syscall: use dup3 in forkAndExecInChild1 on all Linux platforms

The minimum required Linux kernel version for Go 1.18 will be changed to
2.6.32, see #45964. The dup3 syscall was added in 2.6.27, so the
fallback to use the dup2 syscall in forkAndExecInChild1 on some
platforms can be removed.

For #45964

Change-Id: I8e04d7b5b2488990a061a080ed64ea303ad048b8
Reviewed-on: https://go-review.googlesource.com/c/go/+/347350
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>

diff --git a/src/syscall/exec_linux.go b/src/syscall/exec_linux.go
index 68bce7559b929c125d01c00ae9951006fbd47f16..dfc522854560bd4982214782a4091223971904e6 100644 (file)
--- a/src/syscall/exec_linux.go
+++ b/src/syscall/exec_linux.go
@@ -448,13 +448,7 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
        // so that pass 2 won't stomp on an fd it needs later.
        if pipe < nextfd {
                _, _, err1 = RawSyscall(SYS_DUP3, uintptr(pipe), uintptr(nextfd), O_CLOEXEC)
-               if _SYS_dup != SYS_DUP3 && err1 == ENOSYS {
-                       _, _, err1 = RawSyscall(_SYS_dup, uintptr(pipe), uintptr(nextfd), 0)
-                       if err1 != 0 {
-                               goto childerror
-                       }
-                       RawSyscall(fcntl64Syscall, uintptr(nextfd), F_SETFD, FD_CLOEXEC)
-               } else if err1 != 0 {
+               if err1 != 0 {
                        goto childerror
                }
                pipe = nextfd
@@ -466,13 +460,7 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
                                nextfd++
                        }
                        _, _, err1 = RawSyscall(SYS_DUP3, uintptr(fd[i]), uintptr(nextfd), O_CLOEXEC)
-                       if _SYS_dup != SYS_DUP3 && err1 == ENOSYS {
-                               _, _, err1 = RawSyscall(_SYS_dup, uintptr(fd[i]), uintptr(nextfd), 0)
-                               if err1 != 0 {
-                                       goto childerror
-                               }
-                               RawSyscall(fcntl64Syscall, uintptr(nextfd), F_SETFD, FD_CLOEXEC)
-                       } else if err1 != 0 {
+                       if err1 != 0 {
                                goto childerror
                        }
                        fd[i] = nextfd
@@ -497,7 +485,7 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
                }
                // The new fd is created NOT close-on-exec,
                // which is exactly what we want.
-               _, _, err1 = RawSyscall(_SYS_dup, uintptr(fd[i]), uintptr(i), 0)
+               _, _, err1 = RawSyscall(SYS_DUP3, uintptr(fd[i]), uintptr(i), 0)
                if err1 != 0 {
                        goto childerror
                }

diff --git a/src/syscall/syscall_dup2_linux.go b/src/syscall/syscall_dup2_linux.go
deleted file mode 100644 (file)
index 351a96e..0000000
--- a/src/syscall/syscall_dup2_linux.go
+++ /dev/null
@@ -1,11 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !android && (386 || amd64 || arm || mips || mipsle || mips64 || mips64le || ppc64 || ppc64le || s390x)
-// +build !android
-// +build 386 amd64 arm mips mipsle mips64 mips64le ppc64 ppc64le s390x
-
-package syscall
-
-const _SYS_dup = SYS_DUP2

diff --git a/src/syscall/syscall_dup3_linux.go b/src/syscall/syscall_dup3_linux.go
deleted file mode 100644 (file)
index 66ec67b..0000000
--- a/src/syscall/syscall_dup3_linux.go
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build android || arm64 || riscv64
-// +build android arm64 riscv64
-
-package syscall
-
-const _SYS_dup = SYS_DUP3