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The C based gRPC (C++, Python, Ruby, Objective-C, PHP, C#)
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154 lines
5.6 KiB
154 lines
5.6 KiB
/* pb_encode.h: Functions to encode protocol buffers. Depends on pb_encode.c. |
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* The main function is pb_encode. You also need an output stream, and the |
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* field descriptions created by nanopb_generator.py. |
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*/ |
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#ifndef PB_ENCODE_H_INCLUDED |
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#define PB_ENCODE_H_INCLUDED |
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#include "pb.h" |
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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/* Structure for defining custom output streams. You will need to provide |
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* a callback function to write the bytes to your storage, which can be |
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* for example a file or a network socket. |
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* |
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* The callback must conform to these rules: |
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* |
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* 1) Return false on IO errors. This will cause encoding to abort. |
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* 2) You can use state to store your own data (e.g. buffer pointer). |
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* 3) pb_write will update bytes_written after your callback runs. |
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* 4) Substreams will modify max_size and bytes_written. Don't use them |
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* to calculate any pointers. |
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*/ |
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struct pb_ostream_s |
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{ |
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#ifdef PB_BUFFER_ONLY |
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/* Callback pointer is not used in buffer-only configuration. |
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* Having an int pointer here allows binary compatibility but |
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* gives an error if someone tries to assign callback function. |
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* Also, NULL pointer marks a 'sizing stream' that does not |
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* write anything. |
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*/ |
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int *callback; |
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#else |
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bool (*callback)(pb_ostream_t *stream, const pb_byte_t *buf, size_t count); |
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#endif |
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void *state; /* Free field for use by callback implementation. */ |
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size_t max_size; /* Limit number of output bytes written (or use SIZE_MAX). */ |
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size_t bytes_written; /* Number of bytes written so far. */ |
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#ifndef PB_NO_ERRMSG |
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const char *errmsg; |
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#endif |
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}; |
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/*************************** |
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* Main encoding functions * |
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***************************/ |
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/* Encode a single protocol buffers message from C structure into a stream. |
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* Returns true on success, false on any failure. |
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* The actual struct pointed to by src_struct must match the description in fields. |
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* All required fields in the struct are assumed to have been filled in. |
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* |
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* Example usage: |
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* MyMessage msg = {}; |
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* uint8_t buffer[64]; |
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* pb_ostream_t stream; |
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* |
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* msg.field1 = 42; |
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* stream = pb_ostream_from_buffer(buffer, sizeof(buffer)); |
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* pb_encode(&stream, MyMessage_fields, &msg); |
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*/ |
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bool pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); |
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/* Same as pb_encode, but prepends the length of the message as a varint. |
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* Corresponds to writeDelimitedTo() in Google's protobuf API. |
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*/ |
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bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); |
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/* Encode the message to get the size of the encoded data, but do not store |
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* the data. */ |
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bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct); |
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/************************************** |
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* Functions for manipulating streams * |
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**************************************/ |
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/* Create an output stream for writing into a memory buffer. |
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* The number of bytes written can be found in stream.bytes_written after |
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* encoding the message. |
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* |
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* Alternatively, you can use a custom stream that writes directly to e.g. |
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* a file or a network socket. |
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*/ |
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pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize); |
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/* Pseudo-stream for measuring the size of a message without actually storing |
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* the encoded data. |
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* |
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* Example usage: |
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* MyMessage msg = {}; |
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* pb_ostream_t stream = PB_OSTREAM_SIZING; |
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* pb_encode(&stream, MyMessage_fields, &msg); |
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* printf("Message size is %d\n", stream.bytes_written); |
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*/ |
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#ifndef PB_NO_ERRMSG |
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#define PB_OSTREAM_SIZING {0,0,0,0,0} |
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#else |
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#define PB_OSTREAM_SIZING {0,0,0,0} |
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#endif |
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/* Function to write into a pb_ostream_t stream. You can use this if you need |
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* to append or prepend some custom headers to the message. |
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*/ |
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bool pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count); |
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/************************************************ |
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* Helper functions for writing field callbacks * |
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************************************************/ |
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/* Encode field header based on type and field number defined in the field |
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* structure. Call this from the callback before writing out field contents. */ |
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bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field); |
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/* Encode field header by manually specifing wire type. You need to use this |
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* if you want to write out packed arrays from a callback field. */ |
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bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number); |
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/* Encode an integer in the varint format. |
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* This works for bool, enum, int32, int64, uint32 and uint64 field types. */ |
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bool pb_encode_varint(pb_ostream_t *stream, uint64_t value); |
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/* Encode an integer in the zig-zagged svarint format. |
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* This works for sint32 and sint64. */ |
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bool pb_encode_svarint(pb_ostream_t *stream, int64_t value); |
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/* Encode a string or bytes type field. For strings, pass strlen(s) as size. */ |
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bool pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size); |
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/* Encode a fixed32, sfixed32 or float value. |
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* You need to pass a pointer to a 4-byte wide C variable. */ |
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bool pb_encode_fixed32(pb_ostream_t *stream, const void *value); |
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/* Encode a fixed64, sfixed64 or double value. |
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* You need to pass a pointer to a 8-byte wide C variable. */ |
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bool pb_encode_fixed64(pb_ostream_t *stream, const void *value); |
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/* Encode a submessage field. |
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* You need to pass the pb_field_t array and pointer to struct, just like |
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* with pb_encode(). This internally encodes the submessage twice, first to |
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* calculate message size and then to actually write it out. |
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*/ |
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bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); |
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#ifdef __cplusplus |
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} /* extern "C" */ |
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#endif |
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#endif
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