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){
218 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)pData;
220 implicit_has = false;
221 else if ((PB_LTYPE(field->type) == PB_LTYPE_STRING && *(const char*)pData == '\0') ||
222 (field->data_size == sizeof(uint_least8_t) && *(const uint_least8_t*)pData == 0) ||
223 (field->data_size == sizeof(uint_least16_t) && *(const uint_least16_t*)pData == 0) ||
224 (field->data_size == sizeof(uint32_t) && *(const uint_least32_t*)pData == 0) ||
225 (field->data_size == sizeof(uint64_t) && *(const uint_least64_t*)pData == 0))
226 implicit_has = false;
228 pSize = &implicit_has;
231 pSize = &implicit_has;
233 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
235 /* pData is a pointer to the field, which contains pointer to
236 * the data. If the 2nd pointer is NULL, it is interpreted as if
237 * the has_field was false.
240 pData = *(const void* const*)pData;
241 implicit_has = (pData != NULL);
244 switch (PB_HTYPE(field->type))
246 case PB_HTYPE_REQUIRED:
248 PB_RETURN_ERROR(stream, "missing required field");
249 if (!pb_encode_tag_for_field(stream, field))
251 if (!func(stream, field, pData))
255 case PB_HTYPE_OPTIONAL:
256 if (*(const bool*)pSize)
258 if (!pb_encode_tag_for_field(stream, field))
261 if (!func(stream, field, pData))
266 case PB_HTYPE_REPEATED:
267 if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func))
272 if (*(const pb_size_t*)pSize == field->tag)
274 if (!pb_encode_tag_for_field(stream, field))
277 if (!func(stream, field, pData))
283 PB_RETURN_ERROR(stream, "invalid field type");
289 /* Encode a field with callback semantics. This means that a user function is
290 * called to provide and encode the actual data. */
291 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
292 const pb_field_t *field, const void *pData)
294 const pb_callback_t *callback = (const pb_callback_t*)pData;
296 #ifdef PB_OLD_CALLBACK_STYLE
297 const void *arg = callback->arg;
299 void * const *arg = &(callback->arg);
302 if (callback->funcs.encode != NULL)
304 if (!callback->funcs.encode(stream, field, arg))
305 PB_RETURN_ERROR(stream, "callback error");
310 /* Encode a single field of any callback or static type. */
311 static bool checkreturn encode_field(pb_ostream_t *stream,
312 const pb_field_t *field, const void *pData)
314 switch (PB_ATYPE(field->type))
316 case PB_ATYPE_STATIC:
317 case PB_ATYPE_POINTER:
318 return encode_basic_field(stream, field, pData);
320 case PB_ATYPE_CALLBACK:
321 return encode_callback_field(stream, field, pData);
324 PB_RETURN_ERROR(stream, "invalid field type");
328 /* Default handler for extension fields. Expects to have a pb_field_t
329 * pointer in the extension->type->arg field. */
330 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
331 const pb_extension_t *extension)
333 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
335 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
337 /* For pointer extensions, the pointer is stored directly
338 * in the extension structure. This avoids having an extra
340 return encode_field(stream, field, &extension->dest);
344 return encode_field(stream, field, extension->dest);
348 /* Walk through all the registered extensions and give them a chance
349 * to encode themselves. */
350 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
351 const pb_field_t *field, const void *pData)
353 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
359 if (extension->type->encode)
360 status = extension->type->encode(stream, extension);
362 status = default_extension_encoder(stream, extension);
367 extension = extension->next;
373 /*********************
374 * Encode all fields *
375 *********************/
377 static void *remove_const(const void *p)
379 /* Note: this casts away const, in order to use the common field iterator
380 * logic for both encoding and decoding. */
389 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
391 pb_field_iter_t iter;
392 if (!pb_field_iter_begin(&iter, fields, remove_const(src_struct)))
393 return true; /* Empty message type */
396 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION)
398 /* Special case for the extension field placeholder */
399 if (!encode_extension_field(stream, iter.pos, iter.pData))
405 if (!encode_field(stream, iter.pos, iter.pData))
408 } while (pb_field_iter_next(&iter));
413 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
415 return pb_encode_submessage(stream, fields, src_struct);
418 bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct)
420 pb_ostream_t stream = PB_OSTREAM_SIZING;
422 if (!pb_encode(&stream, fields, src_struct))
425 *size = stream.bytes_written;
429 /********************
431 ********************/
432 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
434 pb_byte_t buffer[10];
439 pb_byte_t v = (pb_byte_t)value;
440 return pb_write(stream, &v, 1);
445 buffer[i] = (pb_byte_t)((value & 0x7F) | 0x80);
449 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
451 return pb_write(stream, buffer, i);
454 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
458 zigzagged = ~((uint64_t)value << 1);
460 zigzagged = (uint64_t)value << 1;
462 return pb_encode_varint(stream, zigzagged);
465 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
467 uint32_t val = *(const uint32_t*)value;
469 bytes[0] = (pb_byte_t)(val & 0xFF);
470 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
471 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
472 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
473 return pb_write(stream, bytes, 4);
476 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
478 uint64_t val = *(const uint64_t*)value;
480 bytes[0] = (pb_byte_t)(val & 0xFF);
481 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
482 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
483 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
484 bytes[4] = (pb_byte_t)((val >> 32) & 0xFF);
485 bytes[5] = (pb_byte_t)((val >> 40) & 0xFF);
486 bytes[6] = (pb_byte_t)((val >> 48) & 0xFF);
487 bytes[7] = (pb_byte_t)((val >> 56) & 0xFF);
488 return pb_write(stream, bytes, 8);
491 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
493 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
494 return pb_encode_varint(stream, tag);
497 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
499 pb_wire_type_t wiretype;
500 switch (PB_LTYPE(field->type))
502 case PB_LTYPE_VARINT:
503 case PB_LTYPE_UVARINT:
504 case PB_LTYPE_SVARINT:
505 wiretype = PB_WT_VARINT;
508 case PB_LTYPE_FIXED32:
509 wiretype = PB_WT_32BIT;
512 case PB_LTYPE_FIXED64:
513 wiretype = PB_WT_64BIT;
517 case PB_LTYPE_STRING:
518 case PB_LTYPE_SUBMESSAGE:
519 case PB_LTYPE_FIXED_LENGTH_BYTES:
520 wiretype = PB_WT_STRING;
524 PB_RETURN_ERROR(stream, "invalid field type");
527 return pb_encode_tag(stream, wiretype, field->tag);
530 bool checkreturn pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size)
532 if (!pb_encode_varint(stream, (uint64_t)size))
535 return pb_write(stream, buffer, size);
538 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
540 /* First calculate the message size using a non-writing substream. */
541 pb_ostream_t substream = PB_OSTREAM_SIZING;
545 if (!pb_encode(&substream, fields, src_struct))
548 stream->errmsg = substream.errmsg;
553 size = substream.bytes_written;
555 if (!pb_encode_varint(stream, (uint64_t)size))
558 if (stream->callback == NULL)
559 return pb_write(stream, NULL, size); /* Just sizing */
561 if (stream->bytes_written + size > stream->max_size)
562 PB_RETURN_ERROR(stream, "stream full");
564 /* Use a substream to verify that a callback doesn't write more than
565 * what it did the first time. */
566 substream.callback = stream->callback;
567 substream.state = stream->state;
568 substream.max_size = size;
569 substream.bytes_written = 0;
571 substream.errmsg = NULL;
574 status = pb_encode(&substream, fields, src_struct);
576 stream->bytes_written += substream.bytes_written;
577 stream->state = substream.state;
579 stream->errmsg = substream.errmsg;
582 if (substream.bytes_written != size)
583 PB_RETURN_ERROR(stream, "submsg size changed");
590 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
594 if (field->data_size == sizeof(int_least8_t))
595 value = *(const int_least8_t*)src;
596 else if (field->data_size == sizeof(int_least16_t))
597 value = *(const int_least16_t*)src;
598 else if (field->data_size == sizeof(int32_t))
599 value = *(const int32_t*)src;
600 else if (field->data_size == sizeof(int64_t))
601 value = *(const int64_t*)src;
603 PB_RETURN_ERROR(stream, "invalid data_size");
605 return pb_encode_varint(stream, (uint64_t)value);
608 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
612 if (field->data_size == sizeof(uint_least8_t))
613 value = *(const uint_least8_t*)src;
614 else if (field->data_size == sizeof(uint_least16_t))
615 value = *(const uint_least16_t*)src;
616 else if (field->data_size == sizeof(uint32_t))
617 value = *(const uint32_t*)src;
618 else if (field->data_size == sizeof(uint64_t))
619 value = *(const uint64_t*)src;
621 PB_RETURN_ERROR(stream, "invalid data_size");
623 return pb_encode_varint(stream, value);
626 static bool checkreturn pb_enc_svarint(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_svarint(stream, value);
644 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
647 return pb_encode_fixed64(stream, src);
650 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
653 return pb_encode_fixed32(stream, src);
656 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
658 const pb_bytes_array_t *bytes = NULL;
660 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED_LENGTH_BYTES)
661 return pb_encode_string(stream, (const pb_byte_t*)src, field->data_size);
663 bytes = (const pb_bytes_array_t*)src;
667 /* Treat null pointer as an empty bytes field */
668 return pb_encode_string(stream, NULL, 0);
671 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
672 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
674 PB_RETURN_ERROR(stream, "bytes size exceeded");
677 return pb_encode_string(stream, bytes->bytes, bytes->size);
680 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
683 size_t max_size = field->data_size;
684 const char *p = (const char*)src;
686 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
687 max_size = (size_t)-1;
691 size = 0; /* Treat null pointer as an empty string */
695 /* strnlen() is not always available, so just use a loop */
696 while (size < max_size && *p != '\0')
703 return pb_encode_string(stream, (const pb_byte_t*)src, size);
706 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
708 if (field->ptr == NULL)
709 PB_RETURN_ERROR(stream, "invalid field descriptor");
711 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);