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)
165 func = PB_ENCODERS[PB_LTYPE(field->type)];
166 pSize = (const char*)pData + field->size_offset;
168 switch (PB_HTYPE(field->type))
170 case PB_HTYPE_REQUIRED:
171 if (!pb_encode_tag_for_field(stream, field))
173 if (!func(stream, field, pData))
177 case PB_HTYPE_OPTIONAL:
178 if (*(const bool*)pSize)
180 if (!pb_encode_tag_for_field(stream, field))
183 if (!func(stream, field, pData))
188 case PB_HTYPE_REPEATED:
189 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
194 PB_RETURN_ERROR(stream, "invalid field type");
200 /* Encode a field with callback semantics. This means that a user function is
201 * called to provide and encode the actual data. */
202 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
203 const pb_field_t *field, const void *pData)
205 const pb_callback_t *callback = (const pb_callback_t*)pData;
207 #ifdef PB_OLD_CALLBACK_STYLE
208 const void *arg = callback->arg;
210 void * const *arg = &(callback->arg);
213 if (callback->funcs.encode != NULL)
215 if (!callback->funcs.encode(stream, field, arg))
216 PB_RETURN_ERROR(stream, "callback error");
221 /* Encode a single field of any callback or static type. */
222 static bool checkreturn encode_field(pb_ostream_t *stream,
223 const pb_field_t *field, const void *pData)
225 switch (PB_ATYPE(field->type))
227 case PB_ATYPE_STATIC:
228 return encode_static_field(stream, field, pData);
230 case PB_ATYPE_CALLBACK:
231 return encode_callback_field(stream, field, pData);
234 PB_RETURN_ERROR(stream, "invalid field type");
238 /* Default handler for extension fields. Expects to have a pb_field_t
239 * pointer in the extension->type->arg field. */
240 static bool checkreturn default_extension_handler(pb_ostream_t *stream,
241 const pb_extension_t *extension)
243 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
244 return encode_field(stream, field, extension->dest);
247 /* Walk through all the registered extensions and give them a chance
248 * to encode themselves. */
249 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
250 const pb_field_t *field, const void *pData)
252 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
258 if (extension->type->encode)
259 status = extension->type->encode(stream, extension);
261 status = default_extension_handler(stream, extension);
266 extension = extension->next;
272 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
274 const pb_field_t *field = fields;
275 const void *pData = src_struct;
276 size_t prev_size = 0;
278 while (field->tag != 0)
280 pData = (const char*)pData + prev_size + field->data_offset;
281 prev_size = field->data_size;
283 /* Special case for static arrays */
284 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
285 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
287 prev_size *= field->array_size;
290 if (PB_LTYPE(field->type) == PB_LTYPE_EXTENSION)
292 /* Special case for the extension field placeholder */
293 if (!encode_extension_field(stream, field, pData))
299 if (!encode_field(stream, field, pData))
309 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
311 return pb_encode_submessage(stream, fields, src_struct);
314 /* Helper functions */
315 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
321 return pb_write(stream, (uint8_t*)&value, 1);
325 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
329 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
331 return pb_write(stream, buffer, i);
334 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
338 zigzagged = (uint64_t)(~(value << 1));
340 zigzagged = (uint64_t)(value << 1);
342 return pb_encode_varint(stream, zigzagged);
345 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
347 #ifdef __BIG_ENDIAN__
348 const uint8_t *bytes = value;
350 lebytes[0] = bytes[3];
351 lebytes[1] = bytes[2];
352 lebytes[2] = bytes[1];
353 lebytes[3] = bytes[0];
354 return pb_write(stream, lebytes, 4);
356 return pb_write(stream, (const uint8_t*)value, 4);
360 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
362 #ifdef __BIG_ENDIAN__
363 const uint8_t *bytes = value;
365 lebytes[0] = bytes[7];
366 lebytes[1] = bytes[6];
367 lebytes[2] = bytes[5];
368 lebytes[3] = bytes[4];
369 lebytes[4] = bytes[3];
370 lebytes[5] = bytes[2];
371 lebytes[6] = bytes[1];
372 lebytes[7] = bytes[0];
373 return pb_write(stream, lebytes, 8);
375 return pb_write(stream, (const uint8_t*)value, 8);
379 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
381 uint64_t tag = wiretype | (field_number << 3);
382 return pb_encode_varint(stream, tag);
385 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
387 pb_wire_type_t wiretype;
388 switch (PB_LTYPE(field->type))
390 case PB_LTYPE_VARINT:
391 case PB_LTYPE_SVARINT:
392 wiretype = PB_WT_VARINT;
395 case PB_LTYPE_FIXED32:
396 wiretype = PB_WT_32BIT;
399 case PB_LTYPE_FIXED64:
400 wiretype = PB_WT_64BIT;
404 case PB_LTYPE_STRING:
405 case PB_LTYPE_SUBMESSAGE:
406 wiretype = PB_WT_STRING;
410 PB_RETURN_ERROR(stream, "invalid field type");
413 return pb_encode_tag(stream, wiretype, field->tag);
416 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
418 if (!pb_encode_varint(stream, (uint64_t)size))
421 return pb_write(stream, buffer, size);
424 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
426 /* First calculate the message size using a non-writing substream. */
427 pb_ostream_t substream = PB_OSTREAM_SIZING;
431 if (!pb_encode(&substream, fields, src_struct))
434 size = substream.bytes_written;
436 if (!pb_encode_varint(stream, (uint64_t)size))
439 if (stream->callback == NULL)
440 return pb_write(stream, NULL, size); /* Just sizing */
442 if (stream->bytes_written + size > stream->max_size)
443 PB_RETURN_ERROR(stream, "stream full");
445 /* Use a substream to verify that a callback doesn't write more than
446 * what it did the first time. */
447 substream.callback = stream->callback;
448 substream.state = stream->state;
449 substream.max_size = size;
450 substream.bytes_written = 0;
452 substream.errmsg = NULL;
455 status = pb_encode(&substream, fields, src_struct);
457 stream->bytes_written += substream.bytes_written;
458 stream->state = substream.state;
460 stream->errmsg = substream.errmsg;
463 if (substream.bytes_written != size)
464 PB_RETURN_ERROR(stream, "submsg size changed");
471 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
475 switch (field->data_size)
477 case 1: value = *(const uint8_t*)src; break;
478 case 2: value = *(const uint16_t*)src; break;
479 case 4: value = *(const uint32_t*)src; break;
480 case 8: value = *(const uint64_t*)src; break;
481 default: PB_RETURN_ERROR(stream, "invalid data_size");
484 return pb_encode_varint(stream, value);
487 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
491 switch (field->data_size)
493 case 4: value = *(const int32_t*)src; break;
494 case 8: value = *(const int64_t*)src; break;
495 default: PB_RETURN_ERROR(stream, "invalid data_size");
498 return pb_encode_svarint(stream, value);
501 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
504 return pb_encode_fixed64(stream, src);
507 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
510 return pb_encode_fixed32(stream, src);
513 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
515 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
517 return pb_encode_string(stream, bytes->bytes, bytes->size);
520 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
522 /* strnlen() is not always available, so just use a for-loop */
524 const char *p = (const char*)src;
525 while (size < field->data_size && *p != '\0')
531 return pb_encode_string(stream, (const uint8_t*)src, size);
534 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
536 if (field->ptr == NULL)
537 PB_RETURN_ERROR(stream, "invalid field descriptor");
539 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);