From ce14df303b19f6c9e9327a0d9df1388921c8e583 Mon Sep 17 00:00:00 2001
From: Andreas Olsson <andreas@arrakis.se>
Date: Sun, 20 Sep 2020 12:04:08 +0200
Subject: [PATCH] Don't require `self-update --output` placeholder file

This removes the requirement on `restic self-update --output` to point
to a path of an existing file, to overwrite. In case the specified
path does exist we still want to verify that it's a regular file,
rather than a directory or a device, which gets overwritten.

We also want to verify that a path to a new file exists within an
existing directory. The alternative being running into that issue
after the actual download, etc has completed.

While at it I also replace `errors.Errorf` with the more appropriately
verbose `errors.Fatalf`.

Resolves #2491
---
 changelog/unreleased/issue-2491 |  9 +++++++++
 cmd/restic/cmd_self_update.go   | 18 +++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)
 create mode 100644 changelog/unreleased/issue-2491

diff --git a/changelog/unreleased/issue-2491 b/changelog/unreleased/issue-2491
new file mode 100644
index 000000000..ed1dbdac6
--- /dev/null
+++ b/changelog/unreleased/issue-2491
@@ -0,0 +1,9 @@
+Bugfix: Don't require `self-update --output` placeholder file
+
+`restic self-update --output /path/to/new-restic` used to require that
+new-restic was an existing file, to be overwritten. Now it's possible
+to download an updated restic binary to a new path, without first
+having to create a placeholder file.
+
+https://github.com/restic/restic/issues/2491
+https://github.com/restic/restic/pull/2937
diff --git a/cmd/restic/cmd_self_update.go b/cmd/restic/cmd_self_update.go
index 310c5100f..f71bdf16b 100644
--- a/cmd/restic/cmd_self_update.go
+++ b/cmd/restic/cmd_self_update.go
@@ -4,6 +4,7 @@ package main
 
 import (
 	"os"
+	"path/filepath"
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/selfupdate"
@@ -56,11 +57,18 @@ func runSelfUpdate(opts SelfUpdateOptions, gopts GlobalOptions, args []string) e
 
 	fi, err := os.Lstat(opts.Output)
 	if err != nil {
-		return err
-	}
-
-	if !fi.Mode().IsRegular() {
-		return errors.Errorf("output file %v is not a normal file, use --output to specify a different file", opts.Output)
+		dirname := filepath.Dir(opts.Output)
+		di, err := os.Lstat(dirname)
+		if err != nil {
+			return err
+		}
+		if !di.Mode().IsDir() {
+			return errors.Fatalf("output parent path %v is not a directory, use --output to specify a different file path", dirname)
+		}
+	} else {
+		if !fi.Mode().IsRegular() {
+			return errors.Fatalf("output path %v is not a normal file, use --output to specify a different file path", opts.Output)
+		}
 	}
 
 	Printf("writing restic to %v\n", opts.Output)