diff options
Diffstat (limited to 'pb_decode.c')
| -rw-r--r-- | pb_decode.c | 274 |
1 files changed, 274 insertions, 0 deletions
diff --git a/pb_decode.c b/pb_decode.c new file mode 100644 index 00000000..884cf18e --- /dev/null +++ b/pb_decode.c @@ -0,0 +1,274 @@ +/* pb_decode.c -- decode a protobuf using callback functions + * + * 2011 Petteri Aimonen <jpa@kapsi.fi> + */ + +#include "pb_decode.h" + +const pb_decoder_t PB_DECODERS[PB_LAST_ACT] = { + NULL, + &pb_dec_uint32, + &pb_dec_sint32, + &pb_dec_uint32, // Cast to int32 + &pb_dec_fixed32, + &pb_dec_fixed32, // Cast to int32 + &pb_dec_uint64, + &pb_dec_sint64, + &pb_dec_uint64, // Cast to int64 + &pb_dec_fixed64, + &pb_dec_fixed64, // Cast to int64 + &pb_dec_bool, + &pb_dec_float, + &pb_dec_double, + &pb_dec_bytes, + &pb_dec_string, + &pb_dec_submessage +}; + +enum wire_type { + WT_VARINT = 0, + WT_64BIT = 1, + WT_STRING = 2, + WT_32BIT = 5 +}; + +// Note: pb_decode_varint32 is a bit un-orthodox: +// it will refuse to decode values that exceed uint32 range. +// The Google implementation would simply cast to 32 bits. +bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest) +{ + char byte; + int bitpos = 0; + *dest = 0; + + while (bitpos < 32 && pb_read(stream, &byte, 1)) + { + *dest |= (byte & 0x7F) << bitpos; + bitpos += 7; + + if (!(byte & 0x80)) + return true; + } + + return false; +} + +bool pb_decode_varint64(pb_istream_t *stream, uint64_t *dest) +{ + char byte; + int bitpos = 0; + *dest = 0; + + while (bitpos < 64 && pb_read(stream, &byte, 1)) + { + *dest |= (byte & 0x7F) << bitpos; + bitpos += 7; + + if (!(byte & 0x80)) + return true; + } + + return false; +} + +bool pb_skip_varint(pb_istream_t *stream) +{ + char byte; + do + { + if (!pb_read(stream, &byte, 1)) + return false; + } while (byte & 0x80); + return true; +} + +bool pb_skip_string(pb_istream_t *stream) +{ + uint32_t length; + if (!pb_decode_varint32(stream, &length)) + return false; + + return pb_read(stream, NULL, length); +} + +bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest) +{ + while (stream->bytes_left) + { + uint32_t temp; + if (!pb_decode_varint32(stream, &temp)) + return false; + + int field_number = temp >> 3; + int wire_type = temp & 7; + + const pb_field_t *field = fields; + while (field->field_number != 0) + { + if (field->field_number != field_number) + { + field++; + continue; + } + + void *destfield = dest + field->offset; + + if (field->action == PB_ACT_HAS) + { + *(bool*)destfield = true; + field++; + continue; + } + + pb_decoder_t func = PB_DECODERS[field->action]; + if (!func(stream, field, destfield)) + return false; + + break; + } + + if (field->field_number == 0) // No match found, skip data + { + bool status = false; + switch (wire_type) + { + case WT_VARINT: + status = pb_skip_varint(stream); + break; + + case WT_64BIT: + status = pb_read(stream, NULL, 8); + break; + + case WT_STRING: + status = pb_skip_string(stream); + break; + + case WT_32BIT: + status = pb_read(stream, NULL, 4); + break; + } + + if (!status) + return false; + } + } + + return true; +} + +bool pb_dec_uint32(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + return pb_decode_varint32(stream, (uint32_t*)dest); +} + +bool pb_dec_sint32(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + uint32_t *x = (uint32_t*)dest; + bool status = pb_decode_varint32(stream, x); + *x = (*x >> 1) ^ -(int32_t)(*x & 1); + return status; +} + +bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + char bytes[4] = {0}; + bool status = pb_read(stream, bytes, 4); + *(uint32_t*)dest = + bytes[0] | ((uint32_t)bytes[1] << 8) | + ((uint32_t)bytes[2] << 16) | ((uint32_t)bytes[3] << 24); + return status; +} + +bool pb_dec_uint64(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + return pb_decode_varint64(stream, (uint64_t*)dest); +} + +bool pb_dec_sint64(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + uint64_t *x = (uint64_t*)dest; + bool status = pb_decode_varint64(stream, x); + *x = (*x >> 1) ^ -(int64_t)(*x & 1); + return status; +} + +bool pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + char bytes[8] = {0}; + bool status = pb_read(stream, bytes, 8); + *(uint64_t*)dest = + (uint64_t)bytes[0] | ((uint64_t)bytes[1] << 8) | + ((uint64_t)bytes[2] << 16) | ((uint64_t)bytes[3] << 24) | + ((uint64_t)bytes[4] << 32) | ((uint64_t)bytes[5] << 40) | + ((uint64_t)bytes[6] << 48) | ((uint64_t)bytes[7] << 56); + return status; +} + +bool pb_dec_bool(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + uint32_t temp = 0; + bool status = pb_decode_varint32(stream, &temp); + *(bool*)dest = !!temp; + return status; +} + +bool pb_dec_float(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + return pb_read(stream, (char*)dest, sizeof(float)); +} + +bool pb_dec_double(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + return pb_read(stream, (char*)dest, sizeof(double)); +} + +bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + pb_bytearray_t *x = (pb_bytearray_t*)dest; + uint32_t temp; + if (!pb_decode_varint32(stream, &temp)) + return false; + x->size = temp; + + if (x->size > field->fieldsize) + return false; + + return pb_read(stream, x->bytes, x->size); +} + +bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + uint32_t size; + if (!pb_decode_varint32(stream, &size)) + return false; + + if (size > field->fieldsize - 1) + return false; + + bool status = pb_read(stream, (char*)dest, size); + *((char*)dest + size) = 0; + return status; +} + +bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest) +{ + pb_callback_t *x = (pb_callback_t*)dest; + + if (x->funcs.decode == NULL) + return pb_skip_string(stream); + + uint32_t size; + if (!pb_decode_varint32(stream, &size)) + return false; + + if (stream->bytes_left < size) + return false; + + // Make a limited-length istream for decoding submessage + pb_istream_t shortstream = *stream; + shortstream.bytes_left = size; + bool status = x->funcs.decode(&shortstream, field, x->arg); + stream->bytes_left -= size - shortstream.bytes_left; + return status; +} |