Convenience functions to serialize and parse complex data structures to binary blobs. More...
Modules | |
Eet Data Serialization using A Ciphers | |
Most of the Eet Data Serialization have alternative versions that accounts for ciphers to protect their content. | |
Data Structures | |
struct | _Eet_Data_Descriptor_Class |
Instructs Eet about memory management for different needs under serialization and parse process. More... | |
Macros | |
#define | EET_T_UNKNOW 0 |
Unknown data encoding type. | |
#define | EET_T_CHAR 1 |
Data type: char. | |
#define | EET_T_SHORT 2 |
Data type: short. | |
#define | EET_T_INT 3 |
Data type: int. | |
#define | EET_T_LONG_LONG 4 |
Data type: long long. | |
#define | EET_T_FLOAT 5 |
Data type: float. | |
#define | EET_T_DOUBLE 6 |
Data type: double. | |
#define | EET_T_UCHAR 7 |
Data type: unsigned char. | |
#define | EET_T_USHORT 8 |
Data type: unsigned short. | |
#define | EET_T_UINT 9 |
Data type: unsigned int. | |
#define | EET_T_ULONG_LONG 10 |
Data type: unsigned long long. | |
#define | EET_T_STRING 11 |
Data type: char *. | |
#define | EET_T_INLINED_STRING 12 |
Data type: char * (but compressed inside the resulting eet) | |
#define | EET_T_NULL 13 |
Data type: (void *) (only use it if you know why) | |
#define | EET_T_F32P32 14 |
Data type: fixed point 32.32. | |
#define | EET_T_F16P16 15 |
Data type: fixed point 16.16. | |
#define | EET_T_F8P24 16 |
Data type: fixed point 8.24. | |
#define | EET_T_VALUE 17 |
Data type: pointer to Eina_Value. More... | |
#define | EET_T_LAST 18 |
Last data type. | |
#define | EET_G_UNKNOWN 100 |
Unknown group data encoding type. | |
#define | EET_G_ARRAY 101 |
Fixed size array group type. | |
#define | EET_G_VAR_ARRAY 102 |
Variable size array group type. | |
#define | EET_G_LIST 103 |
Linked list group type. | |
#define | EET_G_HASH 104 |
Hash table group type. | |
#define | EET_G_UNION 105 |
Union group type. | |
#define | EET_G_VARIANT 106 |
Selectable subtype group. | |
#define | EET_G_UNKNOWN_NESTED 107 |
Unknown nested group type. More... | |
#define | EET_G_LAST 108 |
Last group type. | |
#define | EET_I_LIMIT 128 |
Other type exist but are reserved for internal purpose. | |
#define | EET_DATA_DESCRIPTOR_CLASS_VERSION 4 |
The version of Eet_Data_Descriptor_Class at the time of the distribution of the sources. More... | |
#define | EET_EINA_STREAM_DATA_DESCRIPTOR_CLASS_SET(clas, type) (eet_eina_stream_data_descriptor_class_set(clas, sizeof (*(clas)), # type, sizeof(type))) |
This macro is an helper that set all the parameter of an Eet_Data_Descriptor_Class correctly when you use Eina data type with stream. More... | |
#define | EET_EINA_FILE_DATA_DESCRIPTOR_CLASS_SET(clas, type) (eet_eina_file_data_descriptor_class_set(clas, sizeof (*(clas)), # type, sizeof(type))) |
This macro is an helper that set all the parameter of an Eet_Data_Descriptor_Class correctly when you use Eina data type with file. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_BASIC(edd, struct_type, name, member, type) |
Adds a basic data element to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_SUB(edd, struct_type, name, member, subtype) |
Adds a sub-element type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_SUB_NESTED(edd, struct_type, name, member, subtype) |
Adds a nested sub-element type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_LIST(edd, struct_type, name, member, subtype) |
Adds a linked list type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_LIST_STRING(edd, struct_type, name, member) |
Adds a linked list of string to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_LIST_UINT(edd, struct_type, name, member) |
Adds a linked list of unsigned integers to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_HASH(edd, struct_type, name, member, subtype) |
Adds a hash type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_HASH_STRING(edd, struct_type, name, member) |
Adds a hash of string to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_HASH_VALUE(edd, struct_type, name, member) |
Adds a hash of generic value storage to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_BASIC_ARRAY(edd, struct_type, name, member, type) |
Adds an array of basic data elements to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_BASIC_VAR_ARRAY(edd, struct_type, name, member, type) |
Adds a variable array of basic data elements to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_ARRAY(edd, struct_type, name, member, subtype) |
Adds a fixed size array type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_VAR_ARRAY(edd, struct_type, name, member, subtype) |
Adds a variable size array type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_VAR_ARRAY_STRING(edd, struct_type, name, member) |
Adds a variable size array type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_UNION(edd, struct_type, name, member, type_member, unified_type) |
Adds an union type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_VARIANT(edd, struct_type, name, member, type_member, unified_type) |
Adds a automatically selectable type to a data descriptor. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_MAPPING(unified_type, name, subtype) |
Adds a mapping to a data descriptor that will be used by union, variant or inherited type. More... | |
#define | EET_DATA_DESCRIPTOR_ADD_MAPPING_BASIC(unified_type, name, basic_type) |
Adds a mapping of a basic type to a data descriptor that will be used by a union type. More... | |
Typedefs | |
typedef struct _Eet_Data_Descriptor | Eet_Data_Descriptor |
Opaque handle that have information on a type members. More... | |
typedef struct _Eet_Data_Descriptor_Class | Eet_Data_Descriptor_Class |
Instructs Eet about memory management for different needs under serialization and parse process. More... | |
typedef int(* | Eet_Descriptor_Hash_Foreach_Callback_Callback) (void *h, const char *k, void *dt, void *fdt) |
Callback prototype for Eet_Descriptor_Hash_Foreach_Callback. More... | |
typedef void *(* | Eet_Descriptor_Mem_Alloc_Callback) (size_t size) |
Callback prototype for Eet_Descriptor_Mem_Alloc. More... | |
typedef void(* | Eet_Descriptor_Mem_Free_Callback) (void *mem) |
Callback prototype for Eet_Descriptor_Mem_Alloc. More... | |
typedef char *(* | Eet_Descriptor_Str_Alloc_Callback) (const char *str) |
Callback prototype for Eet_Descriptor_Str_Alloc. More... | |
typedef void(* | Eet_Descriptor_Str_Free_Callback) (const char *str) |
Callback prototype for Eet_Descriptor_Str_Free. More... | |
typedef void *(* | Eet_Descriptor_List_Next_Callback) (void *l) |
Callback prototype for Eet_Descriptor_List_Next. More... | |
typedef void *(* | Eet_Descriptor_List_Append_Callback) (void *l, void *d) |
Callback prototype for Eet_Descriptor_List_Append. More... | |
typedef void *(* | Eet_Descriptor_List_Data_Callback) (void *l) |
Callback prototype for Eet_Descriptor_List_Data. More... | |
typedef void *(* | Eet_Descriptor_List_Free_Callback) (void *l) |
Callback prototype for Eet_Descriptor_List_Free. More... | |
typedef void(* | Eet_Descriptor_Hash_Foreach_Callback) (void *h, Eet_Descriptor_Hash_Foreach_Callback_Callback func, void *fdt) |
Callback for Eet_Descriptor_Hash_Foreach. More... | |
typedef void *(* | Eet_Descriptor_Hash_Add_Callback) (void *h, const char *k, void *d) |
Callback prototype for Eet_Descriptor_Hash_Add. More... | |
typedef void(* | Eet_Descriptor_Hash_Free_Callback) (void *h) |
Callback prototype for Eet_Descriptor_Hash_Free. More... | |
typedef char *(* | Eet_Descriptor_Str_Direct_Alloc_Callback) (const char *str) |
typedef void(* | Eet_Descriptor_Str_Direct_Free_Callback) (const char *str) |
typedef const char *(* | Eet_Descriptor_Type_Get_Callback) (const void *data, Eina_Bool *unknow) |
Callback prototype for Eet_Descriptor_Type_Get. More... | |
typedef Eina_Bool(* | Eet_Descriptor_Type_Set_Callback) (const char *type, void *data, Eina_Bool unknow) |
Callback prototype for Eet_Descriptor_Type_Set. More... | |
typedef void *(* | Eet_Descriptor_Array_Alloc_Callback) (size_t size) |
Callback prototype for Eet_Descriptor_Array_Alloc. More... | |
typedef void(* | Eet_Descriptor_Array_Free_Callback) (void *mem) |
Callback prototype for Eet_Descriptor_Array_Free. More... | |
Functions | |
EINA_DEPRECATED EAPI Eet_Data_Descriptor * | eet_data_descriptor_new (const char *name, int size, Eet_Descriptor_List_Next_Callback func_list_next, Eet_Descriptor_List_Append_Callback func_list_append, Eet_Descriptor_List_Data_Callback func_list_data, Eet_Descriptor_List_Free_Callback func_list_free, Eet_Descriptor_Hash_Foreach_Callback func_hash_foreach, Eet_Descriptor_Hash_Add_Callback func_hash_add, Eet_Descriptor_Hash_Free_Callback func_hash_free) |
Creates a new empty data structure descriptor. More... | |
EAPI Eet_Data_Descriptor * | eet_data_descriptor_stream_new (const Eet_Data_Descriptor_Class *eddc) |
This function creates a new data descriptor and returns a handle to the new data descriptor. More... | |
EAPI Eet_Data_Descriptor * | eet_data_descriptor_file_new (const Eet_Data_Descriptor_Class *eddc) |
This function creates a new data descriptor and returns a handle to the new data descriptor. More... | |
EAPI Eina_Bool | eet_eina_stream_data_descriptor_class_set (Eet_Data_Descriptor_Class *eddc, unsigned int eddc_size, const char *name, int size) |
This function is an helper that set all the parameters of an Eet_Data_Descriptor_Class correctly when you use Eina data type with a stream. More... | |
EAPI Eina_Bool | eet_eina_file_data_descriptor_class_set (Eet_Data_Descriptor_Class *eddc, unsigned int eddc_size, const char *name, int size) |
This function is an helper that set all the parameter of an Eet_Data_Descriptor_Class correctly when you use Eina data type with a file. More... | |
EAPI void | eet_data_descriptor_free (Eet_Data_Descriptor *edd) |
This function frees a data descriptor when it is not needed anymore. More... | |
EAPI const char * | eet_data_descriptor_name_get (const Eet_Data_Descriptor *edd) |
This function returns the name of a data descriptor. More... | |
EAPI void | eet_data_descriptor_element_add (Eet_Data_Descriptor *edd, const char *name, int type, int group_type, int offset, int count, const char *counter_name, Eet_Data_Descriptor *subtype) |
This function is an internal used by macros. More... | |
EAPI void * | eet_data_read (Eet_File *ef, Eet_Data_Descriptor *edd, const char *name) |
Reads a data structure from an eet file and decodes it. More... | |
EAPI int | eet_data_write (Eet_File *ef, Eet_Data_Descriptor *edd, const char *name, const void *data, int compress) |
Writes a data structure from memory and store in an eet file. More... | |
EAPI int | eet_data_text_dump (const void *data_in, int size_in, Eet_Dump_Callback dumpfunc, void *dumpdata) |
Dumps an eet encoded data structure into ascii text. More... | |
EAPI void * | eet_data_text_undump (const char *text, int textlen, int *size_ret) |
Takes an ascii encoding from eet_data_text_dump() and re-encode in binary. More... | |
EAPI int | eet_data_dump (Eet_File *ef, const char *name, Eet_Dump_Callback dumpfunc, void *dumpdata) |
Dumps an eet encoded data structure from an eet file into ascii text. More... | |
EAPI int | eet_data_undump (Eet_File *ef, const char *name, const char *text, int textlen, int compress) |
Takes an ascii encoding from eet_data_dump() and re-encode in binary. More... | |
EAPI void * | eet_data_descriptor_decode (Eet_Data_Descriptor *edd, const void *data_in, int size_in) |
Decodes a data structure from an arbitrary location in memory. More... | |
EAPI void * | eet_data_descriptor_encode (Eet_Data_Descriptor *edd, const void *data_in, int *size_ret) |
Encodes a dsata struct to memory and return that encoded data. More... | |
Convenience functions to serialize and parse complex data structures to binary blobs.
While Eet core just handles binary blobs, it is often required to save some structured data of different types, such as strings, integers, lists, hashes and so on.
Eet can serialize and then parse data types given some construction instructions. These are defined in two levels:
Given that C provides no introspection, this process can be quite cumbersome, so we provide lots of macros and convenience functions to aid creating the types.
We make now a quick overview of some of the most commonly used elements of this part of the library. A simple example of a configuration system will work as a somewhat real life example that is still simple enough to follow. Only the relevant sections will be shown here, but you can get the full code here.
Ignoring the included headers, we'll begin by defining our configuration struct.
When using Eet, you don't think in matters of what data the program needs to run and which you would like to store. It's all the same and if it makes more sense to keep them together, it's perfectly fine to do so. At the time of telling Eet how your data is comprised you can leave out the things that are runtime only and let Eet take care of the rest for you.
The key used to store the config follows, as well as the variable used to store our data descriptor. This last one is very important. It's the one thing that Eet will use to identify your data, both at the time of writing it to the file and when loading from it.
Now we'll see how to create this descriptor, so Eet knows how to handle our data later on. Begin our function by declaring an Eet_Data_Descriptor_Class, which is used to create the actual descriptor. This class contains the name of our data type, its size and several functions that dictate how Eet should handle memory to allocate the necessary bits to bring our data to life. You, as a user, will very hardly set this class' contents directly. The most common scenario is to use one of the provided macros that set it using the Eina data types, so that's what we'll be doing across all our examples.
Now that we have our descriptor, we need to make it describe something. We do so by telling it which members of our struct we want it to know about and their types. The eet_data_descriptor_element_add() function takes care of this, but it's too cumbersome for normal use, so several macros are provided that make it easier to handle. Even with them, however, code can get very repetitive and it's not uncommon to define custom macros using them to save on typing.
Now our descriptor knows about the parts of our structure that we are interesting in saving. You can see that not all of them are there, yet Eet will find those that need saving and do the right thing. When loading our data, any non-described fields in the structure will be zeroed, so there's no need to worry about garbage memory in them. Refer to the documentation of EET_DATA_DESCRIPTOR_ADD_BASIC to understand what our macro does.
We are done with our descriptor init function and it's proper to have the relevant shutdown. Proper coding guidelines indiciate that all memory allocated should be freed when the program ends, and since you will most likely keep your descriptor around for the life or your application, it's only right to free it at the end.
Not listed here, but included in the full example are functions to create a blank configuration and free it. The first one will only be used when no file exists to load from, or nothing is found in it, but the latter is used regardless of where our data comes from. Unless you are reading direct data from the Eet file, you will be in charge of freeing anything loaded from it.
Now it's time to look at how we can load our config from some file. Begin by opening the Eet file normally.
And now we need to read the data from the file and decode it using our descriptor. Fortunately, that's all done in one single step.
And that's it for all Eet cares about. But since we are dealing with a common case, as is save and load of user configurations, the next fragment of code shows why we have a version field in our struct, and how you can use it to load older configuration files and update them as needed.
Finally, close the file and return the newly loaded config data.
Saving data is just as easy. The full version of the following function includes code to save to a temporary file first, so you can be sure not to lose all your data in the case of a failure mid-writing. You can look at it here.
To close, our main function, which doesn't do much. Just take some arguments from the command line with the name of the file to load and another one where to save again. If input file doesn't exist, a new config structure will be created and saved to our output file.
The following is a list of more advanced and detailed examples.
#define EET_T_VALUE 17 |
Data type: pointer to Eina_Value.
#define EET_G_UNKNOWN_NESTED 107 |
Unknown nested group type.
#define EET_DATA_DESCRIPTOR_CLASS_VERSION 4 |
The version of Eet_Data_Descriptor_Class at the time of the distribution of the sources.
One should define this to its version member so it is compatible with abi changes, or at least will not crash with them.
#define EET_EINA_STREAM_DATA_DESCRIPTOR_CLASS_SET | ( | clas, | |
type | |||
) | (eet_eina_stream_data_descriptor_class_set(clas, sizeof (*(clas)), # type, sizeof(type))) |
This macro is an helper that set all the parameter of an Eet_Data_Descriptor_Class correctly when you use Eina data type with stream.
clas | The Eet_Data_Descriptor_Class you want to set. |
type | The type of the structure described by this class. |
#define EET_EINA_FILE_DATA_DESCRIPTOR_CLASS_SET | ( | clas, | |
type | |||
) | (eet_eina_file_data_descriptor_class_set(clas, sizeof (*(clas)), # type, sizeof(type))) |
This macro is an helper that set all the parameter of an Eet_Data_Descriptor_Class correctly when you use Eina data type with file.
clas | The Eet_Data_Descriptor_Class you want to set. |
type | The type of the structure described by this class. |
EINA_TRUE
if the structure was correctly set (The only reason that could make it fail is if you did give wrong parameter).#define EET_DATA_DESCRIPTOR_ADD_BASIC | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
type | |||
) |
Adds a basic data element to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
type | The type of the member to encode. |
This macro is a convenience macro provided to add a member to the data descriptor edd
. The type of the structure is provided as the struct_type
parameter (for example: struct my_struct). The name
parameter defines a string that will be used to uniquely name that member of the struct (it is suggested to use the struct member itself). The member
parameter is the actual struct member itself (for example: values), and type
is the basic data type of the member which must be one of: EET_T_CHAR, EET_T_SHORT, EET_T_INT, EET_T_LONG_LONG, EET_T_FLOAT, EET_T_DOUBLE, EET_T_UCHAR, EET_T_USHORT, EET_T_UINT, EET_T_ULONG_LONG or EET_T_STRING.
#define EET_DATA_DESCRIPTOR_ADD_SUB | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
subtype | |||
) |
Adds a sub-element type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
subtype | The type of sub-type struct to add. |
This macro lets you easily add a sub-type (a struct that's pointed to by this one). All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype
being the exception. This must be the data descriptor of the struct that is pointed to by this element.
#define EET_DATA_DESCRIPTOR_ADD_SUB_NESTED | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
subtype | |||
) |
Adds a nested sub-element type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
subtype | The type of sub-type struct to add. |
This macro lets you easily add a sub-type: a struct that is nested into this one. If your data is pointed by this element instead of being nested, you should use EET_DATA_DESCRIPTOR_ADD_SUB(). All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_SUB().
#define EET_DATA_DESCRIPTOR_ADD_LIST | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
subtype | |||
) |
Adds a linked list type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
subtype | The type of linked list member to add. |
This macro lets you easily add a linked list of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype
being the exception. This must be the data descriptor of the element that is in each member of the linked list to be stored.
#define EET_DATA_DESCRIPTOR_ADD_LIST_STRING | ( | edd, | |
struct_type, | |||
name, | |||
member | |||
) |
Adds a linked list of string to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
This macro lets you easily add a linked list of char *. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC().
#define EET_DATA_DESCRIPTOR_ADD_LIST_UINT | ( | edd, | |
struct_type, | |||
name, | |||
member | |||
) |
Adds a linked list of unsigned integers to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
This macro lets you easily add a linked list of unsigned int. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC().
#define EET_DATA_DESCRIPTOR_ADD_HASH | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
subtype | |||
) |
Adds a hash type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
subtype | The type of hash member to add. |
This macro lets you easily add a hash of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype
being the exception. This must be the data descriptor of the element that is in each member of the hash to be stored. The hash keys must be strings.
#define EET_DATA_DESCRIPTOR_ADD_HASH_STRING | ( | edd, | |
struct_type, | |||
name, | |||
member | |||
) |
Adds a hash of string to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
This macro lets you easily add a hash of string elements. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_HASH().
#define EET_DATA_DESCRIPTOR_ADD_HASH_VALUE | ( | edd, | |
struct_type, | |||
name, | |||
member | |||
) |
Adds a hash of generic value storage to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
This macro lets you easily add a hash of value elements. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_HASH().
#define EET_DATA_DESCRIPTOR_ADD_BASIC_ARRAY | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
type | |||
) |
Adds an array of basic data elements to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
type | The type of the member to encode. |
This macro lets you easily add a fixed size array of basic data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(). The array must be defined with a fixed size in the declaration of the struct containing it.
#define EET_DATA_DESCRIPTOR_ADD_BASIC_VAR_ARRAY | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
type | |||
) |
Adds a variable array of basic data elements to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
type | The type of the member to encode. |
This macro lets you easily add a variable size array of basic data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(). This assumes you have a struct member (of type EET_T_INT) called member_count (note the _count appended to the member) that holds the number of items in the array. This array will be allocated separately to the struct it is in.
#define EET_DATA_DESCRIPTOR_ADD_ARRAY | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
subtype | |||
) |
Adds a fixed size array type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
subtype | The type of hash member to add. |
This macro lets you easily add a fixed size array of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype
being the exception. This must be the data descriptor of the element that is in each member of the array to be stored. The array must be defined with a fixed size in the declaration of the struct containing it.
#define EET_DATA_DESCRIPTOR_ADD_VAR_ARRAY | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
subtype | |||
) |
Adds a variable size array type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
subtype | The type of hash member to add. |
This macro lets you easily add a variable size array of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype
being the exception. This must be the data descriptor of the element that is in each member of the array to be stored. This assumes you have a struct member (of type EET_T_INT) called member_count (note the _count appended to the member) that holds the number of items in the array. This array will be allocated separately to the struct it is in.
#define EET_DATA_DESCRIPTOR_ADD_VAR_ARRAY_STRING | ( | edd, | |
struct_type, | |||
name, | |||
member | |||
) |
Adds a variable size array type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
This macro lets you easily add a variable size array of strings. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC().
#define EET_DATA_DESCRIPTOR_ADD_UNION | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
type_member, | |||
unified_type | |||
) |
Adds an union type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
type_member | The member that give hints on what is in the union. |
unified_type | Describe all possible type the union could handle. |
This macro lets you easily add an union with a member that specify what is inside. The unified_type
is an Eet_Data_Descriptor, but only the entry that match the name returned by type_get will be used for each serialized data. The type_get and type_set callback of unified_type should be defined.
#define EET_DATA_DESCRIPTOR_ADD_VARIANT | ( | edd, | |
struct_type, | |||
name, | |||
member, | |||
type_member, | |||
unified_type | |||
) |
Adds a automatically selectable type to a data descriptor.
edd | The data descriptor to add the type to. |
struct_type | The type of the struct. |
name | The string name to use to encode/decode this member (must be a constant global and never change). |
member | The struct member itself to be encoded. |
type_member | The member that give hints on what is in the union. |
unified_type | Describe all possible type the union could handle. |
This macro lets you easily define what the content of member
points to depending of the content of type_member
. The type_get and type_set callback of unified_type should be defined. If the the type is not know at the time of restoring it, eet will still call type_set of unified_type
but the pointer will be set to a serialized binary representation of what eet know. This make it possible, to save this pointer again by just returning the string given previously and telling it by setting unknow to EINA_TRUE.
#define EET_DATA_DESCRIPTOR_ADD_MAPPING | ( | unified_type, | |
name, | |||
subtype | |||
) |
Adds a mapping to a data descriptor that will be used by union, variant or inherited type.
unified_type | The data descriptor to add the mapping to. |
name | The string name to get/set type. |
subtype | The matching data descriptor. |
#define EET_DATA_DESCRIPTOR_ADD_MAPPING_BASIC | ( | unified_type, | |
name, | |||
basic_type | |||
) |
Adds a mapping of a basic type to a data descriptor that will be used by a union type.
unified_type | The data descriptor to add the mapping to. |
name | The string name to get/set type. |
basic_type | The matching basic type. |
Opaque handle that have information on a type members.
Descriptors are created using an Eet_Data_Descriptor_Class, and they describe the contents of the structure that will be serialized by Eet. Not all members need be described by it, just those that should be handled by Eet. This way it's possible to have one structure with both data to be saved to a file, like application configuration, and runtime information that would be meaningless to store, but is appropriate to keep together during the program execution. The members are added by means of EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB(), EET_DATA_DESCRIPTOR_ADD_LIST(), EET_DATA_DESCRIPTOR_ADD_HASH() or eet_data_descriptor_element_add().
Instructs Eet about memory management for different needs under serialization and parse process.
Callback protoype for Eet_Dump.
data | To passe to the callback |
str | The string to dump |
Eet_Descriptor_Hash_Foreach_Callback_Callback |
Callback prototype for Eet_Descriptor_Hash_Foreach_Callback.
h | The hash |
k | The key |
dt | The data |
fdt | The data passed to the callback |
Eet_Descriptor_Mem_Alloc_Callback |
Callback prototype for Eet_Descriptor_Mem_Alloc.
size | Is the size of memory to alloc on call of the callback |
Eet_Descriptor_Mem_Free_Callback |
Callback prototype for Eet_Descriptor_Mem_Alloc.
mem | Must be a pointer to free on call of the callback |
Eet_Descriptor_Str_Alloc_Callback |
Callback prototype for Eet_Descriptor_Str_Alloc.
str | Must be the string to alloc |
str | The string to allocate |
Eet_Descriptor_Str_Free_Callback |
Callback prototype for Eet_Descriptor_Str_Free.
str | Must be an allocated string to free |
str | The string to free |
Eet_Descriptor_List_Next_Callback |
Callback prototype for Eet_Descriptor_List_Next.
l | Must be a pointer to the list |
Eet_Descriptor_List_Append_Callback |
Callback prototype for Eet_Descriptor_List_Append.
l | Must be a pointer to the list |
d | The data to append to the list |
Eet_Descriptor_List_Data_Callback |
Callback prototype for Eet_Descriptor_List_Data.
l | Must be a pointer to the list |
Eet_Descriptor_List_Free_Callback |
Callback prototype for Eet_Descriptor_List_Free.
l | Must be a pointer to the list to free |
Eet_Descriptor_Hash_Foreach_Callback |
Callback for Eet_Descriptor_Hash_Foreach.
h | The hash |
func | The function callback to call on each iteration |
fdt | The data to pass to the callbac setted in param func |
Eet_Descriptor_Hash_Add_Callback |
Callback prototype for Eet_Descriptor_Hash_Add.
h | The hash |
k | The key |
d | The data to associate with the 'k' key |
Eet_Descriptor_Hash_Free_Callback |
Callback prototype for Eet_Descriptor_Hash_Free.
h | The hash to free |
Eet_Descriptor_Type_Get_Callback |
Callback prototype for Eet_Descriptor_Type_Get.
data | Data to pass to the callback |
unknow | Eina_Bool FIXME |
Eet_Descriptor_Type_Set_Callback |
Callback prototype for Eet_Descriptor_Type_Set.
type | The type to set |
data | To pass to the callback |
unknow | Eina_Bool FIXME |
Eet_Descriptor_Array_Alloc_Callback |
Callback prototype for Eet_Descriptor_Array_Alloc.
size | The size of the array |
Eet_Descriptor_Array_Free_Callback |
Callback prototype for Eet_Descriptor_Array_Free.
size | The size of the array |
EINA_DEPRECATED EAPI Eet_Data_Descriptor * eet_data_descriptor_new | ( | const char * | name, |
int | size, | ||
Eet_Descriptor_List_Next_Callback | func_list_next, | ||
Eet_Descriptor_List_Append_Callback | func_list_append, | ||
Eet_Descriptor_List_Data_Callback | func_list_data, | ||
Eet_Descriptor_List_Free_Callback | func_list_free, | ||
Eet_Descriptor_Hash_Foreach_Callback | func_hash_foreach, | ||
Eet_Descriptor_Hash_Add_Callback | func_hash_add, | ||
Eet_Descriptor_Hash_Free_Callback | func_hash_free | ||
) |
Creates a new empty data structure descriptor.
name | The string name of this data structure (most be a global constant and never change). |
size | The size of the struct (in bytes). |
func_list_next | The function to get the next list node. |
func_list_append | The function to append a member to a list. |
func_list_data | The function to get the data from a list node. |
func_list_free | The function to free an entire linked list. |
func_hash_foreach | The function to iterate through all hash table entries. |
func_hash_add | The function to add a member to a hash table. |
func_hash_free | The function to free an entire hash table. |
This function creates a new data descriptor and returns a handle to the new data descriptor. On creation it will be empty, containing no contents describing anything other than the shell of the data structure.
You add structure members to the data descriptor using the macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(), depending on what type of member you are adding to the description.
Once you have described all the members of a struct you want loaded, or saved eet can load and save those members for you, encode them into endian-independent serialised data chunks for transmission across a a network or more.
The function pointers to the list and hash table functions are only needed if you use those data types, else you can pass NULL instead.
References _Eet_Data_Descriptor_Class::hash_add, _Eet_Data_Descriptor_Class::hash_foreach, _Eet_Data_Descriptor_Class::hash_free, _Eet_Data_Descriptor_Class::list_append, _Eet_Data_Descriptor_Class::list_data, _Eet_Data_Descriptor_Class::list_free, _Eet_Data_Descriptor_Class::list_next, _Eet_Data_Descriptor_Class::name, _Eet_Data_Descriptor_Class::size, and _Eet_Data_Descriptor_Class::version.
EAPI Eet_Data_Descriptor * eet_data_descriptor_stream_new | ( | const Eet_Data_Descriptor_Class * | eddc | ) |
This function creates a new data descriptor and returns a handle to the new data descriptor.
On creation it will be empty, containing no contents describing anything other than the shell of the data structure.
eddc | The class from where to create the data descriptor. |
You add structure members to the data descriptor using the macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(), depending on what type of member you are adding to the description.
Once you have described all the members of a struct you want loaded or saved, eet can load and save those members for you, encode them into endian-independent serialised data chunks for transmission across a network or more.
This function specially ignores str_direct_alloc and str_direct_free. It is useful when the eet_data you are reading doesn't have a dictionary, like network stream or IPC. It also mean that all string will be allocated and duplicated in memory.
EAPI Eet_Data_Descriptor * eet_data_descriptor_file_new | ( | const Eet_Data_Descriptor_Class * | eddc | ) |
This function creates a new data descriptor and returns a handle to the new data descriptor.
On creation it will be empty, containing no contents describing anything other than the shell of the data structure.
eddc | The class from where to create the data descriptor. |
You add structure members to the data descriptor using the macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(), depending on what type of member you are adding to the description.
Once you have described all the members of a struct you want loaded or saved, eet can load and save those members for you, encode them into endian-independent serialised data chunks for transmission across a a network or more.
This function uses str_direct_alloc and str_direct_free. It is useful when the eet_data you are reading come from a file and have a dictionary. This will reduce memory use and improve the possibility for the OS to page this string out. However, the load speed and memory saving comes with some drawbacks to keep in mind. If you never modify the contents of the structures loaded from the file, all you need to remember is that closing the eet file will make the strings go away. On the other hand, should you need to free a string, before doing so you have to verify that it's not part of the eet dictionary. You can do this in the following way, assuming ef
is a valid Eet_File and str
is a string loaded from said file.
EAPI Eina_Bool eet_eina_stream_data_descriptor_class_set | ( | Eet_Data_Descriptor_Class * | eddc, |
unsigned int | eddc_size, | ||
const char * | name, | ||
int | size | ||
) |
This function is an helper that set all the parameters of an Eet_Data_Descriptor_Class correctly when you use Eina data type with a stream.
eddc | The Eet_Data_Descriptor_Class you want to set. |
eddc_size | The size of the Eet_Data_Descriptor_Class at the compilation time. |
name | The name of the structure described by this class. |
size | The size of the structure described by this class. |
EINA_TRUE
if the structure was correctly set (The only reason that could make it fail is if you did give wrong parameter).References _Eet_Data_Descriptor_Class::array_alloc, _Eet_Data_Descriptor_Class::array_free, EET_DATA_DESCRIPTOR_CLASS_VERSION, EINA_FALSE, eina_list_append(), eina_list_data_get(), eina_list_free(), eina_list_next(), eina_stringshare_add(), eina_stringshare_del(), EINA_TRUE, _Eet_Data_Descriptor_Class::hash_add, _Eet_Data_Descriptor_Class::hash_foreach, _Eet_Data_Descriptor_Class::hash_free, _Eet_Data_Descriptor_Class::list_append, _Eet_Data_Descriptor_Class::list_data, _Eet_Data_Descriptor_Class::list_free, _Eet_Data_Descriptor_Class::list_next, _Eet_Data_Descriptor_Class::mem_alloc, _Eet_Data_Descriptor_Class::mem_free, _Eet_Data_Descriptor_Class::name, _Eet_Data_Descriptor_Class::size, _Eet_Data_Descriptor_Class::str_alloc, _Eet_Data_Descriptor_Class::str_direct_alloc, _Eet_Data_Descriptor_Class::str_direct_free, _Eet_Data_Descriptor_Class::str_free, _Eet_Data_Descriptor_Class::type_get, _Eet_Data_Descriptor_Class::type_set, and _Eet_Data_Descriptor_Class::version.
Referenced by eet_eina_file_data_descriptor_class_set().
EAPI Eina_Bool eet_eina_file_data_descriptor_class_set | ( | Eet_Data_Descriptor_Class * | eddc, |
unsigned int | eddc_size, | ||
const char * | name, | ||
int | size | ||
) |
This function is an helper that set all the parameter of an Eet_Data_Descriptor_Class correctly when you use Eina data type with a file.
eddc | The Eet_Data_Descriptor_Class you want to set. |
eddc_size | The size of the Eet_Data_Descriptor_Class at the compilation time. |
name | The name of the structure described by this class. |
size | The size of the structure described by this class. |
EINA_TRUE
if the structure was correctly set (The only reason that could make it fail is if you did give wrong parameter).References EET_DATA_DESCRIPTOR_CLASS_VERSION, eet_eina_stream_data_descriptor_class_set(), EINA_FALSE, EINA_TRUE, _Eet_Data_Descriptor_Class::hash_add, _Eet_Data_Descriptor_Class::str_direct_alloc, _Eet_Data_Descriptor_Class::str_direct_free, and _Eet_Data_Descriptor_Class::version.
EAPI void eet_data_descriptor_free | ( | Eet_Data_Descriptor * | edd | ) |
This function frees a data descriptor when it is not needed anymore.
edd | The data descriptor to free. |
This function takes a data descriptor handle as a parameter and frees all data allocated for the data descriptor and the handle itself. After this call the descriptor is no longer valid.
References eet_data_descriptor_free().
Referenced by eet_data_descriptor_free().
EAPI const char * eet_data_descriptor_name_get | ( | const Eet_Data_Descriptor * | edd | ) |
This function returns the name of a data descriptor.
edd | The data descriptor to get name. |
References EINA_SAFETY_ON_NULL_RETURN_VAL.
EAPI void eet_data_descriptor_element_add | ( | Eet_Data_Descriptor * | edd, |
const char * | name, | ||
int | type, | ||
int | group_type, | ||
int | offset, | ||
int | count, | ||
const char * | counter_name, | ||
Eet_Data_Descriptor * | subtype | ||
) |
This function is an internal used by macros.
This function is used by macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(). It is complex to use by hand and should be left to be used by the macros, and thus is not documented.
edd | The data descriptor handle to add element (member). |
name | The name of element to be serialized. |
type | The type of element to be serialized, like EET_T_INT. If EET_T_UNKNOW, then it is considered to be a group, list or hash. |
group_type | If element type is EET_T_UNKNOW, then the group_type will specify if it is a list (EET_G_LIST), array (EET_G_ARRAY) and so on. If EET_G_UNKNOWN, then the member is a subtype (pointer to another type defined by another Eet_Data_Descriptor). |
offset | byte offset inside the source memory to be serialized. |
count | number of elements (if EET_G_ARRAY or EET_G_VAR_ARRAY). |
counter_name | variable that defines the name of number of elements. |
subtype | If contains a subtype, then its data descriptor. |
References eet_data_descriptor_element_add(), EET_G_LAST, EET_G_UNION, EET_G_UNKNOWN, EET_G_VAR_ARRAY, EET_G_VARIANT, EET_T_CHAR, EET_T_F32P32, EET_T_F8P24, EET_T_LAST, EET_T_ULONG_LONG, EET_T_UNKNOW, EINA_FALSE, EINA_SAFETY_ON_NULL_RETURN, EINA_TRUE, and INF.
Referenced by eet_data_descriptor_element_add().
EAPI void * eet_data_read | ( | Eet_File * | ef, |
Eet_Data_Descriptor * | edd, | ||
const char * | name | ||
) |
Reads a data structure from an eet file and decodes it.
ef | The eet file handle to read from. |
edd | The data descriptor handle to use when decoding. |
name | The key the data is stored under in the eet file. |
This function decodes a data structure stored in an eet file, returning a pointer to it if it decoded successfully, or NULL on failure. This can save a programmer dozens of hours of work in writing configuration file parsing and writing code, as eet does all that work for the program and presents a program-friendly data structure, just as the programmer likes. Eet can handle members being added or deleted from the data in storage and safely zero-fills unfilled members if they were not found in the data. It checks sizes and headers whenever it reads data, allowing the programmer to not worry about corrupt data.
Once a data structure has been described by the programmer with the fields they wish to save or load, storing or retrieving a data structure from an eet file, or from a chunk of memory is as simple as a single function call.
References eet_data_read_cipher().
Referenced by edje_edit_group_copy(), and edje_mmap_color_class_used_list().
EAPI int eet_data_write | ( | Eet_File * | ef, |
Eet_Data_Descriptor * | edd, | ||
const char * | name, | ||
const void * | data, | ||
int | compress | ||
) |
Writes a data structure from memory and store in an eet file.
ef | The eet file handle to write to. |
edd | The data descriptor to use when encoding. |
name | The key to store the data under in the eet file. |
data | A pointer to the data structure to save and encode. |
compress | Compression flags for storage. |
0
on failure.This function is the reverse of eet_data_read(), saving a data structure to an eet file. The file must have been opening in write mode and the data will be kept in memory until the file is either closed or eet_sync() is called to flush any unwritten changes.
References eet_data_write_cipher().
Referenced by edje_edit_group_copy(), and edje_edit_without_source_save().
EAPI int eet_data_text_dump | ( | const void * | data_in, |
int | size_in, | ||
Eet_Dump_Callback | dumpfunc, | ||
void * | dumpdata | ||
) |
Dumps an eet encoded data structure into ascii text.
data_in | The pointer to the data to decode into a struct. |
size_in | The size of the data pointed to in bytes. |
dumpfunc | The function to call passed a string when new data is converted to text |
dumpdata | The data to pass to the dumpfunc callback. |
1
on success, 0
on failureThis function will take a chunk of data encoded by eet_data_descriptor_encode() and convert it into human readable ascii text. It does this by calling the dumpfunc
callback for all new text that is generated. This callback should append to any existing text buffer and will be passed the pointer dumpdata
as a parameter as well as a string with new text to be appended.
Example:
EAPI void * eet_data_text_undump | ( | const char * | text, |
int | textlen, | ||
int * | size_ret | ||
) |
Takes an ascii encoding from eet_data_text_dump() and re-encode in binary.
text | The pointer to the string data to parse and encode. |
textlen | The size of the string in bytes (not including 0 byte terminator). |
size_ret | This gets filled in with the encoded data blob size in bytes. |
This function will parse the string pointed to by text
and return an encoded data lump the same way eet_data_descriptor_encode() takes an in-memory data struct and encodes into a binary blob. text
is a normal C string.
References eet_data_text_undump_cipher().
EAPI int eet_data_dump | ( | Eet_File * | ef, |
const char * | name, | ||
Eet_Dump_Callback | dumpfunc, | ||
void * | dumpdata | ||
) |
Dumps an eet encoded data structure from an eet file into ascii text.
ef | A valid eet file handle. |
name | Name of the entry. eg: "/base/file_i_want". |
dumpfunc | The function to call passed a string when new data is converted to text |
dumpdata | The data to pass to the dumpfunc callback. |
1
on success, 0
on failureThis function will take an open and valid eet file from eet_open() request the data encoded by eet_data_descriptor_encode() corresponding to the key name
and convert it into human readable ascii text. It does this by calling the dumpfunc
callback for all new text that is generated. This callback should append to any existing text buffer and will be passed the pointer dumpdata
as a parameter as well as a string with new text to be appended.
EAPI int eet_data_undump | ( | Eet_File * | ef, |
const char * | name, | ||
const char * | text, | ||
int | textlen, | ||
int | compress | ||
) |
Takes an ascii encoding from eet_data_dump() and re-encode in binary.
ef | A valid eet file handle. |
name | Name of the entry. eg: "/base/file_i_want". |
text | The pointer to the string data to parse and encode. |
textlen | The size of the string in bytes (not including 0 byte terminator). |
compress | Compression flags (1 == compress, 0 = don't compress). |
1
on success, 0
on failureThis function will parse the string pointed to by text
, encode it the same way eet_data_descriptor_encode() takes an in-memory data struct and encodes into a binary blob.
The data (optionally compressed) will be in ram, pending a flush to disk (it will stay in ram till the eet file handle is closed though).
References eet_data_undump_cipher().
EAPI void * eet_data_descriptor_decode | ( | Eet_Data_Descriptor * | edd, |
const void * | data_in, | ||
int | size_in | ||
) |
Decodes a data structure from an arbitrary location in memory.
edd | The data descriptor to use when decoding. |
data_in | The pointer to the data to decode into a struct. |
size_in | The size of the data pointed to in bytes. |
This function will decode a data structure that has been encoded using eet_data_descriptor_encode(), and return a data structure with all its elements filled out, if successful, or NULL on failure.
The data to be decoded is stored at the memory pointed to by data_in
, and is described by the descriptor pointed to by edd
. The data size is passed in as the value to size_in
, and must be greater than 0 to succeed.
This function is useful for decoding data structures delivered to the application by means other than an eet file, such as an IPC or socket connection, raw files, shared memory etc.
Please see eet_data_read() for more information.
References eet_data_descriptor_decode_cipher().
EAPI void * eet_data_descriptor_encode | ( | Eet_Data_Descriptor * | edd, |
const void * | data_in, | ||
int * | size_ret | ||
) |
Encodes a dsata struct to memory and return that encoded data.
edd | The data descriptor to use when encoding. |
data_in | The pointer to the struct to encode into data. |
size_ret | pointer to the an int to be filled with the decoded size. |
This function takes a data structure in memory and encodes it into a serialised chunk of data that can be decoded again by eet_data_descriptor_decode(). This is useful for being able to transmit data structures across sockets, pipes, IPC or shared file mechanisms, without having to worry about memory space, machine type, endianness etc.
The parameter edd
must point to a valid data descriptor, and data_in
must point to the right data structure to encode. If not, the encoding may fail.
On success a non NULL valid pointer is returned and what size_ret
points to is set to the size of this decoded data, in bytes. When the encoded data is no longer needed, call free() on it. On failure NULL is returned and what size_ret
points to is set to 0.
Please see eet_data_write() for more information.
References eet_data_descriptor_encode_cipher().