fix: tighten Unix platform handling

Adds Linux and macOS platform guards so the analyzer can narrow calls through Utils.IsLinux() and Utils.IsMacOS().

Marks the Linux/macOS autostart and system proxy helpers with explicit platform attributes.

Updates Utils.GetSystemHosts() to read /etc/hosts on Linux and macOS while keeping the existing Windows hosts and hosts.ics merge behavior.

v2rayN/ServiceLib/Common/Utils.cs

@@ -863,6 +863,8 @@ public class Utils
     }
 
     public static Dictionary<string, string> GetSystemHosts()
+    {
+        if (IsWindows())
         {
             var hosts = GetSystemHosts(@"C:\Windows\System32\drivers\etc\hosts");
             var hostsIcs = GetSystemHosts(@"C:\Windows\System32\drivers\etc\hosts.ics");
@@ -875,6 +877,14 @@ public class Utils
             return hosts;
         }
 
+        if (IsLinux() || IsMacOS())
+        {
+            return GetSystemHosts("/etc/hosts");
+        }
+
+        return new Dictionary<string, string>();
+    }
+
     public static async Task<string?> GetCliWrapOutput(string filePath, string? arg)
     {
         return await GetCliWrapOutput(filePath, arg != null ? new List<string>() { arg } : null);
@@ -1117,8 +1127,10 @@ public class Utils
     [SupportedOSPlatformGuard("windows")]
     public static bool IsWindows() => OperatingSystem.IsWindows();
 
+    [SupportedOSPlatformGuard("linux")]
     public static bool IsLinux() => OperatingSystem.IsLinux();
 
+    [SupportedOSPlatformGuard("macos")]
     public static bool IsMacOS() => OperatingSystem.IsMacOS();
 
     [UnsupportedOSPlatformGuard("windows")]

v2rayN/ServiceLib/Handler/AutoStartupHandler.cs

@@ -127,6 +127,7 @@ public static class AutoStartupHandler
 
     #region Linux
 
+    [SupportedOSPlatform("linux")]
     private static async Task ClearTaskLinux()
     {
         try
@@ -140,6 +141,7 @@ public static class AutoStartupHandler
         await Task.CompletedTask;
     }
 
+    [SupportedOSPlatform("linux")]
     private static async Task SetTaskLinux()
     {
         try
@@ -160,6 +162,7 @@ public static class AutoStartupHandler
         }
     }
 
+    [SupportedOSPlatform("linux")]
     private static string GetHomePathLinux()
     {
         var homePath = Path.Combine(Utils.GetHomePath(), ".config", "autostart", $"{Global.AppName}.desktop");
@@ -171,6 +174,7 @@ public static class AutoStartupHandler
 
     #region macOS
 
+    [SupportedOSPlatform("macos")]
     private static async Task ClearTaskOSX()
     {
         try
@@ -190,6 +194,7 @@ public static class AutoStartupHandler
         }
     }
 
+    [SupportedOSPlatform("macos")]
     private static async Task SetTaskOSX()
     {
         try
@@ -207,6 +212,7 @@ public static class AutoStartupHandler
         }
     }
 
+    [SupportedOSPlatform("macos")]
     private static string GetLaunchAgentPathMacOS()
     {
         var homePath = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
@@ -215,6 +221,7 @@ public static class AutoStartupHandler
         return launchAgentPath;
     }
 
+    [SupportedOSPlatform("macos")]
     private static string GenerateLaunchAgentPlist()
     {
         var exePath = Utils.GetExePath();

v2rayN/ServiceLib/Handler/SysProxy/ProxySettingLinux.cs

@@ -1,5 +1,6 @@
 namespace ServiceLib.Handler.SysProxy;
 
+[SupportedOSPlatform("linux")]
 public static class ProxySettingLinux
 {
     private static readonly string _proxySetFileName = $"{Global.ProxySetLinuxShellFileName.Replace(Global.NamespaceSample, "")}.sh";

v2rayN/ServiceLib/Handler/SysProxy/ProxySettingOSX.cs

@@ -1,5 +1,6 @@
 namespace ServiceLib.Handler.SysProxy;
 
+[SupportedOSPlatform("macos")]
 public static class ProxySettingOSX
 {
     private static readonly string _proxySetFileName = $"{Global.ProxySetOSXShellFileName.Replace(Global.NamespaceSample, "")}.sh";