blob: d9c8b2acc01e2b96605849a90e215f0288122ca9 [file] [log] [blame]
/* 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->bytes_written ||
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;
size_t allocsize;
if (src == NULL)
{
/* Threat null pointer as an empty bytes field */
return pb_encode_string(stream, NULL, 0);
}
allocsize = PB_BYTES_ARRAY_T_ALLOCSIZE(bytes->size);
if (allocsize < bytes->size ||
(PB_ATYPE(field->type) == PB_ATYPE_STATIC && allocsize > 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);
}