Revised version: now able to take input from a serial port and, on Li…

…nux, send output to a virtual serial port.

Test: none

gnss/api/u_gnss_ucenter_ubx.py

@@ -176,27 +176,31 @@ def main(source, output_file, responses_only, echo_on, baud_rate):
     '''Main as a function'''
     return_value = 1
 
-    try:
-        # Open the source
-        reading_from_device = False
+    # Open the source
+    reading_from_device = False
+    source_handle = None
+    if os.path.isfile(source):
         try:
             source_handle = open(source, "r", encoding="utf8")
-        except FileNotFoundError:
-            print(f"Cannot open \"{source}\" as a file, trying to open it as a serial device.")
-            try:
-                # Open what is assumed to be a serial device
-                source_handle = serial.Serial(baudrate=baud_rate, timeout=0.05)
-                source_handle.port = source
-                source_handle.open()
-                reading_from_device = True
-            except (ValueError, serial.SerialException) as ex:
-                print(f"{type(ex).__name__} while opening port \"{source}\" for source.")
-                source_handle = None
-        if source_handle:
-            # Open either the output file or a virtual
-            # device that the caller can connect uCenter to
-            output_file_handle = None
-            device_output = None
+        except (NameError, FileNotFoundError, PermissionError) as ex:
+            print(f"{type(ex).__name__} while trying to open \"{source}\".")
+    else:
+        print(f"\"{source}\" is not a file, trying to open it as a device.")
+        try:
+            # Open what is assumed to be a serial device
+            source_handle = serial.Serial(baudrate=baud_rate, timeout=0.05)
+            source_handle.port = source
+            source_handle.open()
+            reading_from_device = True
+        except (ValueError, serial.SerialException) as ex:
+            print(f"{type(ex).__name__} while opening device \"{source}\".")
+            source_handle = None
+    if source_handle:
+        # Open either the output file or a virtual
+        # device that the caller can connect uCenter to
+        output_file_handle = None
+        writing_to_device = False
+        try:
             if output_file:
                 if not os.path.splitext(output_file)[1]:
                     output_file += "." + OUTPUT_FILE_EXTENSION
@@ -209,20 +213,21 @@ def main(source, output_file, responses_only, echo_on, baud_rate):
                         _, device_output = pty.openpty()
                         output_file = os.ttyname(device_output)
                         output_file_handle = serial.Serial(output_file)
+                        writing_to_device = True
                     except (NameError, FileNotFoundError, PermissionError) as ex:
                         print(f"{type(ex).__name__} while trying to create virtual device" \
                               f" for output: : {str(ex)}.")
-                else:
+                if not output_file_handle:
                     # Output file name is source file with modified extension
-                    output_file = os.path.splitext(output_file)[0] + "." + OUTPUT_FILE_EXTENSION
+                    output_file = os.path.splitext(source)[0] + "." + OUTPUT_FILE_EXTENSION
                     output_file_handle = open(output_file, "wb")
             if output_file_handle:
                 print_text = f"Reading from {source}"
                 if output_file:
                     print_text += f", writing to {output_file}"
                 print_text += f", looking for lines containing \"{GNSS_LOG_LINE_MARKER_RECEIVE}\""
                 if not responses_only:
-                    print_text += f" and \"{GNSS_LOG_LINE_MARKER_COMMAND}\""
+                    print_text += f" and \"{GNSS_LOG_LINE_MARKER_COMMAND}\"..."
                 print(print_text)
                 if reading_from_device:
                     print("Use CTRL-C to stop.")
@@ -259,15 +264,15 @@ def main(source, output_file, responses_only, echo_on, baud_rate):
                     pass
                 print(f"Found {message_count} UBX messages(s) in {line_number} line(s).")
                 source_handle.close()
-                if output_file and not device_output and message_count > 0:
+                if output_file and not writing_to_device and message_count > 0:
                     print(f"File {output_file} has been written: you may open it in uCenter.")
                 return_value = 0
             if output_file_handle:
                 output_file_handle.close()
-            except (NameError, FileNotFoundError, PermissionError) as ex:
-                print(f"{type(ex).__name__} while trying to open {output_file} for writing.")
-        else:
-            print(f"Unable to open \"{source}\".")
+        except (NameError, FileNotFoundError, PermissionError) as ex:
+            print(f"{type(ex).__name__} while trying to open {output_file} for writing.")
+    else:
+        print(f"Unable to open \"{source}\".")
 
     return return_value
 
@@ -288,12 +293,12 @@ def main(source, output_file, responses_only, echo_on, baud_rate):
                         " if no extension is given ." +             \
                         OUTPUT_FILE_EXTENSION + " will be added)."  \
                         " If this parameter is omitted and the"     \
-                        " source is a device then, on Linux, the"    \
-                        " output will be written to a virtual COM"  \
-                        " port to which you may connect uCenter"    \
+                        " source is a device then, on Linux only"   \
+                        " I'm afraid, the output will be written"   \
+                        " to a PTY to which you may connect uCenter"\
                         " directly. Otherwise the output will"      \
-                        " be written to the same name as the source" \
-                        " but with extension " +                    \
+                        " be written to the same name as the source"\
+                        " but with extension ." +                   \
                         OUTPUT_FILE_EXTENSION + ".")
     PARSER.add_argument("-r", action="store_true", help="include"   \
                         " only the responses from the GNSS device"  \