/* pb_encode.c -- encode a protobuf using minimal resources * * 2011 Petteri Aimonen <jpa@kapsi.fi> */ #include "pb.h" #include "pb_encode.h" #include "pb_common.h" /* Use the GCC warn_unused_result attribute to check that all return values * are propagated correctly. On other compilers and gcc before 3.4.0 just * ignore the annotation. */ #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4) #define checkreturn #else #define checkreturn __attribute__((warn_unused_result)) #endif /************************************** * Declarations internal to this file * **************************************/ typedef bool (*pb_encoder_t)(pb_ostream_t *stream, const pb_field_t *field, const void *src) checkreturn; static bool checkreturn buf_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count); static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field, const void *pData, size_t count, pb_encoder_t func); static bool checkreturn encode_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData); static bool checkreturn default_extension_encoder(pb_ostream_t *stream, const pb_extension_t *extension); static bool checkreturn encode_extension_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData); static void *pb_const_cast(const void *p); static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src); static bool checkreturn pb_enc_fixed_length_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src); /* --- Function pointers to field encoders --- * Order in the array must match pb_action_t LTYPE numbering. */ static const pb_encoder_t PB_ENCODERS[PB_LTYPES_COUNT] = { &pb_enc_varint, &pb_enc_uvarint, &pb_enc_svarint, &pb_enc_fixed32, &pb_enc_fixed64, &pb_enc_bytes, &pb_enc_string, &pb_enc_submessage, NULL, /* extensions */ &pb_enc_fixed_length_bytes }; /******************************* * pb_ostream_t implementation * *******************************/ static bool checkreturn buf_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count) { size_t i; pb_byte_t *dest = (pb_byte_t*)stream->state; stream->state = dest + count; for (i = 0; i < count; i++) dest[i] = buf[i]; return true; } pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize) { pb_ostream_t stream; #ifdef PB_BUFFER_ONLY stream.callback = (void*)1; /* Just a marker value */ #else stream.callback = &buf_write; #endif stream.state = buf; stream.max_size = bufsize; stream.bytes_written = 0; #ifndef PB_NO_ERRMSG stream.errmsg = NULL; #endif return stream; } bool checkreturn pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count) { if (stream->callback != NULL) { if (stream->bytes_written + count > stream->max_size) PB_RETURN_ERROR(stream, "stream full"); #ifdef PB_BUFFER_ONLY if (!buf_write(stream, buf, count)) PB_RETURN_ERROR(stream, "io error"); #else if (!stream->callback(stream, buf, count)) PB_RETURN_ERROR(stream, "io error"); #endif } stream->bytes_written += count; return true; } /************************* * Encode a single field * *************************/ /* Encode a static array. Handles the size calculations and possible packing. */ static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field, const void *pData, size_t count, pb_encoder_t func) { size_t i; const void *p; size_t size; if (count == 0) return true; if (PB_ATYPE(field->type) != PB_ATYPE_POINTER && count > field->array_size) PB_RETURN_ERROR(stream, "array max size exceeded"); /* We always pack arrays if the datatype allows it. */ if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE) { if (!pb_encode_tag(stream, PB_WT_STRING, field->tag)) return false; /* Determine the total size of packed array. */ if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32) { size = 4 * count; } else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64) { size = 8 * count; } else { pb_ostream_t sizestream = PB_OSTREAM_SIZING; p = pData; for (i = 0; i < count; i++) { if (!func(&sizestream, field, p)) return false; p = (const char*)p + field->data_size; } size = sizestream.bytes_written; } if (!pb_encode_varint(stream, (uint64_t)size)) return false; if (stream->callback == NULL) return pb_write(stream, NULL, size); /* Just sizing.. */ /* Write the data */ p = pData; for (i = 0; i < count; i++) { if (!func(stream, field, p)) return false; p = (const char*)p + field->data_size; } } else { p = pData; for (i = 0; i < count; i++) { if (!pb_encode_tag_for_field(stream, field)) return false; /* Normally the data is stored directly in the array entries, but * for pointer-type string and bytes fields, the array entries are * actually pointers themselves also. So we have to dereference once * more to get to the actual data. */ if (PB_ATYPE(field->type) == PB_ATYPE_POINTER && (PB_LTYPE(field->type) == PB_LTYPE_STRING || PB_LTYPE(field->type) == PB_LTYPE_BYTES)) { if (!func(stream, field, *(const void* const*)p)) return false; } else { if (!func(stream, field, p)) return false; } p = (const char*)p + field->data_size; } } return true; } /* In proto3, all fields are optional and are only encoded if their value is "non-zero". * This function implements the check for the zero value. */ static bool pb_check_proto3_default_value(const pb_field_t *field, const void *pData) { pb_type_t type = field->type; const void *pSize = (const char*)pData + field->size_offset; if (PB_HTYPE(type) == PB_HTYPE_REQUIRED) { /* Required proto2 fields inside proto3 submessage, pretty rare case */ return false; } else if (PB_HTYPE(type) == PB_HTYPE_REPEATED) { /* Repeated fields inside proto3 submessage: present if count != 0 */ return *(const pb_size_t*)pSize == 0; } else if (PB_HTYPE(type) == PB_HTYPE_ONEOF) { /* Oneof fields */ return *(const pb_size_t*)pSize == 0; } else if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL && field->size_offset) { /* Proto2 optional fields inside proto3 submessage */ return *(const bool*)pSize == false; } /* Rest is proto3 singular fields */ if (PB_ATYPE(type) == PB_ATYPE_STATIC) { if (PB_LTYPE(type) == PB_LTYPE_BYTES) { const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)pData; return bytes->size == 0; } else if (PB_LTYPE(type) == PB_LTYPE_STRING) { return *(const char*)pData == '\0'; } else if (PB_LTYPE(type) == PB_LTYPE_FIXED_LENGTH_BYTES) { /* Fixed length bytes is only empty if its length is fixed * as 0. Which would be pretty strange, but we can check * it anyway. */ return field->data_size == 0; } else if (PB_LTYPE(type) == PB_LTYPE_SUBMESSAGE) { /* Check all fields in the submessage to find if any of them * are non-zero. The comparison cannot be done byte-per-byte * because the C struct may contain padding bytes that must * be skipped. */ pb_field_iter_t iter; if (pb_field_iter_begin(&iter, (const pb_field_t*)field->ptr, pb_const_cast(pData))) { do { if (!pb_check_proto3_default_value(iter.pos, iter.pData)) { return false; } } while (pb_field_iter_next(&iter)); } return true; } } { /* Catch-all branch that does byte-per-byte comparison for zero value. * * This is for all pointer fields, and for static PB_LTYPE_VARINT, * UVARINT, SVARINT, FIXED32, FIXED64, EXTENSION fields, and also * callback fields. These all have integer or pointer value which * can be compared with 0. */ pb_size_t i; const char *p = (const char*)pData; for (i = 0; i < field->data_size; i++) { if (p[i] != 0) { return false; } } return true; } } /* Encode a field with static or pointer allocation, i.e. one whose data * is available to the encoder directly. */ static bool checkreturn encode_basic_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData) { pb_encoder_t func; bool implicit_has; const void *pSize = &implicit_has; func = PB_ENCODERS[PB_LTYPE(field->type)]; if (field->size_offset) { /* Static optional, repeated or oneof field */ pSize = (const char*)pData + field->size_offset; } else if (PB_HTYPE(field->type) == PB_HTYPE_OPTIONAL) { /* Proto3 style field, optional but without explicit has_ field. */ implicit_has = !pb_check_proto3_default_value(field, pData); } else { /* Required field, always present */ implicit_has = true; } if (PB_ATYPE(field->type) == PB_ATYPE_POINTER) { /* pData is a pointer to the field, which contains pointer to * the data. If the 2nd pointer is NULL, it is interpreted as if * the has_field was false. */ pData = *(const void* const*)pData; implicit_has = (pData != NULL); } switch (PB_HTYPE(field->type)) { case PB_HTYPE_REQUIRED: if (!pData) PB_RETURN_ERROR(stream, "missing required field"); if (!pb_encode_tag_for_field(stream, field)) return false; if (!func(stream, field, pData)) return false; break; case PB_HTYPE_OPTIONAL: if (*(const bool*)pSize) { if (!pb_encode_tag_for_field(stream, field)) return false; if (!func(stream, field, pData)) return false; } break; case PB_HTYPE_REPEATED: if (!encode_array(stream, field, pData, *(const pb_size_t*)pSize, func)) return false; break; case PB_HTYPE_ONEOF: if (*(const pb_size_t*)pSize == field->tag) { if (!pb_encode_tag_for_field(stream, field)) return false; if (!func(stream, field, pData)) return false; } break; default: PB_RETURN_ERROR(stream, "invalid field type"); } return true; } /* Encode a field with callback semantics. This means that a user function is * called to provide and encode the actual data. */ static bool checkreturn encode_callback_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData) { const pb_callback_t *callback = (const pb_callback_t*)pData; #ifdef PB_OLD_CALLBACK_STYLE const void *arg = callback->arg; #else void * const *arg = &(callback->arg); #endif if (callback->funcs.encode != NULL) { if (!callback->funcs.encode(stream, field, arg)) PB_RETURN_ERROR(stream, "callback error"); } return true; } /* Encode a single field of any callback or static type. */ static bool checkreturn encode_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData) { switch (PB_ATYPE(field->type)) { case PB_ATYPE_STATIC: case PB_ATYPE_POINTER: return encode_basic_field(stream, field, pData); case PB_ATYPE_CALLBACK: return encode_callback_field(stream, field, pData); default: PB_RETURN_ERROR(stream, "invalid field type"); } } /* Default handler for extension fields. Expects to have a pb_field_t * pointer in the extension->type->arg field. */ static bool checkreturn default_extension_encoder(pb_ostream_t *stream, const pb_extension_t *extension) { const pb_field_t *field = (const pb_field_t*)extension->type->arg; if (PB_ATYPE(field->type) == PB_ATYPE_POINTER) { /* For pointer extensions, the pointer is stored directly * in the extension structure. This avoids having an extra * indirection. */ return encode_field(stream, field, &extension->dest); } else { return encode_field(stream, field, extension->dest); } } /* Walk through all the registered extensions and give them a chance * to encode themselves. */ static bool checkreturn encode_extension_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData) { const pb_extension_t *extension = *(const pb_extension_t* const *)pData; PB_UNUSED(field); while (extension) { bool status; if (extension->type->encode) status = extension->type->encode(stream, extension); else status = default_extension_encoder(stream, extension); if (!status) return false; extension = extension->next; } return true; } /********************* * Encode all fields * *********************/ static void *pb_const_cast(const void *p) { /* Note: this casts away const, in order to use the common field iterator * logic for both encoding and decoding. */ union { void *p1; const void *p2; } t; t.p2 = p; return t.p1; } bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct) { pb_field_iter_t iter; if (!pb_field_iter_begin(&iter, fields, pb_const_cast(src_struct))) return true; /* Empty message type */ do { if (PB_LTYPE(iter.pos->type) == PB_LTYPE_EXTENSION) { /* Special case for the extension field placeholder */ if (!encode_extension_field(stream, iter.pos, iter.pData)) return false; } else { /* Regular field */ if (!encode_field(stream, iter.pos, iter.pData)) return false; } } while (pb_field_iter_next(&iter)); return true; } bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct) { return pb_encode_submessage(stream, fields, src_struct); } bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct) { pb_ostream_t stream = PB_OSTREAM_SIZING; if (!pb_encode(&stream, fields, src_struct)) return false; *size = stream.bytes_written; return true; } /******************** * Helper functions * ********************/ bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value) { pb_byte_t buffer[10]; size_t i = 0; if (value <= 0x7F) { pb_byte_t v = (pb_byte_t)value; return pb_write(stream, &v, 1); } while (value) { buffer[i] = (pb_byte_t)((value & 0x7F) | 0x80); value >>= 7; i++; } buffer[i-1] &= 0x7F; /* Unset top bit on last byte */ return pb_write(stream, buffer, i); } bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value) { uint64_t zigzagged; if (value < 0) zigzagged = ~((uint64_t)value << 1); else zigzagged = (uint64_t)value << 1; return pb_encode_varint(stream, zigzagged); } bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value) { uint32_t val = *(const uint32_t*)value; pb_byte_t bytes[4]; bytes[0] = (pb_byte_t)(val & 0xFF); bytes[1] = (pb_byte_t)((val >> 8) & 0xFF); bytes[2] = (pb_byte_t)((val >> 16) & 0xFF); bytes[3] = (pb_byte_t)((val >> 24) & 0xFF); return pb_write(stream, bytes, 4); } bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value) { uint64_t val = *(const uint64_t*)value; pb_byte_t bytes[8]; bytes[0] = (pb_byte_t)(val & 0xFF); bytes[1] = (pb_byte_t)((val >> 8) & 0xFF); bytes[2] = (pb_byte_t)((val >> 16) & 0xFF); bytes[3] = (pb_byte_t)((val >> 24) & 0xFF); bytes[4] = (pb_byte_t)((val >> 32) & 0xFF); bytes[5] = (pb_byte_t)((val >> 40) & 0xFF); bytes[6] = (pb_byte_t)((val >> 48) & 0xFF); bytes[7] = (pb_byte_t)((val >> 56) & 0xFF); return pb_write(stream, bytes, 8); } bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number) { uint64_t tag = ((uint64_t)field_number << 3) | wiretype; return pb_encode_varint(stream, tag); } bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field) { pb_wire_type_t wiretype; switch (PB_LTYPE(field->type)) { case PB_LTYPE_VARINT: case PB_LTYPE_UVARINT: case PB_LTYPE_SVARINT: wiretype = PB_WT_VARINT; break; case PB_LTYPE_FIXED32: wiretype = PB_WT_32BIT; break; case PB_LTYPE_FIXED64: wiretype = PB_WT_64BIT; break; case PB_LTYPE_BYTES: case PB_LTYPE_STRING: case PB_LTYPE_SUBMESSAGE: case PB_LTYPE_FIXED_LENGTH_BYTES: wiretype = PB_WT_STRING; break; default: PB_RETURN_ERROR(stream, "invalid field type"); } return pb_encode_tag(stream, wiretype, field->tag); } bool checkreturn pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size) { if (!pb_encode_varint(stream, (uint64_t)size)) return false; return pb_write(stream, buffer, size); } bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct) { /* First calculate the message size using a non-writing substream. */ pb_ostream_t substream = PB_OSTREAM_SIZING; size_t size; bool status; if (!pb_encode(&substream, fields, src_struct)) { #ifndef PB_NO_ERRMSG stream->errmsg = substream.errmsg; #endif return false; } size = substream.bytes_written; if (!pb_encode_varint(stream, (uint64_t)size)) return false; if (stream->callback == NULL) return pb_write(stream, NULL, size); /* Just sizing */ if (stream->bytes_written + size > stream->max_size) PB_RETURN_ERROR(stream, "stream full"); /* Use a substream to verify that a callback doesn't write more than * what it did the first time. */ substream.callback = stream->callback; substream.state = stream->state; substream.max_size = size; substream.bytes_written = 0; #ifndef PB_NO_ERRMSG substream.errmsg = NULL; #endif status = pb_encode(&substream, fields, src_struct); stream->bytes_written += substream.bytes_written; stream->state = substream.state; #ifndef PB_NO_ERRMSG stream->errmsg = substream.errmsg; #endif if (substream.bytes_written != size) PB_RETURN_ERROR(stream, "submsg size changed"); return status; } /* Field encoders */ static bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src) { int64_t value = 0; if (field->data_size == sizeof(int_least8_t)) value = *(const int_least8_t*)src; else if (field->data_size == sizeof(int_least16_t)) value = *(const int_least16_t*)src; else if (field->data_size == sizeof(int32_t)) value = *(const int32_t*)src; else if (field->data_size == sizeof(int64_t)) value = *(const int64_t*)src; else PB_RETURN_ERROR(stream, "invalid data_size"); return pb_encode_varint(stream, (uint64_t)value); } static bool checkreturn pb_enc_uvarint(pb_ostream_t *stream, const pb_field_t *field, const void *src) { uint64_t value = 0; if (field->data_size == sizeof(uint_least8_t)) value = *(const uint_least8_t*)src; else if (field->data_size == sizeof(uint_least16_t)) value = *(const uint_least16_t*)src; else if (field->data_size == sizeof(uint32_t)) value = *(const uint32_t*)src; else if (field->data_size == sizeof(uint64_t)) value = *(const uint64_t*)src; else PB_RETURN_ERROR(stream, "invalid data_size"); return pb_encode_varint(stream, value); } static bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src) { int64_t value = 0; if (field->data_size == sizeof(int_least8_t)) value = *(const int_least8_t*)src; else if (field->data_size == sizeof(int_least16_t)) value = *(const int_least16_t*)src; else if (field->data_size == sizeof(int32_t)) value = *(const int32_t*)src; else if (field->data_size == sizeof(int64_t)) value = *(const int64_t*)src; else PB_RETURN_ERROR(stream, "invalid data_size"); return pb_encode_svarint(stream, value); } static bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src) { PB_UNUSED(field); return pb_encode_fixed64(stream, src); } static bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src) { PB_UNUSED(field); return pb_encode_fixed32(stream, src); } static bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src) { const pb_bytes_array_t *bytes = NULL; bytes = (const pb_bytes_array_t*)src; if (src == NULL) { /* Treat null pointer as an empty bytes field */ return pb_encode_string(stream, NULL, 0); } if (PB_ATYPE(field->type) == PB_ATYPE_STATIC && PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size) > field->data_size) { PB_RETURN_ERROR(stream, "bytes size exceeded"); } return pb_encode_string(stream, bytes->bytes, bytes->size); } static bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src) { size_t size = 0; size_t max_size = field->data_size; const char *p = (const char*)src; if (PB_ATYPE(field->type) == PB_ATYPE_POINTER) max_size = (size_t)-1; if (src == NULL) { size = 0; /* Treat null pointer as an empty string */ } else { /* strnlen() is not always available, so just use a loop */ while (size < max_size && *p != '\0') { size++; p++; } } return pb_encode_string(stream, (const pb_byte_t*)src, size); } static bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src) { if (field->ptr == NULL) PB_RETURN_ERROR(stream, "invalid field descriptor"); return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src); } static bool checkreturn pb_enc_fixed_length_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src) { return pb_encode_string(stream, (const pb_byte_t*)src, field->data_size); }