Make asan_symbolize.py not crash on Windows.

[thakis]

Summary

asan_symbolize.py isn't needed on Windows, but it's nice if asan has a unified UI on all platforms. So rather than have asan_symolize.py die on startup due to it importing modules that don't exist on Windows, let it peacefully early-exit.

While here, also fix the indent on the argument parsing code.

[thakis]

act as cat on windows

[earthdok]

Wouldn't it be better to do this in the Chromium-specific wrapper (src/tools/valgrind/asan_symbolize.py)?

[glider]

LGTM

lib/asan/scripts/asan_symbolize.py

438

I'd commit the formatting part separately.

474

Nit: spare comma?

[glider]

Note that we've moved away from using asan_symbolize.py in LLVM, so it's mainly used in Chrome.
Do we really want to filter ASan Win reports through asan_symbolize.py?

[thakis]

I thought it's needed if your binary is sandboxed. If we can stop using
asan_symbolize.py in Chromium, I'm happy to do that instead.

[thakis]

put this in SymbolizationLoop instead, so that clients using this as a module benefit from it too

[thakis]

I'll land the indent changes separately, removed that from this change.

In D7227#114653, @earthdok wrote:

Wouldn't it be better to do this in the Chromium-specific wrapper (src/tools/valgrind/asan_symbolize.py)?

I moved it into SymbolizationLoop, so that the specific wrapper will do the right thing automatically.

lib/asan/scripts/asan_symbolize.py

441

err actually, I suppose I should copy stdin to stdout too

474

No, a traiilng comma in a print line makes print not add a \n. This is intentional because line already ends in a \n.

[glider]

Yes, it's needed on Linux/OSX if your binary is sandboxed, but I don't understand why run it on Windows if you don't need it.

[glider]

Still LG

[thakis]

r227326, thanks!

lib/asan/scripts/asan_symbolize.py

 #!/usr/bin/env python
 #===- lib/asan/scripts/asan_symbolize.py -----------------------------------===#
 #
 #                     The LLVM Compiler Infrastructure
 #
 # This file is distributed under the University of Illinois Open Source
 # License. See LICENSE.TXT for details.
 #
 #===------------------------------------------------------------------------===#
 import argparse
 import bisect
 import getopt
 import os
-import pty
 import re
 import subprocess
 import sys
-import termios
 
 symbolizers = {}
 DEBUG = False
 demangle = False
 binutils_prefix = None
 sysroot_path = None
 binary_name_filter = None
 fix_filename_patterns = None

 
 
 class UnbufferedLineConverter(object):
   """
   Wrap a child process that responds to each line of input with one line of
   output.  Uses pty to trick the child into providing unbuffered output.
   """
   def __init__(self, args, close_stderr=False):
+    # Local imports so that the script can start on Windows.
+    import pty
+    import termios
     pid, fd = pty.fork()
     if pid == 0:
       # We're the child. Transfer control to command.
       if close_stderr:
         dev_null = os.open('/dev/null', 0)
         os.dup2(dev_null, 2)
       os.execvp(args[0], args)
     else:
else:
       result = []
       for symbolized_frame in symbolized_lines:
         result.append('    #%s %s' % (str(self.frame_no), symbolized_frame.rstrip()))
         self.frame_no += 1
       return result
 
   def process_logfile(self):
     self.frame_no = 0
-    while True:
-      line = logfile.readline()
-      if not line:
-        break
+    for line in logfile:
       processed = self.process_line(line)
       print '\n'.join(processed)
 
   def process_line(self, line):
     self.current_line = line.rstrip()
     #0 0x7f6e35cf2e45  (/blah/foo.so+0x11fe45)
     stack_trace_line_format = (
         '^( *#([0-9]+) *)(0x[0-9a-f]+) *\((.*)\+(0x[0-9a-f]+)\)')
def process_line(self, line):
     symbolized_line = self.symbolize_address(addr, binary, offset)
     if not symbolized_line:
       if original_binary != binary:
         symbolized_line = self.symbolize_address(addr, binary, offset)
     return self.get_symbolized_lines(symbolized_line)
 
 
 if __name__ == '__main__':
-  parser = argparse.ArgumentParser(formatter_class=argparse.RawDescriptionHelpFormatter,
+  parser = argparse.ArgumentParser(
+      formatter_class=argparse.RawDescriptionHelpFormatter,
       description='ASan symbolization script',
-  epilog='''Example of use:
-  asan_symbolize.py -c "$HOME/opt/cross/bin/arm-linux-gnueabi-" -s "$HOME/SymbolFiles" < asan.log''')
+      epilog='Example of use:\n'
+             'asan_symbolize.py -c "$HOME/opt/cross/bin/arm-linux-gnueabi-" '
+             '-s "$HOME/SymbolFiles" < asan.log')
   parser.add_argument('path_to_cut', nargs='*',
                       help='pattern to be cut from the result file path ')
   parser.add_argument('-d','--demangle', action='store_true',
                       help='demangle function names')
   parser.add_argument('-s', metavar='SYSROOT',
                       help='set path to sysroot for sanitized binaries')
   parser.add_argument('-c', metavar='CROSS_COMPILE',
                       help='set prefix for binutils')
-  parser.add_argument('-l','--logfile', default=sys.stdin, type=argparse.FileType('r'),
+  parser.add_argument('-l','--logfile', default=sys.stdin,
+                      type=argparse.FileType('r'),
                       help='set log file name to parse, default is stdin')
   args = parser.parse_args()
   if args.path_to_cut:
     fix_filename_patterns = args.path_to_cut
   if args.demangle:
     demangle = True
   if args.s:
     binary_name_filter = sysroot_path_filter
     sysroot_path = args.s
   if args.c:
     binutils_prefix = args.c
   if args.logfile:
     logfile = args.logfile
   else:
     logfile = sys.stdin
+
+  if sys.platform == 'win32':
+    # ASan on Windows uses dbghelp.dll to symbolize in-process, which works even
+    # in sandboxed processes.  This script isn't needed there.
+    for line in logfile:
+      print line,
+    sys.exit(0)
+
   loop = SymbolizationLoop(binary_name_filter)
   loop.process_logfile()