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] = {
34 /* pb_ostream_t implementation */
36 static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
38 uint8_t *dest = (uint8_t*)stream->state;
39 stream->state = dest + count;
47 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize)
51 stream.callback = (void*)1; /* Just some marker value */
53 stream.callback = &buf_write;
56 stream.max_size = bufsize;
57 stream.bytes_written = 0;
64 bool checkreturn pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
66 if (stream->callback != NULL)
68 if (stream->bytes_written + count > stream->max_size)
69 PB_RETURN_ERROR(stream, "stream full");
72 if (!buf_write(stream, buf, count))
73 PB_RETURN_ERROR(stream, "io error");
75 if (!stream->callback(stream, buf, count))
76 PB_RETURN_ERROR(stream, "io error");
80 stream->bytes_written += count;
84 /* Main encoding stuff */
86 /* Encode a static array. Handles the size calculations and possible packing. */
87 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
88 const void *pData, size_t count, pb_encoder_t func)
97 /* We always pack arrays if the datatype allows it. */
98 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
100 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
103 /* Determine the total size of packed array. */
104 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
108 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
114 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
116 for (i = 0; i < count; i++)
118 if (!func(&sizestream, field, p))
120 p = (const char*)p + field->data_size;
122 size = sizestream.bytes_written;
125 if (!pb_encode_varint(stream, (uint64_t)size))
128 if (stream->callback == NULL)
129 return pb_write(stream, NULL, size); /* Just sizing.. */
133 for (i = 0; i < count; i++)
135 if (!func(stream, field, p))
137 p = (const char*)p + field->data_size;
143 for (i = 0; i < count; i++)
145 if (!pb_encode_tag_for_field(stream, field))
147 if (!func(stream, field, p))
149 p = (const char*)p + field->data_size;
156 /* Encode a field with static allocation, i.e. one whose data is stored
157 * in the structure itself. */
158 static bool checkreturn encode_static_field(pb_ostream_t *stream,
159 const pb_field_t *field, const void *pData)
164 func = PB_ENCODERS[PB_LTYPE(field->type)];
165 pSize = (const char*)pData + field->size_offset;
167 switch (PB_HTYPE(field->type))
169 case PB_HTYPE_REQUIRED:
170 if (!pb_encode_tag_for_field(stream, field))
172 if (!func(stream, field, pData))
176 case PB_HTYPE_OPTIONAL:
177 if (*(const bool*)pSize)
179 if (!pb_encode_tag_for_field(stream, field))
182 if (!func(stream, field, pData))
187 case PB_HTYPE_REPEATED:
188 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
193 PB_RETURN_ERROR(stream, "invalid field type");
199 /* Encode a field with callback semantics. This means that a user function is
200 * called to provide and encode the actual data. */
201 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
202 const pb_field_t *field, const void *pData)
204 const pb_callback_t *callback = (const pb_callback_t*)pData;
206 #ifdef PB_OLD_CALLBACK_STYLE
207 const void *arg = callback->arg;
209 void * const *arg = &(callback->arg);
212 if (callback->funcs.encode != NULL)
214 if (!callback->funcs.encode(stream, field, arg))
215 PB_RETURN_ERROR(stream, "callback error");
220 /* Encode a single field of any callback or static type. */
221 static bool checkreturn encode_field(pb_ostream_t *stream,
222 const pb_field_t *field, const void *pData)
224 switch (PB_ATYPE(field->type))
226 case PB_ATYPE_STATIC:
227 return encode_static_field(stream, field, pData);
229 case PB_ATYPE_CALLBACK:
230 return encode_callback_field(stream, field, pData);
233 PB_RETURN_ERROR(stream, "invalid field type");
237 /* Default handler for extension fields. Expects to have a pb_field_t
238 * pointer in the extension->type->arg field. */
239 static bool checkreturn default_extension_handler(pb_ostream_t *stream,
240 const pb_extension_t *extension)
242 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
243 return encode_field(stream, field, extension->dest);
246 /* Walk through all the registered extensions and give them a chance
247 * to encode themselves. */
248 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
249 const pb_field_t *field, const void *pData)
251 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
257 if (extension->type->encode)
258 status = extension->type->encode(stream, extension);
260 status = default_extension_handler(stream, extension);
265 extension = extension->next;
271 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
273 const pb_field_t *field = fields;
274 const void *pData = src_struct;
275 size_t prev_size = 0;
277 while (field->tag != 0)
279 pData = (const char*)pData + prev_size + field->data_offset;
280 prev_size = field->data_size;
282 /* Special case for static arrays */
283 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
284 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
286 prev_size *= field->array_size;
289 if (PB_LTYPE(field->type) == PB_LTYPE_EXTENSION)
291 /* Special case for the extension field placeholder */
292 if (!encode_extension_field(stream, field, pData))
298 if (!encode_field(stream, field, pData))
308 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
310 return pb_encode_submessage(stream, fields, src_struct);
313 /* Helper functions */
314 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
320 return pb_write(stream, (uint8_t*)&value, 1);
324 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
328 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
330 return pb_write(stream, buffer, i);
333 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
337 zigzagged = (uint64_t)(~(value << 1));
339 zigzagged = (uint64_t)(value << 1);
341 return pb_encode_varint(stream, zigzagged);
344 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
346 #ifdef __BIG_ENDIAN__
347 const uint8_t *bytes = value;
349 lebytes[0] = bytes[3];
350 lebytes[1] = bytes[2];
351 lebytes[2] = bytes[1];
352 lebytes[3] = bytes[0];
353 return pb_write(stream, lebytes, 4);
355 return pb_write(stream, (const uint8_t*)value, 4);
359 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
361 #ifdef __BIG_ENDIAN__
362 const uint8_t *bytes = value;
364 lebytes[0] = bytes[7];
365 lebytes[1] = bytes[6];
366 lebytes[2] = bytes[5];
367 lebytes[3] = bytes[4];
368 lebytes[4] = bytes[3];
369 lebytes[5] = bytes[2];
370 lebytes[6] = bytes[1];
371 lebytes[7] = bytes[0];
372 return pb_write(stream, lebytes, 8);
374 return pb_write(stream, (const uint8_t*)value, 8);
378 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
380 uint64_t tag = wiretype | (field_number << 3);
381 return pb_encode_varint(stream, tag);
384 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
386 pb_wire_type_t wiretype;
387 switch (PB_LTYPE(field->type))
389 case PB_LTYPE_VARINT:
390 case PB_LTYPE_SVARINT:
391 wiretype = PB_WT_VARINT;
394 case PB_LTYPE_FIXED32:
395 wiretype = PB_WT_32BIT;
398 case PB_LTYPE_FIXED64:
399 wiretype = PB_WT_64BIT;
403 case PB_LTYPE_STRING:
404 case PB_LTYPE_SUBMESSAGE:
405 wiretype = PB_WT_STRING;
409 PB_RETURN_ERROR(stream, "invalid field type");
412 return pb_encode_tag(stream, wiretype, field->tag);
415 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
417 if (!pb_encode_varint(stream, (uint64_t)size))
420 return pb_write(stream, buffer, size);
423 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
425 /* First calculate the message size using a non-writing substream. */
426 pb_ostream_t substream = PB_OSTREAM_SIZING;
430 if (!pb_encode(&substream, fields, src_struct))
433 size = substream.bytes_written;
435 if (!pb_encode_varint(stream, (uint64_t)size))
438 if (stream->callback == NULL)
439 return pb_write(stream, NULL, size); /* Just sizing */
441 if (stream->bytes_written + size > stream->max_size)
442 PB_RETURN_ERROR(stream, "stream full");
444 /* Use a substream to verify that a callback doesn't write more than
445 * what it did the first time. */
446 substream.callback = stream->callback;
447 substream.state = stream->state;
448 substream.max_size = size;
449 substream.bytes_written = 0;
451 substream.errmsg = NULL;
454 status = pb_encode(&substream, fields, src_struct);
456 stream->bytes_written += substream.bytes_written;
457 stream->state = substream.state;
459 stream->errmsg = substream.errmsg;
462 if (substream.bytes_written != size)
463 PB_RETURN_ERROR(stream, "submsg size changed");
470 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
474 switch (field->data_size)
476 case 1: value = *(const uint8_t*)src; break;
477 case 2: value = *(const uint16_t*)src; break;
478 case 4: value = *(const uint32_t*)src; break;
479 case 8: value = *(const uint64_t*)src; break;
480 default: PB_RETURN_ERROR(stream, "invalid data_size");
483 return pb_encode_varint(stream, value);
486 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
490 switch (field->data_size)
492 case 4: value = *(const int32_t*)src; break;
493 case 8: value = *(const int64_t*)src; break;
494 default: PB_RETURN_ERROR(stream, "invalid data_size");
497 return pb_encode_svarint(stream, value);
500 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
503 return pb_encode_fixed64(stream, src);
506 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
509 return pb_encode_fixed32(stream, src);
512 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
514 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
516 return pb_encode_string(stream, bytes->bytes, bytes->size);
519 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
521 /* strnlen() is not always available, so just use a for-loop */
523 const char *p = (const char*)src;
524 while (size < field->data_size && *p != '\0')
530 return pb_encode_string(stream, (const uint8_t*)src, size);
533 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
535 if (field->ptr == NULL)
536 PB_RETURN_ERROR(stream, "invalid field descriptor");
538 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);