remote/client: Provide an internal console

At present Labgrid uses microcom as its console. This has some
limitations:

- console output is lost between when the board is reset and microcom
  connects
- txdelay cannot be handled in microcom, meaning that boards may fail
  to receive expected output
- the console may echo a few characters back to the caller in the time
  between when 'labgrid-client console' is executed and when microcom
  starts (which causes failures with U-Boot test system)

For many use cases, microcom is more than is needed, so provide a simple
internal terminal which resolved the above problems.

It is enabled by a '-i' option to the 'console' command, as well as an
environment variable, so that it can be adjustly without updating a lot
of scripts.

To exit, press Ctrl-] twice, quickly.

Series-changes: 4
- Get internal console working with qemu
- Show a prompt when starting, to indicate it is waiting for the board

Signed-off-by: Simon Glass <sjg@chromium.org>

Author: sjg20

doc/usage.rst

@@ -839,3 +839,14 @@ like this:
   $ labgrid-client -p example allow sirius/john
 
 To remove the allow it is currently necessary to unlock and lock the place.
+
+Internal console
+^^^^^^^^^^^^^^^^
+
+Labgrid uses microcom as its console by default. For situations where this is
+not suitable, an internal console is provided. To use this, provide the
+``--internal`` flag to the ``labgrid client`` command.
+
+When the internal console is used, the console transitions cleanly between use
+within a strategy or driver, and interactive use for the user. The console is
+not closed and therefore there is no loss of data.

labgrid/remote/client.py

@@ -1040,43 +1040,49 @@ def digital_io(self):
             drv.set(False)
 
     async def _console(self, place, target, timeout, *, logfile=None, loop=False, listen_only=False):
+        from ..protocol import ConsoleProtocol
+
         name = self.args.name
-        from ..resource import NetworkSerialPort
 
-        # deactivate console drivers so we are able to connect with microcom
-        try:
-            con = target.get_active_driver("ConsoleProtocol")
-            target.deactivate(con)
-        except NoDriverFoundError:
-            pass
+        if not place.acquired:
+            print("place released")
+            return 255
 
-        resource = target.get_resource(NetworkSerialPort, name=name, wait_avail=False)
+        if self.args.internal or os.environ.get("LG_CONSOLE") == "internal":
+            console = target.get_driver(ConsoleProtocol, name=name)
+            returncode = await term.internal(lambda: self.is_allowed(place), console, logfile, listen_only)
+        else:
+            from ..resource import NetworkSerialPort
 
-        # async await resources
-        timeout = Timeout(timeout)
-        while True:
-            target.update_resources()
-            if resource.avail or (not loop and timeout.expired):
-                break
-            await asyncio.sleep(0.1)
+            # deactivate console drivers so we are able to connect with microcom
+            try:
+                con = target.get_active_driver("ConsoleProtocol")
+                target.deactivate(con)
+            except NoDriverFoundError:
+                pass
 
-        # use zero timeout to prevent blocking sleeps
-        target.await_resources([resource], timeout=0.0)
+            resource = target.get_resource(NetworkSerialPort, name=name, wait_avail=False)
 
-        if not place.acquired:
-            print("place released")
-            return 255
+            # async await resources
+            timeout = Timeout(timeout)
+            while True:
+                target.update_resources()
+                if resource.avail or (not loop and timeout.expired):
+                    break
+                await asyncio.sleep(0.1)
 
-        host, port = proxymanager.get_host_and_port(resource)
+            # use zero timeout to prevent blocking sleeps
+            target.await_resources([resource], timeout=0.0)
+            host, port = proxymanager.get_host_and_port(resource)
 
-        # check for valid resources
-        assert port is not None, "Port is not set"
-        try:
-            returncode = await term.external(
-                lambda: self.is_allowed(place), host, port, resource, logfile, listen_only
-            )
-        except FileNotFoundError as e:
-            raise ServerError(f"failed to execute remote console command: {e}")
+            # check for valid resources
+            assert port is not None, "Port is not set"
+            try:
+                returncode = await term.external(
+                    lambda: self.is_allowed(place), host, port, resource, logfile, listen_only
+                )
+            except FileNotFoundError as e:
+                raise ServerError(f"failed to execute remote console command: {e}")
 
         # Raise an exception if the place was released
         self._check_allowed(place)
@@ -1988,6 +1994,7 @@ def get_parser(auto_doc_mode=False) -> "argparse.ArgumentParser | AutoProgramArg
     subparser.set_defaults(func=ClientSession.digital_io)
 
     subparser = subparsers.add_parser("console", aliases=("con",), help="connect to the console")
+    subparser.add_argument("-i", "--internal", action="store_true", help="use an internal console instead of microcom")
     subparser.add_argument(
         "-l", "--loop", action="store_true", help="keep trying to connect if the console is unavailable"
     )

labgrid/util/term.py

@@ -1,9 +1,16 @@
-"""Terminal handling, using microcom or telnet"""
+"""Terminal handling, using microcom, telnet or an internal function"""
 
 import asyncio
+import collections
 import logging
+import os
 import sys
 import shutil
+import termios
+import time
+
+from pexpect import TIMEOUT
+from serial.serialutil import SerialException
 
 EXIT_CHAR = 0x1d    # FS (Ctrl + ])
 
@@ -69,3 +76,122 @@ async def external(check_allowed, host, port, resource, logfile, listen_only):
     if p.returncode:
         print("connection lost", file=sys.stderr)
     return p.returncode
+
+
+BUF_SIZE = 1024
+
+async def run(check_allowed, cons, log_fd, listen_only):
+    prev = collections.deque(maxlen=2)
+
+    deadline = None
+    to_cons = b''
+    next_cons = time.monotonic()
+    txdelay = cons.txdelay
+
+    # Show a message to indicate we are waiting for output from the board
+    msg = 'Terminal ready...press Ctrl-] twice to exit'
+    sys.stdout.write(msg)
+    sys.stdout.flush()
+    erase_msg = '\b' * len(msg) + ' ' * len(msg) + '\b' * len(msg)
+    have_output = False
+
+    while True:
+        activity = bool(to_cons)
+        try:
+            data = cons.read(size=BUF_SIZE, timeout=0.001)
+            if data:
+                activity = True
+                if not have_output:
+                    # Erase our message
+                    sys.stdout.write(erase_msg)
+                    sys.stdout.flush()
+                    have_output = True
+                sys.stdout.buffer.write(data)
+                sys.stdout.buffer.flush()
+                if log_fd:
+                    log_fd.write(data)
+                    log_fd.flush()
+
+        except TIMEOUT:
+            pass
+
+        except SerialException:
+            break
+
+        if not listen_only:
+            data = os.read(sys.stdin.fileno(), BUF_SIZE)
+            if data:
+                activity = True
+                if not deadline:
+                    deadline = time.monotonic() + .5  # seconds
+                prev.extend(data)
+                count = prev.count(EXIT_CHAR)
+                if count == 2:
+                    break
+
+                to_cons += data
+
+        if to_cons and time.monotonic() > next_cons:
+            cons._write(to_cons[:1])
+            to_cons = to_cons[1:]
+            if txdelay:
+                next_cons += txdelay
+
+        if deadline and time.monotonic() > deadline:
+            prev.clear()
+            deadline = None
+        if check_allowed():
+            break
+        if not activity:
+            time.sleep(.001)
+
+    # Blank line to move past any partial output
+    print()
+
+
+async def internal(check_allowed, cons, logfile, listen_only):
+    """Start an external terminal sessions
+
+    This uses microcom if available, otherwise falls back to telnet.
+
+    Args:
+        check_allowed (lambda): Function to call to make sure the terminal is
+            still accessible. No args. Returns True if allowed, False if not.
+        cons (str): ConsoleProtocol device to read/write
+        logfile (str): Logfile to write output too, or None
+        listen_only (bool): True to ignore keyboard input
+
+    Return:
+        int: Result code
+    """
+    returncode = 0
+    old = None
+    log_fd = None
+    try:
+        if not listen_only and os.isatty(sys.stdout.fileno()):
+            fd = sys.stdin.fileno()
+            old = termios.tcgetattr(fd)
+            new = termios.tcgetattr(fd)
+            new[3] = new[3] & ~(termios.ICANON | termios.ECHO | termios.ISIG)
+            new[6][termios.VMIN] = 0
+            new[6][termios.VTIME] = 0
+            termios.tcsetattr(fd, termios.TCSANOW, new)
+
+        log_fd = None
+        if logfile:
+            log_fd = open(logfile, 'wb')
+
+        logging.info('Console start:')
+        await run(check_allowed, cons, log_fd, listen_only)
+
+    except OSError as err:
+        print('error', err)
+        returncode = 1
+
+    finally:
+        if old:
+            termios.tcsetattr(fd, termios.TCSAFLUSH, old)
+        if log_fd:
+            log_fd.close()
+
+    return returncode

man/labgrid-client.1

@@ -243,7 +243,7 @@ connect to the console
 .INDENT 3.5
 .sp
 .EX
-usage: labgrid\-client console|con [\-l] [\-o] [\-\-logfile FILE] [name]
+usage: labgrid\-client console|con [\-i] [\-l] [\-o] [\-\-logfile FILE] [name]
 .EE
 .UNINDENT
 .UNINDENT
@@ -254,6 +254,11 @@ optional resource name
 .UNINDENT
 .INDENT 0.0
 .TP
+.B \-i, \-\-internal
+use an internal console instead of microcom
+.UNINDENT
+.INDENT 0.0
+.TP
 .B \-l, \-\-loop
 keep trying to connect if the console is unavailable
 .UNINDENT