179 lines
6.4 KiB
C
179 lines
6.4 KiB
C
/* pb_decode.h: Functions to decode protocol buffers. Depends on pb_decode.c.
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* The main function is pb_decode. You also need an input stream, and the
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* field descriptions created by nanopb_generator.py.
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*/
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#ifndef PB_DECODE_H_INCLUDED
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#define PB_DECODE_H_INCLUDED
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#include "pb.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Structure for defining custom input streams. You will need to provide
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* a callback function to read the bytes from your storage, which can be
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* for example a file or a network socket.
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*
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* The callback must conform to these rules:
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*
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* 1) Return false on IO errors. This will cause decoding to abort.
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* 2) You can use state to store your own data (e.g. buffer pointer),
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* and rely on pb_read to verify that no-body reads past bytes_left.
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* 3) Your callback may be used with substreams, in which case bytes_left
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* is different than from the main stream. Don't use bytes_left to compute
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* any pointers.
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*/
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struct pb_istream_s
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{
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#ifdef PB_BUFFER_ONLY
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/* Callback pointer is not used in buffer-only configuration.
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* Having an int pointer here allows binary compatibility but
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* gives an error if someone tries to assign callback function.
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*/
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int *callback;
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#else
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bool (*callback)(pb_istream_t *stream, pb_byte_t *buf, size_t count);
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#endif
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void *state; /* Free field for use by callback implementation */
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size_t bytes_left;
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#ifndef PB_NO_ERRMSG
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const char *errmsg;
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#endif
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};
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/***************************
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* Main decoding functions *
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***************************/
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/* Decode a single protocol buffers message from input stream into a C structure.
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* Returns true on success, false on any failure.
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* The actual struct pointed to by dest must match the description in fields.
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* Callback fields of the destination structure must be initialized by caller.
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* All other fields will be initialized by this function.
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*
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* Example usage:
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* MyMessage msg = {};
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* uint8_t buffer[64];
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* pb_istream_t stream;
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*
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* // ... read some data into buffer ...
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*
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* stream = pb_istream_from_buffer(buffer, count);
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* pb_decode(&stream, MyMessage_fields, &msg);
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*/
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bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
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/* Same as pb_decode, except does not initialize the destination structure
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* to default values. This is slightly faster if you need no default values
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* and just do memset(struct, 0, sizeof(struct)) yourself.
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*
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* This can also be used for 'merging' two messages, i.e. update only the
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* fields that exist in the new message.
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*
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* Note: If this function returns with an error, it will not release any
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* dynamically allocated fields. You will need to call pb_release() yourself.
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*/
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bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
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/* Same as pb_decode, except expects the stream to start with the message size
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* encoded as varint. Corresponds to parseDelimitedFrom() in Google's
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* protobuf API.
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*/
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bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
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/* Same as pb_decode_delimited, except that it does not initialize the destination structure.
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* See pb_decode_noinit
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*/
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bool pb_decode_delimited_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
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/* Same as pb_decode, except allows the message to be terminated with a null byte.
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* NOTE: Until nanopb-0.4.0, pb_decode() also allows null-termination. This behaviour
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* is not supported in most other protobuf implementations, so pb_decode_delimited()
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* is a better option for compatibility.
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*/
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bool pb_decode_nullterminated(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
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#ifdef PB_ENABLE_MALLOC
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/* Release any allocated pointer fields. If you use dynamic allocation, you should
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* call this for any successfully decoded message when you are done with it. If
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* pb_decode() returns with an error, the message is already released.
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*/
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void pb_release(const pb_field_t fields[], void *dest_struct);
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#endif
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/**************************************
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* Functions for manipulating streams *
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**************************************/
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/* Create an input stream for reading from a memory buffer.
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*
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* Alternatively, you can use a custom stream that reads directly from e.g.
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* a file or a network socket.
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*/
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pb_istream_t pb_istream_from_buffer(const pb_byte_t *buf, size_t bufsize);
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/* Function to read from a pb_istream_t. You can use this if you need to
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* read some custom header data, or to read data in field callbacks.
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*/
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bool pb_read(pb_istream_t *stream, pb_byte_t *buf, size_t count);
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/************************************************
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* Helper functions for writing field callbacks *
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************************************************/
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/* Decode the tag for the next field in the stream. Gives the wire type and
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* field tag. At end of the message, returns false and sets eof to true. */
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bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof);
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/* Skip the field payload data, given the wire type. */
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bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type);
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/* Decode an integer in the varint format. This works for enum, int32,
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* int64, uint32 and uint64 field types. */
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#ifndef PB_WITHOUT_64BIT
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bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest);
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#else
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#define pb_decode_varint pb_decode_varint32
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#endif
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/* Decode an integer in the varint format. This works for enum, int32,
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* and uint32 field types. */
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bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest);
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/* Decode a bool value in varint format. */
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bool pb_decode_bool(pb_istream_t *stream, bool *dest);
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/* Decode an integer in the zig-zagged svarint format. This works for sint32
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* and sint64. */
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#ifndef PB_WITHOUT_64BIT
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bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest);
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#else
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bool pb_decode_svarint(pb_istream_t *stream, int32_t *dest);
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#endif
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/* Decode a fixed32, sfixed32 or float value. You need to pass a pointer to
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* a 4-byte wide C variable. */
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bool pb_decode_fixed32(pb_istream_t *stream, void *dest);
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#ifndef PB_WITHOUT_64BIT
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/* Decode a fixed64, sfixed64 or double value. You need to pass a pointer to
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* a 8-byte wide C variable. */
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bool pb_decode_fixed64(pb_istream_t *stream, void *dest);
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#endif
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/* Make a limited-length substream for reading a PB_WT_STRING field. */
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bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream);
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bool pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream);
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif
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