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 void *state; /* Free field for use by callback implementation */ 41 size_t bytes_left; 42 43 #ifndef PB_NO_ERRMSG 44 const char *errmsg; 45 #endif 46 }; 47 48 /*************************** 49 * Main decoding functions * 50 ***************************/ 51 52 /* Decode a single protocol buffers message from input stream into a C structure. 53 * Returns true on success, false on any failure. 54 * The actual struct pointed to by dest must match the description in fields. 55 * Callback fields of the destination structure must be initialized by caller. 56 * All other fields will be initialized by this function. 57 * 58 * Example usage: 59 * MyMessage msg = {}; 60 * uint8_t buffer[64]; 61 * pb_istream_t stream; 62 * 63 * // ... read some data into buffer ... 64 * 65 * stream = pb_istream_from_buffer(buffer, count); 66 * pb_decode(&stream, MyMessage_fields, &msg); 67 */ 68 bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); 69 70 /* Same as pb_decode, except does not initialize the destination structure 71 * to default values. This is slightly faster if you need no default values 72 * and just do memset(struct, 0, sizeof(struct)) yourself. 73 * 74 * This can also be used for 'merging' two messages, i.e. update only the 75 * fields that exist in the new message. 76 * 77 * Note: If this function returns with an error, it will not release any 78 * dynamically allocated fields. You will need to call pb_release() yourself. 79 */ 80 bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); 81 82 /* Same as pb_decode, except expects the stream to start with the message size 83 * encoded as varint. Corresponds to parseDelimitedFrom() in Google's 84 * protobuf API. 85 */ 86 bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); 87 88 /* Same as pb_decode_delimited, except that it does not initialize the destination structure. 89 * See pb_decode_noinit 90 */ 91 bool pb_decode_delimited_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); 92 93 /* Same as pb_decode, except allows the message to be terminated with a null byte. 94 * NOTE: Until nanopb-0.4.0, pb_decode() also allows null-termination. This behaviour 95 * is not supported in most other protobuf implementations, so pb_decode_delimited() 96 * is a better option for compatibility. 97 */ 98 bool pb_decode_nullterminated(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); 99 100 #ifdef PB_ENABLE_MALLOC 101 /* Release any allocated pointer fields. If you use dynamic allocation, you should 102 * call this for any successfully decoded message when you are done with it. If 103 * pb_decode() returns with an error, the message is already released. 104 */ 105 void pb_release(const pb_field_t fields[], void *dest_struct); 106 #endif 107 108 109 /************************************** 110 * Functions for manipulating streams * 111 **************************************/ 112 113 /* Create an input stream for reading from a memory buffer. 114 * 115 * Alternatively, you can use a custom stream that reads directly from e.g. 116 * a file or a network socket. 117 */ 118 pb_istream_t pb_istream_from_buffer(const pb_byte_t *buf, size_t bufsize); 119 120 /* Function to read from a pb_istream_t. You can use this if you need to 121 * read some custom header data, or to read data in field callbacks. 122 */ 123 bool pb_read(pb_istream_t *stream, pb_byte_t *buf, size_t count); 124 125 126 /************************************************ 127 * Helper functions for writing field callbacks * 128 ************************************************/ 129 130 /* Decode the tag for the next field in the stream. Gives the wire type and 131 * field tag. At end of the message, returns false and sets eof to true. */ 132 bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof); 133 134 /* Skip the field payload data, given the wire type. */ 135 bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type); 136 137 /* Decode an integer in the varint format. This works for bool, enum, int32, 138 * int64, uint32 and uint64 field types. */ 139 #ifndef PB_WITHOUT_64BIT 140 bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest); 141 #else 142 #define pb_decode_varint pb_decode_varint32 143 #endif 144 145 /* Decode an integer in the varint format. This works for bool, enum, int32, 146 * and uint32 field types. */ 147 bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest); 148 149 /* Decode an integer in the zig-zagged svarint format. This works for sint32 150 * and sint64. */ 151 #ifndef PB_WITHOUT_64BIT 152 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest); 153 #else 154 bool pb_decode_svarint(pb_istream_t *stream, int32_t *dest); 155 #endif 156 157 /* Decode a fixed32, sfixed32 or float value. You need to pass a pointer to 158 * a 4-byte wide C variable. */ 159 bool pb_decode_fixed32(pb_istream_t *stream, void *dest); 160 161 #ifndef PB_WITHOUT_64BIT 162 /* Decode a fixed64, sfixed64 or double value. You need to pass a pointer to 163 * a 8-byte wide C variable. */ 164 bool pb_decode_fixed64(pb_istream_t *stream, void *dest); 165 #endif 166 167 /* Make a limited-length substream for reading a PB_WT_STRING field. */ 168 bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream); 169 bool pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream); 170 171 #ifdef __cplusplus 172 } /* extern "C" */ 173 #endif 174 175 #endif 176