Wait for terminal size before starting process

This fixes https://github.com/termux/termux-widget/issues/2, which
was caused by the terminal launching the terminal session process
before the terminal size was known.

Also remove the built JNI libraries from source control.

README.md

@@ -20,7 +20,7 @@ Released under [the GPLv3 license](https://www.gnu.org/licenses/gpl.html). Conta
 
 Building JNI libraries
 ======================
-For ease of use, the JNI libraries are checked into version control. Execute the `build-jnilibs.sh` script to rebuild them.
+Execute the `build-jnilibs.sh` script to build the required JNI libraries.
 
 Terminal resources
 ==================

app/src/main/java/com/termux/terminal/JNI.java

@@ -28,7 +28,7 @@ final class JNI {
 	 * @return the file descriptor resulting from opening /dev/ptmx master device. The sub process will have opened the
 	 *         slave device counterpart (/dev/pts/$N) and have it as stdint, stdout and stderr.
 	 */
-	public static native int createSubprocess(String cmd, String cwd, String[] args, String[] envVars, int[] processId);
+	public static native int createSubprocess(String cmd, String cwd, String[] args, String[] envVars, int[] processId, int rows, int columns);
 
 	/** Set the window size for a given pty, which allows connected programs to learn how large their screen is. */
 	public static native void setPtyWindowSize(int fd, int rows, int cols);

app/src/main/java/com/termux/terminal/TerminalSession.java

@@ -82,14 +82,17 @@ public final class TerminalSession extends TerminalOutput {
 	/** Callback which gets notified when a session finishes or changes title. */
 	final SessionChangedCallback mChangeCallback;
 
-	/** The pid of the shell process or -1 if not running. */
+	/** The pid of the shell process. 0 if not started and -1 if finished running. */
 	int mShellPid;
-	int mShellExitStatus = -1;
+
+	/** The exit status of the shell process. Only valid if ${@link #mShellPid} is -1. */
+	int mShellExitStatus;
+
 	/**
 	 * The file descriptor referencing the master half of a pseudo-terminal pair, resulting from calling
 	 * {@link JNI#createSubprocess(String, String, String[], String[], int[])}.
 	 */
-	final int mTerminalFileDescriptor;
+	private int mTerminalFileDescriptor;
 
 	/** Set by the application for user identification of session, not by terminal. */
 	public String mSessionName;
@@ -128,20 +131,26 @@ public final class TerminalSession extends TerminalOutput {
 		}
 	};
 
+	private final String mShellPath;
+	private final String mCwd;
+	private final String[] mArgs;
+	private final String[] mEnv;
+
 	public TerminalSession(String shellPath, String cwd, String[] args, String[] env, SessionChangedCallback changeCallback) {
 		mChangeCallback = changeCallback;
 
-		int[] processId = new int[1];
-		mTerminalFileDescriptor = JNI.createSubprocess(shellPath, cwd, args, env, processId);
-		mShellPid = processId[0];
+		this.mShellPath = shellPath;
+		this.mCwd = cwd;
+		this.mArgs = args;
+		this.mEnv = env;
 	}
 
 	/** Inform the attached pty of the new size and reflow or initialize the emulator. */
 	public void updateSize(int columns, int rows) {
-		JNI.setPtyWindowSize(mTerminalFileDescriptor, rows, columns);
 		if (mEmulator == null) {
 			initializeEmulator(columns, rows);
 		} else {
+			JNI.setPtyWindowSize(mTerminalFileDescriptor, rows, columns);
 			mEmulator.resize(columns, rows);
 		}
 	}
@@ -161,6 +170,11 @@ public final class TerminalSession extends TerminalOutput {
 	 */
 	public void initializeEmulator(int columns, int rows) {
 		mEmulator = new TerminalEmulator(this, columns, rows, /* transcript= */5000);
+
+		int[] processId = new int[1];
+		mTerminalFileDescriptor = JNI.createSubprocess(mShellPath, mCwd, mArgs, mEnv, processId, rows, columns);
+		mShellPid = processId[0];
+
 		final FileDescriptor terminalFileDescriptorWrapped = wrapFileDescriptor(mTerminalFileDescriptor);
 
 		new Thread("TermSessionInputReader[pid=" + mShellPid + "]") {
@@ -204,7 +218,7 @@ public final class TerminalSession extends TerminalOutput {
 	/** Write data to the shell process. */
 	@Override
 	public void write(byte[] data, int offset, int count) {
-		mTerminalToProcessIOQueue.write(data, offset, count);
+		if (mShellPid > 0) mTerminalToProcessIOQueue.write(data, offset, count);
 	}
 
 	/** Write the Unicode code point to the terminal encoded in UTF-8. */

app/src/main/jni/termux.c

@@ -22,7 +22,14 @@ static int throw_runtime_exception(JNIEnv* env, char const* message)
         return -1;
 }
 
-static int create_subprocess(JNIEnv* env, char const* cmd, char const* cwd, char* const argv[], char** envp, int* pProcessId)
+static int create_subprocess(JNIEnv* env,
+                             char const* cmd,
+                             char const* cwd,
+                             char* const argv[],
+                             char** envp,
+                             int* pProcessId,
+                             jint rows,
+                             jint columns)
 {
         int ptm = open("/dev/ptmx", O_RDWR | O_CLOEXEC);
         if (ptm < 0) return throw_runtime_exception(env, "Cannot open /dev/ptmx");
@@ -49,8 +56,8 @@ static int create_subprocess(JNIEnv* env, char const* cmd, char const* cwd, char
         tios.c_iflag &= ~(IXON | IXOFF);
         tcsetattr(ptm, TCSANOW, &tios);
 
-		/** Set initial winsize (better too small than too large). */
-        struct winsize sz = { .ws_row = 20, .ws_col = 20 };
+        /** Set initial winsize. */
+        struct winsize sz = { .ws_row = rows, .ws_col = columns };
         ioctl(ptm, TIOCSWINSZ, &sz);
 
         pid_t pid = fork();
@@ -105,7 +112,16 @@ static int create_subprocess(JNIEnv* env, char const* cmd, char const* cwd, char
         }
 }
 
-JNIEXPORT jint JNICALL Java_com_termux_terminal_JNI_createSubprocess(JNIEnv* env, jclass TERMUX_UNUSED(clazz), jstring cmd, jstring cwd, jobjectArray args, jobjectArray envVars, jintArray processIdArray)
+JNIEXPORT jint JNICALL Java_com_termux_terminal_JNI_createSubprocess(
+    JNIEnv* env,
+    jclass TERMUX_UNUSED(clazz),
+    jstring cmd,
+    jstring cwd,
+    jobjectArray args,
+    jobjectArray envVars,
+    jintArray processIdArray,
+    jint rows,
+    jint columns)
 {
         jsize size = args ? (*env)->GetArrayLength(env, args) : 0;
         char** argv = NULL;
@@ -140,7 +156,7 @@ JNIEXPORT jint JNICALL Java_com_termux_terminal_JNI_createSubprocess(JNIEnv* env
         int procId = 0;
 	char const* cmd_cwd = (*env)->GetStringUTFChars(env, cwd, NULL);
         char const* cmd_utf8 = (*env)->GetStringUTFChars(env, cmd, NULL);
-        int ptm = create_subprocess(env, cmd_utf8, cmd_cwd, argv, envp, &procId);
+        int ptm = create_subprocess(env, cmd_utf8, cmd_cwd, argv, envp, &procId, rows, columns);
         (*env)->ReleaseStringUTFChars(env, cmd, cmd_utf8);
         (*env)->ReleaseStringUTFChars(env, cmd, cmd_cwd);