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 /* Callbacks don't need this function because they usually know the data type
87 * without examining the field structure.
88 * Therefore it is static for now.
90 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
91 const void *pData, size_t count, pb_encoder_t func)
100 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
102 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
105 /* Determine the total size of packed array. */
106 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
110 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
116 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
118 for (i = 0; i < count; i++)
120 if (!func(&sizestream, field, p))
122 p = (const char*)p + field->data_size;
124 size = sizestream.bytes_written;
127 if (!pb_encode_varint(stream, (uint64_t)size))
130 if (stream->callback == NULL)
131 return pb_write(stream, NULL, size); /* Just sizing.. */
135 for (i = 0; i < count; i++)
137 if (!func(stream, field, p))
139 p = (const char*)p + field->data_size;
145 for (i = 0; i < count; i++)
147 if (!pb_encode_tag_for_field(stream, field))
149 if (!func(stream, field, p))
151 p = (const char*)p + field->data_size;
158 bool checkreturn encode_static_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData)
163 func = PB_ENCODERS[PB_LTYPE(field->type)];
164 pSize = (const char*)pData + field->size_offset;
166 switch (PB_HTYPE(field->type))
168 case PB_HTYPE_REQUIRED:
169 if (!pb_encode_tag_for_field(stream, field))
171 if (!func(stream, field, pData))
175 case PB_HTYPE_OPTIONAL:
176 if (*(const bool*)pSize)
178 if (!pb_encode_tag_for_field(stream, field))
181 if (!func(stream, field, pData))
186 case PB_HTYPE_REPEATED:
187 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
192 PB_RETURN_ERROR(stream, "invalid field type");
198 bool checkreturn encode_callback_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData)
200 const pb_callback_t *callback = (const pb_callback_t*)pData;
201 if (callback->funcs.encode != NULL)
203 if (!callback->funcs.encode(stream, field, callback->arg))
204 PB_RETURN_ERROR(stream, "callback error");
209 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
211 const pb_field_t *field = fields;
212 const void *pData = src_struct;
213 size_t prev_size = 0;
215 while (field->tag != 0)
217 pData = (const char*)pData + prev_size + field->data_offset;
218 prev_size = field->data_size;
220 /* Special case for static arrays */
221 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
222 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
224 prev_size *= field->array_size;
227 switch (PB_ATYPE(field->type))
229 case PB_ATYPE_STATIC:
230 if (!encode_static_field(stream, field, pData))
234 case PB_ATYPE_CALLBACK:
235 if (!encode_callback_field(stream, field, pData))
240 PB_RETURN_ERROR(stream, "invalid field type");
249 /* Helper functions */
250 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
256 return pb_write(stream, (uint8_t*)&value, 1);
260 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
264 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
266 return pb_write(stream, buffer, i);
269 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
273 zigzagged = (uint64_t)(~(value << 1));
275 zigzagged = (uint64_t)(value << 1);
277 return pb_encode_varint(stream, zigzagged);
280 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
282 #ifdef __BIG_ENDIAN__
283 const uint8_t *bytes = value;
285 lebytes[0] = bytes[3];
286 lebytes[1] = bytes[2];
287 lebytes[2] = bytes[1];
288 lebytes[3] = bytes[0];
289 return pb_write(stream, lebytes, 4);
291 return pb_write(stream, (const uint8_t*)value, 4);
295 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
297 #ifdef __BIG_ENDIAN__
298 const uint8_t *bytes = value;
300 lebytes[0] = bytes[7];
301 lebytes[1] = bytes[6];
302 lebytes[2] = bytes[5];
303 lebytes[3] = bytes[4];
304 lebytes[4] = bytes[3];
305 lebytes[5] = bytes[2];
306 lebytes[6] = bytes[1];
307 lebytes[7] = bytes[0];
308 return pb_write(stream, lebytes, 8);
310 return pb_write(stream, (const uint8_t*)value, 8);
314 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
316 uint64_t tag = wiretype | (field_number << 3);
317 return pb_encode_varint(stream, tag);
320 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
322 pb_wire_type_t wiretype;
323 switch (PB_LTYPE(field->type))
325 case PB_LTYPE_VARINT:
326 case PB_LTYPE_SVARINT:
327 wiretype = PB_WT_VARINT;
330 case PB_LTYPE_FIXED32:
331 wiretype = PB_WT_32BIT;
334 case PB_LTYPE_FIXED64:
335 wiretype = PB_WT_64BIT;
339 case PB_LTYPE_STRING:
340 case PB_LTYPE_SUBMESSAGE:
341 wiretype = PB_WT_STRING;
345 PB_RETURN_ERROR(stream, "invalid field type");
348 return pb_encode_tag(stream, wiretype, field->tag);
351 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
353 if (!pb_encode_varint(stream, (uint64_t)size))
356 return pb_write(stream, buffer, size);
359 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
361 /* First calculate the message size using a non-writing substream. */
362 pb_ostream_t substream = PB_OSTREAM_SIZING;
366 if (!pb_encode(&substream, fields, src_struct))
369 size = substream.bytes_written;
371 if (!pb_encode_varint(stream, (uint64_t)size))
374 if (stream->callback == NULL)
375 return pb_write(stream, NULL, size); /* Just sizing */
377 if (stream->bytes_written + size > stream->max_size)
378 PB_RETURN_ERROR(stream, "stream full");
380 /* Use a substream to verify that a callback doesn't write more than
381 * what it did the first time. */
382 substream.callback = stream->callback;
383 substream.state = stream->state;
384 substream.max_size = size;
385 substream.bytes_written = 0;
387 substream.errmsg = NULL;
390 status = pb_encode(&substream, fields, src_struct);
392 stream->bytes_written += substream.bytes_written;
393 stream->state = substream.state;
395 stream->errmsg = substream.errmsg;
398 if (substream.bytes_written != size)
399 PB_RETURN_ERROR(stream, "submsg size changed");
406 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
410 switch (field->data_size)
412 case 1: value = *(const uint8_t*)src; break;
413 case 2: value = *(const uint16_t*)src; break;
414 case 4: value = *(const uint32_t*)src; break;
415 case 8: value = *(const uint64_t*)src; break;
416 default: PB_RETURN_ERROR(stream, "invalid data_size");
419 return pb_encode_varint(stream, value);
422 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
426 switch (field->data_size)
428 case 4: value = *(const int32_t*)src; break;
429 case 8: value = *(const int64_t*)src; break;
430 default: PB_RETURN_ERROR(stream, "invalid data_size");
433 return pb_encode_svarint(stream, value);
436 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
439 return pb_encode_fixed64(stream, src);
442 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
445 return pb_encode_fixed32(stream, src);
448 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
450 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
452 return pb_encode_string(stream, bytes->bytes, bytes->size);
455 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
458 return pb_encode_string(stream, (const uint8_t*)src, strlen((const char*)src));
461 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
463 if (field->ptr == NULL)
464 PB_RETURN_ERROR(stream, "invalid field descriptor");
466 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);