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 /* Encode a field with static or pointer allocation, i.e. one whose data
201 * is available to the encoder directly. */
202 static bool checkreturn encode_basic_field(pb_ostream_t *stream,
203 const pb_field_t *field, const void *pData)
207 bool implicit_has = true;
209 func = PB_ENCODERS[PB_LTYPE(field->type)];
211 if (field->size_offset)
212 pSize = (const char*)pData + field->size_offset;
213 else if (!field->size_offset && PB_HTYPE(field->type) == PB_HTYPE_OPTIONAL)
215 /* In proto3 there are optional fields but no has_ flag, do not encode this fields
216 * when value is default or empty. */
217 if(PB_LTYPE(field->type) == PB_LTYPE_BYTES)
219 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)pData;
221 implicit_has = false;
223 else if ((PB_LTYPE(field->type) == PB_LTYPE_STRING && *(const char*)pData == '\0') ||
224 (field->data_size == sizeof(uint_least8_t) && *(const uint_least8_t*)pData == 0) ||
225 (field->data_size == sizeof(uint_least16_t) && *(const uint_least16_t*)pData == 0) ||
226 (field->data_size == sizeof(uint32_t) && *(const uint_least32_t*)pData == 0) ||
227 (field->data_size == sizeof(uint64_t) && *(const uint_least64_t*)pData == 0))
229 implicit_has = false;
231 pSize = &implicit_has;
234 pSize = &implicit_has;
236 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
238 /* pData is a pointer to the field, which contains pointer to
239 * the data. If the 2nd pointer is NULL, it is interpreted as if
240 * the has_field was false.
243 pData = *(const void* const*)pData;
244 implicit_has = (pData != NULL);
247 switch (PB_HTYPE(field->type))
249 case PB_HTYPE_REQUIRED:
251 PB_RETURN_ERROR(stream, "missing required field");
252 if (!pb_encode_tag_for_field(stream, field))
254 if (!func(stream, field, pData))
258 case PB_HTYPE_OPTIONAL:
259 if (*(const bool*)pSize)
261 if (!pb_encode_tag_for_field(stream, field))
264 if (!func(stream, field, pData))
269 case PB_HTYPE_REPEATED:
270 if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func))
275 if (*(const pb_size_t*)pSize == field->tag)
277 if (!pb_encode_tag_for_field(stream, field))
280 if (!func(stream, field, pData))
286 PB_RETURN_ERROR(stream, "invalid field type");
292 /* Encode a field with callback semantics. This means that a user function is
293 * called to provide and encode the actual data. */
294 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
295 const pb_field_t *field, const void *pData)
297 const pb_callback_t *callback = (const pb_callback_t*)pData;
299 #ifdef PB_OLD_CALLBACK_STYLE
300 const void *arg = callback->arg;
302 void * const *arg = &(callback->arg);
305 if (callback->funcs.encode != NULL)
307 if (!callback->funcs.encode(stream, field, arg))
308 PB_RETURN_ERROR(stream, "callback error");
313 /* Encode a single field of any callback or static type. */
314 static bool checkreturn encode_field(pb_ostream_t *stream,
315 const pb_field_t *field, const void *pData)
317 switch (PB_ATYPE(field->type))
319 case PB_ATYPE_STATIC:
320 case PB_ATYPE_POINTER:
321 return encode_basic_field(stream, field, pData);
323 case PB_ATYPE_CALLBACK:
324 return encode_callback_field(stream, field, pData);
327 PB_RETURN_ERROR(stream, "invalid field type");
331 /* Default handler for extension fields. Expects to have a pb_field_t
332 * pointer in the extension->type->arg field. */
333 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
334 const pb_extension_t *extension)
336 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
338 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
340 /* For pointer extensions, the pointer is stored directly
341 * in the extension structure. This avoids having an extra
343 return encode_field(stream, field, &extension->dest);
347 return encode_field(stream, field, extension->dest);
351 /* Walk through all the registered extensions and give them a chance
352 * to encode themselves. */
353 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
354 const pb_field_t *field, const void *pData)
356 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
362 if (extension->type->encode)
363 status = extension->type->encode(stream, extension);
365 status = default_extension_encoder(stream, extension);
370 extension = extension->next;
376 /*********************
377 * Encode all fields *
378 *********************/
380 static void *remove_const(const void *p)
382 /* Note: this casts away const, in order to use the common field iterator
383 * logic for both encoding and decoding. */
392 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
394 pb_field_iter_t iter;
395 if (!pb_field_iter_begin(&iter, fields, remove_const(src_struct)))
396 return true; /* Empty message type */
399 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION)
401 /* Special case for the extension field placeholder */
402 if (!encode_extension_field(stream, iter.pos, iter.pData))
408 if (!encode_field(stream, iter.pos, iter.pData))
411 } while (pb_field_iter_next(&iter));
416 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
418 return pb_encode_submessage(stream, fields, src_struct);
421 bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct)
423 pb_ostream_t stream = PB_OSTREAM_SIZING;
425 if (!pb_encode(&stream, fields, src_struct))
428 *size = stream.bytes_written;
432 /********************
434 ********************/
435 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
437 pb_byte_t buffer[10];
442 pb_byte_t v = (pb_byte_t)value;
443 return pb_write(stream, &v, 1);
448 buffer[i] = (pb_byte_t)((value & 0x7F) | 0x80);
452 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
454 return pb_write(stream, buffer, i);
457 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
461 zigzagged = ~((uint64_t)value << 1);
463 zigzagged = (uint64_t)value << 1;
465 return pb_encode_varint(stream, zigzagged);
468 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
470 uint32_t val = *(const uint32_t*)value;
472 bytes[0] = (pb_byte_t)(val & 0xFF);
473 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
474 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
475 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
476 return pb_write(stream, bytes, 4);
479 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
481 uint64_t val = *(const uint64_t*)value;
483 bytes[0] = (pb_byte_t)(val & 0xFF);
484 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
485 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
486 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
487 bytes[4] = (pb_byte_t)((val >> 32) & 0xFF);
488 bytes[5] = (pb_byte_t)((val >> 40) & 0xFF);
489 bytes[6] = (pb_byte_t)((val >> 48) & 0xFF);
490 bytes[7] = (pb_byte_t)((val >> 56) & 0xFF);
491 return pb_write(stream, bytes, 8);
494 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
496 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
497 return pb_encode_varint(stream, tag);
500 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
502 pb_wire_type_t wiretype;
503 switch (PB_LTYPE(field->type))
505 case PB_LTYPE_VARINT:
506 case PB_LTYPE_UVARINT:
507 case PB_LTYPE_SVARINT:
508 wiretype = PB_WT_VARINT;
511 case PB_LTYPE_FIXED32:
512 wiretype = PB_WT_32BIT;
515 case PB_LTYPE_FIXED64:
516 wiretype = PB_WT_64BIT;
520 case PB_LTYPE_STRING:
521 case PB_LTYPE_SUBMESSAGE:
522 case PB_LTYPE_FIXED_LENGTH_BYTES:
523 wiretype = PB_WT_STRING;
527 PB_RETURN_ERROR(stream, "invalid field type");
530 return pb_encode_tag(stream, wiretype, field->tag);
533 bool checkreturn pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size)
535 if (!pb_encode_varint(stream, (uint64_t)size))
538 return pb_write(stream, buffer, size);
541 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
543 /* First calculate the message size using a non-writing substream. */
544 pb_ostream_t substream = PB_OSTREAM_SIZING;
548 if (!pb_encode(&substream, fields, src_struct))
551 stream->errmsg = substream.errmsg;
556 size = substream.bytes_written;
558 if (!pb_encode_varint(stream, (uint64_t)size))
561 if (stream->callback == NULL)
562 return pb_write(stream, NULL, size); /* Just sizing */
564 if (stream->bytes_written + size > stream->max_size)
565 PB_RETURN_ERROR(stream, "stream full");
567 /* Use a substream to verify that a callback doesn't write more than
568 * what it did the first time. */
569 substream.callback = stream->callback;
570 substream.state = stream->state;
571 substream.max_size = size;
572 substream.bytes_written = 0;
574 substream.errmsg = NULL;
577 status = pb_encode(&substream, fields, src_struct);
579 stream->bytes_written += substream.bytes_written;
580 stream->state = substream.state;
582 stream->errmsg = substream.errmsg;
585 if (substream.bytes_written != size)
586 PB_RETURN_ERROR(stream, "submsg size changed");
593 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
597 if (field->data_size == sizeof(int_least8_t))
598 value = *(const int_least8_t*)src;
599 else if (field->data_size == sizeof(int_least16_t))
600 value = *(const int_least16_t*)src;
601 else if (field->data_size == sizeof(int32_t))
602 value = *(const int32_t*)src;
603 else if (field->data_size == sizeof(int64_t))
604 value = *(const int64_t*)src;
606 PB_RETURN_ERROR(stream, "invalid data_size");
608 return pb_encode_varint(stream, (uint64_t)value);
611 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
615 if (field->data_size == sizeof(uint_least8_t))
616 value = *(const uint_least8_t*)src;
617 else if (field->data_size == sizeof(uint_least16_t))
618 value = *(const uint_least16_t*)src;
619 else if (field->data_size == sizeof(uint32_t))
620 value = *(const uint32_t*)src;
621 else if (field->data_size == sizeof(uint64_t))
622 value = *(const uint64_t*)src;
624 PB_RETURN_ERROR(stream, "invalid data_size");
626 return pb_encode_varint(stream, value);
629 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
633 if (field->data_size == sizeof(int_least8_t))
634 value = *(const int_least8_t*)src;
635 else if (field->data_size == sizeof(int_least16_t))
636 value = *(const int_least16_t*)src;
637 else if (field->data_size == sizeof(int32_t))
638 value = *(const int32_t*)src;
639 else if (field->data_size == sizeof(int64_t))
640 value = *(const int64_t*)src;
642 PB_RETURN_ERROR(stream, "invalid data_size");
644 return pb_encode_svarint(stream, value);
647 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
650 return pb_encode_fixed64(stream, src);
653 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
656 return pb_encode_fixed32(stream, src);
659 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
661 const pb_bytes_array_t *bytes = NULL;
663 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED_LENGTH_BYTES)
664 return pb_encode_string(stream, (const pb_byte_t*)src, field->data_size);
666 bytes = (const pb_bytes_array_t*)src;
670 /* Treat null pointer as an empty bytes field */
671 return pb_encode_string(stream, NULL, 0);
674 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
675 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
677 PB_RETURN_ERROR(stream, "bytes size exceeded");
680 return pb_encode_string(stream, bytes->bytes, bytes->size);
683 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
686 size_t max_size = field->data_size;
687 const char *p = (const char*)src;
689 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
690 max_size = (size_t)-1;
694 size = 0; /* Treat null pointer as an empty string */
698 /* strnlen() is not always available, so just use a loop */
699 while (size < max_size && *p != '\0')
706 return pb_encode_string(stream, (const pb_byte_t*)src, size);
709 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
711 if (field->ptr == NULL)
712 PB_RETURN_ERROR(stream, "invalid field descriptor");
714 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);