GP-5677: Ghidra now writes a "lastrun" file that PyGhidra can look for

to help find the Ghidra installation dir

Ghidra/Features/Base/src/main/java/ghidra/GhidraRun.java

@@ -16,6 +16,8 @@
 package ghidra;
 
 import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
 
 import javax.swing.ToolTipManager;
 
@@ -23,6 +25,7 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
 import docking.framework.SplashScreen;
+import generic.jar.ResourceFile;
 import ghidra.base.help.GhidraHelpService;
 import ghidra.framework.Application;
 import ghidra.framework.GhidraApplicationConfiguration;
@@ -77,6 +80,8 @@ public class GhidraRun implements GhidraLaunchable {
 			log.info("User temp directory: " + Application.getUserTempDirectory());
 			log.info("User cache directory: " + Application.getUserCacheDirectory());
 
+			writeLastRun();
+
 			initializeTooltips();
 
 			updateSplashScreenStatusMessage("Populating Ghidra help...");
@@ -99,6 +104,22 @@ public class GhidraRun implements GhidraLaunchable {
 		mainThread.start();
 	}
 
+	private void writeLastRun() {
+		// Write the Ghidra installation location to the "lastrun" file
+		File settingsDir = Application.getUserSettingsDirectory();
+		ResourceFile rootDir = Application.getApplicationRootDirectory();
+		if (settingsDir != null && rootDir != null) {
+			File lastRunFile = new File(settingsDir.getParentFile(), "lastrun");
+			try {
+				Files.writeString(lastRunFile.toPath(),
+					rootDir.getParentFile().getCanonicalPath() + "\n");
+			}
+			catch (IOException e) {
+				log.error("Failed to write 'lastrun' file", e);
+			}
+		}
+	}
+
 	private String processArguments(String[] args) {
 		//TODO remove this special handling when possible
 		if (args.length == 1 && (args[0].startsWith("-D") || args[0].indexOf(" -D") >= 0)) {

Ghidra/Features/PyGhidra/src/main/py/README.md

@@ -55,7 +55,7 @@ def start(verbose=False, *, install_dir: Path = None) -> "PyGhidraLauncher":
 
     :param verbose: Enable verbose output during JVM startup (Defaults to False)
     :param install_dir: The path to the Ghidra installation directory.
-        (Defaults to the GHIDRA_INSTALL_DIR environment variable)
+        (Defaults to the GHIDRA_INSTALL_DIR environment variable or "lastrun" file)
     :return: The PyGhidraLauncher used to start the JVM
     """
 ```
@@ -222,7 +222,7 @@ def run_script(
         This may be either a Java class or its path. (Defaults to None)
     :param install_dir: The path to the Ghidra installation directory. This parameter is only
         used if Ghidra has not been started yet.
-        (Defaults to the GHIDRA_INSTALL_DIR environment variable)
+        (Defaults to the GHIDRA_INSTALL_DIR environment variable or "lastrun" file)
     :param program_name: The name of the program to open in Ghidra.
         (Defaults to None, which results in the name being derived from "binary_path")
     :param nested_project_location: If True, assumes "project_location" contains an extra nested 
@@ -330,6 +330,10 @@ __2.2.0:__
   [`pyghidra.run_script()`](#pyghidrarun_script) now accept a `nested_project_location` parameter
   which can be set to `False` to open existing Ghidra projects that were created with the
   Ghidra GUI.
+* If a Ghidra installation directory is not specified by the `install_dir` parameter or
+  `GHIDRA_INSTALL_DIR` environment variable, PyGhidra will look for a `lastrun` file in the
+  Ghidra user settings parent directory, and use the installation directory it specifies.  The
+  `lastrun` file is created by Ghidra 11.4 and later.
 
 __2.1.0:__
 * [`pyghidra.open_program()`](#pyghidraopen_program) now accepts a `program_name` parameter, which

Ghidra/Features/PyGhidra/src/main/py/src/pyghidra/core.py

@@ -33,7 +33,7 @@ def start(verbose=False, *, install_dir: Path = None) -> "PyGhidraLauncher":
 
     :param verbose: Enable verbose output during JVM startup (Defaults to False)
     :param install_dir: The path to the Ghidra installation directory.
-        (Defaults to the GHIDRA_INSTALL_DIR environment variable)
+        (Defaults to the GHIDRA_INSTALL_DIR environment variable or "lastrun" file)
     :return: The PyGhidraLauncher used to start the JVM
     """
     from pyghidra.launcher import HeadlessPyGhidraLauncher
@@ -302,7 +302,7 @@ def _flat_api(
         This may be either a Java class or its path. (Defaults to None)
     :param install_dir: The path to the Ghidra installation directory. This parameter is only
         used if Ghidra has not been started yet.
-        (Defaults to the GHIDRA_INSTALL_DIR environment variable)
+        (Defaults to the GHIDRA_INSTALL_DIR environment variable or "lastrun" file)
     :raises ValueError: If the provided language, compiler or loader is invalid.
     :raises TypeError: If the provided loader does not implement `ghidra.app.util.opinion.Loader`.
     """
@@ -378,7 +378,7 @@ def run_script(
         This may be either a Java class or its path. (Defaults to None)
     :param install_dir: The path to the Ghidra installation directory. This parameter is only
         used if Ghidra has not been started yet.
-        (Defaults to the GHIDRA_INSTALL_DIR environment variable)
+        (Defaults to the GHIDRA_INSTALL_DIR environment variable or "lastrun" file)
     :param program_name: The name of the program to open in Ghidra.
         (Defaults to None, which results in the name being derived from "binary_path")
     :param nested_project_location: If True, assumes "project_location" contains an extra nested 

Ghidra/Features/PyGhidra/src/main/py/src/pyghidra/launcher.py

@@ -152,6 +152,29 @@ def _plugin_lock():
             # it will be removed by said process when done
             pass
 
+def _lastrun() -> Path:
+
+    lastrun_file: Path = None
+    lastrun_rel: Path = Path('ghidra/lastrun')
+    
+    # Check for XDG_CONFIG_HOME environment variable
+    xdg_config_home: str = os.environ.get('XDG_CONFIG_HOME')
+    if xdg_config_home:
+        lastrun_file = Path(xdg_config_home) / lastrun_rel
+    else:
+        # Default to platform-specific locations
+        if platform.system() == 'Windows':
+            lastrun_file = Path(os.environ['APPDATA']) / lastrun_rel
+        elif platform.system() == 'Darwin':
+            lastrun_file = Path.home() / 'Library' / lastrun_rel
+        else:
+            lastrun_file = Path.home() / '.config' / lastrun_rel
+            
+    if lastrun_file is not None and lastrun_file.is_file():
+        with open(lastrun_file, "r") as file:
+            return Path(file.readline().strip())
+        
+    return None
 
 class PyGhidraLauncher:
     """
@@ -164,7 +187,7 @@ class PyGhidraLauncher:
 
         :param verbose: True to enable verbose output when starting Ghidra.
         :param install_dir: Ghidra installation directory.
-            (Defaults to the GHIDRA_INSTALL_DIR environment variable)
+            (Defaults to the GHIDRA_INSTALL_DIR environment variable or "lastrun" file)
         :raises ValueError: If the Ghidra installation directory is invalid.
         """
         self._layout = None
@@ -173,7 +196,7 @@ class PyGhidraLauncher:
         self._dev_mode = False
         self._extension_path = None
 
-        install_dir = install_dir or os.getenv("GHIDRA_INSTALL_DIR")
+        install_dir = install_dir or os.getenv("GHIDRA_INSTALL_DIR") or _lastrun()
         self._install_dir = self._validate_install_dir(install_dir)
 
         java_home_override = os.getenv("JAVA_HOME_OVERRIDE")