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;
214 pSize = &implicit_has;
216 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
218 /* pData is a pointer to the field, which contains pointer to
219 * the data. If the 2nd pointer is NULL, it is interpreted as if
220 * the has_field was false.
223 pData = *(const void* const*)pData;
224 implicit_has = (pData != NULL);
227 switch (PB_HTYPE(field->type))
229 case PB_HTYPE_REQUIRED:
231 PB_RETURN_ERROR(stream, "missing required field");
232 if (!pb_encode_tag_for_field(stream, field))
234 if (!func(stream, field, pData))
238 case PB_HTYPE_OPTIONAL:
239 if (*(const bool*)pSize)
241 if (!pb_encode_tag_for_field(stream, field))
244 if (!func(stream, field, pData))
249 case PB_HTYPE_REPEATED:
250 if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func))
255 if (*(const pb_size_t*)pSize == field->tag)
257 if (!pb_encode_tag_for_field(stream, field))
260 if (!func(stream, field, pData))
266 PB_RETURN_ERROR(stream, "invalid field type");
272 /* Encode a field with callback semantics. This means that a user function is
273 * called to provide and encode the actual data. */
274 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
275 const pb_field_t *field, const void *pData)
277 const pb_callback_t *callback = (const pb_callback_t*)pData;
279 #ifdef PB_OLD_CALLBACK_STYLE
280 const void *arg = callback->arg;
282 void * const *arg = &(callback->arg);
285 if (callback->funcs.encode != NULL)
287 if (!callback->funcs.encode(stream, field, arg))
288 PB_RETURN_ERROR(stream, "callback error");
293 /* Encode a single field of any callback or static type. */
294 static bool checkreturn encode_field(pb_ostream_t *stream,
295 const pb_field_t *field, const void *pData)
297 switch (PB_ATYPE(field->type))
299 case PB_ATYPE_STATIC:
300 case PB_ATYPE_POINTER:
301 return encode_basic_field(stream, field, pData);
303 case PB_ATYPE_CALLBACK:
304 return encode_callback_field(stream, field, pData);
307 PB_RETURN_ERROR(stream, "invalid field type");
311 /* Default handler for extension fields. Expects to have a pb_field_t
312 * pointer in the extension->type->arg field. */
313 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
314 const pb_extension_t *extension)
316 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
318 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
320 /* For pointer extensions, the pointer is stored directly
321 * in the extension structure. This avoids having an extra
323 return encode_field(stream, field, &extension->dest);
327 return encode_field(stream, field, extension->dest);
331 /* Walk through all the registered extensions and give them a chance
332 * to encode themselves. */
333 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
334 const pb_field_t *field, const void *pData)
336 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
342 if (extension->type->encode)
343 status = extension->type->encode(stream, extension);
345 status = default_extension_encoder(stream, extension);
350 extension = extension->next;
356 /*********************
357 * Encode all fields *
358 *********************/
360 static void *remove_const(const void *p)
362 /* Note: this casts away const, in order to use the common field iterator
363 * logic for both encoding and decoding. */
372 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
374 pb_field_iter_t iter;
375 if (!pb_field_iter_begin(&iter, fields, remove_const(src_struct)))
376 return true; /* Empty message type */
379 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION)
381 /* Special case for the extension field placeholder */
382 if (!encode_extension_field(stream, iter.pos, iter.pData))
388 if (!encode_field(stream, iter.pos, iter.pData))
391 } while (pb_field_iter_next(&iter));
396 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
398 return pb_encode_submessage(stream, fields, src_struct);
401 bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct)
403 pb_ostream_t stream = PB_OSTREAM_SIZING;
405 if (!pb_encode(&stream, fields, src_struct))
408 *size = stream.bytes_written;
412 /********************
414 ********************/
415 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
417 pb_byte_t buffer[10];
422 pb_byte_t v = (pb_byte_t)value;
423 return pb_write(stream, &v, 1);
428 buffer[i] = (pb_byte_t)((value & 0x7F) | 0x80);
432 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
434 return pb_write(stream, buffer, i);
437 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
441 zigzagged = ~((uint64_t)value << 1);
443 zigzagged = (uint64_t)value << 1;
445 return pb_encode_varint(stream, zigzagged);
448 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
450 uint32_t val = *(const uint32_t*)value;
452 bytes[0] = (pb_byte_t)(val & 0xFF);
453 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
454 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
455 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
456 return pb_write(stream, bytes, 4);
459 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
461 uint64_t val = *(const uint64_t*)value;
463 bytes[0] = (pb_byte_t)(val & 0xFF);
464 bytes[1] = (pb_byte_t)((val >> 8) & 0xFF);
465 bytes[2] = (pb_byte_t)((val >> 16) & 0xFF);
466 bytes[3] = (pb_byte_t)((val >> 24) & 0xFF);
467 bytes[4] = (pb_byte_t)((val >> 32) & 0xFF);
468 bytes[5] = (pb_byte_t)((val >> 40) & 0xFF);
469 bytes[6] = (pb_byte_t)((val >> 48) & 0xFF);
470 bytes[7] = (pb_byte_t)((val >> 56) & 0xFF);
471 return pb_write(stream, bytes, 8);
474 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
476 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
477 return pb_encode_varint(stream, tag);
480 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
482 pb_wire_type_t wiretype;
483 switch (PB_LTYPE(field->type))
485 case PB_LTYPE_VARINT:
486 case PB_LTYPE_UVARINT:
487 case PB_LTYPE_SVARINT:
488 wiretype = PB_WT_VARINT;
491 case PB_LTYPE_FIXED32:
492 wiretype = PB_WT_32BIT;
495 case PB_LTYPE_FIXED64:
496 wiretype = PB_WT_64BIT;
500 case PB_LTYPE_STRING:
501 case PB_LTYPE_SUBMESSAGE:
502 case PB_LTYPE_FIXED_LENGTH_BYTES:
503 wiretype = PB_WT_STRING;
507 PB_RETURN_ERROR(stream, "invalid field type");
510 return pb_encode_tag(stream, wiretype, field->tag);
513 bool checkreturn pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size)
515 if (!pb_encode_varint(stream, (uint64_t)size))
518 return pb_write(stream, buffer, size);
521 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
523 /* First calculate the message size using a non-writing substream. */
524 pb_ostream_t substream = PB_OSTREAM_SIZING;
528 if (!pb_encode(&substream, fields, src_struct))
531 stream->errmsg = substream.errmsg;
536 size = substream.bytes_written;
538 if (!pb_encode_varint(stream, (uint64_t)size))
541 if (stream->callback == NULL)
542 return pb_write(stream, NULL, size); /* Just sizing */
544 if (stream->bytes_written + size > stream->max_size)
545 PB_RETURN_ERROR(stream, "stream full");
547 /* Use a substream to verify that a callback doesn't write more than
548 * what it did the first time. */
549 substream.callback = stream->callback;
550 substream.state = stream->state;
551 substream.max_size = size;
552 substream.bytes_written = 0;
554 substream.errmsg = NULL;
557 status = pb_encode(&substream, fields, src_struct);
559 stream->bytes_written += substream.bytes_written;
560 stream->state = substream.state;
562 stream->errmsg = substream.errmsg;
565 if (substream.bytes_written != size)
566 PB_RETURN_ERROR(stream, "submsg size changed");
573 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
577 if (field->data_size == sizeof(int_least8_t))
578 value = *(const int_least8_t*)src;
579 else if (field->data_size == sizeof(int_least16_t))
580 value = *(const int_least16_t*)src;
581 else if (field->data_size == sizeof(int32_t))
582 value = *(const int32_t*)src;
583 else if (field->data_size == sizeof(int64_t))
584 value = *(const int64_t*)src;
586 PB_RETURN_ERROR(stream, "invalid data_size");
588 return pb_encode_varint(stream, (uint64_t)value);
591 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
595 if (field->data_size == sizeof(uint_least8_t))
596 value = *(const uint_least8_t*)src;
597 else if (field->data_size == sizeof(uint_least16_t))
598 value = *(const uint_least16_t*)src;
599 else if (field->data_size == sizeof(uint32_t))
600 value = *(const uint32_t*)src;
601 else if (field->data_size == sizeof(uint64_t))
602 value = *(const uint64_t*)src;
604 PB_RETURN_ERROR(stream, "invalid data_size");
606 return pb_encode_varint(stream, value);
609 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
613 if (field->data_size == sizeof(int_least8_t))
614 value = *(const int_least8_t*)src;
615 else if (field->data_size == sizeof(int_least16_t))
616 value = *(const int_least16_t*)src;
617 else if (field->data_size == sizeof(int32_t))
618 value = *(const int32_t*)src;
619 else if (field->data_size == sizeof(int64_t))
620 value = *(const int64_t*)src;
622 PB_RETURN_ERROR(stream, "invalid data_size");
624 return pb_encode_svarint(stream, value);
627 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
630 return pb_encode_fixed64(stream, src);
633 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
636 return pb_encode_fixed32(stream, src);
639 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
641 const pb_bytes_array_t *bytes = NULL;
643 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED_LENGTH_BYTES)
644 return pb_encode_string(stream, (const pb_byte_t*)src, field->data_size);
646 bytes = (const pb_bytes_array_t*)src;
650 /* Treat null pointer as an empty bytes field */
651 return pb_encode_string(stream, NULL, 0);
654 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
655 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
657 PB_RETURN_ERROR(stream, "bytes size exceeded");
660 return pb_encode_string(stream, bytes->bytes, bytes->size);
663 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
666 size_t max_size = field->data_size;
667 const char *p = (const char*)src;
669 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
670 max_size = (size_t)-1;
674 size = 0; /* Treat null pointer as an empty string */
678 /* strnlen() is not always available, so just use a loop */
679 while (size < max_size && *p != '\0')
686 return pb_encode_string(stream, (const pb_byte_t*)src, size);
689 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
691 if (field->ptr == NULL)
692 PB_RETURN_ERROR(stream, "invalid field descriptor");
694 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);