From b1a7b26eef46106deec0a954d400e5a1aac47945 Mon Sep 17 00:00:00 2001
From: Ben Radford <benradf@users.noreply.github.com>
Date: Tue, 16 May 2023 15:48:40 +0100
Subject: [PATCH] Rename ReadOnly to Immutable and clarify its purpose.

---
 src/libstore/local-store.cc | 2 +-
 src/libstore/sqlite.cc      | 7 +++----
 src/libstore/sqlite.hh      | 7 +++++--
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 1c5d8fc9e..59685400f 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -490,7 +490,7 @@ void LocalStore::openDB(State & state, bool create)
     /* Open the Nix database. */
     std::string dbPath = dbDir + "/db.sqlite";
     auto & db(state.db);
-    auto openMode = readOnly ? SQLiteOpenMode::ReadOnly
+    auto openMode = readOnly ? SQLiteOpenMode::Immutable
                   : create ? SQLiteOpenMode::Normal
                   : SQLiteOpenMode::NoCreate;
     state.db = SQLite(dbPath, openMode);
diff --git a/src/libstore/sqlite.cc b/src/libstore/sqlite.cc
index 4166cc2cd..7c8decb74 100644
--- a/src/libstore/sqlite.cc
+++ b/src/libstore/sqlite.cc
@@ -53,15 +53,14 @@ static void traceSQL(void * x, const char * sql)
 
 SQLite::SQLite(const Path & path, SQLiteOpenMode mode)
 {
-    bool readOnly = mode == SQLiteOpenMode::ReadOnly;
-
     // useSQLiteWAL also indicates what virtual file system we need.  Using
     // `unix-dotfile` is needed on NFS file systems and on Windows' Subsystem
     // for Linux (WSL) where useSQLiteWAL should be false by default.
     const char *vfs = settings.useSQLiteWAL ? 0 : "unix-dotfile";
-    int flags = readOnly ? SQLITE_OPEN_READONLY : SQLITE_OPEN_READWRITE;
+    bool immutable = mode == SQLiteOpenMode::Immutable;
+    int flags = immutable ? SQLITE_OPEN_READONLY : SQLITE_OPEN_READWRITE;
     if (mode == SQLiteOpenMode::Normal) flags |= SQLITE_OPEN_CREATE;
-    auto uri = "file:" + percentEncode(path) + "?immutable=" + (readOnly ? "1" : "0");
+    auto uri = "file:" + percentEncode(path) + "?immutable=" + (immutable ? "1" : "0");
     int ret = sqlite3_open_v2(uri.c_str(), &db, SQLITE_OPEN_URI | flags, vfs);
     if (ret != SQLITE_OK) {
         const char * err = sqlite3_errstr(ret);
diff --git a/src/libstore/sqlite.hh b/src/libstore/sqlite.hh
index 33f0eeed8..b0e84f8ed 100644
--- a/src/libstore/sqlite.hh
+++ b/src/libstore/sqlite.hh
@@ -23,10 +23,13 @@ enum class SQLiteOpenMode {
      */
     NoCreate,
     /**
-     * Open the database in read-only mode.
+     * Open the database in immutable mode.
+     * In addition to the database being read-only,
+     * no wal or journal files will be created by sqlite.
+     * Use this mode if the database is on a read-only filesystem.
      * Fails with an error if the database does not exist.
      */
-    ReadOnly
+    Immutable
 };
 
 /**