Refactor Sockets to be FileHandle

This allows sockets to be used with standard C library:
    TCPSocket sock;
    sock.open(interface);
    sock.connect("echo.server.foo", 7);
    FILE *stream = fdopen(&sock, "r+");
    fprintf(stream, "Hello World\n");

Author: SeppoTakalo

features/netsocket/Socket.cpp

@@ -121,10 +121,11 @@ nsapi_error_t Socket::bind(const SocketAddress &address)
     return ret;
 }
 
-void Socket::set_blocking(bool blocking)
+int Socket::set_blocking(bool blocking)
 {
     // Socket::set_timeout is thread safe
     set_timeout(blocking ? -1 : 0);
+    return 0;
 }
 
 void Socket::set_timeout(int timeout)

features/netsocket/Socket.h

@@ -25,11 +25,12 @@
 #include "rtos/Mutex.h"
 #include "Callback.h"
 #include "mbed_toolchain.h"
+#include "platform/FileHandle.h"
 
 
 /** Abstract socket class
  */
-class Socket {
+class Socket : public mbed::FileHandle {
 public:
     /** Destroy a socket
      *
@@ -53,15 +54,6 @@ class Socket {
         return open(nsapi_create_stack(stack));
     }
 
-    /** Close the socket
-     *
-     *  Closes any open connection and deallocates any memory associated
-     *  with the socket. Called from destructor if socket is not closed.
-     *
-     *  @return         0 on success, negative error code on failure
-     */
-    nsapi_error_t close();
-    
     /** Subscribes to an IP multicast group
      *
      * @param address   Multicast group IP address
@@ -107,19 +99,6 @@ class Socket {
      */
     nsapi_error_t bind(const SocketAddress &address);
 
-    /** Set blocking or non-blocking mode of the socket
-     *
-     *  Initially all sockets are in blocking mode. In non-blocking mode
-     *  blocking operations such as send/recv/accept return
-     *  NSAPI_ERROR_WOULD_BLOCK if they can not continue.
-     *
-     *  set_blocking(false) is equivalent to set_timeout(-1)
-     *  set_blocking(true) is equivalent to set_timeout(0)
-     *
-     *  @param blocking true for blocking mode, false for non-blocking mode.
-     */
-    void set_blocking(bool blocking);
-    
     /** Set timeout on blocking socket operations
      *
      *  Initially all sockets have unbounded timeouts. NSAPI_ERROR_WOULD_BLOCK
@@ -213,6 +192,38 @@ class Socket {
         attach(mbed::callback(obj, method));
     }
 
+    /* ------Inherited from FileHandle------- */
+    
+    /** Close the socket
+     *
+     *  Closes any open connection and deallocates any memory associated
+     *  with the socket. Called from destructor if socket is not closed.
+     *
+     *  Inherited from FileHandle
+     *
+     *  @return         0 on success, negative error code on failure
+     */
+    virtual nsapi_error_t close();
+
+     /** Set blocking or non-blocking mode of the socket
+     *
+     *  Initially all sockets are in blocking mode. In non-blocking mode
+     *  blocking operations such as send/recv/accept return
+     *  NSAPI_ERROR_WOULD_BLOCK if they can not continue.
+     *
+     *  set_blocking(false) is equivalent to set_timeout(-1)
+     *  set_blocking(true) is equivalent to set_timeout(0)
+     *
+     *  @param blocking true for blocking mode, false for non-blocking mode.
+     */
+    virtual int set_blocking(bool blocking);
+
+    virtual int sync() { return -1; }
+    virtual int isatty() { return true; }
+    virtual off_t seek(off_t offset, int whence = SEEK_SET) { return -1; }
+    virtual off_t size() { return -1; }
+    virtual short poll(short events) { return 0; }
+
 protected:
     Socket();
     virtual nsapi_protocol_t get_proto() = 0;

features/netsocket/TCPServer.h

@@ -89,6 +89,12 @@ class TCPServer : public Socket {
 
     volatile unsigned _pending;
     rtos::Semaphore _accept_sem;
+
+private:
+    /* ------Inherited from FileHandle------- */
+    /* Server sockets cannot really be FileHandle's so moved into private */
+    virtual ssize_t read(void *buffer, size_t size) { return NSAPI_ERROR_UNSUPPORTED; }
+    virtual ssize_t write(const void *buffer, size_t size) { return NSAPI_ERROR_UNSUPPORTED; }    
 };
 
 

features/netsocket/TCPSocket.h

@@ -115,6 +115,10 @@ class TCPSocket : public Socket {
      */
     nsapi_size_or_error_t recv(void *data, nsapi_size_t size);
 
+    /* ------Inherited from FileHandle------- */
+    virtual ssize_t read(void *buffer, size_t size) { return recv(buffer, size); }
+    virtual ssize_t write(const void *buffer, size_t size) { return send(buffer, size); }
+
 protected:
     friend class TCPServer;
 

features/netsocket/UDPSocket.h

@@ -112,6 +112,10 @@ class UDPSocket : public Socket {
     nsapi_size_or_error_t recvfrom(SocketAddress *address,
             void *data, nsapi_size_t size);
 
+    /* ------Inherited from FileHandle------- */
+    virtual ssize_t read(void *buffer, size_t size) { return recvfrom(NULL, buffer, size); }
+    virtual ssize_t write(const void *buffer, size_t size) { return NSAPI_ERROR_UNSUPPORTED; }
+
 protected:
     virtual nsapi_protocol_t get_proto();
     virtual void event();