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.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 : void *state; /* Free field for use by callback implementation. */
41 : size_t max_size; /* Limit number of output bytes written (or use SIZE_MAX). */
42 : size_t bytes_written; /* Number of bytes written so far. */
43 :
44 : #ifndef PB_NO_ERRMSG
45 : const char *errmsg;
46 : #endif
47 : };
48 :
49 : /***************************
50 : * Main encoding functions *
51 : ***************************/
52 :
53 : /* Encode a single protocol buffers message from C structure into a stream.
54 : * Returns true on success, false on any failure.
55 : * The actual struct pointed to by src_struct must match the description in fields.
56 : * All required fields in the struct are assumed to have been filled in.
57 : *
58 : * Example usage:
59 : * MyMessage msg = {};
60 : * uint8_t buffer[64];
61 : * pb_ostream_t stream;
62 : *
63 : * msg.field1 = 42;
64 : * stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
65 : * pb_encode(&stream, MyMessage_fields, &msg);
66 : */
67 : bool pb_encode(pb_ostream_t *stream, const pb_msgdesc_t *fields, const void *src_struct);
68 :
69 : /* Extended version of pb_encode, with several options to control the
70 : * encoding process:
71 : *
72 : * PB_ENCODE_DELIMITED: Prepend the length of message as a varint.
73 : * Corresponds to writeDelimitedTo() in Google's
74 : * protobuf API.
75 : *
76 : * PB_ENCODE_NULLTERMINATED: Append a null byte to the message for termination.
77 : * NOTE: This behaviour is not supported in most other
78 : * protobuf implementations, so PB_ENCODE_DELIMITED
79 : * is a better option for compatibility.
80 : */
81 0 : #define PB_ENCODE_DELIMITED 0x02U
82 0 : #define PB_ENCODE_NULLTERMINATED 0x04U
83 : bool pb_encode_ex(pb_ostream_t *stream, const pb_msgdesc_t *fields, const void *src_struct, unsigned int flags);
84 :
85 : /* Defines for backwards compatibility with code written before nanopb-0.4.0 */
86 : #define pb_encode_delimited(s,f,d) pb_encode_ex(s,f,d, PB_ENCODE_DELIMITED)
87 : #define pb_encode_nullterminated(s,f,d) pb_encode_ex(s,f,d, PB_ENCODE_NULLTERMINATED)
88 :
89 : /* Encode the message to get the size of the encoded data, but do not store
90 : * the data. */
91 : bool pb_get_encoded_size(size_t *size, const pb_msgdesc_t *fields, const void *src_struct);
92 :
93 : /**************************************
94 : * Functions for manipulating streams *
95 : **************************************/
96 :
97 : /* Create an output stream for writing into a memory buffer.
98 : * The number of bytes written can be found in stream.bytes_written after
99 : * encoding the message.
100 : *
101 : * Alternatively, you can use a custom stream that writes directly to e.g.
102 : * a file or a network socket.
103 : */
104 : pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize);
105 :
106 : /* Pseudo-stream for measuring the size of a message without actually storing
107 : * the encoded data.
108 : *
109 : * Example usage:
110 : * MyMessage msg = {};
111 : * pb_ostream_t stream = PB_OSTREAM_SIZING;
112 : * pb_encode(&stream, MyMessage_fields, &msg);
113 : * printf("Message size is %d\n", stream.bytes_written);
114 : */
115 : #ifndef PB_NO_ERRMSG
116 5568 : #define PB_OSTREAM_SIZING {0,0,0,0,0}
117 : #else
118 : #define PB_OSTREAM_SIZING {0,0,0,0}
119 : #endif
120 :
121 : /* Function to write into a pb_ostream_t stream. You can use this if you need
122 : * to append or prepend some custom headers to the message.
123 : */
124 : bool pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count);
125 :
126 :
127 : /************************************************
128 : * Helper functions for writing field callbacks *
129 : ************************************************/
130 :
131 : /* Encode field header based on type and field number defined in the field
132 : * structure. Call this from the callback before writing out field contents. */
133 : bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_iter_t *field);
134 :
135 : /* Encode field header by manually specifying wire type. You need to use this
136 : * if you want to write out packed arrays from a callback field. */
137 : bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number);
138 :
139 : /* Encode an integer in the varint format.
140 : * This works for bool, enum, int32, int64, uint32 and uint64 field types. */
141 : #ifndef PB_WITHOUT_64BIT
142 : bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
143 : #else
144 : bool pb_encode_varint(pb_ostream_t *stream, uint32_t value);
145 : #endif
146 :
147 : /* Encode an integer in the zig-zagged svarint format.
148 : * This works for sint32 and sint64. */
149 : #ifndef PB_WITHOUT_64BIT
150 : bool pb_encode_svarint(pb_ostream_t *stream, int64_t value);
151 : #else
152 : bool pb_encode_svarint(pb_ostream_t *stream, int32_t value);
153 : #endif
154 :
155 : /* Encode a string or bytes type field. For strings, pass strlen(s) as size. */
156 : bool pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size);
157 :
158 : /* Encode a fixed32, sfixed32 or float value.
159 : * You need to pass a pointer to a 4-byte wide C variable. */
160 : bool pb_encode_fixed32(pb_ostream_t *stream, const void *value);
161 :
162 : #ifndef PB_WITHOUT_64BIT
163 : /* Encode a fixed64, sfixed64 or double value.
164 : * You need to pass a pointer to a 8-byte wide C variable. */
165 : bool pb_encode_fixed64(pb_ostream_t *stream, const void *value);
166 : #endif
167 :
168 : #ifdef PB_CONVERT_DOUBLE_FLOAT
169 : /* Encode a float value so that it appears like a double in the encoded
170 : * message. */
171 : bool pb_encode_float_as_double(pb_ostream_t *stream, float value);
172 : #endif
173 :
174 : /* Encode a submessage field.
175 : * You need to pass the pb_field_t array and pointer to struct, just like
176 : * with pb_encode(). This internally encodes the submessage twice, first to
177 : * calculate message size and then to actually write it out.
178 : */
179 : bool pb_encode_submessage(pb_ostream_t *stream, const pb_msgdesc_t *fields, const void *src_struct);
180 :
181 : #ifdef __cplusplus
182 : } /* extern "C" */
183 : #endif
184 :
185 : #endif
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