Detours hooking is incompatible with AnsiCon.

Detours effectively gives Clink's hooks the lowest precedence.  Clink's
hooks need to have high precedence in order to successfully detect when
CMD prints the prompt.

This reverts Clink to use IAT hooking by default.  And it goes further,
using IAT hooking even for ReadConsoleW, which had always used address
hooking.  Originally everything used address hooking, and Martin slowly
converted things to use IAT hooks, but never converted ReadConsoleW.

Clink can be forced to use Detours hooking via `clink inject --detours`.
But don't use `--detours` unless it's the only way to get Clink working.

clink/app/src/host/host_cmd.cpp

@@ -34,7 +34,6 @@ func_SetEnvironmentVariableW_t __Real_SetEnvironmentVariableW = SetEnvironmentVa
 func_WriteConsoleW_t __Real_WriteConsoleW = WriteConsoleW;
 func_ReadConsoleW_t __Real_ReadConsoleW = ReadConsoleW;
 func_GetEnvironmentVariableW_t __Real_GetEnvironmentVariableW = GetEnvironmentVariableW;
-static const char s_kernel_module[] = "kernel32.dll";
 
 //------------------------------------------------------------------------------
 extern bool is_force_reload_scripts();
@@ -60,6 +59,19 @@ static setting_str g_admin_title_prefix(
 
 
 
+//------------------------------------------------------------------------------
+static hook_type get_hook_type()
+{
+    static hook_type s_hook_type = app_context::get()->is_detours() ? detour : iat;
+    return s_hook_type;
+}
+static const char* get_kernel_module()
+{
+    return (get_hook_type() == iat) ? nullptr : "kernel32.dll";
+}
+
+
+
 //------------------------------------------------------------------------------
 static bool get_mui_string(int id, wstr_base& out)
 {
@@ -244,20 +256,22 @@ int host_cmd::validate()
 bool host_cmd::initialise()
 {
     hook_setter hooks;
+    hook_type type = get_hook_type();
+    const char* module = get_kernel_module();
 
     // Hook the setting of the 'prompt' environment variable so we can tag
     // it and detect command entry via a write hook.
     tag_prompt();
-    if (!hooks.attach(s_kernel_module, "SetEnvironmentVariableW", &host_cmd::set_env_var, &__Real_SetEnvironmentVariableW))
+    if (!hooks.attach(type, module, "SetEnvironmentVariableW", &host_cmd::set_env_var, &__Real_SetEnvironmentVariableW))
         return false;
-    if (!hooks.attach(s_kernel_module, "WriteConsoleW", &host_cmd::write_console, &__Real_WriteConsoleW))
+    if (!hooks.attach(type, module, "WriteConsoleW", &host_cmd::write_console, &__Real_WriteConsoleW))
         return false;
 
     // Set a trap to get a callback when cmd.exe fetches PROMPT environment
     // variable.  GetEnvironmentVariableW is always called before displaying the
     // prompt string, so it's a reliable spot to hook regardless how injection
     // is initiated (AutoRun, command line, etc).
-    if (!hooks.attach(s_kernel_module, "GetEnvironmentVariableW", &host_cmd::get_env_var, &__Real_GetEnvironmentVariableW))
+    if (!hooks.attach(type, module, "GetEnvironmentVariableW", &host_cmd::get_env_var, &__Real_GetEnvironmentVariableW))
         return false;
 
     return hooks.commit();
@@ -563,7 +577,7 @@ DWORD WINAPI host_cmd::get_env_var(LPCWSTR lpName, LPWSTR lpBuffer, DWORD nSize)
         s_initialised_system = true;
 
         hook_setter unhook;
-        unhook.detach(&__Real_GetEnvironmentVariableW, get_env_var);
+        unhook.detach(get_hook_type(), get_kernel_module(), "GetEnvironmentVariableW", &__Real_GetEnvironmentVariableW, get_env_var);
         unhook.commit();
 
         host_cmd::get()->initialise_system();
@@ -606,10 +620,13 @@ DWORD WINAPI host_cmd::format_message(DWORD flags, LPCVOID source, DWORD message
 bool host_cmd::initialise_system()
 {
     {
+        hook_type type = get_hook_type();
+        const char* module = get_kernel_module();
+
         // ReadConsoleW is required.
         {
             hook_setter hooks;
-            hooks.attach(s_kernel_module, "ReadConsoleW", &host_cmd::read_console, &__Real_ReadConsoleW);
+            hooks.attach(type, module, "ReadConsoleW", &host_cmd::read_console, &__Real_ReadConsoleW);
             if (!hooks.commit())
                 return false;
         }
@@ -619,7 +636,7 @@ bool host_cmd::initialise_system()
         // prefix, but ignore failure since it's just a minor convenience.
         {
             hook_setter hooks;
-            hooks.add(s_kernel_module, "FormatMessageW", &host_cmd::format_message, &__imp_FormatMessageW);
+            hooks.add(type, module, "FormatMessageW", &host_cmd::format_message, &__imp_FormatMessageW);
             hooks.commit();
         }
 #endif

clink/app/src/loader/inject.cpp

@@ -413,6 +413,7 @@ int inject(int argc, char** argv)
         { "pid",         required_argument,  nullptr, 'd' },
         { "nolog",       no_argument,        nullptr, 'l' },
         { "autorun",     no_argument,        nullptr, '_' },
+        { "detours",     no_argument,        nullptr, '^' },
         { "help",        no_argument,        nullptr, 'h' },
         { nullptr, 0, nullptr, 0 }
     };
@@ -459,14 +460,12 @@ int inject(int argc, char** argv)
             }
             break;
 
-        case 'q': app_desc.quiet = true;        break;
         case 'd': target_pid = atoi(optarg);    break;
+        case 'q': app_desc.quiet = true;        break;
+        case 'l': app_desc.log = false;         break;
+        case '^': app_desc.detours = true;      break;
         case '_': ret = 0; is_autorun = true;   break;
 
-        case 'l':
-            app_desc.log = false;
-            break;
-
         case '?':
         case 'h':
             ret = 0;

clink/app/src/loader/main.cpp

@@ -40,6 +40,8 @@ inline bool __streq(const WCHAR* a, const WCHAR* b)
 
 //------------------------------------------------------------------------------
 // This is exported so that `clink testbed --hook` can simulate injection.
+// This MUST import all APIs that Clink hooks, so that the EXE has IAT entries
+// for them.
 extern "C" {
 __declspec(dllexport) void __stdcall testbed_hook_loop()
 {

clink/app/src/utils/app_context.cpp

@@ -159,6 +159,12 @@ bool app_context::is_quiet() const
     return m_desc.quiet;
 }
 
+//------------------------------------------------------------------------------
+bool app_context::is_detours() const
+{
+    return m_desc.detours;
+}
+
 //------------------------------------------------------------------------------
 void app_context::get_binaries_dir(str_base& out) const
 {

clink/app/src/utils/app_context.h

@@ -20,7 +20,7 @@ class app_context
         bool    log = true;
         bool    inherit_id = false; // Allow auto-detecting id from environment.
         bool    force = false;      // Skip host check (for testbed).
-        char    unused = 0;
+        bool    detours = false;    // Use Detours for hooking, instead of IAT.
         char    state_dir[510];     // = {}; (this crashes cl.exe v18.00.21005.1)
         char    script_path[510];   // = {}; (this crashes cl.exe v18.00.21005.1)
     };
@@ -29,6 +29,7 @@ class app_context
     int         get_id() const;
     bool        is_logging_enabled() const;
     bool        is_quiet() const;
+    bool        is_detours() const;
     void        get_binaries_dir(str_base& out) const;
     void        get_state_dir(str_base& out) const;
     void        get_autostart_command(str_base& out) const;