syscall: Change Dup2 to only return an error.

From-SVN: r184222

libgo/go/syscall/exec_bsd.go

@@ -136,9 +136,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	// so that pass 2 won't stomp on an fd it needs later.
 	nextfd = int(len(fd))
 	if pipe < nextfd {
-		_, err2 := Dup2(pipe, nextfd)
-		if err2 != nil {
-			err1 = err2.(Errno)
+		err1 = raw_dup2(pipe, nextfd)
+		if err1 != 0 {
 			goto childerror
 		}
 		raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
@@ -147,9 +146,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	}
 	for i = 0; i < len(fd); i++ {
 		if fd[i] >= 0 && fd[i] < int(i) {
-			_, err2 := Dup2(fd[i], nextfd)
-			if err2 != nil {
-				err1 = err2.(Errno)
+			err1 = raw_dup2(fd[i], nextfd)
+			if err1 != 0 {
 				goto childerror
 			}
 			raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
@@ -178,9 +176,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 		}
 		// The new fd is created NOT close-on-exec,
 		// which is exactly what we want.
-		_, err2 := Dup2(fd[i], i)
+		err1 = raw_dup2(fd[i], i)
 		if err1 != 0 {
-			err1 = err2.(Errno)
 			goto childerror
 		}
 	}

libgo/go/syscall/exec_linux.go

@@ -161,9 +161,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	// so that pass 2 won't stomp on an fd it needs later.
 	nextfd = int(len(fd))
 	if pipe < nextfd {
-		_, err2 := Dup2(pipe, nextfd)
-		if err2 != nil {
-			err1 = err2.(Errno)
+		err1 = raw_dup2(pipe, nextfd)
+		if err1 != 0 {
 			goto childerror
 		}
 		raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
@@ -172,9 +171,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	}
 	for i = 0; i < len(fd); i++ {
 		if fd[i] >= 0 && fd[i] < int(i) {
-			_, err2 := Dup2(fd[i], nextfd)
-			if err2 != nil {
-				err1 = err2.(Errno)
+			err1 = raw_dup2(fd[i], nextfd)
+			if err1 != 0 {
 				goto childerror
 			}
 			raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
@@ -203,9 +201,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 		}
 		// The new fd is created NOT close-on-exec,
 		// which is exactly what we want.
-		_, err2 := Dup2(fd[i], i);
-		if err2 != nil {
-			err1 = err2.(Errno)
+		err1 = raw_dup2(fd[i], i)
+		if err1 != 0 {
 			goto childerror
 		}
 	}

libgo/go/syscall/exec_unix.go

@@ -47,6 +47,9 @@ import (
 //sysnb	raw_exit(status int)
 //_exit(status int)
 
+//sysnb raw_dup2(oldfd int, newfd int) (err Errno)
+//dup2(oldfd int, newfd int) int
+
 // Note: not raw, returns error rather than Errno.
 //sys	read(fd int, p *byte, np int) (n int, err error)
 //read(fd int, buf *byte, count Size_t) Ssize_t

libgo/go/syscall/libcall_posix.go

@@ -178,7 +178,7 @@ func FDZero(set *FdSet) {
 //sysnb	Dup(oldfd int) (fd int, err error)
 //dup(oldfd int) int
 
-//sysnb	Dup2(oldfd int, newfd int) (fd int, err error)
+//sysnb	Dup2(oldfd int, newfd int) (err error)
 //dup2(oldfd int, newfd int) int
 
 //sys	Exit(code int)