/* pb_encode.c -- encode a protobuf using minimal resources

*

* 2011 Petteri Aimonen <jpa@kapsi.fi>

*/

#define NANOPB_INTERNALS

#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_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_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 (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;

if (!func(stream, field, p))

return false;

p = (const char*)p + field->data_size;

}

}

return true;

}

/* Encode a field with static allocation, i.e. one whose data is stored

* in the structure itself. */

static bool checkreturn encode_static_field(pb_ostream_t *stream,

const pb_field_t *field, const void *pData)

{

pb_encoder_t func;

const void *pSize;

bool dummy = true;

func = PB_ENCODERS[PB_LTYPE(field->type)];

if (field->size_offset)

pSize = (const char*)pData + field->size_offset;

else

pSize = &dummy;

switch (PB_HTYPE(field->type))

{

case PB_HTYPE_REQUIRED:

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:

return encode_static_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;

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);

}

/********************

* 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 = wiretype | (field_number << 3);

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_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))

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 */

bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)

{

uint64_t value = 0;

switch (field->data_size)

{

case 1: value = *(const uint8_t*)src; break;

case 2: value = *(const uint16_t*)src; break;

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);

}

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);

}

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);

}

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);

}

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 (bytes->size + offsetof(pb_bytes_array_t, bytes) > field->data_size)

PB_RETURN_ERROR(stream, "bytes size exceeded");

return pb_encode_string(stream, bytes->bytes, bytes->size);

}

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 for-loop */

size_t size = 0;

const char *p = (const char*)src;

while (size < field->data_size && *p != '\0')

{

size++;

p++;

}

return pb_encode_string(stream, (const uint8_t*)src, size);

}

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);

}