diff options
Diffstat (limited to 'pb_encode.c')
| -rw-r--r-- | pb_encode.c | 667 |
1 files changed, 667 insertions, 0 deletions
diff --git a/pb_encode.c b/pb_encode.c new file mode 100644 index 0000000..dc5a273 --- /dev/null +++ b/pb_encode.c @@ -0,0 +1,667 @@ +/* pb_encode.c -- encode a protobuf using minimal resources + * + * 2011 Petteri Aimonen <jpa@kapsi.fi> + */ + +#include "pb.h" +#include "pb_encode.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 uint8_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 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); + +/* --- 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_ostream_t implementation * + *******************************/ + +static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count) +{ + uint8_t *dest = (uint8_t*)stream->state; + stream->state = dest + count; + + while (count--) + *dest++ = *buf++; + + return true; +} + +pb_ostream_t pb_ostream_from_buffer(uint8_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 uint8_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; +} + +/* 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; + const void *pSize; + bool implicit_has = true; + + func = PB_ENCODERS[PB_LTYPE(field->type)]; + + if (field->size_offset) + pSize = (const char*)pData + field->size_offset; + else + pSize = &implicit_has; + + 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 size_t*)pSize, func)) + 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; + 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; + 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 * + *********************/ + +bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct) +{ + const pb_field_t *field = fields; + const void *pData = src_struct; + size_t prev_size = 0; + + while (field->tag != 0) + { + pData = (const char*)pData + prev_size + field->data_offset; + if (PB_ATYPE(field->type) == PB_ATYPE_POINTER) + prev_size = sizeof(const void*); + else + prev_size = field->data_size; + + /* Special case for static arrays */ + if (PB_ATYPE(field->type) == PB_ATYPE_STATIC && + PB_HTYPE(field->type) == PB_HTYPE_REPEATED) + { + prev_size *= field->array_size; + } + + if (PB_LTYPE(field->type) == PB_LTYPE_EXTENSION) + { + /* Special case for the extension field placeholder */ + if (!encode_extension_field(stream, field, pData)) + return false; + } + else + { + /* Regular field */ + if (!encode_field(stream, field, pData)) + return false; + } + + field++; + } + + 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) +{ + uint8_t buffer[10]; + size_t i = 0; + + if (value == 0) + return pb_write(stream, (uint8_t*)&value, 1); + + while (value) + { + buffer[i] = (uint8_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) +{ + #ifdef __BIG_ENDIAN__ + const uint8_t *bytes = value; + uint8_t lebytes[4]; + lebytes[0] = bytes[3]; + lebytes[1] = bytes[2]; + lebytes[2] = bytes[1]; + lebytes[3] = bytes[0]; + return pb_write(stream, lebytes, 4); + #else + return pb_write(stream, (const uint8_t*)value, 4); + #endif +} + +bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value) +{ + #ifdef __BIG_ENDIAN__ + const uint8_t *bytes = value; + uint8_t lebytes[8]; + lebytes[0] = bytes[7]; + lebytes[1] = bytes[6]; + lebytes[2] = bytes[5]; + lebytes[3] = bytes[4]; + lebytes[4] = bytes[3]; + lebytes[5] = bytes[2]; + lebytes[6] = bytes[1]; + lebytes[7] = bytes[0]; + return pb_write(stream, lebytes, 8); + #else + return pb_write(stream, (const uint8_t*)value, 8); + #endif +} + +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: + 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 uint8_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; + + /* Cases 1 and 2 are for compilers that have smaller types for bool + * or enums. */ + switch (field->data_size) + { + case 1: value = *(const int8_t*)src; break; + case 2: value = *(const int16_t*)src; break; + case 4: value = *(const int32_t*)src; break; + case 8: value = *(const int64_t*)src; break; + default: 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; + + switch (field->data_size) + { + case 4: value = *(const uint32_t*)src; break; + case 8: value = *(const uint64_t*)src; break; + default: 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; + + switch (field->data_size) + { + case 4: value = *(const int32_t*)src; break; + case 8: value = *(const int64_t*)src; break; + default: 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) +{ + 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) +{ + 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 = (const pb_bytes_array_t*)src; + + if (src == NULL) + { + /* Threat 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) +{ + /* strnlen() is not always available, so just use a loop */ + 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; /* Threat null pointer as an empty string */ + } + else + { + while (size < max_size && *p != '\0') + { + size++; + p++; + } + } + + return pb_encode_string(stream, (const uint8_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); +} + |