Fix server debugger for Android >= 9

Add a compilation flag to select the debugger method to use:
 - old: Android < 9
 - new: Android >= 9

See <https://github.com/Genymobile/scrcpy/issues/1187#issuecomment-599075661>

DEVELOP.md

@@ -282,6 +282,15 @@ meson x -Dserver_debugger=true
 meson configure x -Dserver_debugger=true
 ```
 
+If your device runs Android 8 or below, set the `server_debugger_method` to
+`old` in addition:
+
+```bash
+meson x -Dserver_debugger=true -Dserver_debugger_method=old
+# or, if x is already configured
+meson configure x -Dserver_debugger=true -Dserver_debugger_method=old
+```
+
 Then recompile.
 
 When you start scrcpy, it will start a debugger on port 5005 on the device.

app/meson.build

@@ -124,6 +124,9 @@ conf.set('WINDOWS_NOCONSOLE', get_option('windows_noconsole'))
 # run a server debugger and wait for a client to be attached
 conf.set('SERVER_DEBUGGER', get_option('server_debugger'))
 
+# select the debugger method ('old' for Android < 9, 'new' for Android >= 9)
+conf.set('SERVER_DEBUGGER_METHOD_NEW', get_option('server_debugger_method') == 'new')
+
 configure_file(configuration: conf, output: 'config.h')
 
 src_dir = include_directories('src')

app/src/server.c

@@ -244,7 +244,13 @@ execute_server(struct server *server, const struct server_params *params) {
         "app_process",
 #ifdef SERVER_DEBUGGER
 # define SERVER_DEBUGGER_PORT "5005"
+# ifdef SERVER_DEBUGGER_METHOD_NEW
+        /* Android 9 and above */
+        "-XjdwpProvider:internal -XjdwpOptions:transport=dt_socket,suspend=y,server=y,address="
+# else
+        /* Android 8 and below */
         "-agentlib:jdwp=transport=dt_socket,suspend=y,server=y,address="
+# endif
             SERVER_DEBUGGER_PORT,
 #endif
         "/", // unused

meson_options.txt

@@ -6,3 +6,4 @@ option('prebuilt_server', type: 'string', description: 'Path of the prebuilt ser
 option('portable', type: 'boolean', value: false, description: 'Use scrcpy-server from the same directory as the scrcpy executable')
 option('hidpi_support', type: 'boolean', value: true, description: 'Enable High DPI support')
 option('server_debugger', type: 'boolean', value: false, description: 'Run a server debugger and wait for a client to be attached')
+option('server_debugger_method', type: 'combo', choices: ['old', 'new'], value: 'new', description: 'Select the debugger method (Android < 9: "old", Android >= 9: "new")')