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;
202 #ifdef PB_OLD_CALLBACK_STYLE
203 const void *arg = callback->arg;
205 void * const *arg = &(callback->arg);
208 if (callback->funcs.encode != NULL)
210 if (!callback->funcs.encode(stream, field, arg))
211 PB_RETURN_ERROR(stream, "callback error");
216 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
218 const pb_field_t *field = fields;
219 const void *pData = src_struct;
220 size_t prev_size = 0;
222 while (field->tag != 0)
224 pData = (const char*)pData + prev_size + field->data_offset;
225 prev_size = field->data_size;
227 /* Special case for static arrays */
228 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
229 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
231 prev_size *= field->array_size;
234 switch (PB_ATYPE(field->type))
236 case PB_ATYPE_STATIC:
237 if (!encode_static_field(stream, field, pData))
241 case PB_ATYPE_CALLBACK:
242 if (!encode_callback_field(stream, field, pData))
247 PB_RETURN_ERROR(stream, "invalid field type");
256 /* Helper functions */
257 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
263 return pb_write(stream, (uint8_t*)&value, 1);
267 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
271 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
273 return pb_write(stream, buffer, i);
276 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
280 zigzagged = (uint64_t)(~(value << 1));
282 zigzagged = (uint64_t)(value << 1);
284 return pb_encode_varint(stream, zigzagged);
287 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
289 #ifdef __BIG_ENDIAN__
290 const uint8_t *bytes = value;
292 lebytes[0] = bytes[3];
293 lebytes[1] = bytes[2];
294 lebytes[2] = bytes[1];
295 lebytes[3] = bytes[0];
296 return pb_write(stream, lebytes, 4);
298 return pb_write(stream, (const uint8_t*)value, 4);
302 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
304 #ifdef __BIG_ENDIAN__
305 const uint8_t *bytes = value;
307 lebytes[0] = bytes[7];
308 lebytes[1] = bytes[6];
309 lebytes[2] = bytes[5];
310 lebytes[3] = bytes[4];
311 lebytes[4] = bytes[3];
312 lebytes[5] = bytes[2];
313 lebytes[6] = bytes[1];
314 lebytes[7] = bytes[0];
315 return pb_write(stream, lebytes, 8);
317 return pb_write(stream, (const uint8_t*)value, 8);
321 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
323 uint64_t tag = wiretype | (field_number << 3);
324 return pb_encode_varint(stream, tag);
327 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
329 pb_wire_type_t wiretype;
330 switch (PB_LTYPE(field->type))
332 case PB_LTYPE_VARINT:
333 case PB_LTYPE_SVARINT:
334 wiretype = PB_WT_VARINT;
337 case PB_LTYPE_FIXED32:
338 wiretype = PB_WT_32BIT;
341 case PB_LTYPE_FIXED64:
342 wiretype = PB_WT_64BIT;
346 case PB_LTYPE_STRING:
347 case PB_LTYPE_SUBMESSAGE:
348 wiretype = PB_WT_STRING;
352 PB_RETURN_ERROR(stream, "invalid field type");
355 return pb_encode_tag(stream, wiretype, field->tag);
358 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
360 if (!pb_encode_varint(stream, (uint64_t)size))
363 return pb_write(stream, buffer, size);
366 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
368 /* First calculate the message size using a non-writing substream. */
369 pb_ostream_t substream = PB_OSTREAM_SIZING;
373 if (!pb_encode(&substream, fields, src_struct))
376 size = substream.bytes_written;
378 if (!pb_encode_varint(stream, (uint64_t)size))
381 if (stream->callback == NULL)
382 return pb_write(stream, NULL, size); /* Just sizing */
384 if (stream->bytes_written + size > stream->max_size)
385 PB_RETURN_ERROR(stream, "stream full");
387 /* Use a substream to verify that a callback doesn't write more than
388 * what it did the first time. */
389 substream.callback = stream->callback;
390 substream.state = stream->state;
391 substream.max_size = size;
392 substream.bytes_written = 0;
394 substream.errmsg = NULL;
397 status = pb_encode(&substream, fields, src_struct);
399 stream->bytes_written += substream.bytes_written;
400 stream->state = substream.state;
402 stream->errmsg = substream.errmsg;
405 if (substream.bytes_written != size)
406 PB_RETURN_ERROR(stream, "submsg size changed");
413 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
417 switch (field->data_size)
419 case 1: value = *(const uint8_t*)src; break;
420 case 2: value = *(const uint16_t*)src; break;
421 case 4: value = *(const uint32_t*)src; break;
422 case 8: value = *(const uint64_t*)src; break;
423 default: PB_RETURN_ERROR(stream, "invalid data_size");
426 return pb_encode_varint(stream, value);
429 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
433 switch (field->data_size)
435 case 4: value = *(const int32_t*)src; break;
436 case 8: value = *(const int64_t*)src; break;
437 default: PB_RETURN_ERROR(stream, "invalid data_size");
440 return pb_encode_svarint(stream, value);
443 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
446 return pb_encode_fixed64(stream, src);
449 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
452 return pb_encode_fixed32(stream, src);
455 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
457 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
459 return pb_encode_string(stream, bytes->bytes, bytes->size);
462 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
465 return pb_encode_string(stream, (const uint8_t*)src, strlen((const char*)src));
468 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
470 if (field->ptr == NULL)
471 PB_RETURN_ERROR(stream, "invalid field descriptor");
473 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);