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)
63 pb_byte_t *dest = (pb_byte_t*)stream->state;
64 stream->state = dest + count;
66 for (i = 0; i < count; i++)
72 pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize)
76 stream.callback = (void*)1; /* Just a marker value */
78 stream.callback = &buf_write;
81 stream.max_size = bufsize;
82 stream.bytes_written = 0;
89 bool checkreturn pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count)
91 if (stream->callback != NULL)
93 if (stream->bytes_written + count > stream->max_size)
94 PB_RETURN_ERROR(stream, "stream full");
97 if (!buf_write(stream, buf, count))
98 PB_RETURN_ERROR(stream, "io error");
100 if (!stream->callback(stream, buf, count))
101 PB_RETURN_ERROR(stream, "io error");
105 stream->bytes_written += count;
109 /*************************
110 * Encode a single field *
111 *************************/
113 /* Encode a static array. Handles the size calculations and possible packing. */
114 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
115 const void *pData, size_t count, pb_encoder_t func)
124 if (PB_ATYPE(field->type) != PB_ATYPE_POINTER && count > field->array_size)
125 PB_RETURN_ERROR(stream, "array max size exceeded");
127 /* We always pack arrays if the datatype allows it. */
128 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
130 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
133 /* Determine the total size of packed array. */
134 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
138 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
144 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
146 for (i = 0; i < count; i++)
148 if (!func(&sizestream, field, p))
150 p = (const char*)p + field->data_size;
152 size = sizestream.bytes_written;
155 if (!pb_encode_varint(stream, (uint64_t)size))
158 if (stream->callback == NULL)
159 return pb_write(stream, NULL, size); /* Just sizing.. */
163 for (i = 0; i < count; i++)
165 if (!func(stream, field, p))
167 p = (const char*)p + field->data_size;
173 for (i = 0; i < count; i++)
175 if (!pb_encode_tag_for_field(stream, field))
178 /* Normally the data is stored directly in the array entries, but
179 * for pointer-type string and bytes fields, the array entries are
180 * actually pointers themselves also. So we have to dereference once
181 * more to get to the actual data. */
182 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER &&
183 (PB_LTYPE(field->type) == PB_LTYPE_STRING ||
184 PB_LTYPE(field->type) == PB_LTYPE_BYTES))
186 if (!func(stream, field, *(const void* const*)p))
191 if (!func(stream, field, p))
194 p = (const char*)p + field->data_size;
201 /* In proto3, all fields are optional and are only encoded if their value is "non-zero".
202 * This function implements the check for the zero value. */
203 static bool pb_check_proto3_default_value(const pb_field_t *field, const void *pData)
205 if(PB_LTYPE(field->type) == PB_LTYPE_BYTES)
207 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)pData;
208 return bytes->size == 0;
210 else if (PB_LTYPE(field->type) == PB_LTYPE_STRING)
212 return *(const char*)pData == '\0';
214 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED_LENGTH_BYTES)
216 /* Fixed length bytes is only empty if its length is fixed
217 * as 0. Which would be pretty strange, but we can check
219 return field->data_size == 0;
223 /* PB_LTYPE_VARINT, UVARINT, SVARINT, FIXED32, FIXED64,
224 * SUBMESSAGE, EXTENSION: These all have integer or pointer
225 * value which can be compared with 0. This does the check
226 * byte-by-byte to avoid the switch-cast logic used in
227 * pb_enc_varint(). (Casting to char* is safe with regards
228 * to C strict aliasing rules.)
231 const char *p = (const char*)pData;
232 for (i = 0; i < field->data_size; i++)
244 /* Encode a field with static or pointer allocation, i.e. one whose data
245 * is available to the encoder directly. */
246 static bool checkreturn encode_basic_field(pb_ostream_t *stream,
247 const pb_field_t *field, const void *pData)
251 const void *pSize = &implicit_has;
253 func = PB_ENCODERS[PB_LTYPE(field->type)];
255 if (field->size_offset)
257 /* Static optional, repeated or oneof field */
258 pSize = (const char*)pData + field->size_offset;
260 else if (PB_HTYPE(field->type) == PB_HTYPE_OPTIONAL)
262 /* Proto3 style field, optional but without explicit has_ field. */
263 implicit_has = !pb_check_proto3_default_value(field, pData);
267 /* Required field, always present */
271 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
273 /* pData is a pointer to the field, which contains pointer to
274 * the data. If the 2nd pointer is NULL, it is interpreted as if
275 * the has_field was false.
277 pData = *(const void* const*)pData;
278 implicit_has = (pData != NULL);
281 switch (PB_HTYPE(field->type))
283 case PB_HTYPE_REQUIRED:
285 PB_RETURN_ERROR(stream, "missing required field");
286 if (!pb_encode_tag_for_field(stream, field))
288 if (!func(stream, field, pData))
292 case PB_HTYPE_OPTIONAL:
293 if (*(const bool*)pSize)
295 if (!pb_encode_tag_for_field(stream, field))
298 if (!func(stream, field, pData))
303 case PB_HTYPE_REPEATED:
304 if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func))
309 if (*(const pb_size_t*)pSize == field->tag)
311 if (!pb_encode_tag_for_field(stream, field))
314 if (!func(stream, field, pData))
320 PB_RETURN_ERROR(stream, "invalid field type");
326 /* Encode a field with callback semantics. This means that a user function is
327 * called to provide and encode the actual data. */
328 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
329 const pb_field_t *field, const void *pData)
331 const pb_callback_t *callback = (const pb_callback_t*)pData;
333 #ifdef PB_OLD_CALLBACK_STYLE
334 const void *arg = callback->arg;
336 void * const *arg = &(callback->arg);
339 if (callback->funcs.encode != NULL)
341 if (!callback->funcs.encode(stream, field, arg))
342 PB_RETURN_ERROR(stream, "callback error");
347 /* Encode a single field of any callback or static type. */
348 static bool checkreturn encode_field(pb_ostream_t *stream,
349 const pb_field_t *field, const void *pData)
351 switch (PB_ATYPE(field->type))
353 case PB_ATYPE_STATIC:
354 case PB_ATYPE_POINTER:
355 return encode_basic_field(stream, field, pData);
357 case PB_ATYPE_CALLBACK:
358 return encode_callback_field(stream, field, pData);
361 PB_RETURN_ERROR(stream, "invalid field type");
365 /* Default handler for extension fields. Expects to have a pb_field_t
366 * pointer in the extension->type->arg field. */
367 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
368 const pb_extension_t *extension)
370 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
372 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
374 /* For pointer extensions, the pointer is stored directly
375 * in the extension structure. This avoids having an extra
377 return encode_field(stream, field, &extension->dest);
381 return encode_field(stream, field, extension->dest);
385 /* Walk through all the registered extensions and give them a chance
386 * to encode themselves. */
387 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
388 const pb_field_t *field, const void *pData)
390 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
396 if (extension->type->encode)
397 status = extension->type->encode(stream, extension);
399 status = default_extension_encoder(stream, extension);
404 extension = extension->next;
410 /*********************
411 * Encode all fields *
412 *********************/
414 static void *remove_const(const void *p)
416 /* Note: this casts away const, in order to use the common field iterator
417 * logic for both encoding and decoding. */
426 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
428 pb_field_iter_t iter;
429 if (!pb_field_iter_begin(&iter, fields, remove_const(src_struct)))
430 return true; /* Empty message type */
433 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION)
435 /* Special case for the extension field placeholder */
436 if (!encode_extension_field(stream, iter.pos, iter.pData))
442 if (!encode_field(stream, iter.pos, iter.pData))
445 } while (pb_field_iter_next(&iter));
450 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
452 return pb_encode_submessage(stream, fields, src_struct);
455 bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct)
457 pb_ostream_t stream = PB_OSTREAM_SIZING;
459 if (!pb_encode(&stream, fields, src_struct))
462 *size = stream.bytes_written;
466 /********************
468 ********************/
469 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
471 pb_byte_t buffer[10];
476 pb_byte_t v = (pb_byte_t)value;
477 return pb_write(stream, &v, 1);
482 buffer[i] = (pb_byte_t)((value & 0x7F) | 0x80);
486 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
488 return pb_write(stream, buffer, i);
491 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
495 zigzagged = ~((uint64_t)value << 1);
497 zigzagged = (uint64_t)value << 1;
499 return pb_encode_varint(stream, zigzagged);
502 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
504 uint32_t val = *(const uint32_t*)value;
506 bytes[0] = (pb_byte_t)(val & 0xFF);
507 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
508 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
509 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
510 return pb_write(stream, bytes, 4);
513 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
515 uint64_t val = *(const uint64_t*)value;
517 bytes[0] = (pb_byte_t)(val & 0xFF);
518 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
519 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
520 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
521 bytes[4] = (pb_byte_t)((val >> 32) & 0xFF);
522 bytes[5] = (pb_byte_t)((val >> 40) & 0xFF);
523 bytes[6] = (pb_byte_t)((val >> 48) & 0xFF);
524 bytes[7] = (pb_byte_t)((val >> 56) & 0xFF);
525 return pb_write(stream, bytes, 8);
528 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
530 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
531 return pb_encode_varint(stream, tag);
534 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
536 pb_wire_type_t wiretype;
537 switch (PB_LTYPE(field->type))
539 case PB_LTYPE_VARINT:
540 case PB_LTYPE_UVARINT:
541 case PB_LTYPE_SVARINT:
542 wiretype = PB_WT_VARINT;
545 case PB_LTYPE_FIXED32:
546 wiretype = PB_WT_32BIT;
549 case PB_LTYPE_FIXED64:
550 wiretype = PB_WT_64BIT;
554 case PB_LTYPE_STRING:
555 case PB_LTYPE_SUBMESSAGE:
556 case PB_LTYPE_FIXED_LENGTH_BYTES:
557 wiretype = PB_WT_STRING;
561 PB_RETURN_ERROR(stream, "invalid field type");
564 return pb_encode_tag(stream, wiretype, field->tag);
567 bool checkreturn pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size)
569 if (!pb_encode_varint(stream, (uint64_t)size))
572 return pb_write(stream, buffer, size);
575 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
577 /* First calculate the message size using a non-writing substream. */
578 pb_ostream_t substream = PB_OSTREAM_SIZING;
582 if (!pb_encode(&substream, fields, src_struct))
585 stream->errmsg = substream.errmsg;
590 size = substream.bytes_written;
592 if (!pb_encode_varint(stream, (uint64_t)size))
595 if (stream->callback == NULL)
596 return pb_write(stream, NULL, size); /* Just sizing */
598 if (stream->bytes_written + size > stream->max_size)
599 PB_RETURN_ERROR(stream, "stream full");
601 /* Use a substream to verify that a callback doesn't write more than
602 * what it did the first time. */
603 substream.callback = stream->callback;
604 substream.state = stream->state;
605 substream.max_size = size;
606 substream.bytes_written = 0;
608 substream.errmsg = NULL;
611 status = pb_encode(&substream, fields, src_struct);
613 stream->bytes_written += substream.bytes_written;
614 stream->state = substream.state;
616 stream->errmsg = substream.errmsg;
619 if (substream.bytes_written != size)
620 PB_RETURN_ERROR(stream, "submsg size changed");
627 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
631 if (field->data_size == sizeof(int_least8_t))
632 value = *(const int_least8_t*)src;
633 else if (field->data_size == sizeof(int_least16_t))
634 value = *(const int_least16_t*)src;
635 else if (field->data_size == sizeof(int32_t))
636 value = *(const int32_t*)src;
637 else if (field->data_size == sizeof(int64_t))
638 value = *(const int64_t*)src;
640 PB_RETURN_ERROR(stream, "invalid data_size");
642 return pb_encode_varint(stream, (uint64_t)value);
645 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
649 if (field->data_size == sizeof(uint_least8_t))
650 value = *(const uint_least8_t*)src;
651 else if (field->data_size == sizeof(uint_least16_t))
652 value = *(const uint_least16_t*)src;
653 else if (field->data_size == sizeof(uint32_t))
654 value = *(const uint32_t*)src;
655 else if (field->data_size == sizeof(uint64_t))
656 value = *(const uint64_t*)src;
658 PB_RETURN_ERROR(stream, "invalid data_size");
660 return pb_encode_varint(stream, value);
663 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
667 if (field->data_size == sizeof(int_least8_t))
668 value = *(const int_least8_t*)src;
669 else if (field->data_size == sizeof(int_least16_t))
670 value = *(const int_least16_t*)src;
671 else if (field->data_size == sizeof(int32_t))
672 value = *(const int32_t*)src;
673 else if (field->data_size == sizeof(int64_t))
674 value = *(const int64_t*)src;
676 PB_RETURN_ERROR(stream, "invalid data_size");
678 return pb_encode_svarint(stream, value);
681 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
684 return pb_encode_fixed64(stream, src);
687 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
690 return pb_encode_fixed32(stream, src);
693 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
695 const pb_bytes_array_t *bytes = NULL;
697 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED_LENGTH_BYTES)
698 return pb_encode_string(stream, (const pb_byte_t*)src, field->data_size);
700 bytes = (const pb_bytes_array_t*)src;
704 /* Treat null pointer as an empty bytes field */
705 return pb_encode_string(stream, NULL, 0);
708 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
709 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
711 PB_RETURN_ERROR(stream, "bytes size exceeded");
714 return pb_encode_string(stream, bytes->bytes, bytes->size);
717 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
720 size_t max_size = field->data_size;
721 const char *p = (const char*)src;
723 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
724 max_size = (size_t)-1;
728 size = 0; /* Treat null pointer as an empty string */
732 /* strnlen() is not always available, so just use a loop */
733 while (size < max_size && *p != '\0')
740 return pb_encode_string(stream, (const pb_byte_t*)src, size);
743 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
745 if (field->ptr == NULL)
746 PB_RETURN_ERROR(stream, "invalid field descriptor");
748 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);