http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=229618

getnameinfo() does not set errno, it returns a non-zero
value indicating the error.

added EAI_OVERFLOW error

man3/getnameinfo.3

@@ -1,6 +1,9 @@
 .\" This page is in the public domain.
 .\" Almost all details are from RFC 2553.
 .\"
+.\" 2004-12-14, mtk, Added EAI_OVERFLOW error
+.\" 2004-12-14 Fixed description of error return
+.\"
 .TH getnameinfo 3 2000-12-11 "Linux Man Page" "UNIX Programmer's Manual"
 .SH NAME
 getnameinfo \- address-to-name translation in protocol-independent manner
@@ -88,10 +91,7 @@ that have different services for UDP and TCP.
 On success 0 is returned, and node and service names, if requested,
 are filled with NUL-terminated strings, possibly truncated to fit
 the specified buffer lengths.
-On error a nonzero value is returned, and
-.I errno
-is set appropriately.
-.SH ERRORS
+On error one of the following non-zero error codes is returned:
 .TP
 .B EAI_AGAIN
 The name could not be resolved at this time. Try again later.
@@ -116,6 +116,13 @@ The name does not resolve for the supplied parameters.
 NI_NAMEREQD is set and the host's name cannot be located,
 or neither hostname nor service name were requested.
 .TP
+.B EAI_OVERFLOW
+The buffer pointed to by
+.I host
+or
+.I serv
+was too small.
+.TP
 .B EAI_SYSTEM
 A system error occurred. The error code can be found in
 .IR errno .
@@ -125,6 +132,10 @@ A system error occurred. The error code can be found in
 /etc/nsswitch.conf
 .br
 /etc/resolv.conf
+The
+.BR gai_strerror (3)
+function translates these error codes to a human readable string,
+suitable for error reporting.
 .SH NOTE
 In order to assist the programmer in choosing reasonable sizes
 for the supplied buffers,