Line data Source code
1 : /* pb_encode.h: Functions to encode protocol buffers. Depends on pb_encode.c.
2 : * The main function is pb_encode. You also need an output stream, and the
3 : * field descriptions created by nanopb_generator.py.
4 : */
5 :
6 : #ifndef PB_ENCODE_H_INCLUDED
7 : #define PB_ENCODE_H_INCLUDED
8 :
9 : #include "pb_firedancer.h"
10 :
11 : #ifdef __cplusplus
12 : extern "C" {
13 : #endif
14 :
15 : /* Structure for defining custom output streams. You will need to provide
16 : * a callback function to write the bytes to 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 encoding to abort.
22 : * 2) You can use state to store your own data (e.g. buffer pointer).
23 : * 3) pb_write will update bytes_written after your callback runs.
24 : * 4) Substreams will modify max_size and bytes_written. Don't use them
25 : * to calculate any pointers.
26 : */
27 : struct pb_ostream_s
28 : {
29 : #ifdef PB_BUFFER_ONLY
30 : /* Callback pointer is not used in buffer-only configuration.
31 : * Having an int pointer here allows binary compatibility but
32 : * gives an error if someone tries to assign callback function.
33 : * Also, NULL pointer marks a 'sizing stream' that does not
34 : * write anything.
35 : */
36 : const int *callback;
37 : #else
38 : bool (*callback)(pb_ostream_t *stream, const pb_byte_t *buf, size_t count);
39 : #endif
40 :
41 : /* state is a free field for use of the callback function defined above.
42 : * Note that when pb_ostream_from_buffer() is used, it reserves this field
43 : * for its own use.
44 : */
45 : void *state;
46 :
47 : /* Limit number of output bytes written. Can be set to SIZE_MAX. */
48 : size_t max_size;
49 :
50 : /* Number of bytes written so far. */
51 : size_t bytes_written;
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 : /***************************
60 : * Main encoding functions *
61 : ***************************/
62 :
63 : /* Encode a single protocol buffers message from C structure into a stream.
64 : * Returns true on success, false on any failure.
65 : * The actual struct pointed to by src_struct must match the description in fields.
66 : * All required fields in the struct are assumed to have been filled in.
67 : *
68 : * Example usage:
69 : * MyMessage msg = {};
70 : * uint8_t buffer[64];
71 : * pb_ostream_t stream;
72 : *
73 : * msg.field1 = 42;
74 : * stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
75 : * pb_encode(&stream, MyMessage_fields, &msg);
76 : */
77 : bool pb_encode(pb_ostream_t *stream, const pb_msgdesc_t *fields, const void *src_struct);
78 :
79 : /* Extended version of pb_encode, with several options to control the
80 : * encoding process:
81 : *
82 : * PB_ENCODE_DELIMITED: Prepend the length of message as a varint.
83 : * Corresponds to writeDelimitedTo() in Google's
84 : * protobuf API.
85 : *
86 : * PB_ENCODE_NULLTERMINATED: Append a null byte to the message for termination.
87 : * NOTE: This behaviour is not supported in most other
88 : * protobuf implementations, so PB_ENCODE_DELIMITED
89 : * is a better option for compatibility.
90 : */
91 0 : #define PB_ENCODE_DELIMITED 0x02U
92 0 : #define PB_ENCODE_NULLTERMINATED 0x04U
93 : bool pb_encode_ex(pb_ostream_t *stream, const pb_msgdesc_t *fields, const void *src_struct, unsigned int flags);
94 :
95 : /* Defines for backwards compatibility with code written before nanopb-0.4.0 */
96 : #define pb_encode_delimited(s,f,d) pb_encode_ex(s,f,d, PB_ENCODE_DELIMITED)
97 : #define pb_encode_nullterminated(s,f,d) pb_encode_ex(s,f,d, PB_ENCODE_NULLTERMINATED)
98 :
99 : /* Encode the message to get the size of the encoded data, but do not store
100 : * the data. */
101 : bool pb_get_encoded_size(size_t *size, const pb_msgdesc_t *fields, const void *src_struct);
102 :
103 : /**************************************
104 : * Functions for manipulating streams *
105 : **************************************/
106 :
107 : /* Create an output stream for writing into a memory buffer.
108 : * The number of bytes written can be found in stream.bytes_written after
109 : * encoding the message.
110 : *
111 : * Alternatively, you can use a custom stream that writes directly to e.g.
112 : * a file or a network socket.
113 : */
114 : pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize);
115 :
116 : /* Pseudo-stream for measuring the size of a message without actually storing
117 : * the encoded data.
118 : *
119 : * Example usage:
120 : * MyMessage msg = {};
121 : * pb_ostream_t stream = PB_OSTREAM_SIZING;
122 : * pb_encode(&stream, MyMessage_fields, &msg);
123 : * printf("Message size is %d\n", stream.bytes_written);
124 : */
125 : #ifndef PB_NO_ERRMSG
126 1133112 : #define PB_OSTREAM_SIZING {0,0,0,0,0}
127 : #else
128 : #define PB_OSTREAM_SIZING {0,0,0,0}
129 : #endif
130 :
131 : /* Function to write into a pb_ostream_t stream. You can use this if you need
132 : * to append or prepend some custom headers to the message.
133 : */
134 : bool pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count);
135 :
136 :
137 : /************************************************
138 : * Helper functions for writing field callbacks *
139 : ************************************************/
140 :
141 : /* Encode field header based on type and field number defined in the field
142 : * structure. Call this from the callback before writing out field contents. */
143 : bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_iter_t *field);
144 :
145 : /* Encode field header by manually specifying wire type. You need to use this
146 : * if you want to write out packed arrays from a callback field. */
147 : bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number);
148 :
149 : /* Encode an integer in the varint format.
150 : * This works for bool, enum, int32, int64, uint32 and uint64 field types. */
151 : #ifndef PB_WITHOUT_64BIT
152 : bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
153 : #else
154 : bool pb_encode_varint(pb_ostream_t *stream, uint32_t value);
155 : #endif
156 :
157 : /* Encode an integer in the zig-zagged svarint format.
158 : * This works for sint32 and sint64. */
159 : #ifndef PB_WITHOUT_64BIT
160 : bool pb_encode_svarint(pb_ostream_t *stream, int64_t value);
161 : #else
162 : bool pb_encode_svarint(pb_ostream_t *stream, int32_t value);
163 : #endif
164 :
165 : /* Encode a string or bytes type field. For strings, pass strlen(s) as size. */
166 : bool pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size);
167 :
168 : /* Encode a fixed32, sfixed32 or float value.
169 : * You need to pass a pointer to a 4-byte wide C variable. */
170 : bool pb_encode_fixed32(pb_ostream_t *stream, const void *value);
171 :
172 : #ifndef PB_WITHOUT_64BIT
173 : /* Encode a fixed64, sfixed64 or double value.
174 : * You need to pass a pointer to a 8-byte wide C variable. */
175 : bool pb_encode_fixed64(pb_ostream_t *stream, const void *value);
176 : #endif
177 :
178 : #ifdef PB_CONVERT_DOUBLE_FLOAT
179 : /* Encode a float value so that it appears like a double in the encoded
180 : * message. */
181 : bool pb_encode_float_as_double(pb_ostream_t *stream, float value);
182 : #endif
183 :
184 : /* Encode a submessage field.
185 : * You need to pass the pb_field_t array and pointer to struct, just like
186 : * with pb_encode(). This internally encodes the submessage twice, first to
187 : * calculate message size and then to actually write it out.
188 : */
189 : bool pb_encode_submessage(pb_ostream_t *stream, const pb_msgdesc_t *fields, const void *src_struct);
190 :
191 : #ifdef __cplusplus
192 : } /* extern "C" */
193 : #endif
194 :
195 : #endif
|
