tinybson.h

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/**
* @file tinybson.h
*
* A simple subset SAX-style BSON parser and generator. See http://bsonspec.org
*
* Some types and defines taken from the standalone BSON parser/generator
* in the Mongo C connector.
*/

#ifndef _TINYBSON_H
#define _TINYBSON_H

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>

/** subset of the BSON node types we might care about */
typedef enum {
    BSON_EOO = 0,
    BSON_DOUBLE = 1,
    BSON_STRING = 2,
    BSON_OBJECT = 3,
    BSON_ARRAY = 4,
    BSON_BINDATA = 5,
    BSON_UNDEFINED = 6,
    BSON_BOOL = 8,
    BSON_DATE = 9,
    BSON_nullptr = 10,
    BSON_INT32 = 16,
    BSON_INT64 = 18
} bson_type_t;

typedef enum bson_binary_subtype {
    BSON_BIN_BINARY = 0,
    BSON_BIN_USER = 128
} bson_binary_subtype_t;

/**
 * Maximum node name length.
 */
#define BSON_MAXNAME        32

/**
 * Buffer growth increment when writing to a buffer.
 */
#define BSON_BUF_INCREMENT  128

/**
 * Node structure passed to the callback.
 */
typedef struct bson_node_s {
    char            name[BSON_MAXNAME];
    bson_type_t     type;
    bson_binary_subtype_t   subtype;
    union {
        int64_t     i;
        double      d;
        bool        b;
    };
} *bson_node_t;

typedef struct bson_decoder_s *bson_decoder_t;

/**
 * Node callback.
 *
 * The node callback function's return value is returned by bson_decoder_next.
 */
typedef int (* bson_decoder_callback)(bson_decoder_t decoder, void *priv, bson_node_t node);

struct bson_decoder_s {
    /* file reader state */
    int         fd;

    /* buffer reader state */
    uint8_t         *buf;
    size_t          bufsize;
    unsigned        bufpos;

    bool            dead;
    bson_decoder_callback   callback;
    void            *priv;
    unsigned        nesting;
    struct bson_node_s  node;
    int32_t         pending;
};

/**
 * Initialise the decoder to read from a file.
 *
 * @param decoder       Decoder state structure to be initialised.
 * @param fd            File to read BSON data from.
 * @param callback      Callback to be invoked by bson_decoder_next
 * @param priv          Callback private data, stored in node.
 * @return          Zero on success.
 */
__EXPORT int bson_decoder_init_file(bson_decoder_t decoder, int fd, bson_decoder_callback callback, void *priv);

/**
 * Initialise the decoder to read from a buffer in memory.
 *
 * @param decoder       Decoder state structure to be initialised.
 * @param buf           Buffer to read from.
 * @param bufsize       Size of the buffer (BSON object may be smaller).  May be
 *              passed as zero if the buffer size should be extracted from the
 *              BSON header only.
 * @param callback      Callback to be invoked by bson_decoder_next
 * @param priv      Callback private data, stored in node.
 * @return          Zero on success.
 */
__EXPORT int bson_decoder_init_buf(bson_decoder_t decoder, void *buf, unsigned bufsize, bson_decoder_callback callback,
                   void *priv);

/**
 * Process the next node from the stream and invoke the callback.
 *
 * @param decoder       Decoder state, must have been initialised with bson_decoder_init.
 * @return          -1 if parsing encountered an error, 0 if the BSON stream has ended,
 *              otherwise the return value from the callback.
 */
__EXPORT int bson_decoder_next(bson_decoder_t decoder);

/**
 * Copy node data.
 *
 * @param decoder       Decoder state, must have been initialised with bson_decoder_init.
 */
__EXPORT int bson_decoder_copy_data(bson_decoder_t decoder, void *buf);

/**
 * Report copyable data size.
 *
 * @param decoder       Decoder state, must have been initialised with bson_decoder_init.
 */
__EXPORT size_t bson_decoder_data_pending(bson_decoder_t decoder);

/**
 * Encoder state structure.
 */
typedef struct bson_encoder_s {
    /* file writer state */
    int     fd;

    /* buffer writer state */
    uint8_t     *buf;
    unsigned    bufsize;
    unsigned    bufpos;

    bool        realloc_ok;
    bool        dead;

} *bson_encoder_t;

/**
 * Initialze the encoder for writing to a file.
 *
 * @param encoder       Encoder state structure to be initialised.
 * @param fd            File to write to.
 * @return          Zero on success.
 */
__EXPORT int bson_encoder_init_file(bson_encoder_t encoder, int fd);

/**
 * Initialze the encoder for writing to a file.
 *
 * @param encoder       Encoder state structure to be initialised.
 * @param fd            File to write to.
 * @param buf           Buffer pointer to use, can't be nullptr
 * @param bufsize       Supplied buffer size
 * @return          Zero on success.
 */
__EXPORT int bson_encoder_init_buf_file(bson_encoder_t encoder, int fd, void *buf, unsigned bufsize);

/**
 * Initialze the encoder for writing to a buffer.
 *
 * @param encoder       Encoder state structure to be initialised.
 * @param buf           Buffer pointer to use, or nullptr if the buffer
 *              should be allocated by the encoder.
 * @param bufsize       Maximum buffer size, or zero for no limit. If
 *              the buffer is supplied, the size of the supplied buffer.
 * @return          Zero on success.
 */
__EXPORT int bson_encoder_init_buf(bson_encoder_t encoder, void *buf, unsigned bufsize);

/**
 * Finalise the encoded stream.
 *
 * @param encoder       The encoder to finalise.
 */
__EXPORT int bson_encoder_fini(bson_encoder_t encoder);

/**
 * Fetch the size of the encoded object; only valid for buffer operations.
 */
__EXPORT int bson_encoder_buf_size(bson_encoder_t encoder);

/**
 * Get a pointer to the encoded object buffer.
 *
 * Note that if the buffer was allocated by the encoder, it is the caller's responsibility
 * to free this buffer.
 */
__EXPORT void *bson_encoder_buf_data(bson_encoder_t encoder);

/**
 * Append a boolean to the encoded stream.
 *
 * @param encoder       Encoder state.
 * @param name          Node name.
 * @param value         Value to be encoded.
 */
__EXPORT int bson_encoder_append_bool(bson_encoder_t encoder, const char *name, bool value);

/**
 * Append an integer to the encoded stream.
 *
 * @param encoder       Encoder state.
 * @param name          Node name.
 * @param value         Value to be encoded.
 */
__EXPORT int bson_encoder_append_int(bson_encoder_t encoder, const char *name, int64_t value);

/**
 * Append a double to the encoded stream
 *
 * @param encoder       Encoder state.
 * @param name          Node name.
 * @param value         Value to be encoded.
 */
__EXPORT int bson_encoder_append_double(bson_encoder_t encoder, const char *name, double value);

/**
 * Append a string to the encoded stream.
 *
 * @param encoder       Encoder state.
 * @param name          Node name.
 * @param string        Nul-terminated C string.
 */
__EXPORT int bson_encoder_append_string(bson_encoder_t encoder, const char *name, const char *string);

/**
 * Append a binary blob to the encoded stream.
 *
 * @param encoder       Encoder state.
 * @param name          Node name.
 * @param subtype       Binary data subtype.
 * @param size          Data size.
 * @param data          Buffer containing data to be encoded.
 */
__EXPORT int bson_encoder_append_binary(bson_encoder_t encoder, const char *name, bson_binary_subtype_t subtype,
                    size_t size, const void *data);


#endif