tools: Allow LogAnalyzer to read from stdin rather than just files

Use - intead of the filename

Tools/LogAnalyzer/DataflashLog.py

@@ -8,6 +8,7 @@ import collections
 import os
 import numpy
 import bisect
+import sys
 
 
 class Format:
@@ -280,7 +281,10 @@ class DataflashLog:
         '''returns on successful log read (including bad lines if ignoreBadlines==True), will throw an Exception otherwise'''
         # TODO: dataflash log parsing code is pretty hacky, should re-write more methodically
         self.filename = logfile
-        f = open(self.filename, 'r')
+        if self.filename == '<stdin>':
+            f = sys.stdin
+        else:
+            f = open(self.filename, 'r')
         if f.read(4) == '\xa3\x95\x80\x80':
             raise Exception("Unable to parse binary log files at this time, will be added soon")
         f.seek(0)
@@ -385,7 +389,7 @@ class DataflashLog:
 
         # gather some general stats about the log
         self.lineCount  = lineNumber
-        self.filesizeKB = os.path.getsize(self.filename) / 1024.0
+        self.filesizeKB = f.tell() / 1024.0
         # TODO: switch duration calculation to use TimeMS values rather than GPS timestemp
         if "GPS" in self.channels:
             # the GPS time label changed at some point, need to handle both

Tools/LogAnalyzer/LogAnalyzer.py

@@ -206,7 +206,7 @@ def main():
 
     # deal with command line arguments
     parser = argparse.ArgumentParser(description='Analyze an APM Dataflash log for known issues')
-    parser.add_argument('logfile', type=argparse.FileType('r'), help='path to Dataflash log file')
+    parser.add_argument('logfile', type=argparse.FileType('r'), help='path to Dataflash log file (or - for stdin)')
     parser.add_argument('-q', '--quiet',  metavar='', action='store_const', const=True, help='quiet mode, do not print results')
     parser.add_argument('-p', '--profile', metavar='', action='store_const', const=True, help='output performance profiling data')
     parser.add_argument('-s', '--skip_bad', metavar='', action='store_const', const=True, help='skip over corrupt dataflash lines')