pb_decode.h

00001 #ifndef _PB_DECODE_H_
00002 #define _PB_DECODE_H_
00003 
00004 /* pb_decode.h: Functions to decode protocol buffers. Depends on pb_decode.c.
00005  * The main function is pb_decode. You will also need to create an input
00006  * stream, which is easiest to do with pb_istream_from_buffer().
00007  * 
00008  * You also need structures and their corresponding pb_field_t descriptions.
00009  * These are usually generated from .proto-files with a script.
00010  */
00011 
00012 #include <stdbool.h>
00013 #include "pb.h"
00014 
00015 #ifdef __cplusplus
00016 extern "C" {
00017 #endif
00018 
00019 /* Lightweight input stream.
00020  * You can provide a callback function for reading or use
00021  * pb_istream_from_buffer.
00022  * 
00023  * Rules for callback:
00024  * 1) Return false on IO errors. This will cause decoding to abort.
00025  * 
00026  * 2) You can use state to store your own data (e.g. buffer pointer),
00027  * and rely on pb_read to verify that no-body reads past bytes_left.
00028  * 
00029  * 3) Your callback may be used with substreams, in which case bytes_left
00030  * is different than from the main stream. Don't use bytes_left to compute
00031  * any pointers.
00032  */
00033 struct _pb_istream_t
00034 {
00035 #ifdef PB_BUFFER_ONLY
00036     /* Callback pointer is not used in buffer-only configuration.
00037      * Having an int pointer here allows binary compatibility but
00038      * gives an error if someone tries to assign callback function.
00039      */
00040     int *callback;
00041 #else
00042     bool (*callback)(pb_istream_t *stream, uint8_t *buf, size_t count);
00043 #endif
00044 
00045     void *state; /* Free field for use by callback implementation */
00046     size_t bytes_left;
00047     
00048 #ifndef PB_NO_ERRMSG
00049     const char *errmsg;
00050 #endif
00051 };
00052 
00053 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize);
00054 bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count);
00055 
00056 /* Decode from stream to destination struct.
00057  * Returns true on success, false on any failure.
00058  * The actual struct pointed to by dest must match the description in fields.
00059  */
00060 bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
00061 
00062 /* Same as pb_decode, except does not initialize the destination structure
00063  * to default values. This is slightly faster if you need no default values
00064  * and just do memset(struct, 0, sizeof(struct)) yourself.
00065  */
00066 bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
00067 
00068 /* --- Helper functions ---
00069  * You may want to use these from your caller or callbacks.
00070  */
00071 
00072 /* Decode the tag for the next field in the stream. Gives the wire type and
00073  * field tag. At end of the message, returns false and sets eof to true. */
00074 bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof);
00075 
00076 /* Skip the field payload data, given the wire type. */
00077 bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type);
00078 
00079 /* Decode an integer in the varint format. This works for bool, enum, int32,
00080  * int64, uint32 and uint64 field types. */
00081 bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest);
00082 
00083 /* Decode an integer in the zig-zagged svarint format. This works for sint32
00084  * and sint64. */
00085 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest);
00086 
00087 /* Decode a fixed32, sfixed32 or float value. You need to pass a pointer to
00088  * a 4-byte wide C variable. */
00089 bool pb_decode_fixed32(pb_istream_t *stream, void *dest);
00090 
00091 /* Decode a fixed64, sfixed64 or double value. You need to pass a pointer to
00092  * a 8-byte wide C variable. */
00093 bool pb_decode_fixed64(pb_istream_t *stream, void *dest);
00094 
00095 /* Make a limited-length substream for reading a PB_WT_STRING field. */
00096 bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream);
00097 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream);
00098 
00099 /* --- Internal functions ---
00100  * These functions are not terribly useful for the average library user, but
00101  * are exported to make the unit testing and extending nanopb easier.
00102  */
00103 
00104 #ifdef NANOPB_INTERNALS
00105 bool pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest);
00106 bool pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest);
00107 bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest);
00108 bool pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest);
00109 
00110 bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest);
00111 bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest);
00112 bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest);
00113 
00114 bool pb_skip_varint(pb_istream_t *stream);
00115 bool pb_skip_string(pb_istream_t *stream);
00116 #endif
00117 
00118 #ifdef __cplusplus
00119 } /* extern "C" */
00120 #endif
00121 
00122 #endif