1 /* pb_encode.c -- encode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
9 /* Use the GCC warn_unused_result attribute to check that all return values
10 * are propagated correctly. On other compilers and gcc before 3.4.0 just
11 * ignore the annotation.
13 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
16 #define checkreturn __attribute__((warn_unused_result))
19 /**************************************
20 * Declarations internal to this file *
21 **************************************/
22 typedef bool (*pb_encoder_t)(pb_ostream_t *stream, const pb_field_t *field, const void *src) checkreturn;
24 static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count);
25 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field, const void *pData, size_t count, pb_encoder_t func);
26 static bool checkreturn encode_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData);
27 static bool checkreturn default_extension_encoder(pb_ostream_t *stream, const pb_extension_t *extension);
28 static bool checkreturn encode_extension_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData);
29 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
30 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
31 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
32 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
33 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src);
34 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
35 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src);
36 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);
38 /* --- Function pointers to field encoders ---
39 * Order in the array must match pb_action_t LTYPE numbering.
41 static const pb_encoder_t PB_ENCODERS[PB_LTYPES_COUNT] = {
54 /*******************************
55 * pb_ostream_t implementation *
56 *******************************/
58 static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
60 uint8_t *dest = (uint8_t*)stream->state;
61 stream->state = dest + count;
69 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize)
73 stream.callback = (void*)1; /* Just a marker value */
75 stream.callback = &buf_write;
78 stream.max_size = bufsize;
79 stream.bytes_written = 0;
86 bool checkreturn pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
88 if (stream->callback != NULL)
90 if (stream->bytes_written + count > stream->max_size)
91 PB_RETURN_ERROR(stream, "stream full");
94 if (!buf_write(stream, buf, count))
95 PB_RETURN_ERROR(stream, "io error");
97 if (!stream->callback(stream, buf, count))
98 PB_RETURN_ERROR(stream, "io error");
102 stream->bytes_written += count;
106 /*************************
107 * Encode a single field *
108 *************************/
110 /* Encode a static array. Handles the size calculations and possible packing. */
111 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
112 const void *pData, size_t count, pb_encoder_t func)
121 if (PB_ATYPE(field->type) != PB_ATYPE_POINTER && count > field->array_size)
122 PB_RETURN_ERROR(stream, "array max size exceeded");
124 /* We always pack arrays if the datatype allows it. */
125 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
127 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
130 /* Determine the total size of packed array. */
131 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
135 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
141 pb_ostream_t sizestream = PB_OSTREAM_SIZING;
143 for (i = 0; i < count; i++)
145 if (!func(&sizestream, field, p))
147 p = (const char*)p + field->data_size;
149 size = sizestream.bytes_written;
152 if (!pb_encode_varint(stream, (uint64_t)size))
155 if (stream->callback == NULL)
156 return pb_write(stream, NULL, size); /* Just sizing.. */
160 for (i = 0; i < count; i++)
162 if (!func(stream, field, p))
164 p = (const char*)p + field->data_size;
170 for (i = 0; i < count; i++)
172 if (!pb_encode_tag_for_field(stream, field))
175 /* Normally the data is stored directly in the array entries, but
176 * for pointer-type string and bytes fields, the array entries are
177 * actually pointers themselves also. So we have to dereference once
178 * more to get to the actual data. */
179 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER &&
180 (PB_LTYPE(field->type) == PB_LTYPE_STRING ||
181 PB_LTYPE(field->type) == PB_LTYPE_BYTES))
183 if (!func(stream, field, *(const void* const*)p))
188 if (!func(stream, field, p))
191 p = (const char*)p + field->data_size;
198 /* Encode a field with static or pointer allocation, i.e. one whose data
199 * is available to the encoder directly. */
200 static bool checkreturn encode_basic_field(pb_ostream_t *stream,
201 const pb_field_t *field, const void *pData)
205 bool implicit_has = true;
207 func = PB_ENCODERS[PB_LTYPE(field->type)];
209 if (field->size_offset)
210 pSize = (const char*)pData + field->size_offset;
212 pSize = &implicit_has;
214 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
216 /* pData is a pointer to the field, which contains pointer to
217 * the data. If the 2nd pointer is NULL, it is interpreted as if
218 * the has_field was false.
221 pData = *(const void* const*)pData;
222 implicit_has = (pData != NULL);
225 switch (PB_HTYPE(field->type))
227 case PB_HTYPE_REQUIRED:
229 PB_RETURN_ERROR(stream, "missing required field");
230 if (!pb_encode_tag_for_field(stream, field))
232 if (!func(stream, field, pData))
236 case PB_HTYPE_OPTIONAL:
237 if (*(const bool*)pSize)
239 if (!pb_encode_tag_for_field(stream, field))
242 if (!func(stream, field, pData))
247 case PB_HTYPE_REPEATED:
248 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
253 PB_RETURN_ERROR(stream, "invalid field type");
259 /* Encode a field with callback semantics. This means that a user function is
260 * called to provide and encode the actual data. */
261 static bool checkreturn encode_callback_field(pb_ostream_t *stream,
262 const pb_field_t *field, const void *pData)
264 const pb_callback_t *callback = (const pb_callback_t*)pData;
266 #ifdef PB_OLD_CALLBACK_STYLE
267 const void *arg = callback->arg;
269 void * const *arg = &(callback->arg);
272 if (callback->funcs.encode != NULL)
274 if (!callback->funcs.encode(stream, field, arg))
275 PB_RETURN_ERROR(stream, "callback error");
280 /* Encode a single field of any callback or static type. */
281 static bool checkreturn encode_field(pb_ostream_t *stream,
282 const pb_field_t *field, const void *pData)
284 switch (PB_ATYPE(field->type))
286 case PB_ATYPE_STATIC:
287 case PB_ATYPE_POINTER:
288 return encode_basic_field(stream, field, pData);
290 case PB_ATYPE_CALLBACK:
291 return encode_callback_field(stream, field, pData);
294 PB_RETURN_ERROR(stream, "invalid field type");
298 /* Default handler for extension fields. Expects to have a pb_field_t
299 * pointer in the extension->type->arg field. */
300 static bool checkreturn default_extension_encoder(pb_ostream_t *stream,
301 const pb_extension_t *extension)
303 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
304 return encode_field(stream, field, extension->dest);
307 /* Walk through all the registered extensions and give them a chance
308 * to encode themselves. */
309 static bool checkreturn encode_extension_field(pb_ostream_t *stream,
310 const pb_field_t *field, const void *pData)
312 const pb_extension_t *extension = *(const pb_extension_t* const *)pData;
318 if (extension->type->encode)
319 status = extension->type->encode(stream, extension);
321 status = default_extension_encoder(stream, extension);
326 extension = extension->next;
332 /*********************
333 * Encode all fields *
334 *********************/
336 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
338 const pb_field_t *field = fields;
339 const void *pData = src_struct;
340 size_t prev_size = 0;
342 while (field->tag != 0)
344 pData = (const char*)pData + prev_size + field->data_offset;
345 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
346 prev_size = sizeof(const void*);
348 prev_size = field->data_size;
350 /* Special case for static arrays */
351 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
352 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
354 prev_size *= field->array_size;
357 if (PB_LTYPE(field->type) == PB_LTYPE_EXTENSION)
359 /* Special case for the extension field placeholder */
360 if (!encode_extension_field(stream, field, pData))
366 if (!encode_field(stream, field, pData))
376 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
378 return pb_encode_submessage(stream, fields, src_struct);
381 /********************
383 ********************/
384 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
390 return pb_write(stream, (uint8_t*)&value, 1);
394 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
398 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
400 return pb_write(stream, buffer, i);
403 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
407 zigzagged = ~((uint64_t)value << 1);
409 zigzagged = (uint64_t)value << 1;
411 return pb_encode_varint(stream, zigzagged);
414 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
416 #ifdef __BIG_ENDIAN__
417 const uint8_t *bytes = value;
419 lebytes[0] = bytes[3];
420 lebytes[1] = bytes[2];
421 lebytes[2] = bytes[1];
422 lebytes[3] = bytes[0];
423 return pb_write(stream, lebytes, 4);
425 return pb_write(stream, (const uint8_t*)value, 4);
429 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
431 #ifdef __BIG_ENDIAN__
432 const uint8_t *bytes = value;
434 lebytes[0] = bytes[7];
435 lebytes[1] = bytes[6];
436 lebytes[2] = bytes[5];
437 lebytes[3] = bytes[4];
438 lebytes[4] = bytes[3];
439 lebytes[5] = bytes[2];
440 lebytes[6] = bytes[1];
441 lebytes[7] = bytes[0];
442 return pb_write(stream, lebytes, 8);
444 return pb_write(stream, (const uint8_t*)value, 8);
448 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
450 uint64_t tag = ((uint64_t)field_number << 3) | wiretype;
451 return pb_encode_varint(stream, tag);
454 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
456 pb_wire_type_t wiretype;
457 switch (PB_LTYPE(field->type))
459 case PB_LTYPE_VARINT:
460 case PB_LTYPE_UVARINT:
461 case PB_LTYPE_SVARINT:
462 wiretype = PB_WT_VARINT;
465 case PB_LTYPE_FIXED32:
466 wiretype = PB_WT_32BIT;
469 case PB_LTYPE_FIXED64:
470 wiretype = PB_WT_64BIT;
474 case PB_LTYPE_STRING:
475 case PB_LTYPE_SUBMESSAGE:
476 wiretype = PB_WT_STRING;
480 PB_RETURN_ERROR(stream, "invalid field type");
483 return pb_encode_tag(stream, wiretype, field->tag);
486 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
488 if (!pb_encode_varint(stream, (uint64_t)size))
491 return pb_write(stream, buffer, size);
494 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
496 /* First calculate the message size using a non-writing substream. */
497 pb_ostream_t substream = PB_OSTREAM_SIZING;
501 if (!pb_encode(&substream, fields, src_struct))
504 stream->errmsg = substream.errmsg;
509 size = substream.bytes_written;
511 if (!pb_encode_varint(stream, (uint64_t)size))
514 if (stream->callback == NULL)
515 return pb_write(stream, NULL, size); /* Just sizing */
517 if (stream->bytes_written + size > stream->max_size)
518 PB_RETURN_ERROR(stream, "stream full");
520 /* Use a substream to verify that a callback doesn't write more than
521 * what it did the first time. */
522 substream.callback = stream->callback;
523 substream.state = stream->state;
524 substream.max_size = size;
525 substream.bytes_written = 0;
527 substream.errmsg = NULL;
530 status = pb_encode(&substream, fields, src_struct);
532 stream->bytes_written += substream.bytes_written;
533 stream->state = substream.state;
535 stream->errmsg = substream.errmsg;
538 if (substream.bytes_written != size)
539 PB_RETURN_ERROR(stream, "submsg size changed");
546 static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
550 /* Cases 1 and 2 are for compilers that have smaller types for bool
552 switch (field->data_size)
554 case 1: value = *(const int8_t*)src; break;
555 case 2: value = *(const int16_t*)src; break;
556 case 4: value = *(const int32_t*)src; break;
557 case 8: value = *(const int64_t*)src; break;
558 default: PB_RETURN_ERROR(stream, "invalid data_size");
561 return pb_encode_varint(stream, (uint64_t)value);
564 static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
568 switch (field->data_size)
570 case 4: value = *(const uint32_t*)src; break;
571 case 8: value = *(const uint64_t*)src; break;
572 default: PB_RETURN_ERROR(stream, "invalid data_size");
575 return pb_encode_varint(stream, value);
578 static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
582 switch (field->data_size)
584 case 4: value = *(const int32_t*)src; break;
585 case 8: value = *(const int64_t*)src; break;
586 default: PB_RETURN_ERROR(stream, "invalid data_size");
589 return pb_encode_svarint(stream, value);
592 static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
595 return pb_encode_fixed64(stream, src);
598 static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
601 return pb_encode_fixed32(stream, src);
604 static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
606 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
610 /* Threat null pointer as an empty bytes field */
611 return pb_encode_string(stream, NULL, 0);
614 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
615 PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size)
617 PB_RETURN_ERROR(stream, "bytes size exceeded");
620 return pb_encode_string(stream, bytes->bytes, bytes->size);
623 static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
625 /* strnlen() is not always available, so just use a loop */
627 size_t max_size = field->data_size;
628 const char *p = (const char*)src;
630 if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
631 max_size = (size_t)-1;
635 size = 0; /* Threat null pointer as an empty string */
639 while (size < max_size && *p != '\0')
646 return pb_encode_string(stream, (const uint8_t*)src, size);
649 static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
651 if (field->ptr == NULL)
652 PB_RETURN_ERROR(stream, "invalid field descriptor");
654 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);