[sql] Allow restricting database to user read access.

sql/connection.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sql/connection.h"
 
 #include <string.h>
 
 #include "base/files/file_path.h"
 #include "base/file_util.h"
@@ skipping 150 matching lines @@
   // handler.  In that case maintain the sense of |was_valid_| which
   // previously held for this ref.
   was_valid_ = was_valid_ && forced;
 }
 
 Connection::Connection()
     : db_(NULL),
       page_size_(0),
       cache_size_(0),
       exclusive_locking_(false),
+      restrict_to_user_(false),
       transaction_nesting_(0),
       needs_rollback_(false),
       in_memory_(false),
       poisoned_(false) {
 }
 
 Connection::~Connection() {
   Close();
 }
 
@@ skipping 540 matching lines @@
     // Histogram failures specific to initial open for debugging
     // purposes.
     UMA_HISTOGRAM_ENUMERATION("Sqlite.OpenFailure", err & 0xff, 50);
 
     OnSqliteError(err, NULL);
     Close();
     db_ = NULL;
     return false;
   }
 
+  // TODO(shess): OS_WIN support?
+#if defined(OS_POSIX)
+  if (restrict_to_user_) {
+    DCHECK_NE(file_name, std::string(":memory"));
+    base::FilePath file_path(file_name);
+    int mode = 0;
+    // TODO(shess): Arguably, failure to retrieve and change
+    // permissions should be fatal if the file exists.
+    if (file_util::GetPosixFilePermissions(file_path, &mode)) {
+      mode &= file_util::FILE_PERMISSION_USER_MASK;
+      file_util::SetPosixFilePermissions(file_path, mode);
+
+      // SQLite sets the permissions on these files from the main
+      // database on create.  Set them here in case they already exist
+      // at this point.  Failure to set these permissions should not
+      // be fatal unless the file doesn't exist.
+      base::FilePath journal_path(file_name + FILE_PATH_LITERAL("-journal"));
+      base::FilePath wal_path(file_name + FILE_PATH_LITERAL("-wal"));
+      file_util::SetPosixFilePermissions(journal_path, mode);
+      file_util::SetPosixFilePermissions(wal_path, mode);
+    }
+  }
+#endif  // defined(OS_POSIX)
+
   // SQLite uses a lookaside buffer to improve performance of small mallocs.
   // Chromium already depends on small mallocs being efficient, so we disable
   // this to avoid the extra memory overhead.
   // This must be called immediatly after opening the database before any SQL
   // statements are run.
   sqlite3_db_config(db_, SQLITE_DBCONFIG_LOOKASIDE, NULL, 0, 0);
 
   // sqlite3_open() does not actually read the database file (unless a
   // hot journal is found).  Successfully executing this pragma on an
   // existing database requires a valid header on page 1.
@@ skipping 161 matching lines @@
   }
 
   // Best effort to put things back as they were before.
   const char kNoWritableSchema[] = "PRAGMA writable_schema = OFF";
   ignore_result(Execute(kNoWritableSchema));
 
   return ret;
 }
 
 }  // namespace sql