Added: Write termux shell environment to /data/data/com.termux/files/usr/etc/termux/termux.env on app startup and package changes

The `termux.env` can be sourced by shells to set termux environment normally exported. This can be useful for users starting termux shells with `adb` `run-as` or `root`. The file will not contain `SHELL_CMD__` variables since those are shell command specific.

The items in the `termux.env` file have the format `export name="value"`.
The `"`\$` characters will be escaped with `a backslash `\`, like `\"` if characters are for literal value. Note that if `$` is escaped and if its part of variable, then variable expansion will not happen if `.env` file is sourced. The `\` at the end of a value line means line continuation. Value can contain newline characters.

The `termux.env` file should be sourceable by `POSIX` compliant shells like `bash`, `zsh`, `sh`, android's `mksh`, etc. Other shells with require manual parsing of the file to export variables.

Related discussion #2565

app/src/main/java/com/termux/app/TermuxApplication.java

@@ -12,6 +12,7 @@ import com.termux.shared.termux.crash.TermuxCrashUtils;
 import com.termux.shared.termux.file.TermuxFileUtils;
 import com.termux.shared.termux.settings.preferences.TermuxAppSharedPreferences;
 import com.termux.shared.termux.settings.properties.TermuxAppSharedProperties;
+import com.termux.shared.termux.shell.command.environment.TermuxShellEnvironment;
 import com.termux.shared.termux.shell.am.TermuxAmSocketServer;
 import com.termux.shared.termux.shell.TermuxShellManager;
 import com.termux.shared.termux.theme.TermuxThemeUtils;
@@ -48,9 +49,8 @@ public class TermuxApplication extends Application {
         // Check and create termux files directory. If failed to access it like in case of secondary
         // user or external sd card installation, then don't run files directory related code
         Error error = TermuxFileUtils.isTermuxFilesDirectoryAccessible(this, true, true);
-        if (error != null) {
+        boolean isTermuxFilesDirectoryAccessible = error == null;
-            Logger.logErrorExtended(LOG_TAG, "Termux files directory is not accessible\n" + error);
+        if (isTermuxFilesDirectoryAccessible) {
-        } else {
             Logger.logInfo(LOG_TAG, "Termux files directory is accessible");
 
             error = TermuxFileUtils.isAppsTermuxAppDirectoryAccessible(true, true);
@@ -59,10 +59,17 @@ public class TermuxApplication extends Application {
                 return;
             }
 
+            // Setup termux-am-socket server
             TermuxAmSocketServer.setupTermuxAmSocketServer(context);
+        } else {
+            Logger.logErrorExtended(LOG_TAG, "Termux files directory is not accessible\n" + error);
+        }
 
         // Init TermuxShellEnvironment constants and caches after everything has been setup including termux-am-socket server
         TermuxShellEnvironment.init(this);
+
+        if (isTermuxFilesDirectoryAccessible) {
+            TermuxShellEnvironment.writeEnvironmentToFile(this);
         }
     }
 

app/src/main/java/com/termux/app/TermuxService.java

@@ -19,6 +19,7 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.termux.R;
+import com.termux.app.event.SystemEventReceiver;
 import com.termux.app.terminal.TermuxTerminalSessionClient;
 import com.termux.shared.termux.plugins.TermuxPluginUtils;
 import com.termux.shared.data.IntentUtils;
@@ -116,6 +117,8 @@ public final class TermuxService extends Service implements AppShell.AppShellCli
         mShellManager = TermuxShellManager.getShellManager();
 
         runStartForeground();
+
+        SystemEventReceiver.registerPackageUpdateEvents(this);
     }
 
     @SuppressLint("Wakelock")
@@ -172,6 +175,9 @@ public final class TermuxService extends Service implements AppShell.AppShellCli
             killAllTermuxExecutionCommands();
 
         TermuxShellManager.onAppExit(this);
+
+        SystemEventReceiver.unregisterPackageUpdateEvents(this);
+
         runStopForeground();
     }
 

app/src/main/java/com/termux/app/event/SystemEventReceiver.java

@@ -2,12 +2,18 @@ package com.termux.app.event;
 
 import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.net.Uri;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.termux.shared.data.IntentUtils;
 import com.termux.shared.logger.Logger;
+import com.termux.shared.termux.TermuxUtils;
+import com.termux.shared.termux.file.TermuxFileUtils;
+import com.termux.shared.termux.shell.command.environment.TermuxShellEnvironment;
 import com.termux.shared.termux.shell.TermuxShellManager;
 
 public class SystemEventReceiver extends BroadcastReceiver {
@@ -35,6 +41,11 @@ public class SystemEventReceiver extends BroadcastReceiver {
             case Intent.ACTION_BOOT_COMPLETED:
                 onActionBootCompleted(context, intent);
                 break;
+            case Intent.ACTION_PACKAGE_ADDED:
+            case Intent.ACTION_PACKAGE_REMOVED:
+            case Intent.ACTION_PACKAGE_REPLACED:
+                onActionPackageUpdated(context, intent);
+                break;
             default:
                 Logger.logError(LOG_TAG, "Invalid action \"" + action + "\" passed to " + LOG_TAG);
         }
@@ -44,4 +55,37 @@ public class SystemEventReceiver extends BroadcastReceiver {
         TermuxShellManager.onActionBootCompleted(context, intent);
     }
 
+    public synchronized void onActionPackageUpdated(@NonNull Context context, @NonNull Intent intent) {
+        Uri data = intent.getData();
+        if (data != null && TermuxUtils.isUriDataForTermuxPluginPackage(data)) {
+            Logger.logDebug(LOG_TAG, intent.getAction().replaceAll("^android.intent.action.", "") +
+                " event received for \"" + data.toString().replaceAll("^package:", "") + "\"");
+            if (TermuxFileUtils.isTermuxFilesDirectoryAccessible(context, false, false) == null)
+                TermuxShellEnvironment.writeEnvironmentToFile(context);
+        }
+    }
+
+
+
+    /**
+     * Register {@link SystemEventReceiver} to listen to {@link Intent#ACTION_PACKAGE_ADDED},
+     * {@link Intent#ACTION_PACKAGE_REMOVED} and {@link Intent#ACTION_PACKAGE_REPLACED} broadcasts.
+     * They must be registered dynamically and cannot be registered implicitly in
+     * the AndroidManifest.xml due to Android 8+ restrictions.
+     *
+     *  https://developer.android.com/guide/components/broadcast-exceptions
+     */
+    public synchronized static void registerPackageUpdateEvents(@NonNull Context context) {
+        IntentFilter intentFilter = new IntentFilter();
+        intentFilter.addAction(Intent.ACTION_PACKAGE_ADDED);
+        intentFilter.addAction(Intent.ACTION_PACKAGE_REMOVED);
+        intentFilter.addAction(Intent.ACTION_PACKAGE_REPLACED);
+        intentFilter.addDataScheme("package");
+        context.registerReceiver(getInstance(), intentFilter);
+    }
+
+    public synchronized static void unregisterPackageUpdateEvents(@NonNull Context context) {
+        context.unregisterReceiver(getInstance());
+    }
+
 }

termux-shared/src/main/java/com/termux/shared/shell/command/environment/ShellEnvironmentUtils.java

@@ -42,6 +42,60 @@ public class ShellEnvironmentUtils {
         return environmentList;
     }
 
+    /**
+     * Convert environment {@link HashMap} to {@link String} where each item equals "key=value".
+     *
+     */
+    @NonNull
+    public static String convertEnvironmentToDotEnvFile(@NonNull HashMap<String, String> environmentMap) {
+        return convertEnvironmentToDotEnvFile(convertEnvironmentMapToEnvironmentVariableList(environmentMap));
+    }
+
+    /**
+     * Convert environment {@link HashMap} to `.env` file {@link String}.
+     *
+     * The items in the `.env` file have the format `export name="value"`.
+     *
+     * If the {@link ShellEnvironmentVariable#escaped} is set to {@code true}, then
+     * {@link ShellEnvironmentVariable#value} will be considered to be a literal value that has
+     * already been escaped by the caller, otherwise all the `"`\$` in the value will be escaped
+     * with `a backslash `\`, like `\"`. Note that if `$` is escaped and if its part of variable,
+     * then variable expansion will not happen if `.env` file is sourced.
+     *
+     * The `\` at the end of a value line means line continuation. Value can contain newline characters.
+     *
+     * Check {@link #isValidEnvironmentVariableName(String)} and {@link #isValidEnvironmentVariableValue(String)}
+     * for valid variable names and values.
+     *
+     * https://github.com/ko1nksm/shdotenv#env-file-syntax
+     * https://github.com/ko1nksm/shdotenv/blob/main/docs/specification.md
+     */
+    @NonNull
+    public static String convertEnvironmentToDotEnvFile(@NonNull List<ShellEnvironmentVariable> environmentList) {
+        StringBuilder environment = new StringBuilder();
+        Collections.sort(environmentList);
+        for (ShellEnvironmentVariable variable : environmentList) {
+            if (isValidEnvironmentVariableNameValuePair(variable.name, variable.value, true) && variable.value != null) {
+                environment.append("export ").append(variable.name).append("=\"")
+                    .append(variable.escaped ? variable.value : variable.value.replaceAll("([\"`\\\\$])", "\\\\$1"))
+                    .append("\"\n");
+            }
+        }
+        return environment.toString();
+    }
+
+    /**
+     * Convert environment {@link HashMap} to {@link List< ShellEnvironmentVariable >}. Each item
+     * will have its {@link ShellEnvironmentVariable#escaped} set to {@code false}.
+     */
+    @NonNull
+    public static List<ShellEnvironmentVariable> convertEnvironmentMapToEnvironmentVariableList(@NonNull HashMap<String, String> environmentMap) {
+        List<ShellEnvironmentVariable> environmentList = new ArrayList<>();
+        for (String name :environmentMap.keySet()) {
+            environmentList.add(new ShellEnvironmentVariable(name, environmentMap.get(name), false));
+        }
+        return environmentList;
+    }
 
     /**
      * Check if environment variable name and value pair is valid. Errors will be logged if

termux-shared/src/main/java/com/termux/shared/shell/command/environment/ShellEnvironmentVariable.java

@@ -0,0 +1,28 @@
+package com.termux.shared.shell.command.environment;
+
+public class ShellEnvironmentVariable implements Comparable<ShellEnvironmentVariable> {
+
+    /** The name for environment variable */
+    public String name;
+
+    /** The value for environment variable */
+    public String value;
+
+    /** If environment variable {@link #value} is already escaped. */
+    public boolean escaped;
+
+    public ShellEnvironmentVariable(String name, String value) {
+        this(name, value, false);
+    }
+
+    public ShellEnvironmentVariable(String name, String value, boolean escaped) {
+        this.name = name;
+        this.value = value;
+        this.escaped = escaped;
+    }
+
+    @Override
+    public int compareTo(ShellEnvironmentVariable other) {
+        return this.name.compareTo(other.name);
+    }
+}

termux-shared/src/main/java/com/termux/shared/termux/TermuxConstants.java

@@ -11,7 +11,7 @@ import java.util.Formatter;
 import java.util.List;
 
 /*
- * Version: v0.49.0
+ * Version: v0.50.0
  * SPDX-License-Identifier: MIT
  *
  * Changelog
@@ -266,8 +266,11 @@ import java.util.List;
  *      - Removed `TERMUX_GAME_PACKAGES_GITHUB_*`, `TERMUX_SCIENCE_PACKAGES_GITHUB_*`,
  *          `TERMUX_ROOT_PACKAGES_GITHUB_*`, `TERMUX_UNSTABLE_PACKAGES_GITHUB_*`
  *
- * - 0.49.0 (2022-06-10)
+ * - 0.49.0 (2022-06-11)
  *      - Added `TERMUX_ENV_PREFIX_ROOT`.
+ *
+ * - 0.50.0 (2022-06-11)
+ *      - Added `TERMUX_CONFIG_PREFIX_DIR_PATH`, `TERMUX_ENV_FILE_PATH` and `TERMUX_ENV_TEMP_FILE_PATH`.
  */
 
 /**
@@ -650,6 +653,11 @@ public final class TermuxConstants {
     /** Termux app config home directory */
     public static final File TERMUX_CONFIG_HOME_DIR = new File(TERMUX_CONFIG_HOME_DIR_PATH);
 
+    /** Termux app config $PREFIX directory path */
+    public static final String TERMUX_CONFIG_PREFIX_DIR_PATH = TERMUX_ETC_PREFIX_DIR_PATH + "/termux"; // Default: "/data/data/com.termux/files/usr/etc/termux"
+    /** Termux app config $PREFIX directory */
+    public static final File TERMUX_CONFIG_PREFIX_DIR = new File(TERMUX_CONFIG_PREFIX_DIR_PATH);
+
 
     /** Termux app data home directory path */
     public static final String TERMUX_DATA_HOME_DIR_PATH = TERMUX_HOME_DIR_PATH + "/.termux"; // Default: "/data/data/com.termux/files/home/.termux"
@@ -756,6 +764,12 @@ public final class TermuxConstants {
     public static final String TERMUX_CRASH_LOG_BACKUP_FILE_PATH = TERMUX_HOME_DIR_PATH + "/crash_log_backup.md"; // Default: "/data/data/com.termux/files/home/crash_log_backup.md"
 
 
+    /** Termux app environment file path */
+    public static final String TERMUX_ENV_FILE_PATH = TERMUX_CONFIG_PREFIX_DIR_PATH + "/termux.env"; // Default: "/data/data/com.termux/files/usr/etc/termux/termux.env"
+
+    /** Termux app environment temp file path */
+    public static final String TERMUX_ENV_TEMP_FILE_PATH = TERMUX_CONFIG_PREFIX_DIR_PATH + "/termux.env.tmp"; // Default: "/data/data/com.termux/files/usr/etc/termux/termux.env.tmp"
+
 
 
 

termux-shared/src/main/java/com/termux/shared/termux/TermuxUtils.java

@@ -6,6 +6,7 @@ import android.content.Intent;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
+import android.net.Uri;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -273,6 +274,17 @@ public class TermuxUtils {
 
 
 
+    /** Returns {@code true} if {@link Uri} has `package:` scheme for {@link TermuxConstants#TERMUX_PACKAGE_NAME} or its sub plugin package. */
+    public static boolean isUriDataForTermuxOrPluginPackage(@NonNull Uri data) {
+        return data.toString().equals("package:" + TermuxConstants.TERMUX_PACKAGE_NAME) ||
+            data.toString().startsWith("package:" + TermuxConstants.TERMUX_PACKAGE_NAME + ".");
+    }
+
+    /** Returns {@code true} if {@link Uri} has `package:` scheme for {@link TermuxConstants#TERMUX_PACKAGE_NAME} sub plugin package. */
+    public static boolean isUriDataForTermuxPluginPackage(@NonNull Uri data) {
+        return data.toString().startsWith("package:" + TermuxConstants.TERMUX_PACKAGE_NAME + ".");
+    }
+
     /**
      * Send the {@link TermuxConstants#BROADCAST_TERMUX_OPENED} broadcast to notify apps that Termux
      * app has been opened.

termux-shared/src/main/java/com/termux/shared/termux/shell/command/environment/TermuxShellEnvironment.java

@@ -4,8 +4,13 @@ import android.content.Context;
 
 import androidx.annotation.NonNull;
 
+import com.termux.shared.errors.Error;
+import com.termux.shared.file.FileUtils;
+import com.termux.shared.logger.Logger;
 import com.termux.shared.shell.command.ExecutionCommand;
 import com.termux.shared.shell.command.environment.AndroidShellEnvironment;
+import com.termux.shared.shell.command.environment.ShellEnvironmentUtils;
+import com.termux.shared.shell.command.environment.ShellCommandShellEnvironment;
 import com.termux.shared.termux.TermuxBootstrap;
 import com.termux.shared.termux.TermuxConstants;
 import com.termux.shared.termux.shell.TermuxShellUtils;
@@ -28,11 +33,32 @@ public class TermuxShellEnvironment extends AndroidShellEnvironment {
         shellCommandShellEnvironment = new TermuxShellCommandShellEnvironment();
     }
 
+
     /** Init {@link TermuxShellEnvironment} constants and caches. */
     public synchronized static void init(@NonNull Context currentPackageContext) {
         TermuxAppShellEnvironment.setTermuxAppEnvironment(currentPackageContext);
     }
 
+    /** Init {@link TermuxShellEnvironment} constants and caches. */
+    public synchronized static void writeEnvironmentToFile(@NonNull Context currentPackageContext) {
+        HashMap<String, String> environmentMap = new TermuxShellEnvironment().getEnvironment(currentPackageContext, false);
+        String environmentString = ShellEnvironmentUtils.convertEnvironmentToDotEnvFile(environmentMap);
+
+        // Write environment string to temp file and then move to final location since otherwise
+        // writing may happen while file is being sourced/read
+        Error error = FileUtils.writeTextToFile("termux.env.tmp", TermuxConstants.TERMUX_ENV_TEMP_FILE_PATH,
+            Charset.defaultCharset(), environmentString, false);
+        if (error != null) {
+            Logger.logErrorExtended(LOG_TAG, error.toString());
+            return;
+        }
+
+        error = FileUtils.moveRegularFile("termux.env.tmp", TermuxConstants.TERMUX_ENV_TEMP_FILE_PATH, TermuxConstants.TERMUX_ENV_FILE_PATH, true);
+        if (error != null) {
+            Logger.logErrorExtended(LOG_TAG, error.toString());
+        }
+    }
+
     /** Get shell environment for Termux. */
     @NonNull
     @Override