From 7b6203d0d421a3362b58d1a8b7c68459afc16034 Mon Sep 17 00:00:00 2001
From: Evgeniy Stratonikov <evgeniy@nspcc.ru>
Date: Tue, 21 Sep 2021 08:09:49 +0300
Subject: [PATCH 1/2] wallet: allow to open in read-only mode, fix #2182

If wallet was opened via `NewWalletFromFile`, open it as read-only first
and re-open for write if needed.

Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>
---
 pkg/wallet/wallet.go | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/pkg/wallet/wallet.go b/pkg/wallet/wallet.go
index ca32a4790..fe18ac7d2 100644
--- a/pkg/wallet/wallet.go
+++ b/pkg/wallet/wallet.go
@@ -56,12 +56,13 @@ func NewWallet(location string) (*Wallet, error) {
 
 // NewWalletFromFile creates a Wallet from the given wallet file path.
 func NewWalletFromFile(path string) (*Wallet, error) {
-	file, err := os.OpenFile(path, os.O_RDWR, os.ModeAppend)
+	file, err := os.Open(path)
 	if err != nil {
 		return nil, err
 	}
+	defer file.Close()
+
 	wall := &Wallet{
-		rw:   file,
 		path: file.Name(),
 	}
 	if err := json.NewDecoder(file).Decode(wall); err != nil {
@@ -162,6 +163,13 @@ func (w *Wallet) savePretty() error {
 }
 
 func (w *Wallet) writeRaw(data []byte) error {
+	if w.rw == nil {
+		f, err := os.OpenFile(w.path, os.O_RDWR, os.ModeAppend)
+		if err != nil {
+			return err
+		}
+		w.rw = f
+	}
 	if err := w.rewind(); err != nil {
 		return err
 	}

From cb5b075e7da52fa49c00e4c43885befaa760e5ca Mon Sep 17 00:00:00 2001
From: Evgeniy Stratonikov <evgeniy@nspcc.ru>
Date: Mon, 27 Sep 2021 10:45:42 +0300
Subject: [PATCH 2/2] wallet: do not store file handle

Close immediately after read/write. This can be a bit slower but
we store everything in memory anyway and code size is smaller.
`wallet.Close()` method is now a no-op.

Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>
---
 pkg/wallet/wallet.go | 41 +++--------------------------------------
 1 file changed, 3 insertions(+), 38 deletions(-)

diff --git a/pkg/wallet/wallet.go b/pkg/wallet/wallet.go
index fe18ac7d2..63d74fcca 100644
--- a/pkg/wallet/wallet.go
+++ b/pkg/wallet/wallet.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"io"
+	"io/ioutil"
 	"os"
 
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
@@ -34,9 +35,6 @@ type Wallet struct {
 
 	// Path where the wallet file is located..
 	path string
-
-	// ReadWriter for reading and writing wallet data.
-	rw io.ReadWriter
 }
 
 // Extra stores imported token contracts.
@@ -51,6 +49,7 @@ func NewWallet(location string) (*Wallet, error) {
 	if err != nil {
 		return nil, err
 	}
+	defer file.Close()
 	return newWallet(file), nil
 }
 
@@ -80,7 +79,6 @@ func newWallet(rw io.ReadWriter) *Wallet {
 		Version:  walletVersion,
 		Accounts: []*Account{},
 		Scrypt:   keys.NEP2ScryptParams(),
-		rw:       rw,
 		path:     path,
 	}
 }
@@ -163,37 +161,7 @@ func (w *Wallet) savePretty() error {
 }
 
 func (w *Wallet) writeRaw(data []byte) error {
-	if w.rw == nil {
-		f, err := os.OpenFile(w.path, os.O_RDWR, os.ModeAppend)
-		if err != nil {
-			return err
-		}
-		w.rw = f
-	}
-	if err := w.rewind(); err != nil {
-		return err
-	}
-
-	_, err := w.rw.Write(data)
-	if err != nil {
-		return err
-	}
-
-	if f, ok := w.rw.(*os.File); ok {
-		if err := f.Truncate(int64(len(data))); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func (w *Wallet) rewind() error {
-	if s, ok := w.rw.(io.Seeker); ok {
-		if _, err := s.Seek(0, io.SeekStart); err != nil {
-			return err
-		}
-	}
-	return nil
+	return ioutil.WriteFile(w.path, data, 0644)
 }
 
 // JSON outputs a pretty JSON representation of the wallet.
@@ -203,9 +171,6 @@ func (w *Wallet) JSON() ([]byte, error) {
 
 // Close closes the internal rw if its an io.ReadCloser.
 func (w *Wallet) Close() {
-	if rc, ok := w.rw.(io.ReadCloser); ok {
-		rc.Close()
-	}
 }
 
 // GetAccount returns account corresponding to the provided scripthash.