Update Android port

* doc/emacs/android.texi (Android Startup, Android Environment):
Document that restrictions on starting Emacs have been lifted.

* java/README: Document Java for Emacs developers and how the
Android port works.

* java/org/gnu/emacs/EmacsApplication.java (EmacsApplication)
(findDumpFile): New function.
(onCreate): Factor out dump file finding functions to there.

* java/org/gnu/emacs/EmacsNative.java (EmacsNative): Update
function declarations.
* java/org/gnu/emacs/EmacsNoninteractive.java
(EmacsNoninteractive): New class.

* java/org/gnu/emacs/EmacsService.java (EmacsService, getApkFile)
(onCreate): Pass classpath to setEmacsParams.
* java/org/gnu/emacs/EmacsThread.java (EmacsThread): Make run an
override.
* lisp/loadup.el: Don't dump on Android when noninteractive.
* lisp/shell.el (shell--command-completion-data): Handle
inaccessible directories.
* src/Makefile.in (android-emacs): Link with gnulib.
* src/android-emacs.c (main): Implement to launch app-process
and then EmacsNoninteractive.
* src/android.c (setEmacsParams): New argument `class_path'.
Don't set stuff up when running noninteractive.
* src/android.h (initEmacs): Likewise.
* src/androidfont.c (init_androidfont):
* src/androidselect.c (init_androidselect): Don't initialize
when running noninteractive.
* src/emacs.c (load_pdump): New argument `dump_file'.
(android_emacs_init): Give new argument `dump_file' to
`load_pdump'.
* src/sfntfont-android.c (init_sfntfont_android): Don't
initialize when running noninteractive.

8 files changed, 205 insertions, 39 deletions

diff --git a/src/Makefile.in b/src/Makefile.in
index 29beb519abb..fe745770b9f 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -768,7 +768,7 @@ libemacs.so: $(ALLOBJS) $(LIBEGNU_ARCHIVE) $(EMACSRES) \
 
 android-emacs: libemacs.so android-emacs.o
 	$(AM_V_CCLD)$(CC) -o $@ $(ALL_CFLAGS) $(LDFLAGS) 	\
-	  -L. "-l:libemacs.so" android-emacs.o
+	  $(LIBEGNU_ARCHIVE) -L. "-l:libemacs.so" android-emacs.o
 endif
 
 ## The following oldxmenu-related rules are only (possibly) used if
diff --git a/src/android-emacs.c b/src/android-emacs.c
index d4fa14e39fb..c1f2a6f43bb 100644
--- a/src/android-emacs.c
+++ b/src/android-emacs.c
@@ -18,13 +18,88 @@ You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 #include <config.h>
-#include "android.h"
+#include <stdio.h>
+#include <alloca.h>
+#include <string.h>
+#include <unistd.h>
 
-/* android-emacs is a wrapper around libemacs.  It simply calls
-   android_emacs_init with the argv and argc given to it.  */
+/* android-emacs is a wrapper around /system/bin/app_process(64).
+   It invokes app_process(64) with the right class path and then
+   starts org.gnu.emacs.EmacsNoninteractive.
+
+   The main function in that class tries to load an activity thread
+   and obtain a context and asset manager before calling
+   android_emacs_init, which is required for Emacs to find required
+   preloaded Lisp.  */
 
 int
 main (int argc, char **argv)
 {
-  return android_emacs_init (argc, argv);
+  char **args;
+  int i;
+  char *bootclasspath, *emacs_class_path;
+
+  /* Allocate enough to hold the arguments to app_process.  */
+  args = alloca ((10 + argc) * sizeof *args);
+
+  /* Clear args.  */
+  memset (args, 0, (10 + argc) * sizeof *args);
+
+  /* First, figure out what program to start.  */
+#if defined __x86_64__ || defined __aarch64__
+  args[0] = (char *) "/system/bin/app_process64";
+#else
+  args[0] = (char *) "/system/bin/app_process";
+#endif
+
+  /* Next, obtain the boot class path.  */
+  bootclasspath = getenv ("BOOTCLASSPATH");
+
+  /* And the Emacs class path.  */
+  emacs_class_path = getenv ("EMACS_CLASS_PATH");
+
+  if (!bootclasspath)
+    {
+      fprintf (stderr, "The BOOTCLASSPATH environment variable"
+	       " is not set.  As a result, Emacs does not know"
+	       " how to start app_process.\n"
+	       "This is likely a change in the Android platform."
+	       "  Please report this to bug-gnu-emacs@gnu.org.\n");
+      return 1;
+    }
+
+  if (!emacs_class_path)
+    {
+      fprintf (stderr, "EMACS_CLASS_PATH not set."
+	       "  Please make sure Emacs is being started"
+	       " from within a running copy of Emacs.\n");
+      return 1;
+    }
+
+  if (asprintf (&bootclasspath, "-Djava.class.path=%s:%s",
+		bootclasspath, emacs_class_path) < 0)
+    {
+      perror ("asprintf");
+      return 1;
+    }
+
+  args[1] = bootclasspath;
+  args[2] = (char *) "/system/bin";
+  args[3] = (char *) "--nice-name=emacs";
+  args[4] = (char *) "org.gnu.emacs.EmacsNoninteractive";
+
+  /* Arguments from here on are passed to main in
+     EmacsNoninteractive.java.  */
+  args[5] = argv[0];
+
+  /* Now copy the rest of the arguments over.  */
+  for (i = 1; i < argc; ++i)
+    args[5 + i] = argv[i];
+
+  /* Finally, try to start the app_process.  */
+  execvp (args[0], args);
+
+  /* If exit fails, return an error indication.  */
+  perror ("exec");
+  return 1;
 }
diff --git a/src/android.c b/src/android.c
index c186b462360..8c4442e3397 100644
--- a/src/android.c
+++ b/src/android.c
@@ -145,6 +145,10 @@ char *android_game_path;
 /* The directory used to store temporary files.  */
 char *android_cache_dir;
 
+/* The list of archive files within which the Java virtual macine
+   looks for class files.  */
+char *android_class_path;
+
 /* The display's pixel densities.  */
 double android_pixel_density_x, android_pixel_density_y;
 
@@ -1315,6 +1319,7 @@ NATIVE_NAME (setEmacsParams) (JNIEnv *env, jobject object,
 			      jobject cache_dir,
 			      jfloat pixel_density_x,
 			      jfloat pixel_density_y,
+			      jobject class_path,
 			      jobject emacs_service_object)
 {
   int pipefd[2];
@@ -1372,19 +1377,30 @@ NATIVE_NAME (setEmacsParams) (JNIEnv *env, jobject object,
      object from being deleted.  */
   (*env)->NewGlobalRef (env, local_asset_manager);
 
-  /* Create a pipe and duplicate it to stdout and stderr.  Next, make
-     a thread that prints stderr to the system log.  */
+  if (emacs_service_object)
+    {
+      /* Create a pipe and duplicate it to stdout and stderr.  Next,
+	 make a thread that prints stderr to the system log.
 
-  if (pipe2 (pipefd, O_CLOEXEC) < 0)
-    emacs_abort ();
+         Notice that this function is called in one of two ways.  The
+         first is when Emacs is being started as a GUI application by
+         the system, and the second is when Emacs is being started by
+         libandroid-emacs.so as an ordinary noninteractive Emacs.
 
-  if (dup2 (pipefd[1], 2) < 0)
-    emacs_abort ();
-  close (pipefd[1]);
+         In the second case, stderr is usually connected to a PTY, so
+         this is unnecessary.  */
 
-  if (pthread_create (&thread, NULL, android_run_debug_thread,
-		      (void *) (intptr_t) pipefd[0]))
-    emacs_abort ();
+      if (pipe2 (pipefd, O_CLOEXEC) < 0)
+	emacs_abort ();
+
+      if (dup2 (pipefd[1], 2) < 0)
+	emacs_abort ();
+      close (pipefd[1]);
+
+      if (pthread_create (&thread, NULL, android_run_debug_thread,
+			  (void *) (intptr_t) pipefd[0]))
+	emacs_abort ();
+    }
 
   /* Now set the path to the site load directory.  */
 
@@ -1430,6 +1446,23 @@ NATIVE_NAME (setEmacsParams) (JNIEnv *env, jobject object,
   (*env)->ReleaseStringUTFChars (env, (jstring) cache_dir,
 				 java_string);
 
+  if (class_path)
+    {
+      java_string = (*env)->GetStringUTFChars (env, (jstring) class_path,
+					       NULL);
+
+      if (!java_string)
+	emacs_abort ();
+
+      android_class_path = strdup ((const char *) java_string);
+
+      if (!android_files_dir)
+	emacs_abort ();
+
+      (*env)->ReleaseStringUTFChars (env, (jstring) class_path,
+				     java_string);
+    }
+
   /* Calculate the site-lisp path.  */
 
   android_site_load_path = malloc (PATH_MAX + 1);
@@ -1450,16 +1483,32 @@ NATIVE_NAME (setEmacsParams) (JNIEnv *env, jobject object,
 		       "Site-lisp directory: %s\n"
 		       "Files directory: %s\n"
 		       "Native code directory: %s\n"
-		       "Game score path: %s\n",
+		       "Game score path: %s\n"
+		       "Class path: %s\n",
 		       android_site_load_path,
 		       android_files_dir,
-		       android_lib_dir, android_game_path);
+		       android_lib_dir, android_game_path,
+		       (android_class_path
+			? android_class_path
+			: "None"));
+
+  if (android_class_path)
+    /* Set EMACS_CLASS_PATH to the class path where
+       EmacsNoninteractive can be found.  */
+    setenv ("EMACS_CLASS_PATH", android_class_path, 1);
+
+  /* Set LD_LIBRARY_PATH to an appropriate value.  */
+  setenv ("LD_LIBRARY_PATH", android_lib_dir, 1);
 
   /* Make a reference to the Emacs service.  */
-  emacs_service = (*env)->NewGlobalRef (env, emacs_service_object);
 
-  if (!emacs_service)
-    emacs_abort ();
+  if (emacs_service_object)
+    {
+      emacs_service = (*env)->NewGlobalRef (env, emacs_service_object);
+
+      if (!emacs_service)
+	emacs_abort ();
+    }
 
   /* Set up events.  */
   android_init_events ();
@@ -1660,12 +1709,14 @@ android_init_emacs_window (void)
 }
 
 extern JNIEXPORT void JNICALL
-NATIVE_NAME (initEmacs) (JNIEnv *env, jobject object, jarray argv)
+NATIVE_NAME (initEmacs) (JNIEnv *env, jobject object, jarray argv,
+			 jobject dump_file_object)
 {
   char **c_argv;
   jsize nelements, i;
   jobject argument;
   const char *c_argument;
+  char *dump_file;
 
   android_java_env = env;
 
@@ -1705,9 +1756,34 @@ NATIVE_NAME (initEmacs) (JNIEnv *env, jobject object, jarray argv)
     __android_log_print (ANDROID_LOG_WARN, __func__,
 			 "chdir: %s", strerror (errno));
 
-  /* Initialize the Android GUI.  */
-  android_init_gui = true;
-  android_emacs_init (nelements, c_argv);
+  /* Initialize the Android GUI as long as the service object was
+     set.  */
+
+  if (emacs_service)
+    android_init_gui = true;
+
+  /* Now see if a dump file has been specified and should be used.  */
+  dump_file = NULL;
+
+  if (dump_file_object)
+    {
+      c_argument
+	= (*env)->GetStringUTFChars (env, (jstring) dump_file_object,
+				     NULL);
+
+      /* Copy the Java string data once.  */
+      dump_file = strdup (c_argument);
+
+      /* Release the Java string data.  */
+      (*env)->ReleaseStringUTFChars (env, (jstring) dump_file_object,
+				     c_argument);
+    }
+
+  /* Delete local references to objects that are no longer needed.  */
+  ANDROID_DELETE_LOCAL_REF (argv);
+  ANDROID_DELETE_LOCAL_REF (dump_file_object);
+
+  android_emacs_init (nelements, c_argv, dump_file);
   /* android_emacs_init should never return.  */
   emacs_abort ();
 }
diff --git a/src/android.h b/src/android.h
index ce0ccfc4338..6c20995e4a1 100644
--- a/src/android.h
+++ b/src/android.h
@@ -38,15 +38,11 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include "lisp.h"
 #endif
 
-/* This must be used in every symbol declaration to export it to the
-   JNI Emacs wrapper.  */
-#define ANDROID_EXPORT __attribute__ ((visibility ("default")))
-
-extern bool ANDROID_EXPORT android_init_gui;
-extern int ANDROID_EXPORT android_emacs_init (int, char **);
+extern bool android_init_gui;
 
 #ifndef ANDROID_STUBIFY
 
+extern int android_emacs_init (int, char **, char *);
 extern int android_select (int, fd_set *, fd_set *, fd_set *,
 			   struct timespec *);
 
diff --git a/src/androidfont.c b/src/androidfont.c
index bec5a59ca77..55f45758352 100644
--- a/src/androidfont.c
+++ b/src/androidfont.c
@@ -1104,6 +1104,9 @@ syms_of_androidfont (void)
 void
 init_androidfont (void)
 {
+  if (!android_init_gui)
+    return;
+
   android_init_font_driver ();
   android_init_font_spec ();
   android_init_font_metrics ();
diff --git a/src/androidselect.c b/src/androidselect.c
index 2e2f2d7e483..4585d64b7e8 100644
--- a/src/androidselect.c
+++ b/src/androidselect.c
@@ -240,6 +240,9 @@ init_androidselect (void)
   jobject tem;
   jmethodID make_clipboard;
 
+  if (!android_init_gui)
+    return;
+
   android_init_emacs_clipboard ();
 
   make_clipboard = clipboard_class.make_clipboard;
diff --git a/src/emacs.c b/src/emacs.c
index b0c19fe0070..a24f9960494 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -875,19 +875,23 @@ dump_error_to_string (int result)
     }
 }
 
-/* This function returns the Emacs executable.  */
+/* This function returns the Emacs executable.  DUMP_FILE is ignored
+   outside of Android.  Otherwise, it is the name of the dump file to
+   use, or NULL if Emacs should look for a ``--dump-file'' argument
+   instead.  */
+
 static char *
-load_pdump (int argc, char **argv)
+load_pdump (int argc, char **argv, char *dump_file)
 {
 #if defined HAVE_ANDROID && !defined ANDROID_STUBIFY
-  char *dump_file = NULL;
   int skip_args = 0, result;
 
   while (skip_args < argc - 1)
     {
-      if (argmatch (argv, argc, "-dump-file", "--dump-file", 6,
-		    &dump_file, &skip_args)
-	  || argmatch (argv, argc, "--", NULL, 2, NULL, &skip_args))
+      if (argmatch (argv, argc, "-dump-file", "--dump-file",
+		    6, &dump_file, &skip_args)
+	  || argmatch (argv, argc, "--", NULL, 2, NULL,
+		       &skip_args))
 	break;
       skip_args++;
     }
@@ -933,7 +937,7 @@ load_pdump (int argc, char **argv)
 
   /* Look for an explicitly-specified dump file.  */
   const char *path_exec = PATH_EXEC;
-  char *dump_file = NULL;
+  dump_file = NULL;
   int skip_args = 0;
   while (skip_args < argc - 1)
     {
@@ -1276,7 +1280,7 @@ maybe_load_seccomp (int argc, char **argv)
 
 #if defined HAVE_ANDROID && !defined ANDROID_STUBIFY
 int
-android_emacs_init (int argc, char **argv)
+android_emacs_init (int argc, char **argv, char *dump_file)
 #else
 int
 main (int argc, char **argv)
@@ -1286,6 +1290,12 @@ main (int argc, char **argv)
      for pointers.  */
   void *stack_bottom_variable;
   int old_argc;
+#if !(defined HAVE_ANDROID && !defined ANDROID_STUBIFY)
+  char *dump_file;
+
+  /* This is just a dummy argument used to avoid extra defines.  */
+  dump_file = NULL;
+#endif
 
   /* First, check whether we should apply a seccomp filter.  This
      should come at the very beginning to allow the filter to protect
@@ -1415,7 +1425,7 @@ main (int argc, char **argv)
 
 #ifdef HAVE_PDUMPER
   if (attempt_load_pdump)
-    initial_emacs_executable = load_pdump (argc, argv);
+    initial_emacs_executable = load_pdump (argc, argv, dump_file);
 #else
   ptrdiff_t bufsize;
   initial_emacs_executable = find_emacs_executable (argv[0], &bufsize);
diff --git a/src/sfntfont-android.c b/src/sfntfont-android.c
index bc8f1b35b84..ab90a2e4ecd 100644
--- a/src/sfntfont-android.c
+++ b/src/sfntfont-android.c
@@ -729,6 +729,9 @@ syms_of_sfntfont_android_for_pdumper (void)
 void
 init_sfntfont_android (void)
 {
+  if (!android_init_gui)
+    return;
+
   /* Make sure to pick the right Sans Serif font depending on what
      version of Android the device is running.  */
 #if HAVE_DECL_ANDROID_GET_DEVICE_API_LEVEL