# native_child_process.h
## Overview
The **native_child_process.h** file declares the APIs used to create a native child process and establish an IPC channel between the main process and child process. A maximum of 512 child processes can be started through this module and [childProcessManager](js-apis-app-ability-childProcessManager.md) (non-SELF_FORK mode).
**Library**: libchild_process.so
**System capability**: SystemCapability.Ability.AbilityRuntime.Core
**Since**: 12
**Related module**: [ChildProcess](c-apis-ability-childprocess.md)
## Summary
### Files
| Name | Description |
| ------------------------------------------------------ | -------------------------------------------------------------------------------------------------- |
| [native_child_process.h](native__child__process_8h.md) | Declares the APIs used to create a native child process and establish an IPC channel between the main process and child process.
File to include:
Library: libchild_process.so|
### Types
| Name | Description |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ----------------- |
| typedef enum Ability_NativeChildProcess_ErrCode [Ability_NativeChildProcess_ErrCode](c-apis-ability-childprocess.md#ability_nativechildprocess_errcode) | Defines an enum for the error codes used by the native child process module.|
| typedef void(\* [OH_Ability_OnNativeChildProcessStarted](c-apis-ability-childprocess.md#oh_ability_onnativechildprocessstarted)) (int errCode, OHIPCRemoteProxy \*remoteProxy) | Defines a callback function for notifying the child process startup result.|
| typedef struct [NativeChildProcess_Fd](c-apis-ability-childprocess.md#nativechildprocess_fd) | Defines a struct for the file descriptor of a child process.|
| typedef struct [NativeChildProcess_FdList](c-apis-ability-childprocess.md#nativechildprocess_fdlist) | Defines a struct for the linked list of file descriptors of a child process.|
| typedef struct [NativeChildProcess_Args](c-apis-ability-childprocess.md#nativechildprocess_args) | Defines a struct for the arguments used for starting a child process.|
| typedef struct [NativeChildProcess_Options](c-apis-ability-childprocess.md#nativechildprocess_options) | Defines a struct for the startup configuration options of a child process.|
### Enums
| Name | Description |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------- |
| [Ability_NativeChildProcess_ErrCode](c-apis-ability-childprocess.md#ability_nativechildprocess_errcode) {
NCP_NO_ERROR = 0,
NCP_ERR_INVALID_PARAM = 401,
NCP_ERR_NOT_SUPPORTED = 801,
NCP_ERR_INTERNAL = 16000050,
NCP_ERR_BUSY = 16010001,
NCP_ERR_TIMEOUT = 16010002,
NCP_ERR_SERVICE_ERROR = 16010003,
NCP_ERR_MULTI_PROCESS_DISABLED = 16010004,
NCP_ERR_ALREADY_IN_CHILD = 16010005,
NCP_ERR_MAX_CHILD_PROCESSES_REACHED = 16010006,
NCP_ERR_LIB_LOADING_FAILED = 16010007,
NCP_ERR_CONNECTION_FAILED = 16010008
} | Enumerates the error codes used by the native child process module.|
| [NativeChildProcess_IsolationMode](c-apis-ability-childprocess.md#nativechildprocess_isolationmode) {
NCP_ISOLATION_MODE_NORMAL = 0,
NCP_ISOLATION_MODE_ISOLATED = 1,
} | Enumerates the isolation modes of a child process.|
### Functions
| Name | Description |
| ------------------------------------------------------------ | ------------------------------------------------------------ |
| int [OH_Ability_CreateNativeChildProcess](c-apis-ability-childprocess.md#oh_ability_createnativechildprocess) (const char \*libName, [OH_Ability_OnNativeChildProcessStarted](c-apis-ability-childprocess.md#oh_ability_onnativechildprocessstarted) onProcessStarted) | Creates a child process, loads the specified dynamic library file, and returns the startup result asynchronously through a callback parameter. The callback notification is an independent thread. When implementing the callback function, pay attention to thread synchronization and do not perform time-consuming operations to avoid long-time blocking.
NOTE
Currently, this function is valid only for 2-in-1 devices, and a process can start only one native child process by using this function. |
| [Ability_NativeChildProcess_ErrCode](c-apis-ability-childprocess.md#ability_nativechildprocess_errcode) [OH_Ability_StartNativeChildProcess](c-apis-ability-childprocess.md#oh_ability_startnativechildprocess)(const char\* entry, [NativeChildProcess_Args](c-apis-ability-childprocess.md#nativechildprocess_args) args, [NativeChildProcess_Options](c-apis-ability-childprocess.md#nativechildprocess_options) options, int32_t *pid) | Starts a child process, loads the specified dynamic library file, and calls the entry function. Arguments can be passed to the child process.
NOTE
Currently, this function is valid only for 2-in-1 devices and tablets. |