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 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
31 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
32 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
33 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
34 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src);
35 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
36 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src);
37 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);
39 /* --- Function pointers to field encoders ---
40 * Order in the array must match pb_action_t LTYPE numbering.
42 static const pb_encoder_t PB_ENCODERS[PB_LTYPES_COUNT] = {
52 NULL, /* extensions */
53 &pb_enc_bytes /* PB_LTYPE_FIXED_LENGTH_BYTES */
56 /*******************************
57 * pb_ostream_t implementation *
58 *******************************/
60 static bool checkreturn buf_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count)
62 pb_byte_t *dest = (pb_byte_t*)stream->state;
63 stream->state = dest + count;
71 pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize)
75 stream.callback = (void*)1; /* Just a marker value */
77 stream.callback = &buf_write;
80 stream.max_size = bufsize;
81 stream.bytes_written = 0;
88 bool checkreturn pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count)
90 if (stream->callback != NULL)
92 if (stream->bytes_written + count > stream->max_size)
93 PB_RETURN_ERROR(stream, "stream full");
96 if (!buf_write(stream, buf, count))
97 PB_RETURN_ERROR(stream, "io error");
99 if (!stream->callback(stream, buf, count))
100 PB_RETURN_ERROR(stream, "io error");
104 stream->bytes_written += count;
108 /*************************
109 * Encode a single field *
110 *************************/
112 /* Encode a static array. Handles the size calculations and possible packing. */
113 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
114 const void *pData, size_t count, pb_encoder_t func)
123 if (PB_ATYPE(field->type) != PB_ATYPE_POINTER && count > field->array_size)
124 PB_RETURN_ERROR(stream, "array max size exceeded");
126 /* We always pack arrays if the datatype allows it. */
127 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
129 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
132 /* Determine the total size of packed array. */
133 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
137 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
143 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
145 for (i = 0; i < count; i++)
147 if (!func(&sizestream, field, p))
149 p = (const char*)p + field->data_size;
151 size = sizestream.bytes_written;
154 if (!pb_encode_varint(stream, (uint64_t)size))
157 if (stream->callback == NULL)
158 return pb_write(stream, NULL, size); /* Just sizing.. */
162 for (i = 0; i < count; i++)
164 if (!func(stream, field, p))
166 p = (const char*)p + field->data_size;
172 for (i = 0; i < count; i++)
174 if (!pb_encode_tag_for_field(stream, field))
177 /* Normally the data is stored directly in the array entries, but
178 * for pointer-type string and bytes fields, the array entries are
179 * actually pointers themselves also. So we have to dereference once
180 * more to get to the actual data. */
181 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER &&
182 (PB_LTYPE(field->type) == PB_LTYPE_STRING ||
183 PB_LTYPE(field->type) == PB_LTYPE_BYTES))
185 if (!func(stream, field, *(const void* const*)p))
190 if (!func(stream, field, p))
193 p = (const char*)p + field->data_size;
200 /* In proto3, all fields are optional and are only encoded if their value is "non-zero".
201 * This function implements the check for the zero value. */
202 static bool pb_check_proto3_default_value(const pb_field_t *field, const void *pData)
204 if(PB_LTYPE(field->type) == PB_LTYPE_BYTES)
206 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)pData;
207 return bytes->size == 0;
209 else if (PB_LTYPE(field->type) == PB_LTYPE_STRING)
211 return *(const char*)pData == '\0';
213 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED_LENGTH_BYTES)
215 /* Fixed length bytes is only empty if its length is fixed
216 * as 0. Which would be pretty strange, but we can check
218 return field->data_size == 0;
222 /* PB_LTYPE_VARINT, UVARINT, SVARINT, FIXED32, FIXED64,
223 * SUBMESSAGE, EXTENSION: These all have integer or pointer
224 * value which can be compared with 0. This does the check
225 * byte-by-byte to avoid the switch-cast logic used in
226 * pb_enc_varint(). (Casting to char* is safe with regards
227 * to C strict aliasing rules.)
230 const char *p = (const char*)pData;
231 for (i = 0; i < field->data_size; i++)
243 /* Encode a field with static or pointer allocation, i.e. one whose data
244 * is available to the encoder directly. */
245 static bool checkreturn encode_basic_field(pb_ostream_t *stream,
246 const pb_field_t *field, const void *pData)
250 const void *pSize = &implicit_has;
252 func = PB_ENCODERS[PB_LTYPE(field->type)];
254 if (field->size_offset)
256 /* Static optional, repeated or oneof field */
257 pSize = (const char*)pData + field->size_offset;
259 else if (PB_HTYPE(field->type) == PB_HTYPE_OPTIONAL)
261 /* Proto3 style field, optional but without explicit has_ field. */
262 implicit_has = !pb_check_proto3_default_value(field, pData);
266 /* Required field, always present */
270 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
272 /* pData is a pointer to the field, which contains pointer to
273 * the data. If the 2nd pointer is NULL, it is interpreted as if
274 * the has_field was false.
276 pData = *(const void* const*)pData;
277 implicit_has = (pData != NULL);
280 switch (PB_HTYPE(field->type))
282 case PB_HTYPE_REQUIRED:
284 PB_RETURN_ERROR(stream, "missing required field");
285 if (!pb_encode_tag_for_field(stream, field))
287 if (!func(stream, field, pData))
291 case PB_HTYPE_OPTIONAL:
292 if (*(const bool*)pSize)
294 if (!pb_encode_tag_for_field(stream, field))
297 if (!func(stream, field, pData))
302 case PB_HTYPE_REPEATED:
303 if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func))
308 if (*(const pb_size_t*)pSize == field->tag)
310 if (!pb_encode_tag_for_field(stream, field))
313 if (!func(stream, field, pData))
319 PB_RETURN_ERROR(stream, "invalid field type");
325 /* Encode a field with callback semantics. This means that a user function is
326 * called to provide and encode the actual data. */
327 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
328 const pb_field_t *field, const void *pData)
330 const pb_callback_t *callback = (const pb_callback_t*)pData;
332 #ifdef PB_OLD_CALLBACK_STYLE
333 const void *arg = callback->arg;
335 void * const *arg = &(callback->arg);
338 if (callback->funcs.encode != NULL)
340 if (!callback->funcs.encode(stream, field, arg))
341 PB_RETURN_ERROR(stream, "callback error");
346 /* Encode a single field of any callback or static type. */
347 static bool checkreturn encode_field(pb_ostream_t *stream,
348 const pb_field_t *field, const void *pData)
350 switch (PB_ATYPE(field->type))
352 case PB_ATYPE_STATIC:
353 case PB_ATYPE_POINTER:
354 return encode_basic_field(stream, field, pData);
356 case PB_ATYPE_CALLBACK:
357 return encode_callback_field(stream, field, pData);
360 PB_RETURN_ERROR(stream, "invalid field type");
364 /* Default handler for extension fields. Expects to have a pb_field_t
365 * pointer in the extension->type->arg field. */
366 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
367 const pb_extension_t *extension)
369 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
371 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
373 /* For pointer extensions, the pointer is stored directly
374 * in the extension structure. This avoids having an extra
376 return encode_field(stream, field, &extension->dest);
380 return encode_field(stream, field, extension->dest);
384 /* Walk through all the registered extensions and give them a chance
385 * to encode themselves. */
386 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
387 const pb_field_t *field, const void *pData)
389 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
395 if (extension->type->encode)
396 status = extension->type->encode(stream, extension);
398 status = default_extension_encoder(stream, extension);
403 extension = extension->next;
409 /*********************
410 * Encode all fields *
411 *********************/
413 static void *remove_const(const void *p)
415 /* Note: this casts away const, in order to use the common field iterator
416 * logic for both encoding and decoding. */
425 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
427 pb_field_iter_t iter;
428 if (!pb_field_iter_begin(&iter, fields, remove_const(src_struct)))
429 return true; /* Empty message type */
432 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION)
434 /* Special case for the extension field placeholder */
435 if (!encode_extension_field(stream, iter.pos, iter.pData))
441 if (!encode_field(stream, iter.pos, iter.pData))
444 } while (pb_field_iter_next(&iter));
449 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
451 return pb_encode_submessage(stream, fields, src_struct);
454 bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct)
456 pb_ostream_t stream = PB_OSTREAM_SIZING;
458 if (!pb_encode(&stream, fields, src_struct))
461 *size = stream.bytes_written;
465 /********************
467 ********************/
468 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
470 pb_byte_t buffer[10];
475 pb_byte_t v = (pb_byte_t)value;
476 return pb_write(stream, &v, 1);
481 buffer[i] = (pb_byte_t)((value & 0x7F) | 0x80);
485 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
487 return pb_write(stream, buffer, i);
490 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
494 zigzagged = ~((uint64_t)value << 1);
496 zigzagged = (uint64_t)value << 1;
498 return pb_encode_varint(stream, zigzagged);
501 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
503 uint32_t val = *(const uint32_t*)value;
505 bytes[0] = (pb_byte_t)(val & 0xFF);
506 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
507 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
508 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
509 return pb_write(stream, bytes, 4);
512 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
514 uint64_t val = *(const uint64_t*)value;
516 bytes[0] = (pb_byte_t)(val & 0xFF);
517 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
518 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
519 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
520 bytes[4] = (pb_byte_t)((val >> 32) & 0xFF);
521 bytes[5] = (pb_byte_t)((val >> 40) & 0xFF);
522 bytes[6] = (pb_byte_t)((val >> 48) & 0xFF);
523 bytes[7] = (pb_byte_t)((val >> 56) & 0xFF);
524 return pb_write(stream, bytes, 8);
527 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
529 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
530 return pb_encode_varint(stream, tag);
533 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
535 pb_wire_type_t wiretype;
536 switch (PB_LTYPE(field->type))
538 case PB_LTYPE_VARINT:
539 case PB_LTYPE_UVARINT:
540 case PB_LTYPE_SVARINT:
541 wiretype = PB_WT_VARINT;
544 case PB_LTYPE_FIXED32:
545 wiretype = PB_WT_32BIT;
548 case PB_LTYPE_FIXED64:
549 wiretype = PB_WT_64BIT;
553 case PB_LTYPE_STRING:
554 case PB_LTYPE_SUBMESSAGE:
555 case PB_LTYPE_FIXED_LENGTH_BYTES:
556 wiretype = PB_WT_STRING;
560 PB_RETURN_ERROR(stream, "invalid field type");
563 return pb_encode_tag(stream, wiretype, field->tag);
566 bool checkreturn pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size)
568 if (!pb_encode_varint(stream, (uint64_t)size))
571 return pb_write(stream, buffer, size);
574 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
576 /* First calculate the message size using a non-writing substream. */
577 pb_ostream_t substream = PB_OSTREAM_SIZING;
581 if (!pb_encode(&substream, fields, src_struct))
584 stream->errmsg = substream.errmsg;
589 size = substream.bytes_written;
591 if (!pb_encode_varint(stream, (uint64_t)size))
594 if (stream->callback == NULL)
595 return pb_write(stream, NULL, size); /* Just sizing */
597 if (stream->bytes_written + size > stream->max_size)
598 PB_RETURN_ERROR(stream, "stream full");
600 /* Use a substream to verify that a callback doesn't write more than
601 * what it did the first time. */
602 substream.callback = stream->callback;
603 substream.state = stream->state;
604 substream.max_size = size;
605 substream.bytes_written = 0;
607 substream.errmsg = NULL;
610 status = pb_encode(&substream, fields, src_struct);
612 stream->bytes_written += substream.bytes_written;
613 stream->state = substream.state;
615 stream->errmsg = substream.errmsg;
618 if (substream.bytes_written != size)
619 PB_RETURN_ERROR(stream, "submsg size changed");
626 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
630 if (field->data_size == sizeof(int_least8_t))
631 value = *(const int_least8_t*)src;
632 else if (field->data_size == sizeof(int_least16_t))
633 value = *(const int_least16_t*)src;
634 else if (field->data_size == sizeof(int32_t))
635 value = *(const int32_t*)src;
636 else if (field->data_size == sizeof(int64_t))
637 value = *(const int64_t*)src;
639 PB_RETURN_ERROR(stream, "invalid data_size");
641 return pb_encode_varint(stream, (uint64_t)value);
644 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
648 if (field->data_size == sizeof(uint_least8_t))
649 value = *(const uint_least8_t*)src;
650 else if (field->data_size == sizeof(uint_least16_t))
651 value = *(const uint_least16_t*)src;
652 else if (field->data_size == sizeof(uint32_t))
653 value = *(const uint32_t*)src;
654 else if (field->data_size == sizeof(uint64_t))
655 value = *(const uint64_t*)src;
657 PB_RETURN_ERROR(stream, "invalid data_size");
659 return pb_encode_varint(stream, value);
662 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
666 if (field->data_size == sizeof(int_least8_t))
667 value = *(const int_least8_t*)src;
668 else if (field->data_size == sizeof(int_least16_t))
669 value = *(const int_least16_t*)src;
670 else if (field->data_size == sizeof(int32_t))
671 value = *(const int32_t*)src;
672 else if (field->data_size == sizeof(int64_t))
673 value = *(const int64_t*)src;
675 PB_RETURN_ERROR(stream, "invalid data_size");
677 return pb_encode_svarint(stream, value);
680 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
683 return pb_encode_fixed64(stream, src);
686 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
689 return pb_encode_fixed32(stream, src);
692 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
694 const pb_bytes_array_t *bytes = NULL;
696 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED_LENGTH_BYTES)
697 return pb_encode_string(stream, (const pb_byte_t*)src, field->data_size);
699 bytes = (const pb_bytes_array_t*)src;
703 /* Treat null pointer as an empty bytes field */
704 return pb_encode_string(stream, NULL, 0);
707 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
708 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
710 PB_RETURN_ERROR(stream, "bytes size exceeded");
713 return pb_encode_string(stream, bytes->bytes, bytes->size);
716 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
719 size_t max_size = field->data_size;
720 const char *p = (const char*)src;
722 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
723 max_size = (size_t)-1;
727 size = 0; /* Treat null pointer as an empty string */
731 /* strnlen() is not always available, so just use a loop */
732 while (size < max_size && *p != '\0')
739 return pb_encode_string(stream, (const pb_byte_t*)src, size);
742 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
744 if (field->ptr == NULL)
745 PB_RETURN_ERROR(stream, "invalid field descriptor");
747 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);