gcode: Don't silently discard characters inside a command name

Don't silently drop leading numbers and unusual characters at the
start of a command - for example, don't interpret '99M88' as 'M88'.

Don't silently drop spaces in a command - for example, don't interpret
"M 101" as the command "M101".  Doing so will cause other parts of the
code (such as get_raw_command_parameters() ) to not work properly.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

2 files changed, 11 insertions, 7 deletions

diff --git a/docs/Config_Changes.md b/docs/Config_Changes.md
index 5535dc85..ecac5a7a 100644
--- a/docs/Config_Changes.md
+++ b/docs/Config_Changes.md
@@ -8,6 +8,12 @@ All dates in this document are approximate.
 
 ## Changes
 
+20241201: In some cases Klipper may have ignored leading characters or
+spaces in a traditional G-Code command. For example, "99M123" may have
+been interpreted as "M123" and "M 321" may have been interpreted as
+"M321". Klipper will now report these cases with an "Unknown command"
+warning.
+
 20241112: Option `CHIPS=<chip_name>` in `TEST_RESONANCES` and
 `SHAPER_CALIBRATE` requires specifying the full name(s) of the accel
 chip(s). For example, `adxl345 rpi` instead of short name - `rpi`.
diff --git a/klippy/gcode.py b/klippy/gcode.py
index ee2a09d9..8a6b3b8d 100644
--- a/klippy/gcode.py
+++ b/klippy/gcode.py
@@ -198,16 +198,14 @@ class GCodeDispatch:
                 line = line[:cpos]
             # Break line into parts and determine command
             parts = self.args_r.split(line.upper())
-            numparts = len(parts)
-            cmd = ""
-            if numparts >= 3 and parts[1] != 'N':
-                cmd = parts[1] + parts[2].strip()
-            elif numparts >= 5 and parts[1] == 'N':
+            if ''.join(parts[:2]) == 'N':
                 # Skip line number at start of command
-                cmd = parts[3] + parts[4].strip()
+                cmd = ''.join(parts[3:5]).strip()
+            else:
+                cmd = ''.join(parts[:3]).strip()
             # Build gcode "params" dictionary
             params = { parts[i]: parts[i+1].strip()
-                       for i in range(1, numparts, 2) }
+                       for i in range(1, len(parts), 2) }
             gcmd = GCodeCommand(self, cmd, origline, params, need_ack)
             # Invoke handler for command
             handler = self.gcode_handlers.get(cmd, self.cmd_default)