1 /* pb_encode.c -- encode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
10 /* Use the GCC warn_unused_result attribute to check that all return values
11 * are propagated correctly. On other compilers and gcc before 3.4.0 just
12 * ignore the annotation.
14 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
17 #define checkreturn __attribute__((warn_unused_result))
20 /**************************************
21 * Declarations internal to this file *
22 **************************************/
23 typedef bool (*pb_encoder_t)(pb_ostream_t *stream, const pb_field_t *field, const void *src) checkreturn;
25 static bool checkreturn buf_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count);
26 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field, const void *pData, size_t count, pb_encoder_t func);
27 static bool checkreturn encode_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData);
28 static bool checkreturn default_extension_encoder(pb_ostream_t *stream, const pb_extension_t *extension);
29 static bool checkreturn encode_extension_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData);
30 static void *pb_const_cast(const void *p);
31 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
32 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
33 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
34 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
35 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src);
36 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
37 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src);
38 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);
39 static bool checkreturn pb_enc_fixed_length_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
41 /* --- Function pointers to field encoders ---
42 * Order in the array must match pb_action_t LTYPE numbering.
44 static const pb_encoder_t PB_ENCODERS[PB_LTYPES_COUNT] = {
54 NULL, /* extensions */
55 &pb_enc_fixed_length_bytes
58 /*******************************
59 * pb_ostream_t implementation *
60 *******************************/
62 static bool checkreturn buf_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count)
65 pb_byte_t *dest = (pb_byte_t*)stream->state;
66 stream->state = dest + count;
68 for (i = 0; i < count; i++)
74 pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize)
78 stream.callback = (void*)1; /* Just a marker value */
80 stream.callback = &buf_write;
83 stream.max_size = bufsize;
84 stream.bytes_written = 0;
91 bool checkreturn pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count)
93 if (stream->callback != NULL)
95 if (stream->bytes_written + count > stream->max_size)
96 PB_RETURN_ERROR(stream, "stream full");
99 if (!buf_write(stream, buf, count))
100 PB_RETURN_ERROR(stream, "io error");
102 if (!stream->callback(stream, buf, count))
103 PB_RETURN_ERROR(stream, "io error");
107 stream->bytes_written += count;
111 /*************************
112 * Encode a single field *
113 *************************/
115 /* Encode a static array. Handles the size calculations and possible packing. */
116 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
117 const void *pData, size_t count, pb_encoder_t func)
126 if (PB_ATYPE(field->type) != PB_ATYPE_POINTER && count > field->array_size)
127 PB_RETURN_ERROR(stream, "array max size exceeded");
129 /* We always pack arrays if the datatype allows it. */
130 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
132 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
135 /* Determine the total size of packed array. */
136 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
140 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
146 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
148 for (i = 0; i < count; i++)
150 if (!func(&sizestream, field, p))
152 p = (const char*)p + field->data_size;
154 size = sizestream.bytes_written;
157 if (!pb_encode_varint(stream, (uint64_t)size))
160 if (stream->callback == NULL)
161 return pb_write(stream, NULL, size); /* Just sizing.. */
165 for (i = 0; i < count; i++)
167 if (!func(stream, field, p))
169 p = (const char*)p + field->data_size;
175 for (i = 0; i < count; i++)
177 if (!pb_encode_tag_for_field(stream, field))
180 /* Normally the data is stored directly in the array entries, but
181 * for pointer-type string and bytes fields, the array entries are
182 * actually pointers themselves also. So we have to dereference once
183 * more to get to the actual data. */
184 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER &&
185 (PB_LTYPE(field->type) == PB_LTYPE_STRING ||
186 PB_LTYPE(field->type) == PB_LTYPE_BYTES))
188 if (!func(stream, field, *(const void* const*)p))
193 if (!func(stream, field, p))
196 p = (const char*)p + field->data_size;
203 /* In proto3, all fields are optional and are only encoded if their value is "non-zero".
204 * This function implements the check for the zero value. */
205 static bool pb_check_proto3_default_value(const pb_field_t *field, const void *pData)
207 pb_type_t type = field->type;
208 const void *pSize = (const char*)pData + field->size_offset;
210 if (PB_HTYPE(type) == PB_HTYPE_REQUIRED)
212 /* Required proto2 fields inside proto3 submessage, pretty rare case */
215 else if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
217 /* Repeated fields inside proto3 submessage: present if count != 0 */
218 return *(const pb_size_t*)pSize == 0;
220 else if (PB_HTYPE(type) == PB_HTYPE_ONEOF)
223 return *(const pb_size_t*)pSize == 0;
225 else if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL && field->size_offset)
227 /* Proto2 optional fields inside proto3 submessage */
228 return *(const bool*)pSize == false;
231 /* Rest is proto3 singular fields */
233 if (PB_ATYPE(type) == PB_ATYPE_STATIC)
235 if (PB_LTYPE(type) == PB_LTYPE_BYTES)
237 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)pData;
238 return bytes->size == 0;
240 else if (PB_LTYPE(type) == PB_LTYPE_STRING)
242 return *(const char*)pData == '\0';
244 else if (PB_LTYPE(type) == PB_LTYPE_FIXED_LENGTH_BYTES)
246 /* Fixed length bytes is only empty if its length is fixed
247 * as 0. Which would be pretty strange, but we can check
249 return field->data_size == 0;
251 else if (PB_LTYPE(type) == PB_LTYPE_SUBMESSAGE)
253 /* Check all fields in the submessage to find if any of them
254 * are non-zero. The comparison cannot be done byte-per-byte
255 * because the C struct may contain padding bytes that must
258 pb_field_iter_t iter;
259 if (pb_field_iter_begin(&iter, (const pb_field_t*)field->ptr, pb_const_cast(pData)))
263 if (!pb_check_proto3_default_value(iter.pos, iter.pData))
267 } while (pb_field_iter_next(&iter));
274 /* Catch-all branch that does byte-per-byte comparison for zero value.
276 * This is for all pointer fields, and for static PB_LTYPE_VARINT,
277 * UVARINT, SVARINT, FIXED32, FIXED64, EXTENSION fields, and also
278 * callback fields. These all have integer or pointer value which
279 * can be compared with 0.
282 const char *p = (const char*)pData;
283 for (i = 0; i < field->data_size; i++)
295 /* Encode a field with static or pointer allocation, i.e. one whose data
296 * is available to the encoder directly. */
297 static bool checkreturn encode_basic_field(pb_ostream_t *stream,
298 const pb_field_t *field, const void *pData)
302 const void *pSize = &implicit_has;
304 func = PB_ENCODERS[PB_LTYPE(field->type)];
306 if (field->size_offset)
308 /* Static optional, repeated or oneof field */
309 pSize = (const char*)pData + field->size_offset;
311 else if (PB_HTYPE(field->type) == PB_HTYPE_OPTIONAL)
313 /* Proto3 style field, optional but without explicit has_ field. */
314 implicit_has = !pb_check_proto3_default_value(field, pData);
318 /* Required field, always present */
322 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
324 /* pData is a pointer to the field, which contains pointer to
325 * the data. If the 2nd pointer is NULL, it is interpreted as if
326 * the has_field was false.
328 pData = *(const void* const*)pData;
329 implicit_has = (pData != NULL);
332 switch (PB_HTYPE(field->type))
334 case PB_HTYPE_REQUIRED:
336 PB_RETURN_ERROR(stream, "missing required field");
337 if (!pb_encode_tag_for_field(stream, field))
339 if (!func(stream, field, pData))
343 case PB_HTYPE_OPTIONAL:
344 if (*(const bool*)pSize)
346 if (!pb_encode_tag_for_field(stream, field))
349 if (!func(stream, field, pData))
354 case PB_HTYPE_REPEATED:
355 if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func))
360 if (*(const pb_size_t*)pSize == field->tag)
362 if (!pb_encode_tag_for_field(stream, field))
365 if (!func(stream, field, pData))
371 PB_RETURN_ERROR(stream, "invalid field type");
377 /* Encode a field with callback semantics. This means that a user function is
378 * called to provide and encode the actual data. */
379 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
380 const pb_field_t *field, const void *pData)
382 const pb_callback_t *callback = (const pb_callback_t*)pData;
384 #ifdef PB_OLD_CALLBACK_STYLE
385 const void *arg = callback->arg;
387 void * const *arg = &(callback->arg);
390 if (callback->funcs.encode != NULL)
392 if (!callback->funcs.encode(stream, field, arg))
393 PB_RETURN_ERROR(stream, "callback error");
398 /* Encode a single field of any callback or static type. */
399 static bool checkreturn encode_field(pb_ostream_t *stream,
400 const pb_field_t *field, const void *pData)
402 switch (PB_ATYPE(field->type))
404 case PB_ATYPE_STATIC:
405 case PB_ATYPE_POINTER:
406 return encode_basic_field(stream, field, pData);
408 case PB_ATYPE_CALLBACK:
409 return encode_callback_field(stream, field, pData);
412 PB_RETURN_ERROR(stream, "invalid field type");
416 /* Default handler for extension fields. Expects to have a pb_field_t
417 * pointer in the extension->type->arg field. */
418 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
419 const pb_extension_t *extension)
421 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
423 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
425 /* For pointer extensions, the pointer is stored directly
426 * in the extension structure. This avoids having an extra
428 return encode_field(stream, field, &extension->dest);
432 return encode_field(stream, field, extension->dest);
436 /* Walk through all the registered extensions and give them a chance
437 * to encode themselves. */
438 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
439 const pb_field_t *field, const void *pData)
441 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
447 if (extension->type->encode)
448 status = extension->type->encode(stream, extension);
450 status = default_extension_encoder(stream, extension);
455 extension = extension->next;
461 /*********************
462 * Encode all fields *
463 *********************/
465 static void *pb_const_cast(const void *p)
467 /* Note: this casts away const, in order to use the common field iterator
468 * logic for both encoding and decoding. */
477 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
479 pb_field_iter_t iter;
480 if (!pb_field_iter_begin(&iter, fields, pb_const_cast(src_struct)))
481 return true; /* Empty message type */
484 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION)
486 /* Special case for the extension field placeholder */
487 if (!encode_extension_field(stream, iter.pos, iter.pData))
493 if (!encode_field(stream, iter.pos, iter.pData))
496 } while (pb_field_iter_next(&iter));
501 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
503 return pb_encode_submessage(stream, fields, src_struct);
506 bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct)
508 pb_ostream_t stream = PB_OSTREAM_SIZING;
510 if (!pb_encode(&stream, fields, src_struct))
513 *size = stream.bytes_written;
517 /********************
519 ********************/
520 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
522 pb_byte_t buffer[10];
527 pb_byte_t v = (pb_byte_t)value;
528 return pb_write(stream, &v, 1);
533 buffer[i] = (pb_byte_t)((value & 0x7F) | 0x80);
537 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
539 return pb_write(stream, buffer, i);
542 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
546 zigzagged = ~((uint64_t)value << 1);
548 zigzagged = (uint64_t)value << 1;
550 return pb_encode_varint(stream, zigzagged);
553 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
555 uint32_t val = *(const uint32_t*)value;
557 bytes[0] = (pb_byte_t)(val & 0xFF);
558 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
559 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
560 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
561 return pb_write(stream, bytes, 4);
564 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
566 uint64_t val = *(const uint64_t*)value;
568 bytes[0] = (pb_byte_t)(val & 0xFF);
569 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
570 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
571 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
572 bytes[4] = (pb_byte_t)((val >> 32) & 0xFF);
573 bytes[5] = (pb_byte_t)((val >> 40) & 0xFF);
574 bytes[6] = (pb_byte_t)((val >> 48) & 0xFF);
575 bytes[7] = (pb_byte_t)((val >> 56) & 0xFF);
576 return pb_write(stream, bytes, 8);
579 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
581 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
582 return pb_encode_varint(stream, tag);
585 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
587 pb_wire_type_t wiretype;
588 switch (PB_LTYPE(field->type))
590 case PB_LTYPE_VARINT:
591 case PB_LTYPE_UVARINT:
592 case PB_LTYPE_SVARINT:
593 wiretype = PB_WT_VARINT;
596 case PB_LTYPE_FIXED32:
597 wiretype = PB_WT_32BIT;
600 case PB_LTYPE_FIXED64:
601 wiretype = PB_WT_64BIT;
605 case PB_LTYPE_STRING:
606 case PB_LTYPE_SUBMESSAGE:
607 case PB_LTYPE_FIXED_LENGTH_BYTES:
608 wiretype = PB_WT_STRING;
612 PB_RETURN_ERROR(stream, "invalid field type");
615 return pb_encode_tag(stream, wiretype, field->tag);
618 bool checkreturn pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size)
620 if (!pb_encode_varint(stream, (uint64_t)size))
623 return pb_write(stream, buffer, size);
626 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
628 /* First calculate the message size using a non-writing substream. */
629 pb_ostream_t substream = PB_OSTREAM_SIZING;
633 if (!pb_encode(&substream, fields, src_struct))
636 stream->errmsg = substream.errmsg;
641 size = substream.bytes_written;
643 if (!pb_encode_varint(stream, (uint64_t)size))
646 if (stream->callback == NULL)
647 return pb_write(stream, NULL, size); /* Just sizing */
649 if (stream->bytes_written + size > stream->max_size)
650 PB_RETURN_ERROR(stream, "stream full");
652 /* Use a substream to verify that a callback doesn't write more than
653 * what it did the first time. */
654 substream.callback = stream->callback;
655 substream.state = stream->state;
656 substream.max_size = size;
657 substream.bytes_written = 0;
659 substream.errmsg = NULL;
662 status = pb_encode(&substream, fields, src_struct);
664 stream->bytes_written += substream.bytes_written;
665 stream->state = substream.state;
667 stream->errmsg = substream.errmsg;
670 if (substream.bytes_written != size)
671 PB_RETURN_ERROR(stream, "submsg size changed");
678 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
682 if (field->data_size == sizeof(int_least8_t))
683 value = *(const int_least8_t*)src;
684 else if (field->data_size == sizeof(int_least16_t))
685 value = *(const int_least16_t*)src;
686 else if (field->data_size == sizeof(int32_t))
687 value = *(const int32_t*)src;
688 else if (field->data_size == sizeof(int64_t))
689 value = *(const int64_t*)src;
691 PB_RETURN_ERROR(stream, "invalid data_size");
693 return pb_encode_varint(stream, (uint64_t)value);
696 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
700 if (field->data_size == sizeof(uint_least8_t))
701 value = *(const uint_least8_t*)src;
702 else if (field->data_size == sizeof(uint_least16_t))
703 value = *(const uint_least16_t*)src;
704 else if (field->data_size == sizeof(uint32_t))
705 value = *(const uint32_t*)src;
706 else if (field->data_size == sizeof(uint64_t))
707 value = *(const uint64_t*)src;
709 PB_RETURN_ERROR(stream, "invalid data_size");
711 return pb_encode_varint(stream, value);
714 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
718 if (field->data_size == sizeof(int_least8_t))
719 value = *(const int_least8_t*)src;
720 else if (field->data_size == sizeof(int_least16_t))
721 value = *(const int_least16_t*)src;
722 else if (field->data_size == sizeof(int32_t))
723 value = *(const int32_t*)src;
724 else if (field->data_size == sizeof(int64_t))
725 value = *(const int64_t*)src;
727 PB_RETURN_ERROR(stream, "invalid data_size");
729 return pb_encode_svarint(stream, value);
732 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
735 return pb_encode_fixed64(stream, src);
738 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
741 return pb_encode_fixed32(stream, src);
744 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
746 const pb_bytes_array_t *bytes = NULL;
748 bytes = (const pb_bytes_array_t*)src;
752 /* Treat null pointer as an empty bytes field */
753 return pb_encode_string(stream, NULL, 0);
756 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
757 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
759 PB_RETURN_ERROR(stream, "bytes size exceeded");
762 return pb_encode_string(stream, bytes->bytes, bytes->size);
765 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
768 size_t max_size = field->data_size;
769 const char *p = (const char*)src;
771 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
772 max_size = (size_t)-1;
776 size = 0; /* Treat null pointer as an empty string */
780 /* strnlen() is not always available, so just use a loop */
781 while (size < max_size && *p != '\0')
788 return pb_encode_string(stream, (const pb_byte_t*)src, size);
791 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
793 if (field->ptr == NULL)
794 PB_RETURN_ERROR(stream, "invalid field descriptor");
796 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);
799 static bool checkreturn pb_enc_fixed_length_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
801 return pb_encode_string(stream, (const pb_byte_t*)src, field->data_size);