Library Functions Manual

NAME¶

msgpuck.h - MsgPuck is a simple and efficient MsgPack encoder/decoder library in a single self-contained file.

SYNOPSIS¶

#include <stdlib.h>
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
#include <string.h>
#include <assert.h>
#include <stdarg.h>
#include <stdio.h>

Enumerations¶

enum mp_type { MP_NIL = 0, MP_UINT, MP_INT, MP_STR, MP_BIN, MP_ARRAY, MP_MAP, MP_BOOL, MP_FLOAT, MP_DOUBLE, MP_EXT }
MsgPack data types.

Functions¶

MP_PROTO enum mp_type mp_typeof (const char c)
Determine MsgPack type by a first byte c of encoded data. MP_PROTO uint32_t mp_sizeof_array (uint32_t size)
Calculate exact buffer size needed to store an array header of size elements. Maximum return value is 5. For performance reasons you can preallocate buffer for maximum size without calling the function. MP_PROTO char * mp_encode_array (char *data, uint32_t size)
Encode an array header of size elements. MP_PROTO ptrdiff_t mp_check_array (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode an array header. MP_PROTO uint32_t mp_decode_array (const char **data)
Decode an array header from MsgPack data. MP_PROTO uint32_t mp_sizeof_map (uint32_t size)
Calculate exact buffer size needed to store a map header of size elements. Maximum return value is 5. For performance reasons you can preallocate buffer for maximum size without calling the function. MP_PROTO char * mp_encode_map (char *data, uint32_t size)
Encode a map header of size elements. MP_PROTO ptrdiff_t mp_check_map (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode a map header. MP_PROTO uint32_t mp_decode_map (const char **data)
Decode a map header from MsgPack data. MP_PROTO uint32_t mp_sizeof_uint (uint64_t num)
Calculate exact buffer size needed to store an integer num. Maximum return value is 9. For performance reasons you can preallocate buffer for maximum size without calling the function. Example usage: MP_PROTO uint32_t mp_sizeof_int (int64_t num)
Calculate exact buffer size needed to store an integer num. Maximum return value is 9. For performance reasons you can preallocate buffer for maximum size without calling the function. MP_PROTO char * mp_encode_uint (char *data, uint64_t num)
Encode an unsigned integer num. It is your responsibility to ensure that data has enough space. MP_PROTO char * mp_encode_int (char *data, int64_t num)
Encode a signed integer num. It is your responsibility to ensure that data has enough space. MP_PROTO ptrdiff_t mp_check_uint (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode an uint. MP_PROTO ptrdiff_t mp_check_int (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode an int. MP_PROTO uint64_t mp_decode_uint (const char **data)
Decode an unsigned integer from MsgPack data. MP_PROTO int64_t mp_decode_int (const char **data)
Decode a signed integer from MsgPack data. MP_PROTO int mp_compare_uint (const char *data_a, const char *data_b)
Compare two packed unsigned integers. MP_PROTO uint32_t mp_sizeof_float (float num)
Calculate exact buffer size needed to store a float num. The return value is always 5. The function was added to provide integrity of the library. MP_PROTO uint32_t mp_sizeof_double (double num)
Calculate exact buffer size needed to store a double num. The return value is either 5 or 9. The function was added to provide integrity of the library. For performance reasons you can preallocate buffer for maximum size without calling the function. MP_PROTO char * mp_encode_float (char *data, float num)
Encode a float num. It is your responsibility to ensure that data has enough space. MP_PROTO char * mp_encode_double (char *data, double num)
Encode a double num. It is your responsibility to ensure that data has enough space. MP_PROTO ptrdiff_t mp_check_float (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode a float. MP_PROTO ptrdiff_t mp_check_double (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode a double. MP_PROTO float mp_decode_float (const char **data)
Decode a float from MsgPack data. MP_PROTO double mp_decode_double (const char **data)
Decode a double from MsgPack data. MP_PROTO uint32_t mp_sizeof_strl (uint32_t len)
Calculate exact buffer size needed to store a string header of length num. Maximum return value is 5. For performance reasons you can preallocate buffer for maximum size without calling the function. MP_PROTO uint32_t mp_sizeof_str (uint32_t len)
Equivalent to mp_sizeof_strl(len) + len. MP_PROTO uint32_t mp_sizeof_binl (uint32_t len)
Calculate exact buffer size needed to store a binstring header of length num. Maximum return value is 5. For performance reasons you can preallocate buffer for maximum size without calling the function. MP_PROTO uint32_t mp_sizeof_bin (uint32_t len)
Equivalent to mp_sizeof_binl(len) + len. MP_PROTO char * mp_encode_strl (char *data, uint32_t len)
Encode a string header of length len. MP_PROTO char * mp_encode_str (char *data, const char *str, uint32_t len)
Encode a string of length len. The function is equivalent to mp_encode_strl() + memcpy. MP_PROTO char * mp_encode_binl (char *data, uint32_t len)
Encode a binstring header of length len. See mp_encode_strl() for more details. MP_PROTO char * mp_encode_bin (char *data, const char *str, uint32_t len)
Encode a binstring of length len. The function is equivalent to mp_encode_binl() + memcpy. MP_PROTO size_t mp_format (char *data, size_t data_size, const char *format,...)
Encode a sequence of values according to format string. Example: mp_format(buf, sz, '[%d {%d%s%d%s}]', 42, 0, 'false', 1, 'true'); to get a msgpack array of two items: number 42 and map (0->'false, 2->'true)Doesnotwriteitemsthatdon'tfittodata_sizeargument. MP_PROTO size_t mp_vformat (char *data, size_t data_size, const char *format, va_list args)
mp_format variation, taking variable argument list Example: va_list args; va_start(args, fmt); mp_vformat(data, data_size, fmt, args); va_end(args); MP_PROTO int mp_fprint (FILE *file, const char *data)
print to file msgpacked data in JSON format. MP_EXT is printed as 'EXT' only MP_PROTO ptrdiff_t mp_check_strl (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode a string header. MP_PROTO ptrdiff_t mp_check_binl (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode a binstring header. MP_PROTO uint32_t mp_decode_strl (const char **data)
Decode a length of a string from MsgPack data. MP_PROTO const char * mp_decode_str (const char **data, uint32_t *len)
Decode a string from MsgPack data. MP_PROTO uint32_t mp_decode_binl (const char **data)
Decode a length of a binstring from MsgPack data. MP_PROTO const char * mp_decode_bin (const char **data, uint32_t *len)
Decode a binstring from MsgPack data. MP_PROTO uint32_t mp_decode_strbinl (const char **data)
Decode a length of a string or binstring from MsgPack data. MP_PROTO const char * mp_decode_strbin (const char **data, uint32_t *len)
Decode a string or binstring from MsgPack data. MP_PROTO uint32_t mp_sizeof_nil (void)
Calculate exact buffer size needed to store the nil value. The return value is always 1. The function was added to provide integrity of the library. MP_PROTO char * mp_encode_nil (char *data)
Encode the nil value. It is your responsibility to ensure that data has enough space. MP_PROTO ptrdiff_t mp_check_nil (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode nil. MP_PROTO void mp_decode_nil (const char **data)
Decode the nil value from MsgPack data. MP_PROTO uint32_t mp_sizeof_bool (bool val)
Calculate exact buffer size needed to store a boolean value. The return value is always 1. The function was added to provide integrity of the library. MP_PROTO char * mp_encode_bool (char *data, bool val)
Encode a bool value val. It is your responsibility to ensure that data has enough space. MP_PROTO ptrdiff_t mp_check_bool (const char *cur, const char *end)
Check that cur buffer has enough bytes to decode a bool value. MP_PROTO bool mp_decode_bool (const char **data)
Decode a bool value from MsgPack data. MP_PROTO void mp_next (const char **data)
Skip one element in a packed data. MP_PROTO int mp_check (const char **data, const char *end)
Equivalent to mp_next() but also validates MsgPack in data.

Detailed Description¶

MsgPuck is a simple and efficient MsgPack encoder/decoder library in a single self-contained file.

MsgPuck

Usage example:

// Encode
char buf[1024];
char *w = buf;
w = mp_encode_array(w, 4)
w = mp_encode_uint(w, 10);
w = mp_encode_str(w, "hello world", strlen("hello world"));
w = mp_encode_bool(w, true);
w = mp_encode_double(w, 3.1415);
// Validate
const char *b = buf;
int r = mp_check(&b, w);
assert(!r)
assert(b == w);
// Decode
uint32_t size;
uint64_t ival;
const char *sval;
uint32_t sval_len;
bool bval;
double dval;
const char *r = buf;
size = mp_decode_array(&r);
// size is 4
ival = mp_decode_uint(&r);
// ival is 10;
sval = mp_decode_str(&r, &sval_len);
// sval is "hello world", sval_len is strlen("hello world")
bval = mp_decode_bool(&r);
// bval is true
dval = mp_decode_double(&r);
// dval is 3.1415
assert(r == w);

Note

Supported compilers. The implementation requires a C99+ or C++03+ compatible compiler.

Inline functions. The implementation is compatible with both C99 and GNU inline functions. Please define MP_SOURCE 1 before #include <msgpuck.h> in a single compilation unit. This module will be used to store non-inlined versions of functions and global tables.

Function Documentation¶

MP_PROTO int mp_check (const char ** data, const char * end)¶

Equivalent to mp_next() but also validates MsgPack in data.

Parameters

data - the pointer to a buffer
end - the end of a buffer

Return values

0 when MsgPack in data is valid.
!= 0 when MsgPack in data is not valid.

Postcondition

*data = *data + mp_sizeof_TYPE() where TYPE is mp_typeof(**data)

*data is not defined if MsgPack is not valid

See also

mp_next()

MP_PROTO ptrdiff_t mp_check_array (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode an array header.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_ARRAY

MP_PROTO ptrdiff_t mp_check_binl (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode a binstring header.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_BIN

MP_PROTO ptrdiff_t mp_check_bool (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode a bool value.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_BOOL

MP_PROTO ptrdiff_t mp_check_double (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode a double.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_DOUBLE

MP_PROTO ptrdiff_t mp_check_float (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode a float.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_FLOAT

MP_PROTO ptrdiff_t mp_check_int (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode an int.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_INT

MP_PROTO ptrdiff_t mp_check_map (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode a map header.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_MAP

MP_PROTO ptrdiff_t mp_check_nil (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode nil.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_NIL

MP_PROTO ptrdiff_t mp_check_strl (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode a string header.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Precondition

cur < end

mp_typeof(*cur) == MP_STR

MP_PROTO ptrdiff_t mp_check_uint (const char * cur, const char * end)¶

Check that cur buffer has enough bytes to decode an uint.

Parameters

cur buffer
end end of the buffer

Return values

0 - buffer has enough bytes
> 0 - the number of remaining bytes to read

Decode a bool value from MsgPack data.

Parameters

data - the pointer to a buffer

Returns

a decoded bool value

Postcondition

*data = *data + mp_sizeof_bool(retval)

MP_PROTO double mp_decode_double (const char ** data)¶

Decode a double from MsgPack data.

Parameters

data - the pointer to a buffer

Returns

a double

Postcondition

*data = *data + mp_sizeof_double(retval)

MP_PROTO float mp_decode_float (const char ** data)¶

Decode a float from MsgPack data.

Parameters

data - the pointer to a buffer

Returns

a float

Postcondition

*data = *data + mp_sizeof_float(retval)

MP_PROTO int64_t mp_decode_int (const char ** data)¶

Decode a signed integer from MsgPack data.

Parameters

data - the pointer to a buffer

Returns

an unsigned number

Postcondition

*data = *data + mp_sizeof_int(retval)

MP_PROTO uint32_t mp_decode_map (const char ** data)¶

Decode a map header from MsgPack data. All map key-value pairs must be decoded after the header.

Parameters

data - the pointer to a buffer

Returns

the number of key/value pairs in a map

Postcondition

Decode an unsigned integer from MsgPack data.

Parameters

data - the pointer to a buffer

Returns

an unsigned number

Postcondition

*data = *data + mp_sizeof_uint(retval)

MP_PROTO char * mp_encode_array (char * data, uint32_t size)¶

Encode an array header of size elements. All array members must be encoded after the header.

Example usage:

// Encode
char buf[1024];
char *w = buf;
w = mp_encode_array(w, 2)
w = mp_encode_uint(w, 10);
w = mp_encode_uint(w, 15);
// Decode
const char *r = buf;
uint32_t size = mp_decode_array(&r);
for (uint32_t i = 0; i < size; i++) {


    uint64_t val = mp_decode_uint(&r);
}
assert (r == w);

It is your responsibility to ensure that data has enough space.

Parameters

data - a buffer
size - a number of elements

Returns

data + mp_sizeof_array(size)

See also

mp_sizeof_array

MP_PROTO char * mp_encode_bin (char * data, const char * str, uint32_t len)¶

Encode a binstring of length len. The function is equivalent to mp_encode_binl() + memcpy.

Parameters

data - a buffer
str - a pointer to binstring data
len - a binstring length

Returns

data + mp_sizeof_bin(len) == data + mp_sizeof_binl(len) + len

See also

mp_encode_strl

Encode a signed integer num. It is your responsibility to ensure that data has enough space.

Parameters

data - a buffer
num - a number

Returns

data + mp_sizeof_int(num)

See also

An usage example

mp_sizeof_int()

Precondition

num < 0

MP_PROTO char * mp_encode_map (char * data, uint32_t size)¶

Encode a map header of size elements. All map key-value pairs must be encoded after the header.

Example usage:

char buf[1024];
// Encode
char *w = buf;
w = mp_encode_map(b, 2);
w = mp_encode_str(b, "key1", 4);
w = mp_encode_str(b, "value1", 6);
w = mp_encode_str(b, "key2", 4);
w = mp_encode_str(b, "value2", 6);
// Decode
const char *r = buf;
uint32_t size = mp_decode_map(&r);
for (uint32_t i = 0; i < size; i++) {


     // Use switch(mp_typeof(**r)) to support more types


    uint32_t key_len, val_len;


    const char *key = mp_decode_str(&r, key_len);


    const char *val = mp_decode_str(&r, val_len);
}
assert (r == w);

It is your responsibility to ensure that data has enough space.

Parameters

data - a buffer
size - a number of key/value pairs

Returns

data + mp_sizeof_map(size)

See also

mp_sizeof_map

MP_PROTO char * mp_encode_nil (char * data)¶

Encode the nil value. It is your responsibility to ensure that data has enough space.

Parameters

data - a buffer

Returns

data + mp_sizeof_nil()

See also

An usage example

mp_sizeof_nil()

MP_PROTO char * mp_encode_str (char * data, const char * str, uint32_t len)¶

Encode a string of length len. The function is equivalent to mp_encode_strl() + memcpy.

Parameters

data - a buffer
str - a pointer to string data
len - a string length

Returns

data + mp_sizeof_str(len) == data + mp_sizeof_strl(len) + len

See also

mp_encode_strl

MP_PROTO char * mp_encode_strl (char * data, uint32_t len)¶

Encode a string header of length len. The function encodes MsgPack header (only header) for a string of length len. You should append actual string data to the buffer manually after encoding the header (exactly len bytes without trailing '\0').

This approach is very useful for cases when the total length of the string is known in advance, but the string data is not stored in a single continuous buffer (e.g. network packets).

It is your responsibility to ensure that data has enough space. Usage example:

char buffer[1024];
char *b = buffer;
b = mp_encode_strl(b, hdr.total_len);
char *s = b;
memcpy(b, pkt1.data, pkt1.len)
b += pkt1.len;
// get next packet
memcpy(b, pkt2.data, pkt2.len)
b += pkt2.len;
// get next packet
memcpy(b, pkt1.data, pkt3.len)
b += pkt3.len;
// Check that all data was received
assert(hdr.total_len == (uint32_t) (b - s))

Hint: you can dynamically reallocate the buffer during the process.

Parameters

data - a buffer
len - a string length

Returns

data + mp_sizeof_strl(len)

See also

mp_sizeof_strl()

MP_PROTO char * mp_encode_uint (char * data, uint64_t num)¶

Encode an unsigned integer num. It is your responsibility to ensure that data has enough space.

Parameters

data - a buffer
num - a number

Returns

data + mp_sizeof_uint(num)

See also

An usage example

mp_sizeof_uint()

MP_PROTO size_t mp_format (char * data, size_t data_size, const char * format, ...)¶

Encode a sequence of values according to format string. Example: mp_format(buf, sz, '[%d {%d%s%d%s}]', 42, 0, 'false', 1, 'true'); to get a msgpack array of two items: number 42 and map (0->'false, 2->'true") Does not write items that don't fit to data_size argument.

Parameters

data - a buffer
data_size - a buffer size
format - zero-end string, containing structure of resulting msgpack and types of next arguments. Format can contain '[' and ']' pairs, defining arrays, '{' and '}' pairs, defining maps, and format specifiers, described below: d, i - int u - unsigned int ld, li - long lu - unsigned long lld, lli - long long llu - unsigned long long hd, hi - short hu - unsigned short hhd, hhi - char (as number) hhu - unsigned char (as number) f - float lf - double b - bool s - zero-end string %.*s - string with specified length %% is ignored smthelse assert and undefined behaviour NIL - a nil value all other symbols are ignored.

Returns

the number of requred bytes.

Return values

> data_size means that is not enough space and whole msgpack was not encoded.

MP_PROTO int mp_fprint (FILE * file, const char * data)¶

print to file msgpacked data in JSON format. MP_EXT is printed as 'EXT' only

Parameters

file - pointer to file (or NULL for stdout)
data - pointer to buffer containing msgpack object

Return values

0 - success
-1 - wrong msgpack

MP_PROTO void mp_next (const char ** data)¶

Skip one element in a packed data. The function is faster than mp_typeof + mp_decode_XXX() combination. For arrays and maps the function also skips all members. For strings and binstrings the function also skips the string data.

Usage example:

char buf[1024];
char *w = buf;
// First MsgPack object
w = mp_encode_uint(w, 10);
// Second MsgPack object
w = mp_encode_array(w, 4);


   w = mp_encode_array(w, 2);


        // Begin of an inner array


        w = mp_encode_str(w, "second inner 1", 14);


        w = mp_encode_str(w, "second inner 2", 14);


        // End of an inner array


   w = mp_encode_str(w, "second", 6);


   w = mp_encode_uint(w, 20);


   w = mp_encode_bool(w, true);
// Third MsgPack object
w = mp_encode_str(w, "third", 5);
// EOF
const char *r = buf;
// First MsgPack object
assert(mp_typeof(**r) == MP_UINT);
mp_next(&r); // skip the first object
// Second MsgPack object
assert(mp_typeof(**r) == MP_ARRAY);
mp_decode_array(&r);


    assert(mp_typeof(**r) == MP_ARRAY); // inner array


    mp_next(&r); // -->> skip the entire inner array (with all members)


    assert(mp_typeof(**r) == MP_STR); // second


    mp_next(&r);


    assert(mp_typeof(**r) == MP_UINT); // 20


    mp_next(&r);


    assert(mp_typeof(**r) == MP_BOOL); // true


    mp_next(&r);
// Third MsgPack object
assert(mp_typeof(**r) == MP_STR); // third
mp_next(&r);
assert(r == w); // EOF

Parameters

data - the pointer to a buffer

Postcondition

*data = *data + mp_sizeof_TYPE() where TYPE is mp_typeof(**data)

MP_PROTO uint32_t mp_sizeof_array (uint32_t size)¶

Calculate exact buffer size needed to store an array header of size elements. Maximum return value is 5. For performance reasons you can preallocate buffer for maximum size without calling the function.

Parameters

size - a number of elements

Returns

buffer size in bytes (max is 5)

MP_PROTO uint32_t mp_sizeof_bin (uint32_t len)¶

Equivalent to mp_sizeof_binl(len) + len.

Parameters

len - a string length

Returns

size in chars (max is 5 + len)

MP_PROTO uint32_t mp_sizeof_binl (uint32_t len)¶

Calculate exact buffer size needed to store a binstring header of length num. Maximum return value is 5. For performance reasons you can preallocate buffer for maximum size without calling the function.

Parameters

len - a string length

Returns

Calculate exact buffer size needed to store an integer num. Maximum return value is 9. For performance reasons you can preallocate buffer for maximum size without calling the function.

Parameters

num - a number

Returns

buffer size in bytes (max is 9)

Precondition

num < 0

MP_PROTO uint32_t mp_sizeof_map (uint32_t size)¶

Calculate exact buffer size needed to store a map header of size elements. Maximum return value is 5. For performance reasons you can preallocate buffer for maximum size without calling the function.

Parameters

size - a number of elements

Returns

Calculate exact buffer size needed to store an integer num. Maximum return value is 9. For performance reasons you can preallocate buffer for maximum size without calling the function. Example usage:

char **data = ...;
char *end = *data;
my_buffer_ensure(mp_sizeof_uint(x), &end);
// my_buffer_ensure(9, &end);
mp_encode_uint(buffer, x);

Parameters

num - a number

Returns

buffer size in bytes (max is 9)

MP_PROTO enum mp_type mp_typeof (const char c)¶

Determine MsgPack type by a first byte c of encoded data. Example usage:

assert(MP_ARRAY == mp_typeof(0x90));

Parameters

c - a first byte of encoded data

Returns

MsgPack type

MP_PROTO size_t mp_vformat (char * data, size_t data_size, const char * format, va_list args)¶

mp_format variation, taking variable argument list Example: va_list args; va_start(args, fmt); mp_vformat(data, data_size, fmt, args); va_end(args);

See also

mp_format()

Author¶

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MsgPuck

Source file:	msgpuck.h.3.en.gz (from libmsgpuck-dev 1.0.3-1.2)
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