fix compilation on unsupported operating systems

Author: Tim Cooper

api_darwin.go

@@ -1,3 +1,5 @@
+// +build darwin
+
 package lfs
 
 import (
@@ -7,11 +9,8 @@ import (
 	"github.com/yuin/gopher-lua"
 )
 
-func attributesFill(tbl *lua.LTable, stat os.FileInfo) {
-	sys, ok := stat.Sys().(*syscall.Stat_t)
-	if !ok {
-		return
-	}
+func attributesFill(tbl *lua.LTable, stat os.FileInfo) error {
+	sys := stat.Sys().(*syscall.Stat_t)
 	tbl.RawSetH(lua.LString("dev"), lua.LNumber(sys.Dev))
 	tbl.RawSetH(lua.LString("ino"), lua.LNumber(sys.Ino))
 	{
@@ -46,4 +45,5 @@ func attributesFill(tbl *lua.LTable, stat os.FileInfo) {
 	tbl.RawSetH(lua.LString("size"), lua.LNumber(sys.Size))
 	tbl.RawSetH(lua.LString("blocks"), lua.LNumber(sys.Blocks))
 	tbl.RawSetH(lua.LString("blksize"), lua.LNumber(sys.Blksize))
+	return nil
 }

api_linux.go

@@ -1,3 +1,5 @@
+// +build linux
+
 package lfs
 
 import (
@@ -7,11 +9,8 @@ import (
 	"github.com/yuin/gopher-lua"
 )
 
-func attributesFill(tbl *lua.LTable, stat os.FileInfo) {
-	sys, ok := stat.Sys().(*syscall.Stat_t)
-	if !ok {
-		return
-	}
+func attributesFill(tbl *lua.LTable, stat os.FileInfo) error {
+	sys := stat.Sys().(*syscall.Stat_t)
 	tbl.RawSetH(lua.LString("dev"), lua.LNumber(sys.Dev))
 	tbl.RawSetH(lua.LString("ino"), lua.LNumber(sys.Ino))
 	{
@@ -46,4 +45,5 @@ func attributesFill(tbl *lua.LTable, stat os.FileInfo) {
 	tbl.RawSetH(lua.LString("size"), lua.LNumber(sys.Size))
 	tbl.RawSetH(lua.LString("blocks"), lua.LNumber(sys.Blocks))
 	tbl.RawSetH(lua.LString("blksize"), lua.LNumber(sys.Blksize))
+	return nil
 }

api_other.go

@@ -0,0 +1,15 @@
+// +build !darwin,!linux
+
+package lfs
+
+import (
+	"errors"
+	"os"
+	"runtime"
+
+	"github.com/yuin/gopher-lua"
+)
+
+func attributesFill(tbl *lua.LTable, stat os.FileInfo) error {
+	return errors.New("unsupported operating system " + runtime.GOOS)
+}

util.go

@@ -16,7 +16,11 @@ func attributes(L *lua.LState, statFunc func(string) (os.FileInfo, error)) int {
 		return 2
 	}
 	table := L.NewTable()
-	attributesFill(table, stat)
+	if err := attributesFill(table, stat); err != nil {
+		L.Push(lua.LNil)
+		L.Push(lua.LString(err.Error()))
+		return 2
+	}
 	if L.GetTop() > 1 {
 		aname := L.CheckString(2)
 		L.Push(table.RawGetH(lua.LString(aname)))