diff options
author | Joshua Haberman <joshua@reverberate.org> | 2009-02-01 12:57:09 -0800 |
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committer | Joshua Haberman <joshua@reverberate.org> | 2009-02-01 12:57:09 -0800 |
commit | d29a54fc976f2dd91f05e40baf0a4b37869a88bf (patch) | |
tree | 0261ae91a9c5e0b0f404f31a6a937cac35d8d49a /pbstream.c |
Initial commit.
Diffstat (limited to 'pbstream.c')
-rw-r--r-- | pbstream.c | 453 |
1 files changed, 453 insertions, 0 deletions
diff --git a/pbstream.c b/pbstream.c new file mode 100644 index 0000000..c300153 --- /dev/null +++ b/pbstream.c @@ -0,0 +1,453 @@ +/* + * pbstream - a stream-oriented implementation of protocol buffers. + * + * Copyright (c) 2008 Joshua Haberman. See LICENSE for details. + */ + +#include <limits.h> +#include <string.h> +#include "pbstream.h" + +/* Branch prediction hints for GCC. */ +#ifdef __GNUC__ +#define likely(x) __builtin_expect((x),1) +#define unlikely(x) __builtin_expect((x),0) +#else +#define likely(x) +#define unlikely(x) +#endif + +/* An array, indexed by pbstream_type, that indicates what wire type is + * expected for the given pbstream type. */ +static enum pbstream_wire_type expected_wire_type[] = { + PBSTREAM_WIRE_TYPE_64BIT, // PBSTREAM_TYPE_DOUBLE, + PBSTREAM_WIRE_TYPE_32BIT, // PBSTREAM_TYPE_FLOAT, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_INT32, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_INT64, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_UINT32, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_UINT64, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_SINT32, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_SINT64, + PBSTREAM_WIRE_TYPE_32BIT, // PBSTREAM_TYPE_FIXED32, + PBSTREAM_WIRE_TYPE_64BIT, // PBSTREAM_TYPE_FIXED64, + PBSTREAM_WIRE_TYPE_32BIT, // PBSTREAM_TYPE_SFIXED32, + PBSTREAM_WIRE_TYPE_64BIT, // PBSTREAM_TYPE_SFIXED64, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_BOOL, + PBSTREAM_WIRE_TYPE_STRING, // PBSTREAM_TYPE_STRING, + PBSTREAM_WIRE_TYPE_STRING, // PBSTREAM_TYPE_BYTES, + PBSTREAM_WIRE_TYPE_VARINT, // PBSTREAM_TYPE_ENUM, + PBSTREAM_WIRE_TYPE_STRING, // PBSTREAM_TYPE_MESSAGE +}; + +/* Reads a varint starting at buf (but not past end), storing the result + * in out_value. Returns whether the operation was successful. */ +enum pbstream_status get_varint(char **buf, char *end, uint64_t *out_value) +{ + *out_value = 0; + int bitpos = 0; + char *b = *buf; + + /* Because we don't check for buffer overrun inside the loop, we require + * that callers use a buffer that is overallocated by at least 9 bytes + * (the maximum we can overrun before the bitpos check catches the problem). */ + for(; *b & 0x80 && bitpos < 64; bitpos += 7, b++) + *out_value |= (*b & 0x7F) << bitpos; + + if(unlikely(bitpos >= 64)) { + return PBSTREAM_ERROR_UNTERMINATED_VARINT; + } + if(unlikely(b > end)) { + return PBSTREAM_STATUS_INCOMPLETE; + } + + *out_value |= (*b & 0x7F) << bitpos; + *buf = b; + return PBSTREAM_STATUS_OK; +} + +/* TODO: the little-endian versions of these functions don't respect alignment. + * While it's hard to believe that this could be less efficient than the + * alternative (the big endian implementation), this deserves some tests and + * measurements to be sure. */ +enum pbstream_status get_32_le(char **buf, char *end, uint32_t *out_value) +{ + char *b = *buf; + char *int32_end = b+4; + if(unlikely(int32_end > end)) + return PBSTREAM_STATUS_INCOMPLETE; + +#if __BYTE_ORDER == __LITTLE_ENDIAN + *out_value = *(uint32_t*)b; +#else + *out_value = b[0] | (b[1] << 8) | (b[2] << 16) | (b[3] << 24); +#endif + *buf = int32_end; + return PBSTREAM_STATUS_OK; +} + +bool get_64_le(char **buf, char *end, uint64_t *out_value) +{ + char *b = *buf; + char *int64_end = b+8; + if(unlikely(int64_end > end)) + return PBSTREAM_STATUS_INCOMPLETE; + +#if __BYTE_ORDER == __LITTLE_ENDIAN + *out_value = *(uint64_t*)buf; +#else + *out_value = (b[0]) | (b[1] << 8 ) | (b[2] << 16) | (b[3] << 24) | + (b[4] << 32) | (b[5] << 40) | (b[6] << 48) | (b[7] << 56); +#endif + *buf = int64_end; + return PBSTREAM_STATUS_OK; +} + +int32_t zigzag_decode_32(uint64_t src) +{ + return 0; /* TODO */ +} + +int64_t zigzag_decode_64(uint64_t src) +{ + return 0; /* TODO */ +} + +/* Parses the next field-number/wire-value pair from the stream of bytes + * starting at *buf, without reading past end. Stores the parsed and wire + * value in *field_number and *wire_value, respectively. + * + * Returns a status indicating whether the operation was successful. If the + * return status is STATUS_INCOMPLETE, returns the number of additional bytes + * requred in *need_more_bytes. Updates *buf to point past the end of the + * parsed data if the operation was successful. + */ +enum pbstream_status pbstream_parse_wire_value(char **buf, char *end, + pbstream_field_number_t *field_number, + struct pbstream_wire_value *wire_value, + int *need_more_bytes) +{ + char *b = *buf; /* Our local buf pointer -- only update buf if we succeed. */ + +#define DECODE(dest, func) \ + do { \ + enum pbstream_status status = func(&b, end, &dest); \ + if(unlikely(status != PBSTREAM_STATUS_OK)) { \ + *need_more_bytes = 0; /* This only arises below in this function. */ \ + return status; \ + } \ + } while (0) + + uint64_t key; + DECODE(key, get_varint); + + *field_number = key >> 3; + wire_value->type = key & 0x07; + + switch(wire_value->type) + { + case PBSTREAM_WIRE_TYPE_VARINT: + DECODE(wire_value->v.varint, get_varint); + break; + + case PBSTREAM_WIRE_TYPE_64BIT: + DECODE(wire_value->v._64bit, get_64_le); + break; + + case PBSTREAM_WIRE_TYPE_STRING: + { + uint64_t string_len; + DECODE(string_len, get_varint); + if (string_len > INT_MAX) { + /* TODO: notice this and fail. */ + } + wire_value->v.string.len = (int)string_len; + if(b + wire_value->v.string.len > end) { + *need_more_bytes = b + wire_value->v.string.len - end; + return PBSTREAM_STATUS_INCOMPLETE; + } + wire_value->v.string.data = b; + b += wire_value->v.string.len; + break; + } + + case PBSTREAM_WIRE_TYPE_START_GROUP: + case PBSTREAM_WIRE_TYPE_END_GROUP: + /* TODO (though these are deprecated, so not high priority). */ + break; + + case PBSTREAM_WIRE_TYPE_32BIT: + DECODE(wire_value->v._32bit, get_32_le); + break; + } + + *buf = b; + return true; +} + +/* Translates from a wire value to a .proto value. The caller should have + * already checked that the wire_value is of the correct type. The pbstream + * type must not be PBSTREAM_TYPE_MESSAGE. This operation always succeeds. */ +void pbstream_translate_field(struct pbstream_wire_value *wire_value, + enum pbstream_type type, + struct pbstream_value *out_value) +{ + out_value->type = type; + switch(type) { + case PBSTREAM_TYPE_DOUBLE: + memcpy(&out_value->v._double, &wire_value->v._64bit, sizeof(double)); + break; + + case PBSTREAM_TYPE_FLOAT: + memcpy(&out_value->v._float, &wire_value->v._32bit, sizeof(float)); + break; + + case PBSTREAM_TYPE_INT32: + out_value->v.int32 = (int32_t)wire_value->v.varint; + break; + + case PBSTREAM_TYPE_INT64: + out_value->v.int64 = (int64_t)zigzag_decode_64(wire_value->v.varint); + break; + + case PBSTREAM_TYPE_UINT32: + out_value->v.uint32 = (uint32_t)wire_value->v.varint; + break; + + case PBSTREAM_TYPE_UINT64: + out_value->v.uint64 = (uint64_t)wire_value->v.varint; + break; + + case PBSTREAM_TYPE_SINT32: + out_value->v.int32 = zigzag_decode_32(wire_value->v.varint); + break; + + case PBSTREAM_TYPE_SINT64: + out_value->v.int64 = zigzag_decode_64(wire_value->v.varint); + break; + + case PBSTREAM_TYPE_FIXED32: + out_value->v.int32 = wire_value->v._32bit; + break; + + case PBSTREAM_TYPE_FIXED64: + out_value->v.int64 = wire_value->v._64bit; + break; + + case PBSTREAM_TYPE_SFIXED32: + out_value->v.int32 = (int32_t)wire_value->v._32bit; + break; + + case PBSTREAM_TYPE_SFIXED64: + out_value->v.int64 = (int64_t)wire_value->v._64bit; + break; + + case PBSTREAM_TYPE_BOOL: + out_value->v._bool = (bool)wire_value->v.varint; + break; + + case PBSTREAM_TYPE_STRING: + out_value->v.string.data = wire_value->v.string.data; + out_value->v.string.len = wire_value->v.string.len; + /* TODO: validate UTF-8? */ + break; + + case PBSTREAM_TYPE_BYTES: + out_value->v.bytes.data = wire_value->v.string.data; + out_value->v.bytes.len = wire_value->v.string.len; + break; + + case PBSTREAM_TYPE_ENUM: + out_value->v._enum = (bool)wire_value->v.varint; + break; + + case PBSTREAM_TYPE_MESSAGE: + /* Should never happen. */ + break; + } +} + +/* Given a wire value that was just parsed and a matching field descriptor, + * processes the given value and performs the appropriate actions. These + * actions include: + * - checking that the wire type is as expected + * - converting the wire type to a .proto type + * - entering a sub-message, if that is in fact what this field implies. + * + * This function also calls user callbacks pertaining to any of the above at + * the appropriate times. */ +void process_value(struct pbstream_parse_state *s, + struct pbstream_wire_value *wire_value, + struct pbstream_field_descriptor *field_descriptor) +{ + /* Check that the wire type is appropriate for this .proto type. */ + if(unlikely(wire_value->type != expected_wire_type[field_descriptor->type])) { + /* Report the type mismatch error. */ + if(s->callbacks.error_callback) { + /* TODO: a nice formatted message. */ + s->callbacks.error_callback(PBSTREAM_ERROR_MISMATCHED_TYPE, NULL, + s->offset, false); + } + + /* Report the wire value we parsed as an unknown value. */ + if(s->callbacks.unknown_value_callback) { + s->callbacks.unknown_value_callback(field_descriptor->field_number, wire_value, + s->user_data); + } + return; + } + + if(field_descriptor->type == PBSTREAM_TYPE_MESSAGE) { + /* We're entering a sub-message. */ + if(s->callbacks.begin_message_callback) { + s->callbacks.begin_message_callback(field_descriptor->d.message, s->user_data); + } + + /* Push and initialize a new stack frame. */ + RESIZE_DYNARRAY(s->stack, s->stack_len+1); + struct pbstream_parse_stack_frame *frame = DYNARRAY_GET_TOP(s->stack); + frame->message_descriptor = field_descriptor->d.message; + frame->end_offset = 0; /* TODO: set this correctly. */ + int num_seen_fields = frame->message_descriptor->num_seen_fields; + INIT_DYNARRAY(frame->seen_fields, num_seen_fields, num_seen_fields); + } + else { + /* This is a scalar value. */ + struct pbstream_value value; + pbstream_translate_field(wire_value, field_descriptor->type, &value); + if(s->callbacks.value_callback) { + s->callbacks.value_callback(field_descriptor, value, s->user_data); + } + } +} + +struct pbstream_field_descriptor *find_field_descriptor_by_number( + struct pbstream_message_descriptor* message_descriptor, + pbstream_field_number_t field_number) +{ + /* Currently a linear search -- could be optimized to do a binary search, + * hash table lookup, or any other number of clever things you might imagine. */ + for (int i = 0; i < message_descriptor->fields_len; i++) + if (message_descriptor->fields[i].field_number == field_number) + return &message_descriptor->fields[i]; + return NULL; +} + +/* Parses and processes the next value from *buf (but not past end), returning + * a status indicating whether the operation succeeded, and calling appropriate + * callbacks. If more data is needed to parse the last partial field, returns + * how many more bytes are needed in need_more_bytes. Updates *buf to point + * past the parsed value if the operation succeeds. */ +enum pbstream_status pbstream_parse_field(struct pbstream_parse_state *s, + char **buf, char *end, + int *need_more_bytes) +{ + struct pbstream_parse_stack_frame *frame = DYNARRAY_GET_TOP(s->stack); + struct pbstream_message_descriptor *message_descriptor = frame->message_descriptor; + + pbstream_field_number_t field_number; + struct pbstream_wire_value wire_value; + enum pbstream_status status; + + /* Decode the raw wire data. */ + status = pbstream_parse_wire_value(buf, end, &field_number, &wire_value, + need_more_bytes); + + if(unlikely(status != PBSTREAM_STATUS_OK)) { + if(status == PBSTREAM_ERROR_UNTERMINATED_VARINT && s->callbacks.error_callback) { + /* TODO: a nice formatted message. */ + s->callbacks.error_callback(PBSTREAM_ERROR_UNTERMINATED_VARINT, NULL, + s->offset, true); + } + s->fatal_error = true; + return status; + } + + /* Find the corresponding field definition from the .proto file. */ + struct pbstream_field_descriptor *field_descriptor; + field_descriptor = find_field_descriptor_by_number(message_descriptor, field_number); + + + if(likely(field_descriptor != NULL)) { + if(field_descriptor->seen_field_num > 0) { + /* Check that this field has not been seen before (unless it's a repeated field) */ + if(frame->seen_fields[field_descriptor->seen_field_num] && + field_descriptor->cardinality != PBSTREAM_CARDINALITY_REPEATED) { + if(s->callbacks.error_callback) { + s->callbacks.error_callback(PBSTREAM_ERROR_DUPLICATE_FIELD, NULL, + s->offset, false); + } + return PBSTREAM_STATUS_ERROR; + } + + /* Mark the field as seen. */ + frame->seen_fields[field_descriptor->seen_field_num] = true; + } + process_value(s, &wire_value, field_descriptor); + } else { + /* This field was not defined in the .proto file. */ + if(s->callbacks.unknown_value_callback) { + s->callbacks.unknown_value_callback(field_number, &wire_value, s->user_data); + } + } + return PBSTREAM_STATUS_OK; +} + +/* Process actions associated with the end of a submessage. This includes: + * - emittin default values for all optional elements (either explicit + * defaults or implicit defaults). + * - emitting errors for any required fields that were not seen. + * - calling the user's callback. + * - popping the stack frame. */ +void process_submessage_end(struct pbstream_parse_state *s) +{ + /* TODO: emit default values for optional elements. either explicit defaults + * (specified in the .proto file) or implicit defaults (which are specified + * in the pbstream definition, by type. */ + + /* TODO: emit errors for required fields that were not seen. */ + + /* Process the end of message by calling the user's callback and popping + * our stack frame. */ + if(s->callbacks.end_message_callback) { + s->callbacks.end_message_callback(s->user_data); + } + + /* Pop the stack frame associated with this submessage. */ + RESIZE_DYNARRAY(s->stack, s->stack_len-1); +} + +/* The user-exposed parsing function -- see the header file for documentation. */ +enum pbstream_status pbstream_parse(struct pbstream_parse_state *s, + char *buf_start, int buf_len, + int *consumed_bytes, int *need_more_bytes) +{ + char *buf = buf_start; + char *end = buf_start + buf_len; + int buf_start_offset = s->offset; + enum pbstream_status status = PBSTREAM_STATUS_OK; + + while(buf < end) { + /* Check for a submessage ending. */ + while(s->offset >= DYNARRAY_GET_TOP(s->stack)->end_offset) { + /* A submessage should end exactly at a field boundary. If we find that + * the submessage length indicated an end in the middle of a field, that + * is an error that indicates data corruption, and we refuse to proceed. */ + if(unlikely(s->offset != DYNARRAY_GET_TOP(s->stack)->end_offset)) { + if(s->callbacks.error_callback) { + s->callbacks.error_callback(PBSTREAM_ERROR_BAD_SUBMESSAGE_END, NULL, + s->offset, true); + } + s->fatal_error = true; + break; + } + process_submessage_end(s); + } + + status = pbstream_parse_field(s, &buf, end, need_more_bytes); + if(status != PBSTREAM_STATUS_OK) + break; + + s->offset = buf_start_offset + (buf - buf_start); + } + return status; +} |