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 if (count > field->array_size)
99 PB_RETURN_ERROR(stream, "array max size exceeded");
101 /* We always pack arrays if the datatype allows it. */
102 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
104 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
107 /* Determine the total size of packed array. */
108 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
112 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
118 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
120 for (i = 0; i < count; i++)
122 if (!func(&sizestream, field, p))
124 p = (const char*)p + field->data_size;
126 size = sizestream.bytes_written;
129 if (!pb_encode_varint(stream, (uint64_t)size))
132 if (stream->callback == NULL)
133 return pb_write(stream, NULL, size); /* Just sizing.. */
137 for (i = 0; i < count; i++)
139 if (!func(stream, field, p))
141 p = (const char*)p + field->data_size;
147 for (i = 0; i < count; i++)
149 if (!pb_encode_tag_for_field(stream, field))
151 if (!func(stream, field, p))
153 p = (const char*)p + field->data_size;
160 /* Encode a field with static allocation, i.e. one whose data is stored
161 * in the structure itself. */
162 static bool checkreturn encode_static_field(pb_ostream_t *stream,
163 const pb_field_t *field, const void *pData)
169 func = PB_ENCODERS[PB_LTYPE(field->type)];
171 if (field->size_offset)
172 pSize = (const char*)pData + field->size_offset;
176 switch (PB_HTYPE(field->type))
178 case PB_HTYPE_REQUIRED:
179 if (!pb_encode_tag_for_field(stream, field))
181 if (!func(stream, field, pData))
185 case PB_HTYPE_OPTIONAL:
186 if (*(const bool*)pSize)
188 if (!pb_encode_tag_for_field(stream, field))
191 if (!func(stream, field, pData))
196 case PB_HTYPE_REPEATED:
197 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
202 PB_RETURN_ERROR(stream, "invalid field type");
208 /* Encode a field with callback semantics. This means that a user function is
209 * called to provide and encode the actual data. */
210 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
211 const pb_field_t *field, const void *pData)
213 const pb_callback_t *callback = (const pb_callback_t*)pData;
215 #ifdef PB_OLD_CALLBACK_STYLE
216 const void *arg = callback->arg;
218 void * const *arg = &(callback->arg);
221 if (callback->funcs.encode != NULL)
223 if (!callback->funcs.encode(stream, field, arg))
224 PB_RETURN_ERROR(stream, "callback error");
229 /* Encode a single field of any callback or static type. */
230 static bool checkreturn encode_field(pb_ostream_t *stream,
231 const pb_field_t *field, const void *pData)
233 switch (PB_ATYPE(field->type))
235 case PB_ATYPE_STATIC:
236 return encode_static_field(stream, field, pData);
238 case PB_ATYPE_CALLBACK:
239 return encode_callback_field(stream, field, pData);
242 PB_RETURN_ERROR(stream, "invalid field type");
246 /* Default handler for extension fields. Expects to have a pb_field_t
247 * pointer in the extension->type->arg field. */
248 static bool checkreturn default_extension_handler(pb_ostream_t *stream,
249 const pb_extension_t *extension)
251 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
252 return encode_field(stream, field, extension->dest);
255 /* Walk through all the registered extensions and give them a chance
256 * to encode themselves. */
257 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
258 const pb_field_t *field, const void *pData)
260 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
266 if (extension->type->encode)
267 status = extension->type->encode(stream, extension);
269 status = default_extension_handler(stream, extension);
274 extension = extension->next;
280 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
282 const pb_field_t *field = fields;
283 const void *pData = src_struct;
284 size_t prev_size = 0;
286 while (field->tag != 0)
288 pData = (const char*)pData + prev_size + field->data_offset;
289 prev_size = field->data_size;
291 /* Special case for static arrays */
292 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
293 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
295 prev_size *= field->array_size;
298 if (PB_LTYPE(field->type) == PB_LTYPE_EXTENSION)
300 /* Special case for the extension field placeholder */
301 if (!encode_extension_field(stream, field, pData))
307 if (!encode_field(stream, field, pData))
317 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
319 return pb_encode_submessage(stream, fields, src_struct);
322 /* Helper functions */
323 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
329 return pb_write(stream, (uint8_t*)&value, 1);
333 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
337 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
339 return pb_write(stream, buffer, i);
342 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
346 zigzagged = (uint64_t)(~(value << 1));
348 zigzagged = (uint64_t)(value << 1);
350 return pb_encode_varint(stream, zigzagged);
353 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
355 #ifdef __BIG_ENDIAN__
356 const uint8_t *bytes = value;
358 lebytes[0] = bytes[3];
359 lebytes[1] = bytes[2];
360 lebytes[2] = bytes[1];
361 lebytes[3] = bytes[0];
362 return pb_write(stream, lebytes, 4);
364 return pb_write(stream, (const uint8_t*)value, 4);
368 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
370 #ifdef __BIG_ENDIAN__
371 const uint8_t *bytes = value;
373 lebytes[0] = bytes[7];
374 lebytes[1] = bytes[6];
375 lebytes[2] = bytes[5];
376 lebytes[3] = bytes[4];
377 lebytes[4] = bytes[3];
378 lebytes[5] = bytes[2];
379 lebytes[6] = bytes[1];
380 lebytes[7] = bytes[0];
381 return pb_write(stream, lebytes, 8);
383 return pb_write(stream, (const uint8_t*)value, 8);
387 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
389 uint64_t tag = wiretype | (field_number << 3);
390 return pb_encode_varint(stream, tag);
393 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
395 pb_wire_type_t wiretype;
396 switch (PB_LTYPE(field->type))
398 case PB_LTYPE_VARINT:
399 case PB_LTYPE_SVARINT:
400 wiretype = PB_WT_VARINT;
403 case PB_LTYPE_FIXED32:
404 wiretype = PB_WT_32BIT;
407 case PB_LTYPE_FIXED64:
408 wiretype = PB_WT_64BIT;
412 case PB_LTYPE_STRING:
413 case PB_LTYPE_SUBMESSAGE:
414 wiretype = PB_WT_STRING;
418 PB_RETURN_ERROR(stream, "invalid field type");
421 return pb_encode_tag(stream, wiretype, field->tag);
424 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
426 if (!pb_encode_varint(stream, (uint64_t)size))
429 return pb_write(stream, buffer, size);
432 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
434 /* First calculate the message size using a non-writing substream. */
435 pb_ostream_t substream = PB_OSTREAM_SIZING;
439 if (!pb_encode(&substream, fields, src_struct))
442 size = substream.bytes_written;
444 if (!pb_encode_varint(stream, (uint64_t)size))
447 if (stream->callback == NULL)
448 return pb_write(stream, NULL, size); /* Just sizing */
450 if (stream->bytes_written + size > stream->max_size)
451 PB_RETURN_ERROR(stream, "stream full");
453 /* Use a substream to verify that a callback doesn't write more than
454 * what it did the first time. */
455 substream.callback = stream->callback;
456 substream.state = stream->state;
457 substream.max_size = size;
458 substream.bytes_written = 0;
460 substream.errmsg = NULL;
463 status = pb_encode(&substream, fields, src_struct);
465 stream->bytes_written += substream.bytes_written;
466 stream->state = substream.state;
468 stream->errmsg = substream.errmsg;
471 if (substream.bytes_written != size)
472 PB_RETURN_ERROR(stream, "submsg size changed");
479 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
483 switch (field->data_size)
485 case 1: value = *(const uint8_t*)src; break;
486 case 2: value = *(const uint16_t*)src; break;
487 case 4: value = *(const uint32_t*)src; break;
488 case 8: value = *(const uint64_t*)src; break;
489 default: PB_RETURN_ERROR(stream, "invalid data_size");
492 return pb_encode_varint(stream, value);
495 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
499 switch (field->data_size)
501 case 4: value = *(const int32_t*)src; break;
502 case 8: value = *(const int64_t*)src; break;
503 default: PB_RETURN_ERROR(stream, "invalid data_size");
506 return pb_encode_svarint(stream, value);
509 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
512 return pb_encode_fixed64(stream, src);
515 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
518 return pb_encode_fixed32(stream, src);
521 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
523 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
525 if (bytes->size + offsetof(pb_bytes_array_t, bytes) > field->data_size)
526 PB_RETURN_ERROR(stream, "bytes size exceeded");
528 return pb_encode_string(stream, bytes->bytes, bytes->size);
531 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
533 /* strnlen() is not always available, so just use a for-loop */
535 const char *p = (const char*)src;
536 while (size < field->data_size && *p != '\0')
542 return pb_encode_string(stream, (const uint8_t*)src, size);
545 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
547 if (field->ptr == NULL)
548 PB_RETURN_ERROR(stream, "invalid field descriptor");
550 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);