# Core ## **Overview** Provides OpenHarmony Driver Foundation \(HDF\) APIs. The HDF implements driver framework capabilities such as driver loading, service management, and driver message model. You can develop drivers based on the HDF. **Since:** 1.0 ## **Summary** ## Files

File Name

Description

hdf_device_desc.h

Declares functions related to driver loading, service obtaining, and power management.

hdf_io_service_if.h

Declares the structures defining driver service objects and event listeners, as well as the functions for obtaining a driver service object, dispatching a driver service call, and registering or unregistering an event listener.

hdf_object.h

Declares the base object provided by the HDF for the driver.

hdf_sbuf.h

Defines functions related to a HdfSBuf. The HDF provides data serialization and deserialization capabilities for data transmission between user-mode applications and kernel-mode drivers.

## Data Structures

Data Structure Name

Description

HdfDeviceObject

Defines the device object.

HdfDeviceIoClient

Defines the client object structure of the I/O service.

IDeviceIoService

Defines the driver service.

SubscriberCallback

Called when the driver subscribes to other driver services.

IPowerEventListener

Defines the power management functions provided by the HDF for the driver.

HdfDriverEntry

Defines the entry structure of the driver in the HDF.

HdfDevEventlistener

Defines a driver event listener object.

HdfIoDispatcher

Defines a driver service call dispatcher.

HdfIoService

Defines a driver service object.

HdfObject

Describes base class objects defined by the HDF.

HdfSBuf

Defines a HdfSBuf.

## Macros

Macro Name and Value

Description

MAX_PRIORITY_NUM    200

The maximum priority for loading the host and device.

HDF_INIT(module)   HDF_DRIVER_INIT(module)

Registers the driver with the HDF.

## Typedefs

Typedef Name

Description

OnEventReceived) (void *priv, uint32_t id, struct HdfSBuf *data)

typedef int(* 

Called when a driver event occurs.

## Enumerations

Enumeration Name

Description

ServicePolicy {   SERVICE_POLICY_NONE = 0, SERVICE_POLICY_PUBLIC, SERVICE_POLICY_CAPACITY, SERVICE_POLICY_FRIENDLY,   SERVICE_POLICY_PRIVATE, SERVICE_POLICY_INVALID }

Enumerates policies for releasing driver services developed based on the HDF.

DevicePreload { DEVICE_PRELOAD_ENABLE = 0, DEVICE_PRELOAD_DISABLE, DEVICE_PRELOAD_INVALID }

Enumerates driver loading policies.

## Functions

Function Name

Description

DevSvcManagerClntGetService (const char *svcName)

const struct HdfObject * 

Obtains the driver service object based on a driver service name.

HdfDeviceGetServiceName (const struct HdfDeviceObject *deviceObject)

const char * 

Obtains the service name of a driver.

HdfDeviceSubscribeService (struct HdfDeviceObject *deviceObject, const char *serviceName, struct SubscriberCallback callback)

int32_t 

Subscribes to a driver service.

HdfDeviceSendEvent (const struct HdfDeviceObject *deviceObject, uint32_t id, const struct HdfSBuf *data)

int32_t 

Sends event messages.

HdfDeviceSendEventToClient (const struct HdfDeviceIoClient *client, uint32_t id, const struct HdfSBuf *data)

int32_t 

Sends an event message to a specified client object.

HdfIoServiceBind (const char *serviceName, mode_t permission)

struct HdfIoService * 

Obtains a driver service object.

HdfIoServiceRecycle (struct HdfIoService *service)

void 

Destroys a specified driver service object to release resources if it is no longer required.

HdfDeviceRegisterEventListener (struct HdfIoService *target, struct HdfDevEventlistener *listener)

int 

Registers a custom HdfDevEventlistener for listening for events reported by a specified driver service object.

HdfDeviceUnregisterEventListener (struct HdfIoService *target, struct HdfDevEventlistener *listener)

int 

Unregisters a previously registered HdfDevEventlistener to release resources if it is no longer required.

HdfSbufWriteBuffer (struct HdfSBuf *sbuf, const void *data, uint32_t writeSize)

bool 

Writes a data segment to a SBuf.

HdfSbufWriteUint64 (struct HdfSBuf *sbuf, uint64_t value)

bool 

Writes a 64-bit unsigned integer to a SBuf.

HdfSbufWriteUint32 (struct HdfSBuf *sbuf, uint32_t value)

bool 

Writes a 32-bit unsigned integer to a SBuf.

HdfSbufWriteUint16 (struct HdfSBuf *sbuf, uint16_t value)

bool 

Writes a 16-bit unsigned integer to a SBuf.

HdfSbufWriteUint8 (struct HdfSBuf *sbuf, uint8_t value)

bool 

Writes an 8-bit unsigned integer to a SBuf.

HdfSbufWriteInt64 (struct HdfSBuf *sbuf, int64_t value)

bool 

Writes a 64-bit signed integer to a SBuf.

HdfSbufWriteInt32 (struct HdfSBuf *sbuf, int32_t value)

bool 

Writes a 32-bit signed integer to a SBuf.

HdfSbufWriteInt16 (struct HdfSBuf *sbuf, int16_t value)

bool 

Writes a 16-bit signed integer to a SBuf.

HdfSbufWriteInt8 (struct HdfSBuf *sbuf, int8_t value)

bool 

Writes an 8-bit signed integer to a SBuf.

HdfSbufWriteString (struct HdfSBuf *sbuf, const char *value)

bool 

Writes a string to a SBuf.

HdfSbufReadBuffer (struct HdfSBuf *sbuf, const void **data, uint32_t *readSize)

bool 

Reads a data segment from a SBuf.

HdfSbufReadUint64 (struct HdfSBuf *sbuf, uint64_t *value)

bool 

Reads a 64-bit unsigned integer from a SBuf.

HdfSbufReadUint32 (struct HdfSBuf *sbuf, uint32_t *value)

bool 

Reads a 32-bit unsigned integer from a SBuf.

HdfSbufReadUint16 (struct HdfSBuf *sbuf, uint16_t *value)

bool 

Reads a 16-bit unsigned integer from a SBuf.

HdfSbufReadUint8 (struct HdfSBuf *sbuf, uint8_t *value)

bool 

Reads an 8-bit unsigned integer from a SBuf.

HdfSbufReadInt64 (struct HdfSBuf *sbuf, int64_t *value)

bool 

Reads a 64-bit signed integer from a SBuf.

HdfSbufReadInt32 (struct HdfSBuf *sbuf, int32_t *value)

bool 

Reads a 32-bit signed integer from a SBuf.

HdfSbufReadInt16 (struct HdfSBuf *sbuf, int16_t *value)

bool 

Reads a 16-bit signed integer from a SBuf.

HdfSbufReadInt8 (struct HdfSBuf *sbuf, int8_t *value)

bool 

Reads an 8-bit signed integer from a SBuf.

HdfSbufReadString (struct HdfSBuf *sbuf)

const char * 

Reads a string from a SBuf.

HdfSbufGetData (const struct HdfSBuf *sbuf)

uint8_t * 

Obtains the pointer to the data stored in aSBuf.

HdfSbufFlush (struct HdfSBuf *sbuf)

void 

Clears the data stored in a SBuf.

HdfSbufGetCapacity (const struct HdfSBuf *sbuf)

size_t 

Obtains the capacity of a SBuf.

HdfSbufGetDataSize (const struct HdfSBuf *sbuf)

size_t 

Obtains the size of the data stored in a SBuf.

HdfSBufObtain (size_t capacity)

struct HdfSBuf * 

Obtains a SBuf instance.

HdfSBufObtainDefaultSize (void)

struct HdfSBuf * 

Obtains a SBuf instance of the default capacity (256 bytes).

HdfSBufBind (uintptr_t base, size_t size)

struct HdfSBuf * 

Creates a SBuf instance with the specified data and size. The pointer to the data stored in the SBuf is released by the caller, and the written data size should not exceed the specified value of size.

HdfSBufRecycle (struct HdfSBuf *sbuf)

void 

Releases a SBuf .

HdfSBufMove (struct HdfSBuf *sbuf)

struct HdfSBuf * 

Creates a SBuf instance with an original SBuf. This function moves the data stored in the original SBuf to the new one without memory copy.

HdfSBufCopy (const struct HdfSBuf *sbuf)

struct HdfSBuf * 

Creates a SBuf instance with an original SBuf. This function copies the data stored in the original SBuf to the new one.

HdfSbufTransDataOwnership (struct HdfSBuf *sbuf)

void 

Transfers the data ownership to a SBuf. Once the SBuf is released, the bound data memory is also released. This function is used together with HdfSBufBind.

## **Details** ## **Macro Definition Documentation** ## HDF\_INIT ``` #define HDF_INIT( module)   HDF_DRIVER_INIT(module) ``` **Description:** Registers the driver with the HDF. For a driver developed based on the HDF, [HDF\_INIT](Core.md#ga99831072fdca13e3c423a14fa6a83c34) must be used to register an entry with the HDF, and the registered object must be of the [HdfDriverEntry](HdfDriverEntry.md) type. **Parameters:**

Name

Description
module Indicates the global variable of the HdfDriverEntry type
## **Typedef Documentation** ## OnEventReceived ``` typedef int(* OnEventReceived) (void *priv, uint32_t id, struct [HdfSBuf](HdfSBuf.md) *data) ``` **Description:** Called when a driver event occurs. You can implement this function and bind it to the custom [HdfDevEventlistener](HdfDevEventlistener.md) object. **Parameters:**

Name

Description
priv Indicates the pointer to the private data bound to this listener.
id Indicates the serial number of the driver event occurred.
data Indicates the pointer to the content data of the driver event.
**Returns:** Returns **0** if the operation is successful; returns a negative value otherwise. ## **Enumeration Type Documentation** ## DevicePreload ``` enum [DevicePreload](Core.md#ga0f3d81b5ff5d3896f7d8cf15f76b451e) ``` **Description:** Enumerates driver loading policies. If a driver developed based on the HDF needs to use the on-demand loading mechanism in the HDF, the **PRELOAD** field must be correctly set in the driver configuration information to control the driver loading mode.

Enumerator

Description
DEVICE_PRELOAD_ENABLE 

The driver is loaded during system startup by default.

DEVICE_PRELOAD_DISABLE 

The driver is not loaded during system startup by default.

DEVICE_PRELOAD_INVALID 

The loading policy is incorrect.

## ServicePolicy ``` enum [ServicePolicy](Core.md#ga172844da8a6908bf7226eee703ad9f80) ``` **Description:** Enumerates policies for releasing driver services developed based on the HDF. If a driver is developed based on the HDF and uses the service management feature of the HDF, you need to configure the policy for releasing services to external systems.

Enumerator

Description
SERVICE_POLICY_NONE 

The driver does not provide services externally.

SERVICE_POLICY_PUBLIC 

The driver provides services for kernel-level applications.

SERVICE_POLICY_CAPACITY 

The driver provides services for both kernel- and user-level applications.

SERVICE_POLICY_FRIENDLY 

Driver services are not released externally but can be subscribed to.

SERVICE_POLICY_PRIVATE 

Driver services are only internally available. They are not released externally and cannot be subscribed to by external users.

SERVICE_POLICY_INVALID 

The service policy is incorrect.

## **Function Documentation** ## DevSvcManagerClntGetService\(\) ``` const struct [HdfObject](HdfObject.md)* DevSvcManagerClntGetService (const char * svcName) ``` **Description:** Obtains the driver service object based on a driver service name. **Parameters:**

Name

Description
serviceName Indicates the pointer to the released driver service name.
**Returns:** Returns the driver service object if the operation is successful; returns **NULL** otherwise. ## HdfDeviceGetServiceName\(\) ``` const char* HdfDeviceGetServiceName (const struct [HdfDeviceObject](HdfDeviceObject.md) * deviceObject) ``` **Description:** Obtains the service name of a driver. If a driver does not save its service name, it can use this function to obtain the service name. **Parameters:**

Name

Description
deviceObject Indicates the pointer to the driver device object.
**Returns:** Returns the service name if the operation is successful; returns **NULL** otherwise. ## HdfDeviceRegisterEventListener\(\) ``` int HdfDeviceRegisterEventListener (struct [HdfIoService](HdfIoService.md) * target, struct [HdfDevEventlistener](HdfDevEventlistener.md) * listener ) ``` **Description:** Registers a custom [HdfDevEventlistener](HdfDevEventlistener.md) for listening for events reported by a specified driver service object. **Parameters:**

Name

Description
target Indicates the pointer to the driver service object to listen, which is obtained through the HdfIoServiceBind function.
listener Indicates the pointer to the listener to register.
**Returns:** Returns **0** if the operation is successful; returns a negative value otherwise. ## HdfDeviceSendEvent\(\) ``` int32_t HdfDeviceSendEvent (const struct [HdfDeviceObject](HdfDeviceObject.md) * deviceObject, uint32_t id, const struct [HdfSBuf](HdfSBuf.md) * data ) ``` **Description:** Sends event messages. When the driver service invokes this function to send a message, all user-level applications that have registered listeners through [HdfDeviceRegisterEventListener](Core.md#gaa7855b3930b5378954927548e5623663) will receive the message. **Parameters:**

Name

Description
deviceObject Indicates the pointer to the driver device object.
id Indicates the ID of the message sending event.
data Indicates the pointer to the message content sent by the driver.
**Returns:** Returns **0** if the operation is successful; returns a non-zero value otherwise. ## HdfDeviceSendEventToClient\(\) ``` int32_t HdfDeviceSendEventToClient (const struct [HdfDeviceIoClient](HdfDeviceIoClient.md) * client, uint32_t id, const struct [HdfSBuf](HdfSBuf.md) * data ) ``` **Description:** Sends an event message to a specified client object. When the driver service invokes this function to send a message, the user-level applications that have registered listeners through [HdfDeviceRegisterEventListener](Core.md#gaa7855b3930b5378954927548e5623663) and correspond to this client object will receive the message. **Parameters:**

Name

Description
client Indicates the pointer to the client object of the driver service.
id Indicates the ID of the message sending event.
data Indicates the pointer to the message content sent by the driver.
**Returns:** Returns **0** if the operation is successful; returns a non-zero value otherwise. ## HdfDeviceSubscribeService\(\) ``` int32_t HdfDeviceSubscribeService (struct [HdfDeviceObject](HdfDeviceObject.md) * deviceObject, const char * serviceName, struct [SubscriberCallback](SubscriberCallback.md) callback ) ``` **Description:** Subscribes to a driver service. If the driver loading time is not perceived, this function can be used to subscribe to the driver service. \(The driver service and the subscriber must be on the same host.\) After the subscribed-to driver service is loaded by the HDF, the framework proactively releases the service interface to the subscriber. **Parameters:**

Name

Description
deviceObject Indicates the pointer to the driver device object of the subscriber.
serviceName Indicates the pointer to the driver service name.
callback Indicates the callback invoked by the HDF after the subscribed-to driver service is loaded.
**Returns:** Returns **0** if the operation is successful; returns a non-zero value otherwise. ## HdfDeviceUnregisterEventListener\(\) ``` int HdfDeviceUnregisterEventListener (struct [HdfIoService](HdfIoService.md) * target, struct [HdfDevEventlistener](HdfDevEventlistener.md) * listener ) ``` **Description:** Unregisters a previously registered [HdfDevEventlistener](HdfDevEventlistener.md) to release resources if it is no longer required. **Parameters:**

Name

Description
target Indicates the pointer to the driver service object that has been listened.
listener Indicates the listener object registered by HdfDeviceRegisterEventListener.
**Returns:** Returns **0** if the operation is successful; returns a negative value otherwise. ## HdfIoServiceBind\(\) ``` struct [HdfIoService](HdfIoService.md)* HdfIoServiceBind (const char * serviceName, mode_t permission ) ``` **Description:** Obtains a driver service object. **Parameters:**

Name

Description
serviceName Indicates the pointer to the name of the service to obtain.
permission Indicates the permission to create device nodes. The default value 0 can be used when this function is called from user space.
**Returns:** Returns the pointer to the driver service object if the operation is successful; returns **NULL** otherwise. ## HdfIoServiceRecycle\(\) ``` void HdfIoServiceRecycle (struct [HdfIoService](HdfIoService.md) * service) ``` **Description:** Destroys a specified driver service object to release resources if it is no longer required. **Parameters:**

Name

Description
service Indicates the pointer to the driver service object to destroy.
## HdfSBufBind\(\) ``` struct [HdfSBuf](HdfSBuf.md)* HdfSBufBind (uintptr_t base, size_t size ) ``` **Description:** Creates a **SBuf** instance with the specified data and size. The pointer to the data stored in the **SBuf** is released by the caller, and the written data size should not exceed the specified value of **size**. **Parameters:**

Name

Description
base Indicates the base of the data to use.
size Indicates the size of the data to use.
**Returns:** Returns the **SBuf** instance. ## HdfSBufCopy\(\) ``` struct [HdfSBuf](HdfSBuf.md)* HdfSBufCopy (const struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Creates a **SBuf** instance with an original **SBuf**. This function copies the data stored in the original **SBuf** to the new one. **Parameters:**

Name

Description
sbuf Indicates the pointer to the original SBuf.
**Returns:** Returns the new **SBuf** instance. ## HdfSbufFlush\(\) ``` void HdfSbufFlush (struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Clears the data stored in a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
## HdfSbufGetCapacity\(\) ``` size_t HdfSbufGetCapacity (const struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Obtains the capacity of a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
**Returns:** Returns the **SBuf** capacity. ## HdfSbufGetData\(\) ``` uint8_t* HdfSbufGetData (const struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Obtains the pointer to the data stored in a**SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
**Returns:** Returns the pointer to the data stored in the target **SBuf**. ## HdfSbufGetDataSize\(\) ``` size_t HdfSbufGetDataSize (const struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Obtains the size of the data stored in a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
**Returns:** Returns the data size. ## HdfSBufMove\(\) ``` struct [HdfSBuf](HdfSBuf.md)* HdfSBufMove (struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Creates a **SBuf** instance with an original **SBuf**. This function moves the data stored in the original **SBuf** to the new one without memory copy. **Parameters:**

Name

Description
sbuf Indicates the pointer to the original SBuf.
**Returns:** Returns the new **SBuf** instance. ## HdfSBufObtain\(\) ``` struct [HdfSBuf](HdfSBuf.md)* HdfSBufObtain (size_t capacity) ``` **Description:** Obtains a **SBuf** instance. **Parameters:**

Name

Description
capacity Indicates the initial capacity of theSBuf.
**Returns:** Returns the **SBuf** instance. ## HdfSBufObtainDefaultSize\(\) ``` struct [HdfSBuf](HdfSBuf.md)* HdfSBufObtainDefaultSize (void ) ``` **Description:** Obtains a **SBuf** instance of the default capacity \(256 bytes\). **Returns:** Returns the **SBuf** instance. ## HdfSbufReadBuffer\(\) ``` bool HdfSbufReadBuffer (struct [HdfSBuf](HdfSBuf.md) * sbuf, const void ** data, uint32_t * readSize ) ``` **Description:** Reads a data segment from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
data Indicates the double pointer to the data read. The data read is stored in *data, which is requested by the caller. The memory pointed to by *data is managed by the SBuf and they share the same lifecycle.
readSize Indicates the pointer to the size of the data read.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadInt16\(\) ``` bool HdfSbufReadInt16 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int16_t * value ) ``` **Description:** Reads a 16-bit signed integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 16-bit signed integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadInt32\(\) ``` bool HdfSbufReadInt32 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int32_t * value ) ``` **Description:** Reads a 32-bit signed integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 32-bit signed integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadInt64\(\) ``` bool HdfSbufReadInt64 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int64_t * value ) ``` **Description:** Reads a 64-bit signed integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 64-bit signed integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadInt8\(\) ``` bool HdfSbufReadInt8 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int8_t * value ) ``` **Description:** Reads an 8-bit signed integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 8-bit signed integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadString\(\) ``` const char* HdfSbufReadString (struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Reads a string from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
**Returns:** Returns the pointer to the string read if the operation is successful; returns **NULL** otherwise. The memory pointed to by this pointer is managed by the **SBuf** and they share the same lifecycle. ## HdfSbufReadUint16\(\) ``` bool HdfSbufReadUint16 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint16_t * value ) ``` **Description:** Reads a 16-bit unsigned integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 16-bit unsigned integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadUint32\(\) ``` bool HdfSbufReadUint32 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint32_t * value ) ``` **Description:** Reads a 32-bit unsigned integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 32-bit unsigned integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadUint64\(\) ``` bool HdfSbufReadUint64 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint64_t * value ) ``` **Description:** Reads a 64-bit unsigned integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 64-bit unsigned integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufReadUint8\(\) ``` bool HdfSbufReadUint8 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint8_t * value ) ``` **Description:** Reads an 8-bit unsigned integer from a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the 8-bit unsigned integer read, which is requested by the caller.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSBufRecycle\(\) ``` void HdfSBufRecycle (struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Releases a **SBuf **. **Parameters:**

Name

Description
sbuf Indicates the pointer to the SBuf to release.
## HdfSbufTransDataOwnership\(\) ``` void HdfSbufTransDataOwnership (struct [HdfSBuf](HdfSBuf.md) * sbuf) ``` **Description:** Transfers the data ownership to a **SBuf**. Once the **SBuf** is released, the bound data memory is also released. This function is used together with [HdfSBufBind](Core.md#gabcc9a442a3b2615828d60a1d4664b4a9). **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
## HdfSbufWriteBuffer\(\) ``` bool HdfSbufWriteBuffer (struct [HdfSBuf](HdfSBuf.md) * sbuf, const void * data, uint32_t writeSize ) ``` **Description:** Writes a data segment to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
data Indicates the pointer to the data segment to write.
writeSize Indicates the size of the data segment to write. The maximum value is 512 KB.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteInt16\(\) ``` bool HdfSbufWriteInt16 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int16_t value ) ``` **Description:** Writes a 16-bit signed integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 16-bit signed integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteInt32\(\) ``` bool HdfSbufWriteInt32 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int32_t value ) ``` **Description:** Writes a 32-bit signed integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 32-bit signed integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteInt64\(\) ``` bool HdfSbufWriteInt64 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int64_t value ) ``` **Description:** Writes a 64-bit signed integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 64-bit signed integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteInt8\(\) ``` bool HdfSbufWriteInt8 (struct [HdfSBuf](HdfSBuf.md) * sbuf, int8_t value ) ``` **Description:** Writes an 8-bit signed integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 8-bit signed integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteString\(\) ``` bool HdfSbufWriteString (struct [HdfSBuf](HdfSBuf.md) * sbuf, const char * value ) ``` **Description:** Writes a string to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the pointer to the string to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteUint16\(\) ``` bool HdfSbufWriteUint16 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint16_t value ) ``` **Description:** Writes a 16-bit unsigned integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 16-bit unsigned integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteUint32\(\) ``` bool HdfSbufWriteUint32 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint32_t value ) ``` **Description:** Writes a 32-bit unsigned integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 32-bit unsigned integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteUint64\(\) ``` bool HdfSbufWriteUint64 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint64_t value ) ``` **Description:** Writes a 64-bit unsigned integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 64-bit unsigned integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise. ## HdfSbufWriteUint8\(\) ``` bool HdfSbufWriteUint8 (struct [HdfSBuf](HdfSBuf.md) * sbuf, uint8_t value ) ``` **Description:** Writes an 8-bit unsigned integer to a **SBuf**. **Parameters:**

Name

Description
sbuf Indicates the pointer to the target SBuf.
value Indicates the 8-bit unsigned integer to write.
**Returns:** Returns **true** if the operation is successful; returns **false** otherwise.