Documented EINVAL error for 'len' < 0.

man2/accept.2

@@ -196,7 +196,9 @@ The system call was interrupted by a signal that was caught
 before a valid connection arrived. 
 .TP
 .B EINVAL
-Socket is not listening for connections.
+Socket is not listening for connections, or
+.I addrlen
+is invalid (e.g., is negative).
 .TP
 .B EMFILE
 The per-process limit of open file descriptors has been reached.

man2/getpeername.2

@@ -72,6 +72,10 @@ The
 parameter points to memory not in a valid part of the
 process address space.
 .TP
+.B EINVAL
+.I namelen
+is invalid (e.g., is negative).
+.TP
 .B ENOBUFS
 Insufficient resources were available in the system
 to perform the operation.

man2/getsockname.2

@@ -72,6 +72,10 @@ The
 parameter points to memory not in a valid part of the
 process address space.
 .TP
+.B EINVAL
+.I namelen
+is invalid (e.g., is negative).
+.TP
 .B ENOBUFS
 Insufficient resources were available in the system
 to perform the operation.

man2/recv.2

@@ -42,16 +42,18 @@ recv, recvfrom, recvmsg \- receive a message from a socket
 .SH SYNOPSIS
 .\" .B #include <sys/uio.h>
 .\" .br
+.nf
 .B #include <sys/types.h>
 .br
 .B #include <sys/socket.h>
 .sp
 .BI "ssize_t recv(int " s ", void *" buf ", size_t " len ", int " flags );
 .sp
-.BI "ssize_t recvfrom(int " s ", void *" buf ", size_t " len ,
-.BI "int " flags ", struct sockaddr *" from ", socklen_t *" fromlen );
+.BI "ssize_t recvfrom(int " s ", void *" buf ", size_t " len ", int " flags , 
+.BI "                 struct sockaddr *" from ", socklen_t *" fromlen );
 .sp
 .BI "ssize_t recvmsg(int " s ", struct msghdr *" msg ", int " flags );
+.fi
 .SH DESCRIPTION
 The
 .BR recvfrom ()
@@ -369,6 +371,7 @@ any data were available.
 .TP
 .B EINVAL
 Invalid argument passed. 
+.\" e.g., msg_namelen < 0 for recvmsg() or fromlen < 0 for recvfrom()
 .TP
 .B ENOMEM
 Could not allocate memory for