From 099eff8891d1d7bd081bb1c9218ff5c0863921b2 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Mon, 15 Nov 2021 12:21:43 +0000
Subject: [PATCH] sftp: refactor so we only have one way of running remote
 commands

This also returns errors from running ssh Hash commands which we
didn't do before.
---
 backend/sftp/sftp.go | 30 +++++-------------------------
 1 file changed, 5 insertions(+), 25 deletions(-)

diff --git a/backend/sftp/sftp.go b/backend/sftp/sftp.go
index 6f77e8d4a..ebdc4a24c 100644
--- a/backend/sftp/sftp.go
+++ b/backend/sftp/sftp.go
@@ -1110,10 +1110,12 @@ func (f *Fs) run(ctx context.Context, cmd string) ([]byte, error) {
 	session.Stdout = &stdout
 	session.Stderr = &stderr
 
+	fs.Debugf(f, "Running remote command: %s", cmd)
 	err = session.Run(cmd)
 	if err != nil {
-		return nil, fmt.Errorf("failed to run %q: %s: %w", cmd, stderr.Bytes(), err)
+		return nil, fmt.Errorf("failed to run %q: %s: %w", cmd, bytes.TrimSpace(stderr.Bytes()), err)
 	}
+	fs.Debugf(f, "Remote command result: %s", bytes.TrimSpace(stdout.Bytes()))
 
 	return stdout.Bytes(), nil
 }
@@ -1230,8 +1232,6 @@ func (o *Object) Remote() string {
 // Hash returns the selected checksum of the file
 // If no checksum is available it returns ""
 func (o *Object) Hash(ctx context.Context, r hash.Type) (string, error) {
-	o.fs.addSession() // Show session in use
-	defer o.fs.removeSession()
 	if o.fs.opt.DisableHashCheck {
 		return "", nil
 	}
@@ -1255,36 +1255,16 @@ func (o *Object) Hash(ctx context.Context, r hash.Type) (string, error) {
 		return "", hash.ErrUnsupported
 	}
 
-	c, err := o.fs.getSftpConnection(ctx)
-	if err != nil {
-		return "", fmt.Errorf("Hash get SFTP connection: %w", err)
-	}
-	session, err := c.sshClient.NewSession()
-	o.fs.putSftpConnection(&c, err)
-	if err != nil {
-		return "", fmt.Errorf("Hash put SFTP connection: %w", err)
-	}
-
-	var stdout, stderr bytes.Buffer
-	session.Stdout = &stdout
-	session.Stderr = &stderr
 	escapedPath := shellEscape(o.path())
 	if o.fs.opt.PathOverride != "" {
 		escapedPath = shellEscape(path.Join(o.fs.opt.PathOverride, o.remote))
 	}
-	err = session.Run(hashCmd + " " + escapedPath)
-	fs.Debugf(nil, "sftp cmd = %s", escapedPath)
+	b, err := o.fs.run(ctx, hashCmd+" "+escapedPath)
 	if err != nil {
-		_ = session.Close()
-		fs.Debugf(o, "Failed to calculate %v hash: %v (%s)", r, err, bytes.TrimSpace(stderr.Bytes()))
-		return "", nil
+		return "", fmt.Errorf("failed to calculate %v hash: %w", r, err)
 	}
 
-	_ = session.Close()
-	b := stdout.Bytes()
-	fs.Debugf(nil, "sftp output = %q", b)
 	str := parseHash(b)
-	fs.Debugf(nil, "sftp hash = %q", str)
 	if r == hash.MD5 {
 		o.md5sum = &str
 	} else if r == hash.SHA1 {