1 /* pb_encode.c -- encode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
6 #define NANOPB_INTERNALS
11 /* The warn_unused_result attribute appeared first in gcc-3.4.0 */
12 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
15 /* Verify that we remember to check all return values for proper error propagation */
16 #define checkreturn __attribute__((warn_unused_result))
19 typedef bool (*pb_encoder_t)(pb_ostream_t *stream, const pb_field_t *field, const void *src) checkreturn;
21 /* --- Function pointers to field encoders ---
22 * Order in the array must match pb_action_t LTYPE numbering.
24 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 /* Callbacks don't need this function because they usually know the data type
88 * without examining the field structure.
89 * Therefore it is static for now.
91 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
92 const void *pData, size_t count, pb_encoder_t func)
101 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
103 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
106 /* Determine the total size of packed array. */
107 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
111 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
117 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
119 for (i = 0; i < count; i++)
121 if (!func(&sizestream, field, p))
123 p = (const char*)p + field->data_size;
125 size = sizestream.bytes_written;
128 if (!pb_encode_varint(stream, (uint64_t)size))
131 if (stream->callback == NULL)
132 return pb_write(stream, NULL, size); /* Just sizing.. */
136 for (i = 0; i < count; i++)
138 if (!func(stream, field, p))
140 p = (const char*)p + field->data_size;
146 for (i = 0; i < count; i++)
148 if (!pb_encode_tag_for_field(stream, field))
150 if (!func(stream, field, p))
152 p = (const char*)p + field->data_size;
159 bool checkreturn encode_static_field(pb_ostream_t *stream, 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 bool checkreturn encode_callback_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData)
201 const pb_callback_t *callback = (const pb_callback_t*)pData;
202 if (callback->funcs.encode != NULL)
204 if (!callback->funcs.encode(stream, field, callback->arg))
205 PB_RETURN_ERROR(stream, "callback error");
210 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
212 const pb_field_t *field = fields;
213 const void *pData = src_struct;
214 size_t prev_size = 0;
216 while (field->tag != 0)
218 pData = (const char*)pData + prev_size + field->data_offset;
219 prev_size = field->data_size;
221 /* Special case for static arrays */
222 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
223 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
225 prev_size *= field->array_size;
228 switch (PB_ATYPE(field->type))
230 case PB_ATYPE_STATIC:
231 if (!encode_static_field(stream, field, pData))
235 case PB_ATYPE_CALLBACK:
236 if (!encode_callback_field(stream, field, pData))
241 PB_RETURN_ERROR(stream, "invalid field type");
250 /* Helper functions */
251 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
257 return pb_write(stream, (uint8_t*)&value, 1);
261 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
265 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
267 return pb_write(stream, buffer, i);
270 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
274 zigzagged = (uint64_t)(~(value << 1));
276 zigzagged = (uint64_t)(value << 1);
278 return pb_encode_varint(stream, zigzagged);
281 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
283 #ifdef __BIG_ENDIAN__
284 const uint8_t *bytes = value;
286 lebytes[0] = bytes[3];
287 lebytes[1] = bytes[2];
288 lebytes[2] = bytes[1];
289 lebytes[3] = bytes[0];
290 return pb_write(stream, lebytes, 4);
292 return pb_write(stream, (const uint8_t*)value, 4);
296 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
298 #ifdef __BIG_ENDIAN__
299 const uint8_t *bytes = value;
301 lebytes[0] = bytes[7];
302 lebytes[1] = bytes[6];
303 lebytes[2] = bytes[5];
304 lebytes[3] = bytes[4];
305 lebytes[4] = bytes[3];
306 lebytes[5] = bytes[2];
307 lebytes[6] = bytes[1];
308 lebytes[7] = bytes[0];
309 return pb_write(stream, lebytes, 8);
311 return pb_write(stream, (const uint8_t*)value, 8);
315 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
317 uint64_t tag = wiretype | (field_number << 3);
318 return pb_encode_varint(stream, tag);
321 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
323 pb_wire_type_t wiretype;
324 switch (PB_LTYPE(field->type))
326 case PB_LTYPE_VARINT:
327 case PB_LTYPE_SVARINT:
328 wiretype = PB_WT_VARINT;
331 case PB_LTYPE_FIXED32:
332 wiretype = PB_WT_32BIT;
335 case PB_LTYPE_FIXED64:
336 wiretype = PB_WT_64BIT;
340 case PB_LTYPE_STRING:
341 case PB_LTYPE_SUBMESSAGE:
342 wiretype = PB_WT_STRING;
346 PB_RETURN_ERROR(stream, "invalid field type");
349 return pb_encode_tag(stream, wiretype, field->tag);
352 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
354 if (!pb_encode_varint(stream, (uint64_t)size))
357 return pb_write(stream, buffer, size);
360 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
362 /* First calculate the message size using a non-writing substream. */
363 pb_ostream_t substream = PB_OSTREAM_SIZING;
367 if (!pb_encode(&substream, fields, src_struct))
370 size = substream.bytes_written;
372 if (!pb_encode_varint(stream, (uint64_t)size))
375 if (stream->callback == NULL)
376 return pb_write(stream, NULL, size); /* Just sizing */
378 if (stream->bytes_written + size > stream->max_size)
379 PB_RETURN_ERROR(stream, "stream full");
381 /* Use a substream to verify that a callback doesn't write more than
382 * what it did the first time. */
383 substream.callback = stream->callback;
384 substream.state = stream->state;
385 substream.max_size = size;
386 substream.bytes_written = 0;
388 substream.errmsg = NULL;
391 status = pb_encode(&substream, fields, src_struct);
393 stream->bytes_written += substream.bytes_written;
394 stream->state = substream.state;
396 stream->errmsg = substream.errmsg;
399 if (substream.bytes_written != size)
400 PB_RETURN_ERROR(stream, "submsg size changed");
407 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
411 switch (field->data_size)
413 case 1: value = *(const uint8_t*)src; break;
414 case 2: value = *(const uint16_t*)src; break;
415 case 4: value = *(const uint32_t*)src; break;
416 case 8: value = *(const uint64_t*)src; break;
417 default: PB_RETURN_ERROR(stream, "invalid data_size");
420 return pb_encode_varint(stream, value);
423 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
427 switch (field->data_size)
429 case 4: value = *(const int32_t*)src; break;
430 case 8: value = *(const int64_t*)src; break;
431 default: PB_RETURN_ERROR(stream, "invalid data_size");
434 return pb_encode_svarint(stream, value);
437 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
440 return pb_encode_fixed64(stream, src);
443 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
446 return pb_encode_fixed32(stream, src);
449 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
451 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
453 return pb_encode_string(stream, bytes->bytes, bytes->size);
456 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
459 return pb_encode_string(stream, (const uint8_t*)src, strlen((const char*)src));
462 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
464 if (field->ptr == NULL)
465 PB_RETURN_ERROR(stream, "invalid field descriptor");
467 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);