General socket operations
[MiniGUI-Processes specific functions]

Defines

• #define sock_write(fd, buff, count)   sock_write_t(fd, buff, count, 0)

  The blocking version of sock_write_t function.
  

• #define sock_read(fd, buff, count)   sock_read_t(fd, buff, count, 0)

  The blocking version of sock_read_t function.
  

Functions

• MG_EXPORT int serv_listen (const char *name)

  Creates a listen socket.
  

• MG_EXPORT int serv_accept (int listenfd, pid_t *pidptr, uid_t *uidptr)

  Waits for a client connection to arrive, and accept it.
  

• MG_EXPORT int cli_conn (const char *name, char project)

  Used by clients to connect to a server.
  

• MG_EXPORT int sock_write_t (int fd, const void *buff, int count, unsigned int timeout)

  Writes data to socket.
  

• MG_EXPORT int sock_read_t (int fd, void *buff, int count, unsigned int timeout)

  Reads data from socket.
  

---

Detailed Description

MiniGUI-Processes uses UNIX domain socket to build the communication between the server and the clients.

You can also use the underlay interfaces which MiniGUI uses to create your own UNIX domain socket.

Example:

#define LISTEN_SOCKET    "/var/tmp/mysocket"

static int listen_fd;

BOOL listen_socket (HWND hwnd)
{
    if ((listen_fd = serv_listen (LISTEN_SOCKET)) < 0)
        return FALSE;
    return RegisterListenFD (fd, POLL_IN, hwnd, NULL);
}

/* 
 * When the server receives the request to connect from a client,
 * the window hwnd will receive a MSG_FDEVENT message.
 * Now the server can accept the request.
 */
int MyWndProc (HWND hwnd, int message, WPARAM wParam, LPARAM lParam)
{
    switch (message) {
        
        ...
        
        case MSG_FDEVENT:
             if (LOWORD (wParam) == listen_fd) { 
                  /* This message comes from the listen socket fd. */
                  pid_t pid;
                  uid_t uid;
                  int conn_fd;
                  conn_fd = serv_accept (listen_fd, &pid, &uid);
                  if (conn_fd >= 0) {
                       RegisterListenFD (conn_fd, POLL_IN, hwnd, NULL);
                  }
             }
             else { 
                  /* Client send a request. */
                  int fd = LOWORD(wParam);
                  /* Handle the request from client. */
                  sock_read_t (fd, ...);
                  sock_write_t (fd, ....);
             }
        break;
        
        ...
        
    }
}

/*
 * Clients can use the following code to connect itself to the server.
 */

    int conn_fd;
    
    if ((conn_fd  = cli_conn (LISTEN_SOCKET, 'b')) >= 0) {
        /* Send a request to the server. */
        sock_write_t (fd, ....);
        /* Get the reply from the server. */
        sock_read_t (fd, ....);
    }

---

Define Documentation

#define sock_read	(	fd,
		buff,
		count		)	sock_read_t(fd, buff, count, 0)

The blocking version of sock_read_t function.

See also:

sock_read_t

Definition at line 1368 of file minigui.h.

#define sock_write	(	fd,
		buff,
		count		)	sock_write_t(fd, buff, count, 0)

The blocking version of sock_write_t function.

See also:

sock_write_t

Definition at line 1360 of file minigui.h.

---

Function Documentation

int cli_conn	(	const char *	name,
		char	project
	)

Used by clients to connect to a server.

This function is used by clients to connect to a server.

The created socket will be located at the directory '/var/tmp', and with name of '/var/tmp/xxxxx-c', where 'xxxxx' is the pid of client. and 'c' is a character to distinguish different projects.

Note that MiniGUI itself uses 'a' as the project character to create socket between 'mginit' and clients.

Parameters:

	name	The name of the well-known listen socket (created by server).
	project	A character to distinguish different projects (Do NOT use 'a').

Returns:

The new connected fd if all OK, < 0 on error.

See also:

serv_listen, serv_accept

int serv_accept	(	int	listenfd,
		pid_t *	pidptr,
		uid_t *	uidptr
	)

Waits for a client connection to arrive, and accept it.

This function is used by the server to wait a connection and accept it.

After creating a listening socket by calling serv_listen, you can call this function to create a connection with a client. We also obtain the client's PID and UID from the pathname that it must bind before calling us.

Parameters:

	listenfd	The fd of listen socket.
	pidptr	The client PID will be saved to this buffer when this function returns.
	uidptr	The client UID will be saved to this buffer when this function returns.

Returns:

The new connected fd if all OK, < 0 on error.

See also:

serv_listen, cli_conn

int serv_listen

(

const char *

name

)

Creates a listen socket.

This function is used by the server to create a listening socket. Any MiniGUI-Processes application can call this function to create a listening socket. The server, i.e. mginit, of MiniGUI-Processes uses this function to create its listening socket, and named the socket to '/var/tmp/minigui'.

Parameters:

name

The path name of the listening socket.

Returns:

The file discriptor of the listening socket created, -1 on error.

Note:

As a convention, you should located the socket in '/var/tmp/' directory.

int sock_read_t	(	int	fd,
		void *	buff,
		int	count,
		unsigned int	timeout
	)

Reads data from socket.

This function reads data which is count bytes long to the buffer buff from the socket fd.

Parameters:

	fd	The file descriptor of the socket.
	buff	The buffer used to save the data.
	count	The length in bytes of the buffer.
	timeout	An upper bound on the amount of time elapsed before sock_read_t returns. When it is zero, sock_read_t can block indefinitely. The timeout value is in the tick count of MiniGUI, and tick count of MiniGUI is in unit of 10 milliseconds.

Returns:

SOCKERR_OK if all OK, < 0 on error.

Return values:

	SOCKERR_OK	Read data successfully.
	SOCKERR_IO	There are some I/O errors occurred.
	SOCKERR_CLOSED	The socket has been closed by the peer.
	SOCKERR_INVARG	You passed invalid arguments.
	SOCKERR_TIMEOUT	Timeout.

Note:

The timeout only goes into effect when this function called by the server of MiniGUI-Processes, i.e. mginit.

See also:

sock_write_t

int sock_write_t	(	int	fd,
		const void *	buff,
		int	count,
		unsigned int	timeout
	)

Writes data to socket.

This function writes the data block pointed to by buff which is count bytes long to the socket fd.

Parameters:

	fd	The file descriptor of the socket.
	buff	The buffer contains the data.
	count	The length in bytes of the buffer.
	timeout	An upper bound on the amount of time elapsed before sock_write_t returns. When it is zero, sock_write_t can block indefinitely. The timeout value is in tick count, and tick count of MiniGUI is in unit of 10 milliseconds.

Returns:

SOCKERR_OK if all OK, < 0 on error.

Return values:

	SOCKERR_OK	Read data successfully.
	SOCKERR_IO	There are some I/O errors occurred.
	SOCKERR_CLOSED	The socket has been closed by the peer.
	SOCKERR_INVARG	You passed invalid arguments.
	SOCKERR_TIMEOUT	Timeout.

Note:

The timeout only goes into effect when this function called by the server of MiniGUI-Processes, i.e. mginit.

See also:

sock_read_t