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_ 7 #define _PB_DECODE_H_ 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_t 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, uint8_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 #ifdef PB_ENABLE_MALLOC 89 /* Release any allocated pointer fields. If you use dynamic allocation, you should 90 * call this for any successfully decoded message when you are done with it. If 91 * pb_decode() returns with an error, the message is already released. 92 */ 93 void pb_release(const pb_field_t fields[], void *dest_struct); 94 #endif 95 96 97 /************************************** 98 * Functions for manipulating streams * 99 **************************************/ 100 101 /* Create an input stream for reading from a memory buffer. 102 * 103 * Alternatively, you can use a custom stream that reads directly from e.g. 104 * a file or a network socket. 105 */ 106 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize); 107 108 /* Function to read from a pb_istream_t. You can use this if you need to 109 * read some custom header data, or to read data in field callbacks. 110 */ 111 bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count); 112 113 114 /************************************************ 115 * Helper functions for writing field callbacks * 116 ************************************************/ 117 118 /* Decode the tag for the next field in the stream. Gives the wire type and 119 * field tag. At end of the message, returns false and sets eof to true. */ 120 bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof); 121 122 /* Skip the field payload data, given the wire type. */ 123 bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type); 124 125 /* Decode an integer in the varint format. This works for bool, enum, int32, 126 * int64, uint32 and uint64 field types. */ 127 bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest); 128 129 /* Decode an integer in the zig-zagged svarint format. This works for sint32 130 * and sint64. */ 131 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest); 132 133 /* Decode a fixed32, sfixed32 or float value. You need to pass a pointer to 134 * a 4-byte wide C variable. */ 135 bool pb_decode_fixed32(pb_istream_t *stream, void *dest); 136 137 /* Decode a fixed64, sfixed64 or double value. You need to pass a pointer to 138 * a 8-byte wide C variable. */ 139 bool pb_decode_fixed64(pb_istream_t *stream, void *dest); 140 141 /* Make a limited-length substream for reading a PB_WT_STRING field. */ 142 bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream); 143 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream); 144 145 #ifdef __cplusplus 146 } /* extern "C" */ 147 #endif 148 149 #endif 150
