1 /* pb_decode.h: Functions to decode protocol buffers. Depends on pb_decode.c. 2 * The main function is pb_decode. You also need an input stream, and the 3 * field descriptions created by nanopb_generator.py. 4 */ 5 6 #ifndef PB_DECODE_H_INCLUDED 7 #define PB_DECODE_H_INCLUDED 8 9 #include "pb.h" 10 11 #ifdef __cplusplus 12 extern "C" { 13 #endif 14 15 /* Structure for defining custom input streams. You will need to provide 16 * a callback function to read the bytes from your storage, which can be 17 * for example a file or a network socket. 18 * 19 * The callback must conform to these rules: 20 * 21 * 1) Return false on IO errors. This will cause decoding to abort. 22 * 2) You can use state to store your own data (e.g. buffer pointer), 23 * and rely on pb_read to verify that no-body reads past bytes_left. 24 * 3) Your callback may be used with substreams, in which case bytes_left 25 * is different than from the main stream. Don't use bytes_left to compute 26 * any pointers. 27 */ 28 struct pb_istream_s 29 { 30 #ifdef PB_BUFFER_ONLY 31 /* Callback pointer is not used in buffer-only configuration. 32 * Having an int pointer here allows binary compatibility but 33 * gives an error if someone tries to assign callback function. 34 */ 35 int *callback; 36 #else 37 bool (*callback)(pb_istream_t *stream, pb_byte_t *buf, size_t count); 38 #endif 39 40 /* state is a free field for use of the callback function defined above. 41 * Note that when pb_istream_from_buffer() is used, it reserves this field 42 * for its own use. 43 */ 44 void *state; 45 46 /* Maximum number of bytes left in this stream. Callback can report 47 * EOF before this limit is reached. Setting a limit is recommended 48 * when decoding directly from file or network streams to avoid 49 * denial-of-service by excessively long messages. 50 */ 51 size_t bytes_left; 52 53 #ifndef PB_NO_ERRMSG 54 /* Pointer to constant (ROM) string when decoding function returns error */ 55 const char *errmsg; 56 #endif 57 }; 58 59 #ifndef PB_NO_ERRMSG 60 #define PB_ISTREAM_EMPTY {0,0,0,0} 61 #else 62 #define PB_ISTREAM_EMPTY {0,0,0} 63 #endif 64 65 /*************************** 66 * Main decoding functions * 67 ***************************/ 68 69 /* Decode a single protocol buffers message from input stream into a C structure. 70 * Returns true on success, false on any failure. 71 * The actual struct pointed to by dest must match the description in fields. 72 * Callback fields of the destination structure must be initialized by caller. 73 * All other fields will be initialized by this function. 74 * 75 * Example usage: 76 * MyMessage msg = {}; 77 * uint8_t buffer[64]; 78 * pb_istream_t stream; 79 * 80 * // ... read some data into buffer ... 81 * 82 * stream = pb_istream_from_buffer(buffer, count); 83 * pb_decode(&stream, MyMessage_fields, &msg); 84 */ 85 bool pb_decode(pb_istream_t *stream, const pb_msgdesc_t *fields, void *dest_struct); 86 87 /* Extended version of pb_decode, with several options to control 88 * the decoding process: 89 * 90 * PB_DECODE_NOINIT: Do not initialize the fields to default values. 91 * This is slightly faster if you do not need the default 92 * values and instead initialize the structure to 0 using 93 * e.g. memset(). This can also be used for merging two 94 * messages, i.e. combine already existing data with new 95 * values. 96 * 97 * PB_DECODE_DELIMITED: Input message starts with the message size as varint. 98 * Corresponds to parseDelimitedFrom() in Google's 99 * protobuf API. 100 * 101 * PB_DECODE_NULLTERMINATED: Stop reading when field tag is read as 0. This allows 102 * reading null terminated messages. 103 * NOTE: Until nanopb-0.4.0, pb_decode() also allows 104 * null-termination. This behaviour is not supported in 105 * most other protobuf implementations, so PB_DECODE_DELIMITED 106 * is a better option for compatibility. 107 * 108 * Multiple flags can be combined with bitwise or (| operator) 109 */ 110 #define PB_DECODE_NOINIT 0x01U 111 #define PB_DECODE_DELIMITED 0x02U 112 #define PB_DECODE_NULLTERMINATED 0x04U 113 bool pb_decode_ex(pb_istream_t *stream, const pb_msgdesc_t *fields, void *dest_struct, unsigned int flags); 114 115 /* Defines for backwards compatibility with code written before nanopb-0.4.0 */ 116 #define pb_decode_noinit(s,f,d) pb_decode_ex(s,f,d, PB_DECODE_NOINIT) 117 #define pb_decode_delimited(s,f,d) pb_decode_ex(s,f,d, PB_DECODE_DELIMITED) 118 #define pb_decode_delimited_noinit(s,f,d) pb_decode_ex(s,f,d, PB_DECODE_DELIMITED | PB_DECODE_NOINIT) 119 #define pb_decode_nullterminated(s,f,d) pb_decode_ex(s,f,d, PB_DECODE_NULLTERMINATED) 120 121 /* Release any allocated pointer fields. If you use dynamic allocation, you should 122 * call this for any successfully decoded message when you are done with it. If 123 * pb_decode() returns with an error, the message is already released. 124 */ 125 void pb_release(const pb_msgdesc_t *fields, void *dest_struct); 126 127 /************************************** 128 * Functions for manipulating streams * 129 **************************************/ 130 131 /* Create an input stream for reading from a memory buffer. 132 * 133 * msglen should be the actual length of the message, not the full size of 134 * allocated buffer. 135 * 136 * Alternatively, you can use a custom stream that reads directly from e.g. 137 * a file or a network socket. 138 */ 139 pb_istream_t pb_istream_from_buffer(const pb_byte_t *buf, size_t msglen); 140 141 /* Function to read from a pb_istream_t. You can use this if you need to 142 * read some custom header data, or to read data in field callbacks. 143 */ 144 bool pb_read(pb_istream_t *stream, pb_byte_t *buf, size_t count); 145 146 147 /************************************************ 148 * Helper functions for writing field callbacks * 149 ************************************************/ 150 151 /* Decode the tag for the next field in the stream. Gives the wire type and 152 * field tag. At end of the message, returns false and sets eof to true. */ 153 bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof); 154 155 /* Skip the field payload data, given the wire type. */ 156 bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type); 157 158 /* Decode an integer in the varint format. This works for enum, int32, 159 * int64, uint32 and uint64 field types. */ 160 #ifndef PB_WITHOUT_64BIT 161 bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest); 162 #else 163 #define pb_decode_varint pb_decode_varint32 164 #endif 165 166 /* Decode an integer in the varint format. This works for enum, int32, 167 * and uint32 field types. */ 168 bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest); 169 170 /* Decode a bool value in varint format. */ 171 bool pb_decode_bool(pb_istream_t *stream, bool *dest); 172 173 /* Decode an integer in the zig-zagged svarint format. This works for sint32 174 * and sint64. */ 175 #ifndef PB_WITHOUT_64BIT 176 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest); 177 #else 178 bool pb_decode_svarint(pb_istream_t *stream, int32_t *dest); 179 #endif 180 181 /* Decode a fixed32, sfixed32 or float value. You need to pass a pointer to 182 * a 4-byte wide C variable. */ 183 bool pb_decode_fixed32(pb_istream_t *stream, void *dest); 184 185 #ifndef PB_WITHOUT_64BIT 186 /* Decode a fixed64, sfixed64 or double value. You need to pass a pointer to 187 * a 8-byte wide C variable. */ 188 bool pb_decode_fixed64(pb_istream_t *stream, void *dest); 189 #endif 190 191 #ifdef PB_CONVERT_DOUBLE_FLOAT 192 /* Decode a double value into float variable. */ 193 bool pb_decode_double_as_float(pb_istream_t *stream, float *dest); 194 #endif 195 196 /* Make a limited-length substream for reading a PB_WT_STRING field. */ 197 bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream); 198 bool pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream); 199 200 #ifdef __cplusplus 201 } /* extern "C" */ 202 #endif 203 204 #endif 205
