From 3869bfd2f95acc4cd7dcc08675155047da1d4676 Mon Sep 17 00:00:00 2001
From: AnErrupTion <anerruption@disroot.org>
Date: Fri, 1 May 2026 17:40:04 +0200
Subject: [PATCH] Add config validation argument (closes #969)

Signed-off-by: AnErrupTion <anerruption@disroot.org>
---
 readme.md    |  6 ++++++
 src/main.zig | 27 ++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/readme.md b/readme.md
index aa23db8..78ebffc 100644
--- a/readme.md
+++ b/readme.md
@@ -226,6 +226,12 @@ You can, of course, still select the init system of your choice when using this
 
 You can find all the configuration in `/etc/ly/config.ini`. The file is fully commented, and includes the default values.
 
+You may also check the validity of your configuration file (i.e. if there are any errors in it) with the following command:
+
+```
+$ ly --validate-config /etc/ly/config.ini
+```
+
 ## Controls
 
 Use the Up/Down arrow keys to change the current field, and the Left/Right arrow keys to scroll through the different fields (whether it be the info line, the desktop environment, or the username). The info line is where messages and errors are displayed.
diff --git a/src/main.zig b/src/main.zig
index 81c44b4..6373751 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -172,7 +172,8 @@ pub fn main(init: std.process.Init) !void {
         \\-h, --help                Shows all commands.
         \\-v, --version             Shows the version of Ly.
         \\-c, --config <str>        Overrides the default configuration path. Example: --config /usr/share/ly
-        \\--use-kmscon-vt           Use KMSCON instead of kernel VT
+        \\--use-kmscon-vt           Uses KMSCON instead of the kernel VT.
+        \\--validate-config <str>   Validates the given configuration file.
     );
 
     var diag = clap.Diagnostic{};
@@ -211,6 +212,30 @@ pub fn main(init: std.process.Init) !void {
         }
         if (res.args.config) |path| config_parent_path = path;
         if (res.args.@"use-kmscon-vt" != 0) state.use_kmscon_vt = true;
+        if (res.args.@"validate-config") |path| {
+            var parser = try IniParser(Config).init(
+                state.allocator,
+                state.io,
+                path,
+                migrator.configFieldHandler,
+            );
+            defer parser.deinit();
+
+            for (parser.errors.items) |err| {
+                std.log.err(
+                    "failed to convert value '{s}' of option '{s}' to type '{s}': {s}",
+                    .{ err.value, err.key, err.type_name, err.error_name },
+                );
+            }
+
+            if (parser.maybe_load_error) |err| {
+                std.log.err("failed to load config file: {s}", .{@errorName(err)});
+                std.process.exit(1);
+            }
+
+            std.log.info("no errors detected!", .{});
+            std.process.exit(0);
+        }
     }
 
     // Load configuration file