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 uint8_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] = {
55 /*******************************
56 * pb_ostream_t implementation *
57 *******************************/
59 static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
61 uint8_t *dest = (uint8_t*)stream->state;
62 stream->state = dest + count;
70 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize)
74 stream.callback = (void*)1; /* Just a marker value */
76 stream.callback = &buf_write;
79 stream.max_size = bufsize;
80 stream.bytes_written = 0;
87 bool checkreturn pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
89 if (stream->callback != NULL)
91 if (stream->bytes_written + count > stream->max_size)
92 PB_RETURN_ERROR(stream, "stream full");
95 if (!buf_write(stream, buf, count))
96 PB_RETURN_ERROR(stream, "io error");
98 if (!stream->callback(stream, buf, count))
99 PB_RETURN_ERROR(stream, "io error");
103 stream->bytes_written += count;
107 /*************************
108 * Encode a single field *
109 *************************/
111 /* Encode a static array. Handles the size calculations and possible packing. */
112 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
113 const void *pData, size_t count, pb_encoder_t func)
122 if (PB_ATYPE(field->type) != PB_ATYPE_POINTER && count > field->array_size)
123 PB_RETURN_ERROR(stream, "array max size exceeded");
125 /* We always pack arrays if the datatype allows it. */
126 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
128 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
131 /* Determine the total size of packed array. */
132 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
136 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
142 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
144 for (i = 0; i < count; i++)
146 if (!func(&sizestream, field, p))
148 p = (const char*)p + field->data_size;
150 size = sizestream.bytes_written;
153 if (!pb_encode_varint(stream, (uint64_t)size))
156 if (stream->callback == NULL)
157 return pb_write(stream, NULL, size); /* Just sizing.. */
161 for (i = 0; i < count; i++)
163 if (!func(stream, field, p))
165 p = (const char*)p + field->data_size;
171 for (i = 0; i < count; i++)
173 if (!pb_encode_tag_for_field(stream, field))
176 /* Normally the data is stored directly in the array entries, but
177 * for pointer-type string and bytes fields, the array entries are
178 * actually pointers themselves also. So we have to dereference once
179 * more to get to the actual data. */
180 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER &&
181 (PB_LTYPE(field->type) == PB_LTYPE_STRING ||
182 PB_LTYPE(field->type) == PB_LTYPE_BYTES))
184 if (!func(stream, field, *(const void* const*)p))
189 if (!func(stream, field, p))
192 p = (const char*)p + field->data_size;
199 /* Encode a field with static or pointer allocation, i.e. one whose data
200 * is available to the encoder directly. */
201 static bool checkreturn encode_basic_field(pb_ostream_t *stream,
202 const pb_field_t *field, const void *pData)
206 bool implicit_has = true;
208 func = PB_ENCODERS[PB_LTYPE(field->type)];
210 if (field->size_offset)
211 pSize = (const char*)pData + field->size_offset;
213 pSize = &implicit_has;
215 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
217 /* pData is a pointer to the field, which contains pointer to
218 * the data. If the 2nd pointer is NULL, it is interpreted as if
219 * the has_field was false.
222 pData = *(const void* const*)pData;
223 implicit_has = (pData != NULL);
226 switch (PB_HTYPE(field->type))
228 case PB_HTYPE_REQUIRED:
230 PB_RETURN_ERROR(stream, "missing required field");
231 if (!pb_encode_tag_for_field(stream, field))
233 if (!func(stream, field, pData))
237 case PB_HTYPE_OPTIONAL:
238 if (*(const bool*)pSize)
240 if (!pb_encode_tag_for_field(stream, field))
243 if (!func(stream, field, pData))
248 case PB_HTYPE_REPEATED:
249 if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func))
254 PB_RETURN_ERROR(stream, "invalid field type");
260 /* Encode a field with callback semantics. This means that a user function is
261 * called to provide and encode the actual data. */
262 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
263 const pb_field_t *field, const void *pData)
265 const pb_callback_t *callback = (const pb_callback_t*)pData;
267 #ifdef PB_OLD_CALLBACK_STYLE
268 const void *arg = callback->arg;
270 void * const *arg = &(callback->arg);
273 if (callback->funcs.encode != NULL)
275 if (!callback->funcs.encode(stream, field, arg))
276 PB_RETURN_ERROR(stream, "callback error");
281 /* Encode a single field of any callback or static type. */
282 static bool checkreturn encode_field(pb_ostream_t *stream,
283 const pb_field_t *field, const void *pData)
285 switch (PB_ATYPE(field->type))
287 case PB_ATYPE_STATIC:
288 case PB_ATYPE_POINTER:
289 return encode_basic_field(stream, field, pData);
291 case PB_ATYPE_CALLBACK:
292 return encode_callback_field(stream, field, pData);
295 PB_RETURN_ERROR(stream, "invalid field type");
299 /* Default handler for extension fields. Expects to have a pb_field_t
300 * pointer in the extension->type->arg field. */
301 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
302 const pb_extension_t *extension)
304 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
306 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
308 /* For pointer extensions, the pointer is stored directly
309 * in the extension structure. This avoids having an extra
311 return encode_field(stream, field, &extension->dest);
315 return encode_field(stream, field, extension->dest);
319 /* Walk through all the registered extensions and give them a chance
320 * to encode themselves. */
321 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
322 const pb_field_t *field, const void *pData)
324 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
330 if (extension->type->encode)
331 status = extension->type->encode(stream, extension);
333 status = default_extension_encoder(stream, extension);
338 extension = extension->next;
344 /*********************
345 * Encode all fields *
346 *********************/
348 static void *remove_const(const void *p)
350 /* Note: this casts away const, in order to use the common field iterator
351 * logic for both encoding and decoding. */
360 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
362 pb_field_iter_t iter;
363 if (!pb_field_iter_begin(&iter, fields, remove_const(src_struct)))
364 return true; /* Empty message type */
367 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION)
369 /* Special case for the extension field placeholder */
370 if (!encode_extension_field(stream, iter.pos, iter.pData))
376 if (!encode_field(stream, iter.pos, iter.pData))
379 } while (pb_field_iter_next(&iter));
384 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
386 return pb_encode_submessage(stream, fields, src_struct);
389 bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct)
391 pb_ostream_t stream = PB_OSTREAM_SIZING;
393 if (!pb_encode(&stream, fields, src_struct))
396 *size = stream.bytes_written;
400 /********************
402 ********************/
403 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
409 return pb_write(stream, (uint8_t*)&value, 1);
413 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
417 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
419 return pb_write(stream, buffer, i);
422 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
426 zigzagged = ~((uint64_t)value << 1);
428 zigzagged = (uint64_t)value << 1;
430 return pb_encode_varint(stream, zigzagged);
433 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
435 #ifdef __BIG_ENDIAN__
436 const uint8_t *bytes = value;
438 lebytes[0] = bytes[3];
439 lebytes[1] = bytes[2];
440 lebytes[2] = bytes[1];
441 lebytes[3] = bytes[0];
442 return pb_write(stream, lebytes, 4);
444 return pb_write(stream, (const uint8_t*)value, 4);
448 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
450 #ifdef __BIG_ENDIAN__
451 const uint8_t *bytes = value;
453 lebytes[0] = bytes[7];
454 lebytes[1] = bytes[6];
455 lebytes[2] = bytes[5];
456 lebytes[3] = bytes[4];
457 lebytes[4] = bytes[3];
458 lebytes[5] = bytes[2];
459 lebytes[6] = bytes[1];
460 lebytes[7] = bytes[0];
461 return pb_write(stream, lebytes, 8);
463 return pb_write(stream, (const uint8_t*)value, 8);
467 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
469 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
470 return pb_encode_varint(stream, tag);
473 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
475 pb_wire_type_t wiretype;
476 switch (PB_LTYPE(field->type))
478 case PB_LTYPE_VARINT:
479 case PB_LTYPE_UVARINT:
480 case PB_LTYPE_SVARINT:
481 wiretype = PB_WT_VARINT;
484 case PB_LTYPE_FIXED32:
485 wiretype = PB_WT_32BIT;
488 case PB_LTYPE_FIXED64:
489 wiretype = PB_WT_64BIT;
493 case PB_LTYPE_STRING:
494 case PB_LTYPE_SUBMESSAGE:
495 wiretype = PB_WT_STRING;
499 PB_RETURN_ERROR(stream, "invalid field type");
502 return pb_encode_tag(stream, wiretype, field->tag);
505 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
507 if (!pb_encode_varint(stream, (uint64_t)size))
510 return pb_write(stream, buffer, size);
513 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
515 /* First calculate the message size using a non-writing substream. */
516 pb_ostream_t substream = PB_OSTREAM_SIZING;
520 if (!pb_encode(&substream, fields, src_struct))
523 stream->errmsg = substream.errmsg;
528 size = substream.bytes_written;
530 if (!pb_encode_varint(stream, (uint64_t)size))
533 if (stream->callback == NULL)
534 return pb_write(stream, NULL, size); /* Just sizing */
536 if (stream->bytes_written + size > stream->max_size)
537 PB_RETURN_ERROR(stream, "stream full");
539 /* Use a substream to verify that a callback doesn't write more than
540 * what it did the first time. */
541 substream.callback = stream->callback;
542 substream.state = stream->state;
543 substream.max_size = size;
544 substream.bytes_written = 0;
546 substream.errmsg = NULL;
549 status = pb_encode(&substream, fields, src_struct);
551 stream->bytes_written += substream.bytes_written;
552 stream->state = substream.state;
554 stream->errmsg = substream.errmsg;
557 if (substream.bytes_written != size)
558 PB_RETURN_ERROR(stream, "submsg size changed");
565 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
569 /* Cases 1 and 2 are for compilers that have smaller types for bool
571 switch (field->data_size)
573 case 1: value = *(const int8_t*)src; break;
574 case 2: value = *(const int16_t*)src; break;
575 case 4: value = *(const int32_t*)src; break;
576 case 8: value = *(const int64_t*)src; break;
577 default: PB_RETURN_ERROR(stream, "invalid data_size");
580 return pb_encode_varint(stream, (uint64_t)value);
583 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
587 switch (field->data_size)
589 case 4: value = *(const uint32_t*)src; break;
590 case 8: value = *(const uint64_t*)src; break;
591 default: PB_RETURN_ERROR(stream, "invalid data_size");
594 return pb_encode_varint(stream, value);
597 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
601 switch (field->data_size)
603 case 4: value = *(const int32_t*)src; break;
604 case 8: value = *(const int64_t*)src; break;
605 default: PB_RETURN_ERROR(stream, "invalid data_size");
608 return pb_encode_svarint(stream, value);
611 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
614 return pb_encode_fixed64(stream, src);
617 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
620 return pb_encode_fixed32(stream, src);
623 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
625 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
629 /* Threat null pointer as an empty bytes field */
630 return pb_encode_string(stream, NULL, 0);
633 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
634 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
636 PB_RETURN_ERROR(stream, "bytes size exceeded");
639 return pb_encode_string(stream, bytes->bytes, bytes->size);
642 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
645 size_t max_size = field->data_size;
646 const char *p = (const char*)src;
648 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
649 max_size = (size_t)-1;
653 size = 0; /* Threat null pointer as an empty string */
657 /* strnlen() is not always available, so just use a loop */
658 while (size < max_size && *p != '\0')
665 return pb_encode_string(stream, (const uint8_t*)src, size);
668 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
670 if (field->ptr == NULL)
671 PB_RETURN_ERROR(stream, "invalid field descriptor");
673 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);