net: fix inconsistent error values on Interface

This change fixes inconsistent error values on Interfaces,
InterfaceAddrs, InterfaceBy{Index,Name}, and Addrs and MulticastAddrs
methods of Interface.

Updates #4856.

Change-Id: I09e65522a22f45c641792d774ebf7a0081b874ad
Reviewed-on: https://go-review.googlesource.com/9140
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 6 insertions, 7 deletions

diff --git a/src/net/interface_bsd.go b/src/net/interface_bsd.go
index 2f66e4fc31..01a67c69a1 100644
--- a/src/net/interface_bsd.go
+++ b/src/net/interface_bsd.go
@@ -7,7 +7,6 @@
 package net
 
 import (
-	"os"
 	"syscall"
 	"unsafe"
 )
@@ -18,11 +17,11 @@ import (
 func interfaceTable(ifindex int) ([]Interface, error) {
 	tab, err := syscall.RouteRIB(syscall.NET_RT_IFLIST, ifindex)
 	if err != nil {
-		return nil, os.NewSyscallError("route rib", err)
+		return nil, err
 	}
 	msgs, err := syscall.ParseRoutingMessage(tab)
 	if err != nil {
-		return nil, os.NewSyscallError("route message", err)
+		return nil, err
 	}
 	return parseInterfaceTable(ifindex, msgs)
 }
@@ -51,7 +50,7 @@ loop:
 func newLink(m *syscall.InterfaceMessage) (*Interface, error) {
 	sas, err := syscall.ParseRoutingSockaddr(m)
 	if err != nil {
-		return nil, os.NewSyscallError("route sockaddr", err)
+		return nil, err
 	}
 	ifi := &Interface{Index: int(m.Header.Index), Flags: linkFlags(m.Header.Flags)}
 	sa, _ := sas[syscall.RTAX_IFP].(*syscall.SockaddrDatalink)
@@ -104,11 +103,11 @@ func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
 	}
 	tab, err := syscall.RouteRIB(syscall.NET_RT_IFLIST, index)
 	if err != nil {
-		return nil, os.NewSyscallError("route rib", err)
+		return nil, err
 	}
 	msgs, err := syscall.ParseRoutingMessage(tab)
 	if err != nil {
-		return nil, os.NewSyscallError("route message", err)
+		return nil, err
 	}
 	var ift []Interface
 	if index == 0 {
@@ -145,7 +144,7 @@ func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
 func newAddr(ifi *Interface, m *syscall.InterfaceAddrMessage) (*IPNet, error) {
 	sas, err := syscall.ParseRoutingSockaddr(m)
 	if err != nil {
-		return nil, os.NewSyscallError("route sockaddr", err)
+		return nil, err
 	}
 	ifa := &IPNet{}
 	switch sa := sas[syscall.RTAX_NETMASK].(type) {