Adds OS internal functions nx_send(), ns_recv(), and nx_recvfrom() which are functionally equivalent to send(), recv(), and recvfrom() except that they do not set the errno variable and do not cause cancellation points.

net/socket/send.c

@@ -46,6 +46,7 @@
 #include <debug.h>
 
 #include <nuttx/cancelpt.h>
+#include <nuttx/net/net.h>
 
 #include "socket/socket.h"
 
@@ -57,63 +58,29 @@
  * Name: psock_send
  *
  * Description:
- *   The send() call may be used only when the socket is in a connected state
- *   (so that the intended recipient is known). The only difference between
- *   send() and write() is the presence of flags. With zero flags parameter,
- *   send() is equivalent to write(). Also, send(sockfd,buf,len,flags) is
- *   equivalent to sendto(sockfd,buf,len,flags,NULL,0).
+ *   The psock_send() call may be used only when the socket is in a
+ *   connected state (so that the intended recipient is known).  This is an
+ *   internal OS interface.  It is functionally equivalent to send() except
+ *   that:
+ *
+ *   - It is not a cancellation point,
+ *   - It does not modify the errno variable, and
+ *   - I accepts the internal socket structure as an input rather than an
+ *     task-specific socket descriptor.
+ *
+ *   See comments with send() for more a more complete description of the
+ *   functionality.
  *
  * Parameters:
- *   psock    An instance of the internal socket structure.
- *   buf      Data to send
- *   len      Length of data to send
- *   flags    Send flags
+ *   psock - An instance of the internal socket structure.
+ *   buf   - Data to send
+ *   len   - Length of data to send
+ *   flags - Send flags
  *
  * Returned Value:
  *   On success, returns the number of characters sent.  On any failure, a
- *   negated errno value is returned.  One of:
- *
- *   EAGAIN or EWOULDBLOCK
- *     The socket is marked non-blocking and the requested operation
- *     would block.
- *   EBADF
- *     An invalid descriptor was specified.
- *   ECONNRESET
- *     Connection reset by peer.
- *   EDESTADDRREQ
- *     The socket is not connection-mode, and no peer address is set.
- *   EFAULT
- *      An invalid user space address was specified for a parameter.
- *   EINTR
- *      A signal occurred before any data was transmitted.
- *   EINVAL
- *      Invalid argument passed.
- *   EISCONN
- *     The connection-mode socket was connected already but a recipient
- *     was specified. (Now either this error is returned, or the recipient
- *     specification is ignored.)
- *   EMSGSIZE
- *     The socket type requires that message be sent atomically, and the
- *     size of the message to be sent made this impossible.
- *   ENOBUFS
- *     The output queue for a network interface was full. This generally
- *     indicates that the interface has stopped sending, but may be
- *     caused by transient congestion.
- *   ENOMEM
- *     No memory available.
- *   ENOTCONN
- *     The socket is not connected, and no target has been given.
- *   ENOTSOCK
- *     The argument s is not a socket.
- *   EOPNOTSUPP
- *     Some bit in the flags argument is inappropriate for the socket
- *     type.
- *   EPIPE
- *     The local end has been shut down on a connection oriented socket.
- *     In this case the process will also receive a SIGPIPE unless
- *     MSG_NOSIGNAL is set.
- *
- * Assumptions:
+ *   negated errno value is returned (See comments with send() for a list
+ *   of the appropriate errno value).
  *
  ****************************************************************************/
 
@@ -144,6 +111,47 @@ ssize_t psock_send(FAR struct socket *psock, FAR const void *buf, size_t len,
   return ret;
 }
 
+/****************************************************************************
+ * Name: nx_send
+ *
+ * Description:
+ *   The nx_send() call may be used only when the socket is in a
+ *   connected state (so that the intended recipient is known).  This is an
+ *   internal OS interface.  It is functionally equivalent to send() except
+ *   that:
+ *
+ *   - It is not a cancellation point, and
+ *   - It does not modify the errno variable.
+ *
+ *   See comments with send() for more a more complete description of the
+ *   functionality.
+ *
+ * Parameters:
+ *   sockfd - Socket descriptor of the socket
+ *   buf    - Data to send
+ *   len    - Length of data to send
+ *   flags  - Send flags
+ *
+ * Returned Value:
+ *   On success, returns the number of characters sent.  On any failure, a
+ *   negated errno value is returned (See comments with send() for a list
+ *   of the appropriate errno value).
+ *
+ ****************************************************************************/
+
+ssize_t nx_send(int sockfd, FAR const void *buf, size_t len, int flags)
+{
+  FAR struct socket *psock;
+
+  /* Get the underlying socket structure */
+
+  psock = sockfd_socket(sockfd);
+
+  /* And let psock_send do all of the work */
+
+  return psock_send(psock, buf, len, flags);
+}
+
 /****************************************************************************
  * Name: send
  *
@@ -155,10 +163,10 @@ ssize_t psock_send(FAR struct socket *psock, FAR const void *buf, size_t len,
  *   equivalent to sendto(sockfd,buf,len,flags,NULL,0).
  *
  * Parameters:
- *   sockfd   Socket descriptor of socket
- *   buf      Data to send
- *   len      Length of data to send
- *   flags    Send flags
+ *   sockfd - Socket descriptor of the socket
+ *   buf    - Data to send
+ *   len    - Length of data to send
+ *   flags  - Send flags
  *
  * Returned Value:
  *   On success, returns the number of characters sent.  On  error,
@@ -210,20 +218,15 @@ ssize_t psock_send(FAR struct socket *psock, FAR const void *buf, size_t len,
 
 ssize_t send(int sockfd, FAR const void *buf, size_t len, int flags)
 {
-  FAR struct socket *psock;
   ssize_t ret;
 
   /* send() is a cancellation point */
 
   (void)enter_cancellation_point();
 
-  /* Get the underlying socket structure */
+  /* Let nx_send() and psock_send() do all of the work*/
 
-  psock = sockfd_socket(sockfd);
-
-  /* And let psock_send do all of the work */
-
-  ret = psock_send(psock, buf, len, flags);
+  ret = nx_send(sockfd, buf, len, flags);
   if (ret < 0)
     {
       set_errno((int)-ret);