Provided by: libbson-doc_2.2.0-1_all 
LIBBSON - API
A Cross Platform BSON Library for C
This site documents the API. For tutorials, guides, and explainers, see MongoDB C Driver <https://www
.mongodb.com/docs/languages/c/c-driver/current/>.
Introduction
libbson builds, parses, and iterates BSON <https://bsonspec.org> documents, the native data format of
MongoDB. It also converts BSON to and from JSON, and provides a platform compatibility layer for the
MongoDB C Driver <https://www.mongoc.org/>.
API Reference
bson_t
BSON Document Abstraction
Synopsis
#include <bson/bson.h>
/**
* bson_empty:
* @b: a bson_t.
*
* Checks to see if @b is an empty BSON document. An empty BSON document is
* a 5 byte document which contains the length (4 bytes) and a single NUL
* byte indicating end of fields.
*/
#define bson_empty(b) /* ... */
/**
* bson_empty0:
*
* Like bson_empty() but treats NULL the same as an empty bson_t document.
*/
#define bson_empty0(b) /* ... */
/**
* bson_clear:
*
* Easily free a bson document and set it to NULL. Use like:
*
* bson_t *doc = bson_new();
* bson_clear (&doc);
* BSON_ASSERT (doc == NULL);
*/
#define bson_clear(bptr) /* ... */
/**
* BSON_MAX_SIZE:
*
* The maximum size in bytes of a BSON document.
*/
#define BSON_MAX_SIZE /* ... */
#define BSON_APPEND_ARRAY(b, key, val) \
bson_append_array (b, key, (int) strlen (key), val)
#define BSON_APPEND_ARRAY_BEGIN(b, key, child) \
bson_append_array_begin (b, key, (int) strlen (key), child)
#define BSON_APPEND_BINARY(b, key, subtype, val, len) \
bson_append_binary (b, key, (int) strlen (key), subtype, val, len)
#define BSON_APPEND_BINARY_UNINIT(b, key, subtype, val, len) \
bson_append_binary_uninit (b, key, (int) strlen (key), subtype, val, len)
#define BSON_APPEND_BOOL(b, key, val) \
bson_append_bool (b, key, (int) strlen (key), val)
#define BSON_APPEND_CODE(b, key, val) \
bson_append_code (b, key, (int) strlen (key), val)
#define BSON_APPEND_CODE_WITH_SCOPE(b, key, val, scope) \
bson_append_code_with_scope (b, key, (int) strlen (key), val, scope)
#define BSON_APPEND_DBPOINTER(b, key, coll, oid) \
bson_append_dbpointer (b, key, (int) strlen (key), coll, oid)
#define BSON_APPEND_DOCUMENT_BEGIN(b, key, child) \
bson_append_document_begin (b, key, (int) strlen (key), child)
#define BSON_APPEND_DOUBLE(b, key, val) \
bson_append_double (b, key, (int) strlen (key), val)
#define BSON_APPEND_DOCUMENT(b, key, val) \
bson_append_document (b, key, (int) strlen (key), val)
#define BSON_APPEND_INT32(b, key, val) \
bson_append_int32 (b, key, (int) strlen (key), val)
#define BSON_APPEND_INT64(b, key, val) \
bson_append_int64 (b, key, (int) strlen (key), val)
#define BSON_APPEND_MINKEY(b, key) \
bson_append_minkey (b, key, (int) strlen (key))
#define BSON_APPEND_DECIMAL128(b, key, val) \
bson_append_decimal128 (b, key, (int) strlen (key), val)
#define BSON_APPEND_MAXKEY(b, key) \
bson_append_maxkey (b, key, (int) strlen (key))
#define BSON_APPEND_NULL(b, key) bson_append_null (b, key, (int) strlen (key))
#define BSON_APPEND_OID(b, key, val) \
bson_append_oid (b, key, (int) strlen (key), val)
#define BSON_APPEND_REGEX(b, key, val, opt) \
bson_append_regex (b, key, (int) strlen (key), val, opt)
#define BSON_APPEND_UTF8(b, key, val) \
bson_append_utf8 (b, key, (int) strlen (key), val, (int) strlen (val))
#define BSON_APPEND_SYMBOL(b, key, val) \
bson_append_symbol (b, key, (int) strlen (key), val, (int) strlen (val))
#define BSON_APPEND_TIME_T(b, key, val) \
bson_append_time_t (b, key, (int) strlen (key), val)
#define BSON_APPEND_TIMEVAL(b, key, val) \
bson_append_timeval (b, key, (int) strlen (key), val)
#define BSON_APPEND_DATE_TIME(b, key, val) \
bson_append_date_time (b, key, (int) strlen (key), val)
#define BSON_APPEND_TIMESTAMP(b, key, val, inc) \
bson_append_timestamp (b, key, (int) strlen (key), val, inc)
#define BSON_APPEND_UNDEFINED(b, key) \
bson_append_undefined (b, key, (int) strlen (key))
#define BSON_APPEND_VALUE(b, key, val) \
bson_append_value (b, key, (int) strlen (key), (val))
typedef struct {
uint32_t flags; /* Internal flags for the bson_t. */
uint32_t len; /* Length of BSON data. */
uint8_t padding[120]; /* Padding for stack allocation. */
} bson_t;
Description
The bson_t <> structure represents a BSON document. This structure manages the underlying BSON encoded
buffer. For mutable documents, it can append new data to the document.
Performance Notes
The bson_t <> structure attempts to use an inline allocation within the structure to speed up performance
of small documents. When this internal buffer has been exhausted, a heap allocated buffer will be
dynamically allocated. Therefore, it is essential to call bson_destroy() <> on allocated documents.
Duplicate Keys
The BSON specification <https://bsonspec.org> allows BSON documents to have duplicate keys. Documents are
stored as an ordered list of key-value pairs. A bson_t <> may contain duplicate keys. Applications should
refrain from generating such documents, because MongoDB server behavior is undefined when a BSON document
contains duplicate keys.
Example
static void
create_on_heap (void)
{
bson_t *b = bson_new ();
BSON_APPEND_INT32 (b, "foo", 123);
BSON_APPEND_UTF8 (b, "bar", "foo");
BSON_APPEND_DOUBLE (b, "baz", 1.23f);
bson_destroy (b);
}
bson_array_builder_t
typedef struct _bson_array_builder_t bson_array_builder_t;
bson_array_builder_t may be used to build BSON arrays. bson_array_builder_t internally tracks and uses
the array index as a key ("0", "1", "2", ...) when appending elements.
Appending an array value
typedef struct _bson_array_builder_t bson_array_builder_t;
bool
bson_append_array_builder_begin (bson_t *bson,
const char *key,
int key_length,
bson_array_builder_t **child);
bool
bson_append_array_builder_end (bson_t *bson, bson_array_builder_t *child);
#define BSON_APPEND_ARRAY_BUILDER_BEGIN(b, key, child) \
bson_append_array_builder_begin (b, key, (int) strlen (key), child)
bson_append_array_builder_begin may be used to append an array as a value. Example:
bson_t parent = BSON_INITIALIZER;
bson_array_builder_t *bab;
bson_append_array_builder_begin(&parent, "foo", 3, &bab);
bson_array_builder_append_int32(bab, 9);
bson_array_builder_append_int32(bab, 8);
bson_array_builder_append_int32(bab, 7);
bson_append_array_builder_end(&parent, bab);
char *str = bson_as_relaxed_extended_json(&parent, NULL);
printf("%s\n", str); // Prints: { "foo" : [ 9, 8, 7 ] }
bson_free(str);
bson_destroy(&parent);
Creating a top-level array
bson_array_builder_t * bson_array_builder_new (void);
bool
bson_array_builder_build (bson_array_builder_t *bab, bson_t *out);
void
bson_array_builder_destroy (bson_array_builder_t *bab);
bson_array_builder_new and bson_array_builder_build may be used to build a top-level BSON array.
bson_array_builder_build initializes and moves BSON data to out. The bson_array_builder_t may be reused
and will start appending a new array at index "0":
Example:
bson_t out;
bson_array_builder_t *bab = bson_array_builder_new();
bson_array_builder_append_int32(bab, 9);
bson_array_builder_append_int32(bab, 8);
bson_array_builder_append_int32(bab, 7);
bson_array_builder_build(bab, &out);
char *str = bson_array_as_relaxed_extended_json(&out, NULL);
printf("%s\n", str); // Prints: [ 9, 8, 7 ]
bson_free(str);
bson_array_builder_destroy(bab);
Appending values to an array
bson_array_builder_append_* functions are provided to append values to a BSON array. The
bson_array_builder_append_* functions internally use bson_append_* and provide the array index as a key:
bool
bson_array_builder_append_value (bson_array_builder_t *bab,
const bson_value_t *value);
bool
bson_array_builder_append_array (bson_array_builder_t *bab,
const bson_t *array);
bool
bson_array_builder_append_binary (bson_array_builder_t *bab,
bson_subtype_t subtype,
const uint8_t *binary,
uint32_t length);
bool
bson_array_builder_append_binary_uninit (bson_array_builder_t *bab,
bson_subtype_t subtype,
uint8_t **binary,
uint32_t length);
bool
bson_array_builder_append_bool (bson_array_builder_t *bab, bool value);
bool
bson_array_builder_append_code (bson_array_builder_t *bab,
const char *javascript);
bool
bson_array_builder_append_code_with_scope (bson_array_builder_t *bab,
const char *javascript,
const bson_t *scope);
bool
bson_array_builder_append_dbpointer (bson_array_builder_t *bab,
const char *collection,
const bson_oid_t *oid);
bool
bson_array_builder_append_double (bson_array_builder_t *bab, double value);
bool
bson_array_builder_append_document (bson_array_builder_t *bab,
const bson_t *value);
bool
bson_array_builder_append_document_begin (bson_array_builder_t *bab,
bson_t *child);
bool
bson_array_builder_append_document_end (bson_array_builder_t *bab,
bson_t *child);
bool
bson_array_builder_append_int32 (bson_array_builder_t *bab, int32_t value);
bool
bson_array_builder_append_int64 (bson_array_builder_t *bab, int64_t value);
bool
bson_array_builder_append_decimal128 (bson_array_builder_t *bab,
const bson_decimal128_t *value);
bool
bson_array_builder_append_iter (bson_array_builder_t *bab,
const bson_iter_t *iter);
bool
bson_array_builder_append_minkey (bson_array_builder_t *bab);
bool
bson_array_builder_append_maxkey (bson_array_builder_t *bab);
bool
bson_array_builder_append_null (bson_array_builder_t *bab);
bool
bson_array_builder_append_oid (bson_array_builder_t *bab,
const bson_oid_t *oid);
bool
bson_array_builder_append_regex (bson_array_builder_t *bab,
const char *regex,
const char *options);
bool
bson_array_builder_append_regex_w_len (bson_array_builder_t *bab,
const char *regex,
int regex_length,
const char *options);
bool
bson_array_builder_append_utf8 (bson_array_builder_t *bab,
const char *value,
int length);
bool
bson_array_builder_append_symbol (bson_array_builder_t *bab,
const char *value,
int length);
bool
bson_array_builder_append_time_t (bson_array_builder_t *bab, time_t value);
bool
bson_array_builder_append_timeval (bson_array_builder_t *bab,
struct timeval *value);
bool
bson_array_builder_append_date_time (bson_array_builder_t *bab, int64_t value);
bool
bson_array_builder_append_now_utc (bson_array_builder_t *bab);
bool
bson_array_builder_append_timestamp (bson_array_builder_t *bab,
uint32_t timestamp,
uint32_t increment);
bool
bson_array_builder_append_undefined (bson_array_builder_t *bab);
bool
bson_array_builder_append_array_builder_begin (bson_array_builder_t *bab,
bson_array_builder_t **child);
bool
bson_array_builder_append_array_builder_end (bson_array_builder_t *bab,
bson_array_builder_t *child);
bson_context_t
BSON OID Generation Context
Synopsis
#include <bson/bson.h>
typedef enum {
BSON_CONTEXT_NONE = 0,
BSON_CONTEXT_DISABLE_PID_CACHE = (1 << 2),
} bson_context_flags_t;
typedef struct _bson_context_t bson_context_t;
bson_context_t *
bson_context_get_default (void);
bson_context_t *
bson_context_new (bson_context_flags_t flags);
void
bson_context_destroy (bson_context_t *context);
Description
The bson_context_t <> structure is context for generation of BSON Object IDs. This context allows
overriding behavior of generating ObjectIDs. The flags BSON_CONTEXT_NONE, BSON_CONTEXT_THREAD_SAFE, and
BSON_CONTEXT_DISABLE_PID_CACHE are the only ones used. The others have no effect.
Example
#include <bson/bson.h>
int
main (int argc, char *argv[])
{
bson_context_t *ctx = NULL;
bson_oid_t oid;
/* use default context, via bson_context_get_default() */
bson_oid_init (&oid, NULL);
/* specify a local context for additional control */
ctx = bson_context_new (BSON_CONTEXT_NONE);
bson_oid_init (&oid, ctx);
bson_context_destroy (ctx);
return 0;
}
bson_decimal128_t
BSON Decimal128 Abstraction
Synopsis
#include <bson/bson.h>
#define BSON_DECIMAL128_STRING 43
#define BSON_DECIMAL128_INF "Infinity"
#define BSON_DECIMAL128_NAN "NaN"
typedef struct {
#if BSON_BYTE_ORDER == BSON_LITTLE_ENDIAN
uint64_t low;
uint64_t high;
#elif BSON_BYTE_ORDER == BSON_BIG_ENDIAN
uint64_t high;
uint64_t low;
#endif
} bson_decimal128_t;
Description
The bson_decimal128_t <> structure represents the IEEE-754 Decimal128 data type. The type
bson_decimal128_t is an aggregate that contains two uint64_ts, named high and low. The declaration and
layout order between them depends on the endian order of the target platform: low will always correspond
to the low-order bits of the Decimal128 object, while high corresponds to the high-order bits. The
bson_decimal128_t always has a size of sixteen (16), and can be bit-cast to/from a _Decimal128.
Example
#include <bson/bson.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
char string[BSON_DECIMAL128_STRING];
bson_decimal128_t decimal128;
bson_decimal128_from_string ("100.00", &decimal128);
bson_decimal128_to_string (&decimal128, string);
printf ("Decimal128 value: %s\n", string);
return 0;
}
bson_error_t
BSON Error Encapsulation
Synopsis
#include <bson/bson.h>
typedef struct {
uint32_t domain;
uint32_t code;
char message[504];
} bson_error_t;
Description
The bson_error_t <> structure is used as an out-parameter to pass error information to the caller. It
should be stack-allocated and does not requiring freeing.
See Handling Errors <https://www.mongodb.com/docs/languages/c/c-driver/current/libbson/tutorials/
errors/>.
Example
bson_reader_t *reader;
bson_error_t error;
reader = bson_reader_new_from_file ("dump.bson", &error);
if (!reader) {
fprintf (
stderr, "ERROR: %d.%d: %s\n", error.domain, error.code, error.message);
}
bson_iter_t
BSON Document Iterator
Synopsis
#include <bson/bson.h>
#define BSON_ITER_HOLDS_DOUBLE(iter) /* ... */
#define BSON_ITER_HOLDS_UTF8(iter) /* ... */
#define BSON_ITER_HOLDS_DOCUMENT(iter) /* ... */
#define BSON_ITER_HOLDS_ARRAY(iter) /* ... */
#define BSON_ITER_HOLDS_BINARY(iter) /* ... */
#define BSON_ITER_HOLDS_VECTOR(iter) /* ... */
#define BSON_ITER_HOLDS_VECTOR_INT8(iter) /* ... */
#define BSON_ITER_HOLDS_VECTOR_FLOAT32(iter) /* ... */
#define BSON_ITER_HOLDS_VECTOR_PACKED_BIT(iter) /* ... */
#define BSON_ITER_HOLDS_UNDEFINED(iter) /* ... */
#define BSON_ITER_HOLDS_OID(iter) /* ... */
#define BSON_ITER_HOLDS_BOOL(iter) /* ... */
#define BSON_ITER_HOLDS_DATE_TIME(iter) /* ... */
#define BSON_ITER_HOLDS_NULL(iter) /* ... */
#define BSON_ITER_HOLDS_REGEX(iter) /* ... */
#define BSON_ITER_HOLDS_DBPOINTER(iter) /* ... */
#define BSON_ITER_HOLDS_CODE(iter) /* ... */
#define BSON_ITER_HOLDS_SYMBOL(iter) /* ... */
#define BSON_ITER_HOLDS_CODEWSCOPE(iter) /* ... */
#define BSON_ITER_HOLDS_INT32(iter) /* ... */
#define BSON_ITER_HOLDS_TIMESTAMP(iter) /* ... */
#define BSON_ITER_HOLDS_INT64(iter) /* ... */
#define BSON_ITER_HOLDS_DECIMAL128(iter) /* ... */
#define BSON_ITER_HOLDS_MAXKEY(iter) /* ... */
#define BSON_ITER_HOLDS_MINKEY(iter) /* ... */
#define BSON_ITER_HOLDS_INT(iter) \
(BSON_ITER_HOLDS_INT32 (iter) || BSON_ITER_HOLDS_INT64 (iter))
#define BSON_ITER_HOLDS_NUMBER(iter) \
(BSON_ITER_HOLDS_INT (iter) || BSON_ITER_HOLDS_DOUBLE (iter))
#define BSON_ITER_IS_KEY(iter, key) \
(0 == strcmp ((key), bson_iter_key ((iter))))
typedef struct {
/*< private >*/
} bson_iter_t;
Description
bson_iter_t <> is a structure used to iterate through the elements of a bson_t <>. It is meant to be used
on the stack and can be discarded at any time as it contains no external allocation. The contents of the
structure should be considered private and may change between releases, however the structure size will
not change.
The bson_t <> MUST be valid for the lifetime of the iter and it is an error to modify the bson_t <> while
using the iter.
Examples
bson_iter_t iter;
if (bson_iter_init (&iter, my_bson_doc)) {
while (bson_iter_next (&iter)) {
printf ("Found a field named: %s\n", bson_iter_key (&iter));
}
}
bson_iter_t iter;
if (bson_iter_init (&iter, my_bson_doc) && bson_iter_find (&iter, "my_field")) {
printf ("Found the field named: %s\n", bson_iter_key (&iter));
}
bson_iter_t iter;
bson_iter_t sub_iter;
if (bson_iter_init_find (&iter, my_bson_doc, "mysubdoc") &&
(BSON_ITER_HOLDS_DOCUMENT (&iter) || BSON_ITER_HOLDS_ARRAY (&iter)) &&
bson_iter_recurse (&iter, &sub_iter)) {
while (bson_iter_next (&sub_iter)) {
printf ("Found key \"%s\" in sub document.\n", bson_iter_key (&sub_iter));
}
}
bson_iter_t iter;
if (bson_iter_init (&iter, my_doc) &&
bson_iter_find_descendant (&iter, "a.b.c.d", &sub_iter)) {
printf ("The type of a.b.c.d is: %d\n", (int) bson_iter_type (&sub_iter));
}
bson_json_reader_t
Bulk JSON to BSON conversion
Synopsis
#include <bson/bson.h>
typedef struct _bson_json_reader_t bson_json_reader_t;
typedef enum {
BSON_JSON_ERROR_READ_CORRUPT_JS = 1,
BSON_JSON_ERROR_READ_INVALID_PARAM,
BSON_JSON_ERROR_READ_CB_FAILURE,
} bson_json_error_code_t;
Description
The bson_json_reader_t <> structure is used for reading a sequence of JSON documents and transforming
them to bson_t <> documents.
This can often be useful if you want to perform bulk operations that are defined in a file containing
JSON documents.
Tip:
bson_json_reader_t <> works upon JSON documents formatted in MongoDB extended JSON <https://www
.mongodb.com/docs/manual/reference/mongodb-extended-json/> format.
Example
/*
* Copyright 2009-present MongoDB, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This program will print each JSON document contained in the provided files
* as a BSON string to STDOUT.
*/
#include <bson/bson.h>
#include <stdlib.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
bson_json_reader_t *reader;
bson_error_t error;
const char *filename;
bson_t doc = BSON_INITIALIZER;
int i;
int b;
/*
* Print program usage if no arguments are provided.
*/
if (argc == 1) {
fprintf (stderr, "usage: %s FILE...\n", argv[0]);
return 1;
}
/*
* Process command line arguments expecting each to be a filename.
*/
for (i = 1; i < argc; i++) {
filename = argv[i];
/*
* Open the filename provided in command line arguments.
*/
if (0 == strcmp (filename, "-")) {
reader = bson_json_reader_new_from_fd (STDIN_FILENO, false);
} else {
if (!(reader = bson_json_reader_new_from_file (filename, &error))) {
fprintf (
stderr, "Failed to open \"%s\": %s\n", filename, error.message);
continue;
}
}
/*
* Convert each incoming document to BSON and print to stdout.
*/
while ((b = bson_json_reader_read (reader, &doc, &error))) {
if (b < 0) {
fprintf (stderr, "Error in json parsing:\n%s\n", error.message);
abort ();
}
if (fwrite (bson_get_data (&doc), 1, doc.len, stdout) != doc.len) {
fprintf (stderr, "Failed to write to stdout, exiting.\n");
exit (1);
}
bson_reinit (&doc);
}
bson_json_reader_destroy (reader);
bson_destroy (&doc);
}
return 0;
}
bson_oid_t
BSON ObjectID Abstraction
Synopsis
#include <bson/bson.h>
typedef struct {
uint8_t bytes[12];
} bson_oid_t;
Description
The bson_oid_t <> structure contains the 12-byte ObjectId notation defined by the BSON ObjectID
specification <https://www.mongodb.com/docs/manual/reference/object-id/>.
ObjectId is a 12-byte BSON type, constructed using:
• a 4-byte value representing the seconds since the Unix epoch (in Big Endian).
• a 5-byte random value.
• a 3-byte counter (Big Endian), starting with a random value.
String Conversion
You can convert an Object ID to a string using bson_oid_to_string() <> and back with
bson_oid_init_from_string() <>.
Hashing
A bson_oid_t <> can be used in hashtables using the function bson_oid_hash() <> and bson_oid_equal() <>.
Comparing
A bson_oid_t <> can be compared to another using bson_oid_compare() <> for qsort() style comparing and
bson_oid_equal() <> for direct equality.
Validating
You can validate that a string containing a hex-encoded ObjectID is valid using the function
bson_oid_is_valid() <>.
Example
#include <bson/bson.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
bson_oid_t oid;
char str[25];
bson_oid_init (&oid, NULL);
bson_oid_to_string (&oid, str);
printf ("%s\n", str);
if (bson_oid_is_valid (str, sizeof str)) {
bson_oid_init_from_string (&oid, str);
}
printf ("The UNIX time was: %u\n", (unsigned) bson_oid_get_time_t (&oid));
return 0;
}
bson_reader_t
Streaming BSON Document Reader
Synopsis
#include <bson/bson.h>
typedef struct _bson_reader_t bson_reader_t;
bson_reader_t *
bson_reader_new_from_handle (void *handle,
bson_reader_read_func_t rf,
bson_reader_destroy_func_t df);
bson_reader_t *
bson_reader_new_from_fd (int fd, bool close_on_destroy);
bson_reader_t *
bson_reader_new_from_file (const char *path, bson_error_t *error);
bson_reader_t *
bson_reader_new_from_data (const uint8_t *data, size_t length);
void
bson_reader_destroy (bson_reader_t *reader);
Description
bson_reader_t <> is a structure used for reading a sequence of BSON documents. The sequence can come from
a file-descriptor, memory region, or custom callbacks.
Example
/*
* Copyright 2009-present MongoDB, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This program will print each BSON document contained in the provided files
* as a JSON string to STDOUT.
*/
#include <bson/bson.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
bson_reader_t *reader;
const bson_t *b;
bson_error_t error;
const char *filename;
char *str;
int i;
/*
* Print program usage if no arguments are provided.
*/
if (argc == 1) {
fprintf (stderr, "usage: %s [FILE | -]...\nUse - for STDIN.\n", argv[0]);
return 1;
}
/*
* Process command line arguments expecting each to be a filename.
*/
for (i = 1; i < argc; i++) {
filename = argv[i];
if (strcmp (filename, "-") == 0) {
reader = bson_reader_new_from_fd (STDIN_FILENO, false);
} else {
if (!(reader = bson_reader_new_from_file (filename, &error))) {
fprintf (
stderr, "Failed to open \"%s\": %s\n", filename, error.message);
continue;
}
}
/*
* Convert each incoming document to JSON and print to stdout.
*/
while ((b = bson_reader_read (reader, NULL))) {
str = bson_as_canonical_extended_json (b, NULL);
fprintf (stdout, "%s\n", str);
bson_free (str);
}
/*
* Cleanup after our reader, which closes the file descriptor.
*/
bson_reader_destroy (reader);
}
return 0;
}
Character and String Routines
We provide a small number of character and string routines to substitute for those that are not available
on all platforms, and routines to make UTF-8 character manipulation convenient.
bson_subtype_t
Binary Field Subtype
Synopsis
#include <bson/bson.h>
typedef enum {
BSON_SUBTYPE_BINARY = 0x00,
BSON_SUBTYPE_FUNCTION = 0x01,
BSON_SUBTYPE_BINARY_DEPRECATED = 0x02,
BSON_SUBTYPE_UUID_DEPRECATED = 0x03,
BSON_SUBTYPE_UUID = 0x04,
BSON_SUBTYPE_MD5 = 0x05,
BSON_SUBTYPE_COLUMN = 0x07,
BSON_SUBTYPE_SENSITIVE = 0x08,
BSON_SUBTYPE_VECTOR = 0x09,
BSON_SUBTYPE_USER = 0x80,
} bson_subtype_t;
Description
This enumeration contains the various subtypes that may be used in a binary field. See <http://bsonspec
.org> for more information.
Example
bson_t doc = BSON_INITIALIZER;
BSON_APPEND_BINARY (&doc, "binary", BSON_SUBTYPE_BINARY, data, data_len);
bson_type_t
BSON Type Enumeration
Synopsis
#include <bson/bson.h>
typedef enum {
BSON_TYPE_EOD = 0x00,
BSON_TYPE_DOUBLE = 0x01,
BSON_TYPE_UTF8 = 0x02,
BSON_TYPE_DOCUMENT = 0x03,
BSON_TYPE_ARRAY = 0x04,
BSON_TYPE_BINARY = 0x05,
BSON_TYPE_UNDEFINED = 0x06,
BSON_TYPE_OID = 0x07,
BSON_TYPE_BOOL = 0x08,
BSON_TYPE_DATE_TIME = 0x09,
BSON_TYPE_NULL = 0x0A,
BSON_TYPE_REGEX = 0x0B,
BSON_TYPE_DBPOINTER = 0x0C,
BSON_TYPE_CODE = 0x0D,
BSON_TYPE_SYMBOL = 0x0E,
BSON_TYPE_CODEWSCOPE = 0x0F,
BSON_TYPE_INT32 = 0x10,
BSON_TYPE_TIMESTAMP = 0x11,
BSON_TYPE_INT64 = 0x12,
BSON_TYPE_DECIMAL128 = 0x13,
BSON_TYPE_MAXKEY = 0x7F,
BSON_TYPE_MINKEY = 0xFF,
} bson_type_t;
Description
The bson_type_t <> enumeration contains all of the types from the BSON Specification <http://bsonspec
.org>. It can be used to determine the type of a field at runtime.
Example
bson_iter_t iter;
if (bson_iter_init_find (&iter, doc, "foo") &&
(BSON_TYPE_INT32 == bson_iter_type (&iter))) {
printf ("'foo' is an int32.\n");
}
bson_unichar_t
Unicode Character Abstraction
Synopsis
typedef uint32_t bson_unichar_t;
Description
bson_unichar_t <> provides an abstraction on a single unicode character. It is the 32-bit representation
of a character. As UTF-8 can contain multi-byte characters, this should be used when iterating through
UTF-8 text.
Example
static void
print_each_char (const char *str)
{
bson_unichar_t c;
for (; *str; str = bson_utf8_next_char (str)) {
c = bson_utf8_get_char (str);
printf ("The numberic value is %u.\n", (unsigned) c);
}
}
bson_validate_flags_t
Document validation options
Synopsis
#include <bson/bson-types.h>
typedef enum {
BSON_VALIDATE_NONE = 0,
BSON_VALIDATE_UTF8 = (1 << 0),
BSON_VALIDATE_DOLLAR_KEYS = (1 << 1),
BSON_VALIDATE_DOT_KEYS = (1 << 2),
BSON_VALIDATE_UTF8_ALLOW_NULL = (1 << 3),
BSON_VALIDATE_EMPTY_KEYS = (1 << 4),
BSON_VALIDATE_CORRUPT = (1 << 5),
} bson_validate_flags_t;
Description
bson_validate_flags_t is a set of binary flags which may be combined to specify a level of BSON document
validation.
A value of 0, false, or BSON_VALIDATE_NONE equivalently requests the minimum applicable level of
validation.
In the context of validation APIs bson_validate() <>, bson_validate_with_error() <>, and
bson_validate_with_error_and_offset() <> the minimum validation still guarantees that a document can be
successfully traversed by bson_iter_visit_all() <>.
Higher level APIs using this type may have different minimum validation levels. For example, libmongoc
functions that take bson_validate_flags_t use 0 to mean the document contents are not visited and
malformed headers will not be detected by the client.
Each defined flag aside from BSON_VALIDATE_NONE describes an optional validation feature that may be
enabled, alone or in combination with other features:
• BSON_VALIDATE_NONE Minimum level of validation; in libbson, validates element headers.
• BSON_VALIDATE_UTF8 All keys and string values are checked for invalid UTF-8.
• BSON_VALIDATE_UTF8_ALLOW_NULL String values are allowed to have embedded NULL bytes. This has no effect
unless BSON_VALIDATE_UTF8 is also passed.
• BSON_VALIDATE_DOLLAR_KEYS Prohibit keys that start with $ outside of a "DBRef" subdocument.
• BSON_VALIDATE_DOT_KEYS Prohibit keys that contain . anywhere in the string.
• BSON_VALIDATE_EMPTY_KEYS Prohibit zero-length keys.
• BSON_VALIDATE_CORRUPT is not a control flag, but is used as an error code when a validation routine
encounters corrupt BSON data.
See also:
bson_validate() <>, bson_validate_with_error() <>, bson_validate_with_error_and_offset() <>.
bson_visitor_t <> can be used for custom validation, Example Custom Validation <#example-custom-validation>.
bson_value_t
BSON Boxed Container Type
Synopsis
#include <bson/bson.h>
typedef struct _bson_value_t {
bson_type_t value_type;
union {
bson_oid_t v_oid;
int64_t v_int64;
int32_t v_int32;
int8_t v_int8;
double v_double;
bool v_bool;
int64_t v_datetime;
struct {
uint32_t timestamp;
uint32_t increment;
} v_timestamp;
struct {
uint32_t len;
char *str;
} v_utf8;
struct {
uint32_t data_len;
uint8_t *data;
} v_doc;
struct {
uint32_t data_len;
uint8_t *data;
bson_subtype_t subtype;
} v_binary;
struct {
char *regex;
char *options;
} v_regex;
struct {
char *collection;
uint32_t collection_len;
bson_oid_t oid;
} v_dbpointer;
struct {
uint32_t code_len;
char *code;
} v_code;
struct {
uint32_t code_len;
char *code;
uint32_t scope_len;
uint8_t *scope_data;
} v_codewscope;
struct {
uint32_t len;
char *symbol;
} v_symbol;
bson_decimal128_t v_decimal128;
} value;
} bson_value_t;
Description
The bson_value_t <> structure is a boxed type for encapsulating a runtime determined type.
Example
const bson_value_t *value;
value = bson_iter_value (&iter);
if (value->value_type == BSON_TYPE_INT32) {
printf ("%d\n", value->value.v_int32);
}
bson_visitor_t
Synopsis
#include <bson/bson.h>
typedef struct {
/* run before / after descending into a document */
bool (*visit_before) (const bson_iter_t *iter, const char *key, void *data);
bool (*visit_after) (const bson_iter_t *iter, const char *key, void *data);
/* corrupt BSON, or unsupported type and visit_unsupported_type not set */
void (*visit_corrupt) (const bson_iter_t *iter, void *data);
/* normal bson field callbacks */
bool (*visit_double) (const bson_iter_t *iter,
const char *key,
double v_double,
void *data);
bool (*visit_utf8) (const bson_iter_t *iter,
const char *key,
size_t v_utf8_len,
const char *v_utf8,
void *data);
bool (*visit_document) (const bson_iter_t *iter,
const char *key,
const bson_t *v_document,
void *data);
bool (*visit_array) (const bson_iter_t *iter,
const char *key,
const bson_t *v_array,
void *data);
bool (*visit_binary) (const bson_iter_t *iter,
const char *key,
bson_subtype_t v_subtype,
size_t v_binary_len,
const uint8_t *v_binary,
void *data);
/* normal field with deprecated "Undefined" BSON type */
bool (*visit_undefined) (const bson_iter_t *iter,
const char *key,
void *data);
bool (*visit_oid) (const bson_iter_t *iter,
const char *key,
const bson_oid_t *v_oid,
void *data);
bool (*visit_bool) (const bson_iter_t *iter,
const char *key,
bool v_bool,
void *data);
bool (*visit_date_time) (const bson_iter_t *iter,
const char *key,
int64_t msec_since_epoch,
void *data);
bool (*visit_null) (const bson_iter_t *iter, const char *key, void *data);
bool (*visit_regex) (const bson_iter_t *iter,
const char *key,
const char *v_regex,
const char *v_options,
void *data);
bool (*visit_dbpointer) (const bson_iter_t *iter,
const char *key,
size_t v_collection_len,
const char *v_collection,
const bson_oid_t *v_oid,
void *data);
bool (*visit_code) (const bson_iter_t *iter,
const char *key,
size_t v_code_len,
const char *v_code,
void *data);
bool (*visit_symbol) (const bson_iter_t *iter,
const char *key,
size_t v_symbol_len,
const char *v_symbol,
void *data);
bool (*visit_codewscope) (const bson_iter_t *iter,
const char *key,
size_t v_code_len,
const char *v_code,
const bson_t *v_scope,
void *data);
bool (*visit_int32) (const bson_iter_t *iter,
const char *key,
int32_t v_int32,
void *data);
bool (*visit_timestamp) (const bson_iter_t *iter,
const char *key,
uint32_t v_timestamp,
uint32_t v_increment,
void *data);
bool (*visit_int64) (const bson_iter_t *iter,
const char *key,
int64_t v_int64,
void *data);
bool (*visit_maxkey) (const bson_iter_t *iter, const char *key, void *data);
bool (*visit_minkey) (const bson_iter_t *iter, const char *key, void *data);
/* if set, called instead of visit_corrupt when an apparently valid BSON
* includes an unrecognized field type (reading future version of BSON) */
void (*visit_unsupported_type) (const bson_iter_t *iter,
const char *key,
uint32_t type_code,
void *data);
bool (*visit_decimal128) (const bson_iter_t *iter,
const char *key,
const bson_decimal128_t *v_decimal128,
void *data);
void *padding[7];
} bson_visitor_t bson_visitor_t;
Description
The bson_visitor_t <> structure provides a series of callbacks that can be called while iterating a BSON
document. This may simplify the conversion of a bson_t <> to a higher level language structure.
If the optional callback visit_unsupported_type is set, it is called instead of visit_corrupt in the
specific case of an unrecognized field type. (Parsing is aborted in either case.) Use this callback to
report an error like "unrecognized type" instead of simply "corrupt BSON". This future-proofs code that
may use an older version of libbson to parse future BSON formats.
Basic Example
#include <bson/bson.h>
#include <stdio.h>
static bool
my_visit_before (const bson_iter_t *iter, const char *key, void *data)
{
int *count = (int *) data;
(*count)++;
/* returning true stops further iteration of the document */
return false;
}
static void
count_fields (bson_t *doc)
{
bson_visitor_t visitor = {0};
bson_iter_t iter;
int count = 0;
visitor.visit_before = my_visit_before;
if (bson_iter_init (&iter, doc)) {
bson_iter_visit_all (&iter, &visitor, &count);
}
printf ("Found %d fields.\n", count);
}
The example below demonstrates how to set your own callbacks to provide information about the location of
corrupt or unsupported BSON document entries.
Example Corruption Check
#include <bson/bson.h>
#include <stdio.h>
typedef struct {
ssize_t *err_offset;
} my_state_t;
static void
my_visit_corrupt (const bson_iter_t *iter, void *data)
{
*(((my_state_t *) data)->err_offset) = iter->off;
}
static void
my_visit_unsupported_type (const bson_iter_t *iter,
const char *key,
uint32_t type_code,
void *data)
{
*(((my_state_t *) data)->err_offset) = iter->off;
}
static void
find_error_location (bson_t *doc)
{
bson_visitor_t visitors = {0};
bson_iter_t iter;
my_state_t state;
ssize_t err_offset = -1;
visitors.visit_corrupt = my_visit_corrupt;
visitors.visit_unsupported_type = my_visit_unsupported_type;
/* provide additional visitors as needed based on your requirements */
state.err_offset = &err_offset;
if (!bson_iter_init (&iter, doc)) {
printf ("Could not initialize iterator!");
exit (1);
}
if (bson_iter_visit_all (&iter, &visitors, &state) ||
err_offset != -1) {
printf ("Found error at offset %d.\n", err_offset);
} else {
printf ("BSON document had no errors.\n");
}
}
The example below demonstrates how to use a visitor to validate a BSON document's maximum depth.
Example Custom Validation
bson-check-depth.c
/* Reports the maximum nested depth of a BSON document. */
#include <bson/bson.h>
#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
typedef struct {
uint32_t depth;
uint32_t max_depth;
bool valid;
} check_depth_t;
bool
_check_depth_document(const bson_iter_t *iter, const char *key, const bson_t *v_document, void *data);
static const bson_visitor_t check_depth_funcs = {
NULL,
NULL,
NULL,
NULL,
NULL,
_check_depth_document,
_check_depth_document,
NULL,
};
bool
_check_depth_document(const bson_iter_t *iter, const char *key, const bson_t *v_document, void *data)
{
check_depth_t *state = (check_depth_t *)data;
bson_iter_t child;
BSON_UNUSED(iter);
BSON_UNUSED(key);
if (!bson_iter_init(&child, v_document)) {
fprintf(stderr, "corrupt\n");
return true; /* cancel */
}
state->depth++;
if (state->depth > state->max_depth) {
state->valid = false;
return true; /* cancel */
}
bson_iter_visit_all(&child, &check_depth_funcs, state);
state->depth--;
return false; /* continue */
}
void
check_depth(const bson_t *bson, uint32_t max_depth)
{
bson_iter_t iter;
check_depth_t state = {0};
if (!bson_iter_init(&iter, bson)) {
fprintf(stderr, "corrupt\n");
}
state.valid = true;
state.max_depth = max_depth;
_check_depth_document(&iter, NULL, bson, &state);
if (!state.valid) {
printf("document exceeds maximum depth of %" PRIu32 "\n", state.max_depth);
} else {
char *as_json = bson_as_canonical_extended_json(bson, NULL);
printf("document %s ", as_json);
printf("is valid\n");
bson_free(as_json);
}
}
int
main(int argc, char **argv)
{
bson_reader_t *bson_reader;
const bson_t *bson;
bool reached_eof;
bson_error_t error;
if (argc != 3) {
fprintf(stderr, "usage: %s FILE MAX_DEPTH\n", argv[0]);
fprintf(stderr, "Checks that the depth of the BSON contained in FILE\n");
fprintf(stderr, "does not exceed MAX_DEPTH\n");
}
const char *const filename = argv[1];
const int max_depth = atoi(argv[2]);
bson_reader = bson_reader_new_from_file(filename, &error);
if (!bson_reader) {
printf("could not read %s: %s\n", filename, error.message);
return 1;
}
BSON_ASSERT(max_depth >= 0 && (uint64_t)max_depth <= UINT32_MAX);
while ((bson = bson_reader_read(bson_reader, &reached_eof))) {
check_depth(bson, (uint32_t)max_depth);
}
if (!reached_eof) {
printf("error reading BSON\n");
}
bson_reader_destroy(bson_reader);
return 0;
}
bson_writer_t
Bulk BSON serialization Abstraction
Synopsis
#include <bson/bson.h>
typedef struct _bson_writer_t bson_writer_t;
bson_writer_t *
bson_writer_new (uint8_t **buf,
size_t *buflen,
size_t offset,
bson_realloc_func realloc_func,
void *realloc_func_ctx);
void
bson_writer_destroy (bson_writer_t *writer);
Description
The bson_writer_t <> API provides an abstraction for serializing many BSON documents to a single memory
region. The memory region may be dynamically allocated and re-allocated as more memory is demanded. This
can be useful when building network packets from a high-level language. For example, you can serialize a
Python Dictionary directly to a single buffer destined for a TCP packet.
Example
#include <bson/bson.h>
int
main (int argc, char *argv[])
{
bson_writer_t *writer;
uint8_t *buf = NULL;
size_t buflen = 0;
bson_t *doc;
writer = bson_writer_new (&buf, &buflen, 0, bson_realloc_ctx, NULL);
for (int i = 0; i < 1000; i++) {
bson_writer_begin (writer, &doc);
BSON_APPEND_INT32 (doc, "i", i);
bson_writer_end (writer);
}
bson_writer_destroy (writer);
bson_free (buf);
return 0;
}
System Clock
BSON Clock Abstraction
Synopsis
int64_t
bson_get_monotonic_time (void);
int
bson_gettimeofday (struct timeval *tv);
Description
The clock abstraction in Libbson provides a cross-platform way to handle timeouts within the BSON
library. It abstracts the differences in implementations of gettimeofday() as well as providing a
monotonic (incrementing only) clock in microseconds.
Memory Management
BSON Memory Abstraction.
Description
Libbson contains a lightweight memory abstraction to make portability to new platforms easier.
Additionally, it helps us integrate with interesting higher-level languages. One caveat, however, is that
Libbson is not designed to deal with Out of Memory (OOM) situations. Doing so requires extreme diligence
throughout the application stack that has rarely been implemented correctly. This may change in the
future. As it stands now, Libbson will abort() under OOM situations.
To aid in language binding integration, Libbson allows for setting a custom memory allocator via
bson_mem_set_vtable() <>. This allocation may be reversed via bson_mem_restore_vtable() <>.
BSON Binary Vector subtype
In Libbson, we use the term Vector to refer to a data representation for compact storage of uniform
elements, defined by the BSON Binary Subtype 9 - Vector <https://github.com/mongodb/specifications/blob/
master/source/bson-binary-vector/bson-binary-vector.md> specification.
Libbson includes API support for Vectors:
• The view APIs provide an efficient way to access elements of Vector fields that reside within bson_t <>
storage.
• Integration between views and other Libbson features: append, array builder, iter.
• Vectors can be converted to and from a plain BSON Array, subject to the specification's type conversion
rules.
The specification currently defines three element types, which Libbson interprets as:
• int8: signed integer elements, equivalent to C int8_t.
• float32: IEEE 754 floating point, 32 bits per element, least-significant byte first. After alignment
and byte swapping, elements are equivalent to C float.
• packed_bit: single-bit integer elements, packed most-significant bit first. Accessible in packed form
as C uint8_t or as unpacked elements using C bool.
Vector Views
bson_vector_int8_view_t
A reference to mutable non-owned BSON Binary data holding a valid Vector of int8 element type.
Synopsis
#include <bson/bson.h>
typedef struct bson_vector_int8_view_t {
/*< private >*/
} bson_vector_int8_view_t;
Description
bson_vector_int8_view_t <> is a structure that acts as an opaque reference to a block of memory that has
been validated as an int8 vector.
It is meant to be passed by value and can be discarded at any time. The contents of the structure should
be considered private.
The bson_t <> MUST be valid for the lifetime of the view and it is an error to modify the bson_t <> while
using the view.
Example
static const int8_t values[] = {1, 2, 3};
const size_t values_count = sizeof values / sizeof values[0];
bson_vector_int8_view_t view;
BSON_ASSERT (BSON_APPEND_VECTOR_INT8_UNINIT (&doc, "vector", values_count, &view));
BSON_ASSERT (bson_vector_int8_view_write (view, values, values_count, 0));
See also:
bson_append_vector_int8_uninit() <>
bson_vector_int8_const_view_t <>
bson_vector_int8_const_view_t
A reference to non-owned const BSON Binary data holding a valid Vector of int8 element type.
Synopsis
#include <bson/bson.h>
typedef struct bson_vector_int8_const_view_t {
/*< private >*/
} bson_vector_int8_const_view_t;
Description
bson_vector_int8_const_view_t <> is a structure that acts as an opaque const reference to a block of
memory that has been validated as an int8 vector.
It is meant to be passed by value and can be discarded at any time. The contents of the structure should
be considered private.
The bson_t <> MUST be valid for the lifetime of the view and it is an error to modify the bson_t <> while
using the view.
Example
bson_iter_t iter;
bson_vector_int8_const_view_t view;
if (bson_iter_init_find (&iter, &doc, "vector") && bson_vector_int8_const_view_from_iter (&view, &iter)) {
size_t length = bson_vector_int8_const_view_length (view);
printf ("Elements in 'vector':\n");
for (size_t i = 0; i < length; i++) {
int8_t element;
BSON_ASSERT (bson_vector_int8_const_view_read (view, &element, 1, i));
printf (" [%d] = %d\n", (int) i, (int) element);
}
}
See also:
bson_vector_int8_view_t <>
bson_vector_float32_view_t
A reference to mutable non-owned BSON Binary data holding a valid Vector of float32 element type.
Synopsis
#include <bson/bson.h>
typedef struct bson_vector_float32_view_t {
/*< private >*/
} bson_vector_float32_view_t;
Description
bson_vector_float32_view_t <> is a structure that acts as an opaque reference to a block of memory that
has been validated as a float32 vector.
It is meant to be passed by value and can be discarded at any time. The contents of the structure should
be considered private.
The bson_t <> MUST be valid for the lifetime of the view and it is an error to modify the bson_t <> while
using the view.
Example
static const float values[] = {1.0f, 2.0f, 3.0f};
const size_t values_count = sizeof values / sizeof values[0];
bson_vector_float32_view_t view;
BSON_ASSERT (BSON_APPEND_VECTOR_FLOAT32_UNINIT (&doc, "vector", values_count, &view));
BSON_ASSERT (bson_vector_float32_view_write (view, values, values_count, 0));
See also:
bson_append_vector_float32_uninit() <>
bson_vector_float32_const_view_t <>
bson_vector_float32_const_view_t
A reference to non-owned const BSON Binary data holding a valid Vector of float32 element type.
Synopsis
#include <bson/bson.h>
typedef struct bson_vector_float32_const_view_t {
/*< private >*/
} bson_vector_float32_const_view_t;
Description
bson_vector_float32_const_view_t <> is a structure that acts as an opaque const reference to a block of
memory that has been validated as a float32 vector.
It is meant to be passed by value and can be discarded at any time. The contents of the structure should
be considered private.
The bson_t <> MUST be valid for the lifetime of the view and it is an error to modify the bson_t <> while
using the view.
Example
bson_iter_t iter;
bson_vector_float32_const_view_t view;
if (bson_iter_init_find (&iter, &doc, "vector") && bson_vector_float32_const_view_from_iter (&view, &iter)) {
size_t length = bson_vector_float32_const_view_length (view);
printf ("Elements in 'vector':\n");
for (size_t i = 0; i < length; i++) {
float element;
BSON_ASSERT (bson_vector_float32_const_view_read (view, &element, 1, i));
printf (" [%d] = %f\n", (int) i, element);
}
}
See also:
bson_vector_float32_view_t <>
bson_vector_packed_bit_view_t
A reference to mutable non-owned BSON Binary data holding a valid Vector of packed_bit element type.
Synopsis
#include <bson/bson.h>
typedef struct bson_vector_packed_bit_view_t {
/*< private >*/
} bson_vector_packed_bit_view_t;
Description
bson_vector_packed_bit_view_t <> is a structure that acts as an opaque reference to a block of memory
that has been validated as a packed_bit vector.
It is meant to be passed by value and can be discarded at any time. The contents of the structure should
be considered private.
The bson_t <> MUST be valid for the lifetime of the view and it is an error to modify the bson_t <> while
using the view.
Example
// Fill a new vector with individual boolean elements
{
static const bool bool_values[] = {true, false, true, true, false};
const size_t bool_values_count = sizeof bool_values / sizeof bool_values[0];
bson_vector_packed_bit_view_t view;
BSON_ASSERT (BSON_APPEND_VECTOR_PACKED_BIT_UNINIT (&doc, "from_bool", bool_values_count, &view));
BSON_ASSERT (bson_vector_packed_bit_view_pack_bool (view, bool_values, bool_values_count, 0));
}
// Fill another new vector with packed bytes
{
static const uint8_t packed_bytes[] = {0xb0};
const size_t unused_bits_count = 3;
const size_t packed_values_count = sizeof packed_bytes * 8 - unused_bits_count;
bson_vector_packed_bit_view_t view;
BSON_ASSERT (BSON_APPEND_VECTOR_PACKED_BIT_UNINIT (&doc, "from_packed", packed_values_count, &view));
BSON_ASSERT (bson_vector_packed_bit_view_write_packed (view, packed_bytes, sizeof packed_bytes, 0));
}
// Compare both vectors. They match exactly.
{
bson_iter_t from_bool_iter, from_packed_iter;
BSON_ASSERT (bson_iter_init_find (&from_bool_iter, &doc, "from_bool"));
BSON_ASSERT (bson_iter_init_find (&from_packed_iter, &doc, "from_packed"));
BSON_ASSERT (bson_iter_binary_equal (&from_bool_iter, &from_packed_iter));
}
See also:
bson_append_vector_packed_bit_uninit() <>
bson_vector_packed_bit_const_view_t <>
bson_vector_packed_bit_const_view_t
A reference to non-owned const BSON Binary data holding a valid Vector of packed_bit element type.
Synopsis
#include <bson/bson.h>
typedef struct bson_vector_packed_bit_const_view_t {
/*< private >*/
} bson_vector_packed_bit_const_view_t;
Description
bson_vector_packed_bit_const_view_t <> is a structure that acts as an opaque const reference to a block
of memory that has been validated as a packed_bit vector.
It is meant to be passed by value and can be discarded at any time. The contents of the structure should
be considered private.
The bson_t <> MUST be valid for the lifetime of the view and it is an error to modify the bson_t <> while
using the view.
Example
bson_iter_t iter;
bson_vector_packed_bit_const_view_t view;
if (bson_iter_init_find (&iter, &doc, "vector") && bson_vector_packed_bit_const_view_from_iter (&view, &iter)) {
size_t length = bson_vector_packed_bit_const_view_length (view);
size_t length_bytes = bson_vector_packed_bit_const_view_length_bytes (view);
size_t padding = bson_vector_packed_bit_const_view_padding (view);
printf ("Elements in 'vector':\n");
for (size_t i = 0; i < length; i++) {
bool element;
BSON_ASSERT (bson_vector_packed_bit_const_view_unpack_bool (view, &element, 1, i));
printf (" elements[%d] = %d\n", (int) i, (int) element);
}
printf ("Bytes in 'vector': (%d bits unused)\n", (int) padding);
for (size_t i = 0; i < length_bytes; i++) {
uint8_t packed_byte;
BSON_ASSERT (bson_vector_packed_bit_const_view_read_packed (view, &packed_byte, 1, i));
printf (" bytes[%d] = 0x%02x\n", (int) i, (unsigned) packed_byte);
}
}
See also:
bson_vector_packed_bit_view_t <>
Integration
• Allocating Vectors inside bson_t <>:
bson_append_vector_int8_uninit()
Synopsis
#define BSON_APPEND_VECTOR_INT8_UNINIT(b, key, count, view) \
bson_append_vector_int8_uninit (b, key, (int) strlen (key), count, view)
bool
bson_append_vector_int8_uninit (bson_t *bson,
const char *key,
int key_length,
size_t element_count,
bson_vector_int8_view_t *view_out);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• element_count: Number of elements to allocate space for.
• view_out: Receives a bson_vector_int8_view_t <> with uninitialized elements.
Description
Appends a new field to bson by allocating a Vector with the indicated number of int8 elements. The
elements will be uninitialized. On success, the caller must write every element in the Vector if the
resulting bson_t <> is to be used.
The view written to *view_out is only valid until bson is otherwise modified or freed.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
bson_append_vector_float32_uninit()
Synopsis
#define BSON_APPEND_VECTOR_FLOAT32_UNINIT(b, key, count, view) \
bson_append_vector_float32_uninit (b, key, (int) strlen (key), count, view)
bool
bson_append_vector_float32_uninit (bson_t *bson,
const char *key,
int key_length,
size_t element_count,
bson_vector_float32_view_t *view_out);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• element_count: Number of elements to allocate space for.
• view_out: Receives a bson_vector_float32_view_t <> with uninitialized elements.
Description
Appends a new field to bson by allocating a Vector with the indicated number of float32 elements. The
elements will be uninitialized. On success, the caller must write every element in the Vector if the
resulting bson_t <> is to be used.
The view written to *view_out is only valid until bson is otherwise modified or freed.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
bson_append_vector_packed_bit_uninit()
Synopsis
#define BSON_APPEND_VECTOR_PACKED_BIT_UNINIT(b, key, count, view) \
bson_append_vector_packed_bit_uninit (b, key, (int) strlen (key), count, view)
bool
bson_append_vector_packed_bit_uninit (bson_t *bson,
const char *key,
int key_length,
size_t element_count,
bson_vector_packed_bit_view_t *view_out);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• element_count: Number of elements to allocate space for.
• view_out: Receives a bson_vector_packed_bit_view_t <> with uninitialized elements.
Description
Appends a new field to bson by allocating a Vector with the indicated number of packed_bit elements. The
elements will be uninitialized. On success, the caller must write every element in the Vector if the
resulting bson_t <> is to be used.
The view written to *view_out is only valid until bson is otherwise modified or freed.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
• Accessing an existing Vector via bson_iter_t <>:
#define BSON_ITER_HOLDS_VECTOR(iter) /* ... */
#define BSON_ITER_HOLDS_VECTOR_INT8(iter) /* ... */
#define BSON_ITER_HOLDS_VECTOR_FLOAT32(iter) /* ... */
#define BSON_ITER_HOLDS_VECTOR_PACKED_BIT(iter) /* ... */
Array Conversion
• Polymorphic array-from-vector:
bson_append_array_from_vector()
Synopsis
#define BSON_APPEND_ARRAY_FROM_VECTOR(b, key, iter) \
bson_append_array_from_vector (b, key, (int) strlen (key), iter)
bool
bson_append_array_from_vector (bson_t *bson,
const char *key,
int key_length,
const bson_iter_t *iter);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• iter: A bson_iter_t <> pointing to any supported BSON Binary Vector subtype <> field.
Description
Converts the Vector pointed to by iter into a plain BSON Array, written to bson under the name key.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX, or if iter doesn't point to a valid recognized Vector type.
See also:
bson_array_builder_append_vector_elements() <>
• Type specific array-from-vector:
bson_append_array_from_vector_int8()
Synopsis
#define BSON_APPEND_ARRAY_FROM_VECTOR_INT8(b, key, view) \
bson_append_array_from_vector_int8 (b, key, (int) strlen (key), view)
bool
bson_append_array_from_vector_int8 (bson_t *bson,
const char *key,
int key_length,
bson_vector_int8_const_view_t view);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• view: A bson_vector_int8_const_view_t <> pointing to validated int8 BSON Binary Vector subtype <>
data.
Description
Converts the Vector pointed to by view into a plain BSON Array, written to bson under the name key.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
See also:
bson_array_builder_append_vector_int8_elements() <>
bson_append_array_from_vector_float32()
Synopsis
#define BSON_APPEND_ARRAY_FROM_VECTOR_FLOAT32(b, key, view) \
bson_append_array_from_vector_float32 (b, key, (int) strlen (key), view)
bool
bson_append_array_from_vector_float32 (bson_t *bson,
const char *key,
int key_length,
bson_vector_float32_const_view_t view);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• view: A bson_vector_float32_const_view_t <> pointing to validated float32 BSON Binary Vector subtype
<> data.
Description
Converts the Vector pointed to by view into a plain BSON Array, written to bson under the name key.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
See also:
bson_array_builder_append_vector_float32_elements() <>
bson_append_array_from_vector_packed_bit()
Synopsis
#define BSON_APPEND_ARRAY_FROM_VECTOR_PACKED_BIT(b, key, view) \
bson_append_array_from_vector_packed_bit (b, key, (int) strlen (key), view)
bool
bson_append_array_from_vector_packed_bit (bson_t *bson,
const char *key,
int key_length,
bson_vector_packed_bit_const_view_t view);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• view: A bson_vector_packed_bit_const_view_t <> pointing to validated packed_bit BSON Binary Vector
subtype <> data.
Description
Converts the Vector pointed to by view into a plain BSON Array, written to bson under the name key.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
See also:
bson_array_builder_append_vector_packed_bit_elements() <>
• Using bson_array_builder_t <> for array-from-vector:
bson_array_builder_append_vector_int8_elements()
Synopsis
bool
bson_array_builder_append_vector_int8_elements (bson_array_builder_t *builder,
bson_vector_int8_const_view_t view);
Parameters
• builder: A valid bson_array_builder_t <>.
• view: A bson_vector_int8_const_view_t <> pointing to validated int8 BSON Binary Vector subtype <>
data.
Description
Converts the Vector pointed to by view into elements of a plain BSON Array, written to builder. Every
element will be losslessly extended from int8_t to int32_t.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
See also:
bson_append_array_from_vector() <>
bson_array_builder_append_vector_elements() <>
bson_array_builder_append_vector_float32_elements()
Synopsis
bool
bson_array_builder_append_vector_float32_elements (bson_array_builder_t *builder,
bson_vector_float32_const_view_t view);
Parameters
• builder: A valid bson_array_builder_t <>.
• view: A bson_vector_float32_const_view_t <> pointing to validated float32 BSON Binary Vector subtype
<> data.
Description
Converts the Vector pointed to by view into elements of a plain BSON Array, written to builder. Every
element will be converted from float to double precision.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
See also:
bson_append_array_from_vector() <>
bson_array_builder_append_vector_elements() <>
bson_array_builder_append_vector_packed_bit_elements()
Synopsis
bool
bson_array_builder_append_vector_packed_bit_elements (bson_array_builder_t *builder,
bson_vector_packed_bit_const_view_t view);
Parameters
• builder: A valid bson_array_builder_t <>.
• view: A bson_vector_packed_bit_const_view_t <> pointing to validated packed_bit BSON Binary Vector
subtype <> data.
Description
Converts the Vector pointed to by view into elements of a plain BSON Array, written to builder. Every
element will be 0 or 1 written as a BSON_TYPE_INT32.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX.
See also:
bson_append_array_from_vector() <>
bson_array_builder_append_vector_elements() <>
bson_array_builder_append_vector_elements()
Synopsis
bool
bson_array_builder_append_vector_elements (bson_array_builder_t *builder,
const bson_iter_t *iter);
Parameters
• builder: A valid bson_array_builder_t <>.
• iter: A bson_iter_t <> pointing to any supported BSON Binary Vector subtype <> field.
Description
Converts the Vector pointed to by iter into elements of a plain BSON Array, written to builder. This
conversion is polymorphic: A converted element type will be chosen based on the type of the input Vector.
For details, see the type-specific versions of this function.
Returns
Returns true if the operation was applied successfully. The function fails if appending the array grows
bson larger than INT32_MAX, or if iter doesn't point to a valid recognized Vector type.
See also:
bson_append_array_from_vector() <>
bson_array_builder_append_vector_int8_elements() <>
bson_array_builder_append_vector_float32_elements() <>
bson_array_builder_append_vector_packed_bit_elements() <>
• Type specific vector-from-array:
bson_append_vector_int8_from_array()
Synopsis
#define BSON_APPEND_VECTOR_INT8_FROM_ARRAY(b, key, iter, err) \
bson_append_vector_int8_from_array (b, key, (int) strlen (key), iter, err)
bool
bson_append_vector_int8_from_array (bson_t *bson,
const char *key,
int key_length,
const bson_iter_t *iter,
bson_error_t *error);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• iter: A bson_iter_t <> referencing array elements that will be converted.
• error: Optional bson_error_t <> for detail about conversion failures.
Description
Appends a new field to bson by converting an Array to a Vector of int8 elements.
For the conversion to succeed, every item in the Array must be an integer (BSON_TYPE_INT32 or
BSON_TYPE_INT64) in the range INT8_MIN (-128) through INT8_MAX (127) inclusive. If any element has an
incorrect type or an out-of-range value, the conversion fails with an error message providing details,
and no changes are made to bson.
The provided iter must be positioned just prior to the first element of the BSON Array. If your input is
a bare BSON Array, set up iter using bson_iter_init() <>. If the input is within a document field, use
bson_iter_recurse() <>.
Returns
Returns true if the operation was applied successfully. On error, returns false and writes additional
error information to error without modifying bson. The error will have a domain of BSON_ERROR_VECTOR and
a code from bson_vector_error_code_t <>.
bson_append_vector_float32_from_array()
Synopsis
#define BSON_APPEND_VECTOR_FLOAT32_FROM_ARRAY(b, key, iter, err) \
bson_append_vector_float32_from_array (b, key, (int) strlen (key), iter, err)
bool
bson_append_vector_float32_from_array (bson_t *bson,
const char *key,
int key_length,
const bson_iter_t *iter,
bson_error_t *error);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• iter: A bson_iter_t <> referencing array elements that will be converted.
• error: Optional bson_error_t <> for detail about conversion failures.
Description
Appends a new field to bson by converting an Array to a Vector of float32 elements.
For the conversion to succeed, every item in the Array must be double-precision floating point number.
(BSON_TYPE_DOUBLE)
The provided iter must be positioned just prior to the first element of the BSON Array. If your input is
a bare BSON Array, set up iter using bson_iter_init() <>. If the input is within a document field, use
bson_iter_recurse() <>.
Returns
Returns true if the operation was applied successfully. On error, returns false and writes additional
error information to error without modifying bson. The error will have a domain of BSON_ERROR_VECTOR and
a code from bson_vector_error_code_t <>.
bson_append_vector_packed_bit_from_array()
Synopsis
#define BSON_APPEND_VECTOR_PACKED_BIT_FROM_ARRAY(b, key, iter, err) \
bson_append_vector_packed_bit_from_array (b, key, (int) strlen (key), iter, err)
bool
bson_append_vector_packed_bit_from_array (bson_t *bson,
const char *key,
int key_length,
const bson_iter_t *iter,
bson_error_t *error);
Parameters
• bson: A bson_t <>.
• key: An ASCII C string containing the name of the field.
• key_length: The length of key in bytes, or -1 to determine the length with strlen().
• iter: A bson_iter_t <> referencing array elements that will be converted.
• error: Optional bson_error_t <> for detail about conversion failures.
Description
Appends a new field to bson by converting an Array to a Vector of packed_bit elements.
For the conversion to succeed, every item in the Array must be either an integer (BSON_TYPE_INT32 or
BSON_TYPE_INT64) with the values 0 or 1, or boolean (BSON_TYPE_BOOL). If any element has an incorrect
type or an out-of-range value, the conversion fails with an error message providing details, and no
changes are made to bson.
The provided iter must be positioned just prior to the first element of the BSON Array. If your input is
a bare BSON Array, set up iter using bson_iter_init() <>. If the input is within a document field, use
bson_iter_recurse() <>.
Returns
Returns true if the operation was applied successfully. On error, returns false and writes additional
error information to error without modifying bson. The error will have a domain of BSON_ERROR_VECTOR and
a code from bson_vector_error_code_t <>.
Additional Definitions
• Binary subtype:
typedef enum {
BSON_SUBTYPE_VECTOR = 0x09,
/* ... */
} bson_subtype_t;
• Byte length of the Vector header:
// Length of the required header for BSON_SUBTYPE_VECTOR, in bytes
#define BSON_VECTOR_HEADER_LEN 2
• Byte length for a Vector with specific element type and count:
bson_vector_int8_binary_data_length()
Calculate the size of a BSON Binary field that would be needed to store a Vector with the indicated
number of int8 elements.
Synopsis
uint32_t
bson_vector_int8_binary_data_length (size_t element_count);
Parameters
• element_count: Number of elements, as a size_t.
Description
Checks element_count against the maximum representable size, and calculates the required Binary size.
Returns
On success, returns the required Binary size as a uint32_t greater than or equal to
BSON_VECTOR_HEADER_LEN. This length includes the 2-byte Vector header, but not the Binary subtype header
or any other BSON headers. If the element_count is too large to represent, returns 0.
bson_vector_float32_binary_data_length()
Calculate the size of a BSON Binary field that would be needed to store a Vector with the indicated
number of float32 elements.
Synopsis
uint32_t
bson_vector_float32_binary_data_length (size_t element_count);
Parameters
• element_count: Number of elements, as a size_t.
Description
Checks element_count against the maximum representable size, and calculates the required Binary size.
Returns
On success, returns the required Binary size as a uint32_t greater than or equal to
BSON_VECTOR_HEADER_LEN. This length includes the 2-byte Vector header, but not the Binary subtype header
or any other BSON headers. If the element_count is too large to represent, returns 0.
bson_vector_packed_bit_binary_data_length()
Calculate the size of a BSON Binary field that would be needed to store a Vector with the indicated
number of packed_bit elements.
Synopsis
uint32_t
bson_vector_packed_bit_binary_data_length (size_t element_count);
Parameters
• element_count: Number of single-bit elements, as a size_t.
Description
Checks element_count against the maximum representable size, and calculates the required Binary size.
Returns
On success, returns the required Binary size as a uint32_t greater than or equal to
BSON_VECTOR_HEADER_LEN. This length includes the 2-byte Vector header, but not the Binary subtype header
or any other BSON headers. If the element_count is too large to represent, returns 0.
• Errors:
// Error "domain"
#define BSON_ERROR_VECTOR 4
bson_vector_error_code_t
BSON Error codes for BSON Binary Vector subtype <> operations that could fail in multiple ways.
Synopsis
#define BSON_ERROR_VECTOR 4
typedef enum {
BSON_VECTOR_ERROR_ARRAY_ELEMENT_TYPE = 1,
BSON_VECTOR_ERROR_ARRAY_ELEMENT_VALUE = 2,
BSON_VECTOR_ERROR_ARRAY_KEY = 3,
BSON_VECTOR_ERROR_MAX_SIZE = 4,
} bson_vector_error_code_t;
Description
The error code values in bson_vector_error_code_t apply to bson_error_t <> values with a category of
BSON_ERROR_CATEGORY and a domain of BSON_ERROR_VECTOR.
• BSON_VECTOR_ERROR_ARRAY_ELEMENT_TYPE: An element was encountered with incorrect type. Location and
type details in message.
• BSON_VECTOR_ERROR_ARRAY_ELEMENT_VALUE: An element was encountered with out-of-range value. Location
and value details in message.
• BSON_VECTOR_ERROR_ARRAY_KEY: An input BSON Array did not contain the expected numeric key value.
Expected and actual keys in message.
• BSON_VECTOR_ERROR_MAX_SIZE: The BSON maximum document size would be exceeded. Equivalent to a failure
from bson_append_* functions that do not return an error.
Libbson Versioning
Versioning Macros and Functions
Macros
The following preprocessor macros can be used to perform various checks based on the version of the
library you are compiling against. This may be useful if you only want to enable a feature on a certain
version of the library.
Synopsis
#define BSON_CHECK_VERSION(major, minor, micro)
#define BSON_MAJOR_VERSION (1)
#define BSON_MINOR_VERSION (4)
#define BSON_MICRO_VERSION (1)
#define BSON_VERSION_S "1.4.1"
#define BSON_VERSION_HEX \
(BSON_MAJOR_VERSION << 24 | BSON_MINOR_VERSION << 16 | \
BSON_MICRO_VERSION << 8)
Only compile a block on Libbson 1.1.0 and newer.
#if BSON_CHECK_VERSION(1, 1, 0)
static void
do_something (void)
{
}
#endif
Libbson Legacy Extended JSON
libbson can produce a non-portable Legacy Extended JSON format.
Warning:
Use of the Legacy Extended JSON format is discouraged. Prefer Canonical Extended JSON or Relaxed
Extended JSON for portability.
MongoDB Extended JSON (v2) <https://www.mongodb.com/docs/manual/reference/mongodb-extended-json/>
describes the preferred Relaxed Extended JSON format and Canonical Extended Formats
libbson's Legacy Extended JSON format matches Relaxed Extended JSON with the following exceptions.
Notation is borrowed from MongoDB Extended JSON (v2) <https://www.mongodb.com/docs/manual/reference/
mongodb-extended-json/>:
┌────────────────────────┬─────────────────────────────────────────────────────────────────────────────┐
│ Type │ Legacy Extended JSON │
├────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ Binary │ │
│ │ { "$binary": "<payload>", "$type": "<t>" } │
├────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ Date │ │
│ │ { "$date" : "<millis>" } │
├────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ Regular Expression │ │
│ │ { "$regex" : "<regexPattern>", "$options" : "<options>" } │
├────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ DBPointer (deprecated) │ │
│ │ { "$ref" : "<collection namespace>", "$id" : "<ObjectId bytes>" } │
├────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ Symbol (deprecated) │ │
│ │ "<string>" │
├────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ Double infinity │ infinity or inf without quotes. Implementation defined. Produces invalid │
│ │ JSON. │
├────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ Double NaN │ nan or nan(n-char-sequence). Implementation defined. Produces invalid JSON. │
└────────────────────────┴─────────────────────────────────────────────────────────────────────────────┘
Author
MongoDB, Inc
Copyright
2009-present, MongoDB, Inc.
2.2.0 Nov 26, 2025 BSON_REFERENCE(3)