From ef69007a43dca07a9e6e81e1450629de8410e1a5 Mon Sep 17 00:00:00 2001
From: Michael Stapelberg <michael@stapelberg.de>
Date: Sat, 9 Apr 2022 00:11:47 +0200
Subject: [PATCH] =?UTF-8?q?use=20renameio=20to=20avoid=20=E2=80=9Ctext=20f?=
 =?UTF-8?q?ile=20busy=E2=80=9D=20errors?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before this commit, extracting a breakglass would fail when /tmp/breakglass*/sh
was busy because it was being run in a separate connection.
---
 go.mod | 1 +
 go.sum | 2 ++
 scp.go | 6 +++---
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index 9218e99..be0fc47 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.17
 require (
 	github.com/gokrazy/gokrazy v0.0.0-20211024151958-b718dd90ae71
 	github.com/gokrazy/internal v0.0.0-20210621162516-1b3b5687a06d
+	github.com/google/renameio/v2 v2.0.0
 	github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf
 	github.com/kr/pty v1.1.8
 	github.com/pkg/sftp v1.13.0
diff --git a/go.sum b/go.sum
index 1889fcd..5d0548f 100644
--- a/go.sum
+++ b/go.sum
@@ -11,6 +11,8 @@ github.com/gokrazy/internal v0.0.0-20210621162516-1b3b5687a06d/go.mod h1:Gqv1x1D
 github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/gopacket v1.1.16/go.mod h1:UCLx9mCmAwsVbn6qQl1WIEt2SO7Nd2fD0th1TBAsqBw=
+github.com/google/renameio/v2 v2.0.0 h1:UifI23ZTGY8Tt29JbYFiuyIU3eX+RNFtUwefq9qAhxg=
+github.com/google/renameio/v2 v2.0.0/go.mod h1:BtmJXm5YlszgC+TD4HOEEUFgkJP3nLxehU6hfe7jRt4=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf h1:7+FW5aGwISbqUtkfmIpZJGRgNFg2ioYPvFaUxdqpDsg=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf/go.mod h1:RpwtwJQFrIEPstU94h88MWPXP2ektJZ8cZ0YntAmXiE=
 github.com/kr/fs v0.1.0 h1:Jskdu9ieNAYnjxsi0LbQp1ulIKZV1LAFgK1tWhpZgl8=
diff --git a/scp.go b/scp.go
index 7ed9e56..9229c7c 100644
--- a/scp.go
+++ b/scp.go
@@ -11,6 +11,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/google/renameio/v2"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -83,15 +84,14 @@ func scpSink(channel ssh.Channel, req *ssh.Request, cmdline []string) error {
 					continue // directory, don’t try to OpenFile() it
 				}
 				mode := h.FileInfo().Mode() & os.ModePerm
-				out, err := os.OpenFile(h.Name, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, mode)
+				out, err := renameio.NewPendingFile(h.Name, renameio.WithStaticPermissions(mode))
 				if err != nil {
 					return err
 				}
 				if _, err := io.Copy(out, tr); err != nil {
-					out.Close()
 					return err
 				}
-				if err := out.Close(); err != nil {
+				if err := out.CloseAtomicallyReplace(); err != nil {
 					return err
 				}
 			}