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pb_decode.h
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pb_decode.h
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/* pb_decode.h: Functions to decode protocol buffers. Depends on pb_decode.c.
* The main function is pb_decode. You also need an input stream, and the
* field descriptions created by nanopb_generator.py.
*/
#ifndef PB_DECODE_H_INCLUDED
#define PB_DECODE_H_INCLUDED
#include "pb.h"
#ifdef __cplusplus
extern "C" {
#endif
/* Structure for defining custom input streams. You will need to provide
* a callback function to read the bytes from your storage, which can be
* for example a file or a network socket.
*
* The callback must conform to these rules:
*
* 1) Return false on IO errors. This will cause decoding to abort.
* 2) You can use state to store your own data (e.g. buffer pointer),
* and rely on pb_read to verify that no-body reads past bytes_left.
* 3) Your callback may be used with substreams, in which case bytes_left
* is different than from the main stream. Don't use bytes_left to compute
* any pointers.
*/
struct pb_istream_s
{
#ifdef PB_BUFFER_ONLY
/* Callback pointer is not used in buffer-only configuration.
* Having an int pointer here allows binary compatibility but
* gives an error if someone tries to assign callback function.
*/
int *callback;
#else
bool (*callback)(pb_istream_t *stream, uint8_t *buf, size_t count);
#endif
void *state; /* Free field for use by callback implementation */
size_t bytes_left;
#ifndef PB_NO_ERRMSG
const char *errmsg;
#endif
};
/***************************
* Main decoding functions *
***************************/
/* Decode a single protocol buffers message from input stream into a C structure.
* Returns true on success, false on any failure.
* The actual struct pointed to by dest must match the description in fields.
* Callback fields of the destination structure must be initialized by caller.
* All other fields will be initialized by this function.
*
* Example usage:
* MyMessage msg = {};
* uint8_t buffer[64];
* pb_istream_t stream;
*
* // ... read some data into buffer ...
*
* stream = pb_istream_from_buffer(buffer, count);
* pb_decode(&stream, MyMessage_fields, &msg);
*/
bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
/* Same as pb_decode, except does not initialize the destination structure
* to default values. This is slightly faster if you need no default values
* and just do memset(struct, 0, sizeof(struct)) yourself.
*
* This can also be used for 'merging' two messages, i.e. update only the
* fields that exist in the new message.
*
* Note: If this function returns with an error, it will not release any
* dynamically allocated fields. You will need to call pb_release() yourself.
*/
bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
/* Same as pb_decode, except expects the stream to start with the message size
* encoded as varint. Corresponds to parseDelimitedFrom() in Google's
* protobuf API.
*/
bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
#ifdef PB_ENABLE_MALLOC
/* Release any allocated pointer fields. If you use dynamic allocation, you should
* call this for any successfully decoded message when you are done with it. If
* pb_decode() returns with an error, the message is already released.
*/
void pb_release(const pb_field_t fields[], void *dest_struct);
#endif
/**************************************
* Functions for manipulating streams *
**************************************/
/* Create an input stream for reading from a memory buffer.
*
* Alternatively, you can use a custom stream that reads directly from e.g.
* a file or a network socket.
*/
pb_istream_t pb_istream_from_buffer(const uint8_t *buf, size_t bufsize);
/* Function to read from a pb_istream_t. You can use this if you need to
* read some custom header data, or to read data in field callbacks.
*/
bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count);
/************************************************
* Helper functions for writing field callbacks *
************************************************/
/* Decode the tag for the next field in the stream. Gives the wire type and
* field tag. At end of the message, returns false and sets eof to true. */
bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof);
/* Skip the field payload data, given the wire type. */
bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type);
/* Decode an integer in the varint format. This works for bool, enum, int32,
* int64, uint32 and uint64 field types. */
bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest);
/* Decode an integer in the zig-zagged svarint format. This works for sint32
* and sint64. */
bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest);
/* Decode a fixed32, sfixed32 or float value. You need to pass a pointer to
* a 4-byte wide C variable. */
bool pb_decode_fixed32(pb_istream_t *stream, void *dest);
/* Decode a fixed64, sfixed64 or double value. You need to pass a pointer to
* a 8-byte wide C variable. */
bool pb_decode_fixed64(pb_istream_t *stream, void *dest);
/* Make a limited-length substream for reading a PB_WT_STRING field. */
bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream);
void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream);
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif