From 25bac8dbf63b85ef130e38e64f7fc4bfed71ece0 Mon Sep 17 00:00:00 2001
From: SeongTae Jeong <seongtaejg@gmail.com>
Date: Sat, 2 Nov 2024 23:19:05 +0900
Subject: [PATCH 1/2] Check database file encoding to set appropriate opening
 mode

Fix: #3714
---
 src/sqlitedb.cpp | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/src/sqlitedb.cpp b/src/sqlitedb.cpp
index 8f2cecb41..fa0eb0966 100644
--- a/src/sqlitedb.cpp
+++ b/src/sqlitedb.cpp
@@ -196,8 +196,43 @@ bool DBBrowserDB::open(const QString& db, bool readOnly)
     if(tryEncryptionSettings(db, &isEncrypted, &cipherSettings) == false)
         return false;
 
+    // Open database file header to determine encoding
+    QFile file(db);
+    if(!file.open(QIODevice::ReadOnly))
+    {
+        lastErrorMessage = tr("Cannot open database file: %1").arg(file.errorString());
+        return false;
+    }
+
+    QByteArray header = file.read(100);
+    file.close();
+
+    const char* encodingBytes = header.constData() + 56;
+    // The variable 'encoding' will have one of the following values:
+    // 1: UTF-8, 2: UTF-16LE, 3: UTF-16BE
+    quint32 encoding = ((quint8)encodingBytes[0] << 24) |
+                   ((quint8)encodingBytes[1] << 16) |
+                   ((quint8)encodingBytes[2] << 8) |
+                   ((quint8)encodingBytes[3]);
+
     // Open database file
-    if(sqlite3_open_v2(db.toUtf8(), &_db, readOnly ? SQLITE_OPEN_READONLY : SQLITE_OPEN_READWRITE, nullptr) != SQLITE_OK)
+    int status=0;
+    if(encoding == 1)
+    {
+        status = sqlite3_open_v2(
+                db.toUtf8(),
+                &_db,
+                readOnly ? SQLITE_OPEN_READONLY : SQLITE_OPEN_READWRITE,
+                nullptr);
+    }
+    else
+    {
+        status = sqlite3_open16(db.constData(), &_db);
+        if (status == SQLITE_OK && readOnly)
+            sqlite3_exec(_db, "PRAGMA query_only = TRUE;", nullptr, nullptr, nullptr);
+    }
+
+    if (status != SQLITE_OK)
     {
         lastErrorMessage = QString::fromUtf8(sqlite3_errmsg(_db));
         return false;

From afb2c431945968e893da287f51eaacacb0c21348 Mon Sep 17 00:00:00 2001
From: SeongTae Jeong <seongtaejg@gmail.com>
Date: Sun, 3 Nov 2024 03:27:10 +0900
Subject: [PATCH 2/2] Use the preprocessor macro instead of the magic number
 for the encoding value

---
 src/sqlitedb.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/sqlitedb.cpp b/src/sqlitedb.cpp
index fa0eb0966..068750a2a 100644
--- a/src/sqlitedb.cpp
+++ b/src/sqlitedb.cpp
@@ -209,7 +209,7 @@ bool DBBrowserDB::open(const QString& db, bool readOnly)
 
     const char* encodingBytes = header.constData() + 56;
     // The variable 'encoding' will have one of the following values:
-    // 1: UTF-8, 2: UTF-16LE, 3: UTF-16BE
+    // SQLITE_UTF8, SQLITE_UTF16LE, SQLITE_UTF16BE (https://www.sqlite.org/fileformat.html#text_encoding)
     quint32 encoding = ((quint8)encodingBytes[0] << 24) |
                    ((quint8)encodingBytes[1] << 16) |
                    ((quint8)encodingBytes[2] << 8) |
@@ -217,7 +217,7 @@ bool DBBrowserDB::open(const QString& db, bool readOnly)
 
     // Open database file
     int status=0;
-    if(encoding == 1)
+    if(encoding == SQLITE_UTF8)
     {
         status = sqlite3_open_v2(
                 db.toUtf8(),