Fix user detection if /etc/login.defs does not contain both UID_MIN and UID_MAX (#1014)

## What are the changes about?

I modified getUserIdRange(), so it checks if either of UID_MIN and UID_MAX is set in /etc/login.defs. If any, but not both, is not set, it uses fallback value. I don't know zig build system, so I added ugly fallback values passthrough.

## What existing issue does this resolve?

#1013

## Pre-requisites

- [X] I have tested & confirmed the changes work locally
- [X] I have read and fully adhere to the rules set in the contributing guidelines found in `CONTRIBUTING.md`

Reviewed-on: https://codeberg.org/fairyglade/ly/pulls/1014
Reviewed-by: AnErrupTion <anerruption+codeberg@disroot.org>

build.zig

@@ -75,6 +75,8 @@ pub fn build(b: *std.Build) !void {
         .target = target,
         .optimize = optimize,
         .enable_x11_support = enable_x11_support,
+        .fallback_uid_min = fallback_uid_min,
+        .fallback_uid_max = fallback_uid_max
     });
     exe.root_module.addImport("ly-ui", ly_ui.module("ly-ui"));
 

ly-core/build.zig

@@ -11,6 +11,13 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
+    const fallback_uid_min = b.option(std.posix.uid_t, "fallback_uid_min", "Set the fallback minimum UID (default is 1000). This value gets embedded into the binary").?;
+    const fallback_uid_max = b.option(std.posix.uid_t, "fallback_uid_max", "Set the fallback maximum UID (default is 60000). This value gets embedded into the binary").?;
+    const build_options = b.addOptions();
+    build_options.addOption(std.posix.uid_t, "fallback_uid_min", fallback_uid_min);
+    build_options.addOption(std.posix.uid_t, "fallback_uid_max", fallback_uid_max);
+    mod.addOptions("build_options", build_options);
+
     const zigini = b.dependency("zigini", .{ .target = target, .optimize = optimize });
     mod.addImport("zigini", zigini.module("zigini"));
 

ly-core/src/interop.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const builtin = @import("builtin");
+const build_options = @import("build_options");
 const UidRange = @import("UidRange.zig");
 const pwd = @import("pwd");
 const stdlib = @import("stdlib");
@@ -145,21 +146,32 @@ fn PlatformStruct() type {
 
                 var iterator = std.mem.splitScalar(u8, login_defs_buffer, '\n');
                 var uid_range = UidRange{};
-                var nameFound = false;
+                var uid_min_Found = false;
+                var uid_max_Found = false;
 
                 while (iterator.next()) |line| {
                     const trimmed_line = std.mem.trim(u8, line, " \n\r\t");
 
                     if (std.mem.startsWith(u8, trimmed_line, "UID_MIN")) {
                         uid_range.uid_min = try parseValue(std.posix.uid_t, "UID_MIN", trimmed_line);
-                        nameFound = true;
+                        uid_min_Found = true;
                     } else if (std.mem.startsWith(u8, trimmed_line, "UID_MAX")) {
                         uid_range.uid_max = try parseValue(std.posix.uid_t, "UID_MAX", trimmed_line);
-                        nameFound = true;
+                        uid_max_Found = true;
                     }
                 }
 
-                if (!nameFound) return error.UidNameNotFound;
+                if (!(uid_min_Found or uid_max_Found)) {
+                    return error.UidNameNotFound;
+                }
+
+                if (!uid_min_Found) {
+                    uid_range.uid_min = build_options.fallback_uid_min;
+                }
+
+                if (!uid_max_Found) {
+                    uid_range.uid_max = build_options.fallback_uid_max;
+                }
 
                 return uid_range;
             }

ly-ui/build.zig

@@ -11,10 +11,15 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
+    const fallback_uid_min = b.option(std.posix.uid_t, "fallback_uid_min", "Set the fallback minimum UID (default is 1000). This value gets embedded into the binary");
+    const fallback_uid_max = b.option(std.posix.uid_t, "fallback_uid_max", "Set the fallback maximum UID (default is 60000). This value gets embedded into the binary");
+
     const ly_core = b.dependency("ly_core", .{
         .target = target,
         .optimize = optimize,
         .enable_x11_support = enable_x11_support,
+        .fallback_uid_min = fallback_uid_min,
+        .fallback_uid_max = fallback_uid_max
     });
     mod.addImport("ly-core", ly_core.module("ly-core"));