1 /* pb_encode.c -- encode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
6 #define NANOPB_INTERNALS
10 /* The warn_unused_result attribute appeared first in gcc-3.4.0 */
11 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
14 /* Verify that we remember to check all return values for proper error propagation */
15 #define checkreturn __attribute__((warn_unused_result))
18 typedef bool (*pb_encoder_t)(pb_ostream_t *stream, const pb_field_t *field, const void *src) checkreturn;
20 /* --- Function pointers to field encoders ---
21 * Order in the array must match pb_action_t LTYPE numbering.
23 static const pb_encoder_t PB_ENCODERS[PB_LTYPES_COUNT] = {
35 /* pb_ostream_t implementation */
37 static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
39 uint8_t *dest = (uint8_t*)stream->state;
40 stream->state = dest + count;
48 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize)
52 stream.callback = (void*)1; /* Just some marker value */
54 stream.callback = &buf_write;
57 stream.max_size = bufsize;
58 stream.bytes_written = 0;
65 bool checkreturn pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
67 if (stream->callback != NULL)
69 if (stream->bytes_written + count > stream->max_size)
70 PB_RETURN_ERROR(stream, "stream full");
73 if (!buf_write(stream, buf, count))
74 PB_RETURN_ERROR(stream, "io error");
76 if (!stream->callback(stream, buf, count))
77 PB_RETURN_ERROR(stream, "io error");
81 stream->bytes_written += count;
85 /* Main encoding stuff */
87 /* Encode a static array. Handles the size calculations and possible packing. */
88 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
89 const void *pData, size_t count, pb_encoder_t func)
98 /* We always pack arrays if the datatype allows it. */
99 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
101 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
104 /* Determine the total size of packed array. */
105 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
109 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
115 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
117 for (i = 0; i < count; i++)
119 if (!func(&sizestream, field, p))
121 p = (const char*)p + field->data_size;
123 size = sizestream.bytes_written;
126 if (!pb_encode_varint(stream, (uint64_t)size))
129 if (stream->callback == NULL)
130 return pb_write(stream, NULL, size); /* Just sizing.. */
134 for (i = 0; i < count; i++)
136 if (!func(stream, field, p))
138 p = (const char*)p + field->data_size;
144 for (i = 0; i < count; i++)
146 if (!pb_encode_tag_for_field(stream, field))
148 if (!func(stream, field, p))
150 p = (const char*)p + field->data_size;
157 /* Encode a field with static allocation, i.e. one whose data is stored
158 * in the structure itself. */
159 static bool checkreturn encode_static_field(pb_ostream_t *stream,
160 const pb_field_t *field, const void *pData)
166 func = PB_ENCODERS[PB_LTYPE(field->type)];
168 if (field->size_offset)
169 pSize = (const char*)pData + field->size_offset;
173 switch (PB_HTYPE(field->type))
175 case PB_HTYPE_REQUIRED:
176 if (!pb_encode_tag_for_field(stream, field))
178 if (!func(stream, field, pData))
182 case PB_HTYPE_OPTIONAL:
183 if (*(const bool*)pSize)
185 if (!pb_encode_tag_for_field(stream, field))
188 if (!func(stream, field, pData))
193 case PB_HTYPE_REPEATED:
194 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
199 PB_RETURN_ERROR(stream, "invalid field type");
205 /* Encode a field with callback semantics. This means that a user function is
206 * called to provide and encode the actual data. */
207 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
208 const pb_field_t *field, const void *pData)
210 const pb_callback_t *callback = (const pb_callback_t*)pData;
212 #ifdef PB_OLD_CALLBACK_STYLE
213 const void *arg = callback->arg;
215 void * const *arg = &(callback->arg);
218 if (callback->funcs.encode != NULL)
220 if (!callback->funcs.encode(stream, field, arg))
221 PB_RETURN_ERROR(stream, "callback error");
226 /* Encode a single field of any callback or static type. */
227 static bool checkreturn encode_field(pb_ostream_t *stream,
228 const pb_field_t *field, const void *pData)
230 switch (PB_ATYPE(field->type))
232 case PB_ATYPE_STATIC:
233 return encode_static_field(stream, field, pData);
235 case PB_ATYPE_CALLBACK:
236 return encode_callback_field(stream, field, pData);
239 PB_RETURN_ERROR(stream, "invalid field type");
243 /* Default handler for extension fields. Expects to have a pb_field_t
244 * pointer in the extension->type->arg field. */
245 static bool checkreturn default_extension_handler(pb_ostream_t *stream,
246 const pb_extension_t *extension)
248 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
249 return encode_field(stream, field, extension->dest);
252 /* Walk through all the registered extensions and give them a chance
253 * to encode themselves. */
254 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
255 const pb_field_t *field, const void *pData)
257 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
263 if (extension->type->encode)
264 status = extension->type->encode(stream, extension);
266 status = default_extension_handler(stream, extension);
271 extension = extension->next;
277 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
279 const pb_field_t *field = fields;
280 const void *pData = src_struct;
281 size_t prev_size = 0;
283 while (field->tag != 0)
285 pData = (const char*)pData + prev_size + field->data_offset;
286 prev_size = field->data_size;
288 /* Special case for static arrays */
289 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
290 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
292 prev_size *= field->array_size;
295 if (PB_LTYPE(field->type) == PB_LTYPE_EXTENSION)
297 /* Special case for the extension field placeholder */
298 if (!encode_extension_field(stream, field, pData))
304 if (!encode_field(stream, field, pData))
314 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
316 return pb_encode_submessage(stream, fields, src_struct);
319 /* Helper functions */
320 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
326 return pb_write(stream, (uint8_t*)&value, 1);
330 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
334 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
336 return pb_write(stream, buffer, i);
339 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
343 zigzagged = (uint64_t)(~(value << 1));
345 zigzagged = (uint64_t)(value << 1);
347 return pb_encode_varint(stream, zigzagged);
350 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
352 #ifdef __BIG_ENDIAN__
353 const uint8_t *bytes = value;
355 lebytes[0] = bytes[3];
356 lebytes[1] = bytes[2];
357 lebytes[2] = bytes[1];
358 lebytes[3] = bytes[0];
359 return pb_write(stream, lebytes, 4);
361 return pb_write(stream, (const uint8_t*)value, 4);
365 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
367 #ifdef __BIG_ENDIAN__
368 const uint8_t *bytes = value;
370 lebytes[0] = bytes[7];
371 lebytes[1] = bytes[6];
372 lebytes[2] = bytes[5];
373 lebytes[3] = bytes[4];
374 lebytes[4] = bytes[3];
375 lebytes[5] = bytes[2];
376 lebytes[6] = bytes[1];
377 lebytes[7] = bytes[0];
378 return pb_write(stream, lebytes, 8);
380 return pb_write(stream, (const uint8_t*)value, 8);
384 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
386 uint64_t tag = wiretype | (field_number << 3);
387 return pb_encode_varint(stream, tag);
390 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
392 pb_wire_type_t wiretype;
393 switch (PB_LTYPE(field->type))
395 case PB_LTYPE_VARINT:
396 case PB_LTYPE_SVARINT:
397 wiretype = PB_WT_VARINT;
400 case PB_LTYPE_FIXED32:
401 wiretype = PB_WT_32BIT;
404 case PB_LTYPE_FIXED64:
405 wiretype = PB_WT_64BIT;
409 case PB_LTYPE_STRING:
410 case PB_LTYPE_SUBMESSAGE:
411 wiretype = PB_WT_STRING;
415 PB_RETURN_ERROR(stream, "invalid field type");
418 return pb_encode_tag(stream, wiretype, field->tag);
421 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
423 if (!pb_encode_varint(stream, (uint64_t)size))
426 return pb_write(stream, buffer, size);
429 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
431 /* First calculate the message size using a non-writing substream. */
432 pb_ostream_t substream = PB_OSTREAM_SIZING;
436 if (!pb_encode(&substream, fields, src_struct))
439 size = substream.bytes_written;
441 if (!pb_encode_varint(stream, (uint64_t)size))
444 if (stream->callback == NULL)
445 return pb_write(stream, NULL, size); /* Just sizing */
447 if (stream->bytes_written + size > stream->max_size)
448 PB_RETURN_ERROR(stream, "stream full");
450 /* Use a substream to verify that a callback doesn't write more than
451 * what it did the first time. */
452 substream.callback = stream->callback;
453 substream.state = stream->state;
454 substream.max_size = size;
455 substream.bytes_written = 0;
457 substream.errmsg = NULL;
460 status = pb_encode(&substream, fields, src_struct);
462 stream->bytes_written += substream.bytes_written;
463 stream->state = substream.state;
465 stream->errmsg = substream.errmsg;
468 if (substream.bytes_written != size)
469 PB_RETURN_ERROR(stream, "submsg size changed");
476 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
480 switch (field->data_size)
482 case 1: value = *(const uint8_t*)src; break;
483 case 2: value = *(const uint16_t*)src; break;
484 case 4: value = *(const uint32_t*)src; break;
485 case 8: value = *(const uint64_t*)src; break;
486 default: PB_RETURN_ERROR(stream, "invalid data_size");
489 return pb_encode_varint(stream, value);
492 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
496 switch (field->data_size)
498 case 4: value = *(const int32_t*)src; break;
499 case 8: value = *(const int64_t*)src; break;
500 default: PB_RETURN_ERROR(stream, "invalid data_size");
503 return pb_encode_svarint(stream, value);
506 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
509 return pb_encode_fixed64(stream, src);
512 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
515 return pb_encode_fixed32(stream, src);
518 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
520 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
522 return pb_encode_string(stream, bytes->bytes, bytes->size);
525 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
527 /* strnlen() is not always available, so just use a for-loop */
529 const char *p = (const char*)src;
530 while (size < field->data_size && *p != '\0')
536 return pb_encode_string(stream, (const uint8_t*)src, size);
539 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
541 if (field->ptr == NULL)
542 PB_RETURN_ERROR(stream, "invalid field descriptor");
544 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);