Merge "Read-ony transactions may modify TEMP tables" into main
diff --git a/core/java/android/database/sqlite/SQLiteConnection.java b/core/java/android/database/sqlite/SQLiteConnection.java
index b96d832..ecffe9e 100644
--- a/core/java/android/database/sqlite/SQLiteConnection.java
+++ b/core/java/android/database/sqlite/SQLiteConnection.java
@@ -121,8 +121,12 @@
     // The native SQLiteConnection pointer.  (FOR INTERNAL USE ONLY)
     private long mConnectionPtr;
 
+    // Restrict this connection to read-only operations.
     private boolean mOnlyAllowReadOnlyOperations;
 
+    // Allow this connection to treat updates to temporary tables as read-only operations.
+    private boolean mAllowTempTableRetry = Flags.sqliteAllowTempTables();
+
     // The number of times attachCancellationSignal has been called.
     // Because SQLite statement execution can be reentrant, we keep track of how many
     // times we have attempted to attach a cancellation signal to the connection so that
@@ -142,6 +146,7 @@
     private static native void nativeFinalizeStatement(long connectionPtr, long statementPtr);
     private static native int nativeGetParameterCount(long connectionPtr, long statementPtr);
     private static native boolean nativeIsReadOnly(long connectionPtr, long statementPtr);
+    private static native boolean nativeUpdatesTempOnly(long connectionPtr, long statementPtr);
     private static native int nativeGetColumnCount(long connectionPtr, long statementPtr);
     private static native String nativeGetColumnName(long connectionPtr, long statementPtr,
             int index);
@@ -1097,7 +1102,7 @@
         try {
             final int numParameters = nativeGetParameterCount(mConnectionPtr, statementPtr);
             final int type = DatabaseUtils.getSqlStatementTypeExtended(sql);
-            final boolean readOnly = nativeIsReadOnly(mConnectionPtr, statementPtr);
+            boolean readOnly = nativeIsReadOnly(mConnectionPtr, statementPtr);
             statement = obtainPreparedStatement(sql, statementPtr, numParameters, type, readOnly,
                     seqNum);
             if (!skipCache && isCacheable(type)) {
@@ -1265,13 +1270,20 @@
 
     /**
      * Verify that the statement is read-only, if the connection only allows read-only
-     * operations.
+     * operations.  If the connection allows updates to temporary tables, then the statement is
+     * read-only if the only updates are to temporary tables.
      * @param statement The statement to check.
      * @throws SQLiteException if the statement could update the database inside a read-only
      * transaction.
      */
     void throwIfStatementForbidden(PreparedStatement statement) {
         if (mOnlyAllowReadOnlyOperations && !statement.mReadOnly) {
+            if (mAllowTempTableRetry) {
+                statement.mReadOnly =
+                        nativeUpdatesTempOnly(mConnectionPtr, statement.mStatementPtr);
+                if (statement.mReadOnly) return;
+            }
+
             throw new SQLiteException("Cannot execute this statement because it "
                     + "might modify the database but the connection is read-only.");
         }
diff --git a/core/java/android/database/sqlite/flags.aconfig b/core/java/android/database/sqlite/flags.aconfig
index 62a5123..92ef9c2 100644
--- a/core/java/android/database/sqlite/flags.aconfig
+++ b/core/java/android/database/sqlite/flags.aconfig
@@ -7,3 +7,11 @@
      description: "SQLite APIs held back for Android 15"
      bug: "279043253"
 }
+
+flag {
+     name: "sqlite_allow_temp_tables"
+     namespace: "system_performance"
+     is_fixed_read_only: true
+     description: "Permit updates to TEMP tables in read-only transactions"
+     bug: "317993835"
+}
diff --git a/core/jni/android_database_SQLiteConnection.cpp b/core/jni/android_database_SQLiteConnection.cpp
index 893cc98..6f1c763 100644
--- a/core/jni/android_database_SQLiteConnection.cpp
+++ b/core/jni/android_database_SQLiteConnection.cpp
@@ -82,10 +82,16 @@
     const String8 path;
     const String8 label;
 
+    // The prepared statement used to determine which tables are updated by a statement.  This
+    // is is initially null.  It is set non-null on first use.
+    sqlite3_stmt* tableQuery;
+
     volatile bool canceled;
 
     SQLiteConnection(sqlite3* db, int openFlags, const String8& path, const String8& label) :
-        db(db), openFlags(openFlags), path(path), label(label), canceled(false) { }
+            db(db), openFlags(openFlags), path(path), label(label), tableQuery(nullptr),
+            canceled(false) { }
+
 };
 
 // Called each time a statement begins execution, when tracing is enabled.
@@ -188,6 +194,9 @@
 
     if (connection) {
         ALOGV("Closing connection %p", connection->db);
+        if (connection->tableQuery != nullptr) {
+            sqlite3_finalize(connection->tableQuery);
+        }
         int err = sqlite3_close(connection->db);
         if (err != SQLITE_OK) {
             // This can happen if sub-objects aren't closed first.  Make sure the caller knows.
@@ -419,6 +428,46 @@
     return sqlite3_stmt_readonly(statement) != 0;
 }
 
+static jboolean nativeUpdatesTempOnly(JNIEnv* env, jclass,
+        jlong connectionPtr, jlong statementPtr) {
+    sqlite3_stmt* statement = reinterpret_cast<sqlite3_stmt*>(statementPtr);
+    SQLiteConnection* connection = reinterpret_cast<SQLiteConnection*>(connectionPtr);
+
+    int result = SQLITE_OK;
+    if (connection->tableQuery == nullptr) {
+        static char const* sql =
+                "SELECT COUNT(*) FROM tables_used(?) WHERE schema != 'temp' AND wr != 0";
+        result = sqlite3_prepare_v2(connection->db, sql, -1, &connection->tableQuery, nullptr);
+        if (result != SQLITE_OK) {
+            ALOGE("failed to compile query table: %s",
+                  sqlite3_errstr(sqlite3_extended_errcode(connection->db)));
+            return false;
+        }
+    }
+
+    // A temporary, to simplify the code.
+    sqlite3_stmt* query = connection->tableQuery;
+    sqlite3_reset(query);
+    sqlite3_clear_bindings(query);
+    result = sqlite3_bind_text(query, 1, sqlite3_sql(statement), -1, SQLITE_STATIC);
+    if (result != SQLITE_OK) {
+        ALOGE("tables bind pointer returns %s", sqlite3_errstr(result));
+        return false;
+    }
+    result = sqlite3_step(query);
+    if (result != SQLITE_ROW) {
+        ALOGE("tables query error: %d/%s", result, sqlite3_errstr(result));
+        // Make sure the query is no longer bound to the statement.
+        sqlite3_clear_bindings(query);
+        return false;
+    }
+
+    int count = sqlite3_column_int(query, 0);
+    // Make sure the query is no longer bound to the statement SQL string.
+    sqlite3_clear_bindings(query);
+    return count == 0;
+}
+
 static jint nativeGetColumnCount(JNIEnv* env, jclass clazz, jlong connectionPtr,
         jlong statementPtr) {
     sqlite3_stmt* statement = reinterpret_cast<sqlite3_stmt*>(statementPtr);
@@ -915,6 +964,8 @@
             (void*)nativeGetParameterCount },
     { "nativeIsReadOnly", "(JJ)Z",
             (void*)nativeIsReadOnly },
+    { "nativeUpdatesTempOnly", "(JJ)Z",
+            (void*)nativeUpdatesTempOnly },
     { "nativeGetColumnCount", "(JJ)I",
             (void*)nativeGetColumnCount },
     { "nativeGetColumnName", "(JJI)Ljava/lang/String;",
diff --git a/core/tests/coretests/src/android/database/sqlite/SQLiteDatabaseTest.java b/core/tests/coretests/src/android/database/sqlite/SQLiteDatabaseTest.java
index 3fc08ee..bd5f809 100644
--- a/core/tests/coretests/src/android/database/sqlite/SQLiteDatabaseTest.java
+++ b/core/tests/coretests/src/android/database/sqlite/SQLiteDatabaseTest.java
@@ -26,6 +26,9 @@
 import android.database.Cursor;
 import android.database.DatabaseUtils;
 import android.os.SystemClock;
+import android.platform.test.annotations.RequiresFlagsEnabled;
+import android.platform.test.flag.junit.CheckFlagsRule;
+import android.platform.test.flag.junit.DeviceFlagsValueProvider;
 import android.test.AndroidTestCase;
 import android.util.Log;
 
@@ -35,6 +38,7 @@
 
 import org.junit.After;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -53,6 +57,10 @@
 @SmallTest
 public class SQLiteDatabaseTest {
 
+    @Rule
+    public final CheckFlagsRule mCheckFlagsRule =
+            DeviceFlagsValueProvider.createCheckFlagsRule();
+
     private static final String TAG = "SQLiteDatabaseTest";
 
     private final Context mContext = InstrumentationRegistry.getInstrumentation().getContext();
@@ -347,4 +355,50 @@
 
         assertTrue("ReadThread failed with errors: " + errors, errors.isEmpty());
     }
+
+    @RequiresFlagsEnabled(Flags.FLAG_SQLITE_ALLOW_TEMP_TABLES)
+    @Test
+    public void testTempTable() {
+        boolean allowed;
+        allowed = true;
+        mDatabase.beginTransactionReadOnly();
+        try {
+            mDatabase.execSQL("CREATE TEMP TABLE t1 (i int, j int);");
+            mDatabase.execSQL("INSERT INTO t1 (i, j) VALUES (2, 20)");
+            mDatabase.execSQL("INSERT INTO t1 (i, j) VALUES (3, 30)");
+
+            final String sql = "SELECT i FROM t1 WHERE j = 30";
+            try (SQLiteRawStatement s = mDatabase.createRawStatement(sql)) {
+                assertTrue(s.step());
+                assertEquals(3, s.getColumnInt(0));
+            }
+
+        } catch (SQLiteException e) {
+            allowed = false;
+        } finally {
+            mDatabase.endTransaction();
+        }
+        assertTrue(allowed);
+
+        // Repeat the test on the main schema.
+        allowed = true;
+        mDatabase.beginTransactionReadOnly();
+        try {
+            mDatabase.execSQL("CREATE TABLE t2 (i int, j int);");
+            mDatabase.execSQL("INSERT INTO t2 (i, j) VALUES (2, 20)");
+            mDatabase.execSQL("INSERT INTO t2 (i, j) VALUES (3, 30)");
+
+            final String sql = "SELECT i FROM t2 WHERE j = 30";
+            try (SQLiteRawStatement s = mDatabase.createRawStatement(sql)) {
+                assertTrue(s.step());
+                assertEquals(3, s.getColumnInt(0));
+            }
+
+        } catch (SQLiteException e) {
+            allowed = false;
+        } finally {
+            mDatabase.endTransaction();
+        }
+        assertFalse(allowed);
+    }
 }