Ensure termux files directory is accessible before bootstrap installation and provide better info when running as secondary user/profile

Termux will check if termux files directory `/data/data/com.termux/files` has rwx permission access before installing bootstrap or starting terminal. Missing permission will automatically be set if possible. The `/data/data/com.termux` directory will also be created if it did not already exist, like if android did not already create it.

Users will now also be shown a crash notification if they attempt to start termux as a secondary user or in a work profile with info of the "alternate" termux files directory `/data/user/<id>/com.termux` set by android and the profile owner app if running under work profile (not secondary user). A notification will also be shown if the termux files directory (not "alternate") is not accessible.

Related #2168

termux-shared/src/main/java/com/termux/shared/file/TermuxFileUtils.java

@@ -1,7 +1,10 @@
 package com.termux.shared.file;
 
+import android.content.Context;
 import android.os.Environment;
 
+import androidx.annotation.NonNull;
+
 import com.termux.shared.models.errors.Error;
 import com.termux.shared.termux.TermuxConstants;
 
@@ -9,6 +12,7 @@ import java.io.File;
 import java.util.regex.Pattern;
 
 public class TermuxFileUtils {
+
     /**
      * Replace "$PREFIX/" or "~/" prefix with termux absolute paths.
      *
@@ -120,4 +124,41 @@ public class TermuxFileUtils {
             ignoreErrorsIfPathIsInParentDirPath, ignoreIfNotExecutable);
     }
 
+    /**
+     * Validate the existence and permissions of {@link TermuxConstants#TERMUX_FILES_DIR_PATH}.
+     *
+     * The directory will not be created manually but by calling {@link Context#getFilesDir()}
+     * so that android itself creates it. The `/data/data/[package_name]` directory cannot be
+     * created by an app itself. Note that the path returned by {@link Context#getFilesDir()} will
+     * be under `/data/user/[id]/[package_name]` instead of `/data/data/[package_name]`
+     * defined by default by {@link TermuxConstants#TERMUX_FILES_DIR_PATH}, where id will be 0 for
+     * primary user and a higher number for other users/profiles. If app is running under work profile
+     * or secondary user, then {@link TermuxConstants#TERMUX_FILES_DIR_PATH} will not be accessible
+     * and will not be automatically created, unless there is a bind mount from `/data/user/[id]`
+     * to `/data/data`, ideally in the right namespace.
+     *
+     * The permissions set to directory will be {@link FileUtils#APP_WORKING_DIRECTORY_PERMISSIONS}.
+     *
+     * https://source.android.com/devices/tech/admin/multi-user
+     *
+     * @param context The {@link Context} for operations.
+     * @param createDirectoryIfMissing The {@code boolean} that decides if directory file
+     *                                 should be created if its missing.
+     * @param setMissingPermissions The {@code boolean} that decides if permissions are to be
+     *                              automatically set.
+     * @return Returns the {@code error} if path is not a directory file, failed to create it,
+     * or validating permissions failed, otherwise {@code null}.
+     */
+    public static Error isTermuxFilesDirectoryAccessible(@NonNull final Context context, boolean createDirectoryIfMissing, boolean setMissingPermissions) {
+        if (createDirectoryIfMissing)
+            context.getFilesDir();
+
+        if (setMissingPermissions)
+            FileUtils.setMissingFilePermissions("Termux files directory", TermuxConstants.TERMUX_FILES_DIR_PATH,
+                FileUtils.APP_WORKING_DIRECTORY_PERMISSIONS);
+
+        return FileUtils.checkMissingFilePermissions("Termux files directory", TermuxConstants.TERMUX_FILES_DIR_PATH,
+            FileUtils.APP_WORKING_DIRECTORY_PERMISSIONS, false);
+    }
+
 }

termux-shared/src/main/java/com/termux/shared/packages/PackageUtils.java

@@ -1,9 +1,12 @@
 package com.termux.shared.packages;
 
+import android.app.admin.DevicePolicyManager;
+import android.content.ComponentName;
 import android.content.Context;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
+import android.os.UserManager;
 
 import androidx.annotation.NonNull;
 
@@ -14,6 +17,7 @@ import com.termux.shared.logger.Logger;
 import com.termux.shared.termux.TermuxConstants;
 
 import java.security.MessageDigest;
+import java.util.List;
 
 import javax.annotation.Nullable;
 
@@ -163,7 +167,7 @@ public class PackageUtils {
      * Get the {@code SHA-256 digest} of signing certificate for the package associated with the {@code context}.
      *
      * @param context The {@link Context} for the package.
-     * @return Returns the{@code SHA-256 digest}. This will be {@code null} if an exception is raised.
+     * @return Returns the {@code SHA-256 digest}. This will be {@code null} if an exception is raised.
      */
     @Nullable
     public static String getSigningCertificateSHA256DigestForPackage(@NonNull final Context context) {
@@ -184,4 +188,53 @@ public class PackageUtils {
         }
     }
 
+
+
+    /**
+     * Get the serial number for the current user.
+     *
+     * @param context The {@link Context} for operations.
+     * @return Returns the serial number. This will be {@code null} if failed to get it.
+     */
+    @Nullable
+    public static Long getSerialNumberForCurrentUser(@NonNull Context context) {
+        UserManager userManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
+        if (userManager == null) return null;
+        return userManager.getSerialNumberForUser(android.os.Process.myUserHandle());
+    }
+
+    /**
+     * Check if the current user is the primary user. This is done by checking if the the serial
+     * number for the current user equals 0.
+     *
+     * @param context The {@link Context} for operations.
+     * @return Returns {@code true} if the current user is the primary user, otherwise [@code false}.
+     */
+    public static boolean isCurrentUserThePrimaryUser(@NonNull Context context) {
+        Long userId = getSerialNumberForCurrentUser(context);
+        return userId != null && userId == 0;
+    }
+
+    /**
+     * Get the profile owner package name for the current user.
+     *
+     * @param context The {@link Context} for operations.
+     * @return Returns the profile owner package name. This will be {@code null} if failed to get it
+     * or no profile owner for the current user.
+     */
+    @Nullable
+    public static String getProfileOwnerPackageNameForUser(@NonNull Context context) {
+        DevicePolicyManager devicePolicyManager = (DevicePolicyManager) context.getSystemService(Context.DEVICE_POLICY_SERVICE);
+        if (devicePolicyManager == null) return null;
+        List<ComponentName> activeAdmins = devicePolicyManager.getActiveAdmins();
+        if (activeAdmins != null){
+            for (ComponentName admin:activeAdmins){
+                String packageName = admin.getPackageName();
+                if(devicePolicyManager.isProfileOwnerApp(packageName))
+                    return packageName;
+            }
+        }
+        return null;
+    }
+
 }

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

@@ -40,6 +40,17 @@ public class AndroidUtils {
         AndroidUtils.appendPropertyToMarkdown(markdownString,"TARGET_SDK", PackageUtils.getTargetSDKForPackage(context));
         AndroidUtils.appendPropertyToMarkdown(markdownString,"IS_DEBUG_BUILD", PackageUtils.isAppForPackageADebugBuild(context));
 
+        String filesDir = context.getFilesDir().getAbsolutePath();
+        if (!filesDir.equals("/data/user/0/" + context.getPackageName() + "/files") &&
+            !filesDir.equals("/data/data/" + context.getPackageName() + "/files"))
+        AndroidUtils.appendPropertyToMarkdown(markdownString,"FILES_DIR", filesDir);
+
+        Long userId = PackageUtils.getSerialNumberForCurrentUser(context);
+        if (userId == null || userId != 0)
+            AndroidUtils.appendPropertyToMarkdown(markdownString,"USER_ID", userId);
+
+        AndroidUtils.appendPropertyToMarkdownIfSet(markdownString,"PROFILE_OWNER", PackageUtils.getProfileOwnerPackageNameForUser(context));
+
         return markdownString.toString();
     }
 
@@ -139,7 +150,7 @@ public class AndroidUtils {
         return systemProperties;
     }
 
-    private static String getSystemPropertyWithAndroidAPI(@NonNull String property) {
+    public static String getSystemPropertyWithAndroidAPI(@NonNull String property) {
         try {
             return System.getProperty(property);
         } catch (Exception e) {
@@ -148,17 +159,17 @@ public class AndroidUtils {
         }
     }
 
-    private static void appendPropertyToMarkdownIfSet(StringBuilder markdownString, String label, Object value) {
+    public static void appendPropertyToMarkdownIfSet(StringBuilder markdownString, String label, Object value) {
         if (value == null) return;
         if (value instanceof String && (((String) value).isEmpty()) || "REL".equals(value)) return;
         markdownString.append("\n").append(getPropertyMarkdown(label, value));
     }
 
-    static void appendPropertyToMarkdown(StringBuilder markdownString, String label, Object value) {
+    public static void appendPropertyToMarkdown(StringBuilder markdownString, String label, Object value) {
         markdownString.append("\n").append(getPropertyMarkdown(label, value));
     }
 
-    private static String getPropertyMarkdown(String label, Object value) {
+    public static String getPropertyMarkdown(String label, Object value) {
         return MarkdownUtils.getSingleLineMarkdownStringEntry(label, value, "-");
     }
 

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

@@ -8,9 +8,11 @@ import android.content.pm.ResolveInfo;
 import androidx.annotation.NonNull;
 
 import com.termux.shared.R;
+import com.termux.shared.file.TermuxFileUtils;
 import com.termux.shared.logger.Logger;
 import com.termux.shared.markdown.MarkdownUtils;
 import com.termux.shared.models.ExecutionCommand;
+import com.termux.shared.models.errors.Error;
 import com.termux.shared.packages.PackageUtils;
 import com.termux.shared.shell.TermuxShellEnvironmentClient;
 import com.termux.shared.shell.TermuxTask;
@@ -210,6 +212,13 @@ public class TermuxUtils {
 
         markdownString.append((AndroidUtils.getAppInfoMarkdownString(context)));
 
+        Error error;
+        error = TermuxFileUtils.isTermuxFilesDirectoryAccessible(context, true, true);
+        if (error != null) {
+            AndroidUtils.appendPropertyToMarkdown(markdownString, "TERMUX_FILES_DIR", TermuxConstants.TERMUX_FILES_DIR_PATH);
+            AndroidUtils.appendPropertyToMarkdown(markdownString, "IS_TERMUX_FILES_DIR_ACCESSIBLE", "false - " + Error.getMinimalErrorString(error));
+        }
+
         String signingCertificateSHA256Digest = PackageUtils.getSigningCertificateSHA256DigestForPackage(context);
         if (signingCertificateSHA256Digest != null) {
             AndroidUtils.appendPropertyToMarkdown(markdownString,"APK_RELEASE", getAPKRelease(signingCertificateSHA256Digest));