb_make_string_substream(stream, &substream))
327 while (substream.bytes_left && *size < iter->current->array_size)
329 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
330 if (!func(&substream, iter->current, pItem))
334 status = (substream.bytes_left == 0);
335 pb_close_string_substream(stream, &substream);
341 size_t *size = (size_t*)iter->pSize;
342 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
343 if (*size >= iter->current->array_size)
344 PB_RETURN_ERROR(stream, "array overflow");
347 return func(stream, iter->current, pItem);
350 case PB_HTYPE_CALLBACK:
352 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
354 if (pCallback->funcs.decode == NULL)
355 return pb_skip_field(stream, wire_type);
357 if (wire_type == PB_WT_STRING)
359 pb_istream_t substream;
361 if (!pb_make_string_substream(stream, &substream))
364 while (substream.bytes_left)
366 if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
367 PB_RETURN_ERROR(stream, "callback failed");
370 pb_close_string_substream(stream, &substream);
375 /* Copy the single scalar value to stack.
376 * This is required so that we can limit the stream length,
377 * which in turn allows to use same callback for packed and
378 * not-packed fields. */
379 pb_istream_t substream;
381 size_t size = sizeof(buffer);
383 if (!read_raw_value(stream, wire_type, buffer, &size))
385 substream = pb_istream_from_buffer(buffer, size);
387 return pCallback->funcs.decode(&substream, iter->current, pCallback->arg);
392 PB_RETURN_ERROR(stream, "invalid field type");
396 /* Initialize message fields to default values, recursively */
397 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
399 pb_field_iterator_t iter;
400 pb_field_init(&iter, fields, dest_struct);
402 /* Initialize size/has fields and apply default values */
405 if (iter.current->tag == 0)
408 /* Initialize the size field for optional/repeated fields to 0. */
409 if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL)
411 *(bool*)iter.pSize = false;
413 else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY)
415 *(size_t*)iter.pSize = 0;
416 continue; /* Array is empty, no need to initialize contents */
419 /* Initialize field contents to default value */
420 if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK)
422 continue; /* Don't overwrite callback */
424 else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
426 pb_message_set_to_defaults((const pb_field_t *) iter.current->ptr, iter.pData);
428 else if (iter.current->ptr != NULL)
430 memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
434 memset(iter.pData, 0, iter.current->data_size);
436 } while (pb_field_next(&iter));
439 /*********************
440 * Decode all fields *
441 *********************/
443 bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
445 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
446 pb_field_iterator_t iter;
448 pb_field_init(&iter, fields, dest_struct);
450 while (stream->bytes_left)
453 pb_wire_type_t wire_type;
456 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
464 if (!pb_field_find(&iter, tag))
466 /* No match found, skip data */
467 if (!pb_skip_field(stream, wire_type))
472 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED
473 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
475 fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
478 if (!decode_field(stream, wire_type, &iter))
482 /* Check that all required fields were present. */
483 pb_field_init(&iter, fields, dest_struct);
485 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED &&
486 iter.required_field_index < PB_MAX_REQUIRED_FIELDS &&
487 !(fields_seen[iter.required_field_index >> 3] & (1 << (iter.required_field_index & 7))))
489 PB_RETURN_ERROR(stream, "missing required field");
491 } while (pb_field_next(&iter));
496 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
498 pb_message_set_to_defaults(fields, dest_struct);
499 return pb_decode_noinit(stream, fields, dest_struct);
504 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
507 if (!pb_decode_varint(stream, &value))
511 *dest = (int64_t)(~(value >> 1));
513 *dest = (int64_t)(value >> 1);
518 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
520 #ifdef __BIG_ENDIAN__
521 uint8_t *bytes = (uint8_t*)dest;
524 if (!pb_read(stream, lebytes, 4))
527 bytes[0] = lebytes[3];
528 bytes[1] = lebytes[2];
529 bytes[2] = lebytes[1];
530 bytes[3] = lebytes[0];
533 return pb_read(stream, (uint8_t*)dest, 4);
537 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
539 #ifdef __BIG_ENDIAN__
540 uint8_t *bytes = (uint8_t*)dest;
543 if (!pb_read(stream, lebytes, 8))
546 bytes[0] = lebytes[7];
547 bytes[1] = lebytes[6];
548 bytes[2] = lebytes[5];
549 bytes[3] = lebytes[4];
550 bytes[4] = lebytes[3];
551 bytes[5] = lebytes[2];
552 bytes[6] = lebytes[1];
553 bytes[7] = lebytes[0];
556 return pb_read(stream, (uint8_t*)dest, 8);
560 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
563 bool status = pb_decode_varint(stream, &value);
565 switch (field->data_size)
567 case 1: *(uint8_t*)dest = (uint8_t)value; break;
568 case 2: *(uint16_t*)dest = (uint16_t)value; break;
569 case 4: *(uint32_t*)dest = (uint32_t)value; break;
570 case 8: *(uint64_t*)dest = value; break;
571 default: PB_RETURN_ERROR(stream, "invalid data_size");
577 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
580 bool status = pb_decode_svarint(stream, &value);
582 switch (field->data_size)
584 case 4: *(int32_t*)dest = (int32_t)value; break;
585 case 8: *(int64_t*)dest = value; break;
586 default: PB_RETURN_ERROR(stream, "invalid data_size");
592 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
595 return pb_decode_fixed32(stream, dest);
598 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
601 return pb_decode_fixed64(stream, dest);
604 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
606 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
609 if (!pb_decode_varint32(stream, &temp))
613 /* Check length, noting the space taken by the size_t header. */
614 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
615 PB_RETURN_ERROR(stream, "bytes overflow");
617 return pb_read(stream, x->bytes, x->size);
620 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
624 if (!pb_decode_varint32(stream, &size))
627 /* Check length, noting the null terminator */
628 if (size + 1 > field->data_size)
629 PB_RETURN_ERROR(stream, "string overflow");
631 status = pb_read(stream, (uint8_t*)dest, size);
632 *((uint8_t*)dest + size) = 0;
636 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
639 pb_istream_t substream;
640 const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
642 if (!pb_make_string_substream(stream, &substream))
645 if (field->ptr == NULL)
646 PB_RETURN_ERROR(stream, "invalid field descriptor");
648 /* New array entries need to be initialized, while required and optional
649 * submessages have already been initialized in the top-level pb_decode. */
650 if (PB_HTYPE(field->type) == PB_HTYPE_ARRAY)
651 status = pb_decode(&substream, submsg_fields, dest);
653 status = pb_decode_noinit(&substream, submsg_fields, dest);
655 pb_close_string_substream(stream, &substream);