Add strace_inputs.py to strace a test executable and detect its dependencies.

tools/isolate/strace_inputs.py

Index: tools/isolate/strace_inputs.py
diff --git a/tools/isolate/strace_inputs.py b/tools/isolate/strace_inputs.py
new file mode 100755
index 0000000000000000000000000000000000000000..cdb34f4aa35a2e08c2739ff66b13f19b82baf39d
--- /dev/null
+++ b/tools/isolate/strace_inputs.py
@@ -0,0 +1,162 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Runs strace on a test and processes the logs to extract the dependencies from
+the source tree.
+
+Automatically extracts directories where all the files are used to make the
+dependencies list more compact.
+"""
+
+import os
+import re
+import subprocess
+import sys
+
+
+BASE_DIR = os.path.dirname(os.path.abspath(__file__))
+ROOT_DIR = os.path.dirname(os.path.dirname(BASE_DIR))
+
+IGNORED = (
+  '/dev',
+  '/etc',
+  '/home',
+  '/lib',
+  '/proc',
+  '/sys',
+  '/tmp',
+  '/usr',
+  '/var',
+)
+
+
+def gen_trace(cmd, cwd, logname, silent):
+  """Runs strace on an executable."""
+  strace = ['strace', '-f', '-e', 'trace=open', '-o', logname]
+  stdout = stderr = None
+  if silent:
+    stdout = subprocess.PIPE
+    stderr = subprocess.PIPE
+
+  cmd = [os.path.normpath(os.path.join(cwd, c)) for c in cmd]
+  p = subprocess.Popen(
+      strace + cmd, cwd=cwd, stdout=stdout, stderr=stderr)
+  out, err = p.communicate()
+  if p.returncode != 0:
+    print 'Failure: %d' % p.returncode
+    # pylint: disable=E1103
+    print ''.join(out.splitlines(True)[-100:])
+    print ''.join(err.splitlines(True)[-100:])
+  return p.returncode
+
+
+def parse_log(filename, blacklist):
+  """Processes a strace log and returns the files opened and the files that do
+  not exist.
+
+  Most of the time, files that do not exist are temporary test files that should
+  be put in /tmp instead. See http://crbug.com/116251
+
+  TODO(maruel): Process chdir() calls so relative paths can be processed.
+  """
+  files = set()
+  non_existent = set()
+  for line in open(filename):
+    # 1=pid, 2=filepath, 3=mode, 4=result
+    m = re.match(r'^(\d+)\s+open\("([^"]+)", ([^\)]+)\)\s+= (.+)$', line)
+    if not m:
+      continue
+    if m.group(4).startswith('-1') or 'O_DIRECTORY' in m.group(3):
+      # Not present or a directory.
+      continue
+    filepath = m.group(2)
+    if blacklist(filepath):
+      continue
+    if not os.path.isfile(filepath):
+      non_existent.add(filepath)
+    else:
+      files.add(filepath)
+  return files, non_existent
+
+
+def relevant_files(files, root):
+  """Trims the list of files to keep the expected files and unexpected files.
+
+  Unexpected files are files that are not based inside the |root| directory.
+  """
+  expected = []
+  unexpected = []
+  for f in files:
+    if f.startswith(root):
+      expected.append(f[len(root):])
+    else:
+      unexpected.append(f)
+  return sorted(set(expected)), sorted(set(unexpected))
+
+
+def extract_directories(files, root):
+  """Detects if all the files in a directory were loaded and if so, replace the
+  individual files by the directory entry.
+  """
+  directories = set(os.path.dirname(f) for f in files)
+  files = set(files)
+  for directory in sorted(directories, reverse=True):
+    actual = set(
+      os.path.join(directory, f) for f in
+      os.listdir(os.path.join(root, directory))
+      if not f.endswith(('.svn', '.pyc'))
+    )
+    if not (actual - files):
+      files -= actual
+      files.add(directory + '/')
+  return sorted(files)
+
+
+def strace_inputs(unittest, cmd):
+  """Tries to load the logs if available. If not, strace the test."""
+  logname = os.path.join(BASE_DIR, os.path.basename(unittest))
+  if not os.path.isfile(logname):
+    returncode = gen_trace(cmd, ROOT_DIR, logname, True)
+    if returncode:
+      return returncode
+
+  def blacklist(f):
+    """Strips ignored paths."""
+    return f.startswith(IGNORED) or f.endswith('.pyc')
+
+  files, non_existent = parse_log(logname, blacklist)
+  print('Total: %d' % len(files))
+  print('Non existent: %d' % len(non_existent))
+  for f in non_existent:
+    print('  %s' % f)
+
+  expected, unexpected = relevant_files(files, ROOT_DIR + '/')
+  if unexpected:
+    print('Unexpected: %d' % len(unexpected))
+    for f in unexpected:
+      print('  %s' % f)
+
+  simplified = extract_directories(expected, ROOT_DIR)
+  print('Interesting: %d reduced to %d' % (len(expected), len(simplified)))
+  for f in simplified:
+    print('  %s' % f)
+
+  return 0
+
+
+def main():
+  if len(sys.argv) < 3:
+    print >> sys.stderr, (
+        'Usage: strace_inputs.py [testname] [cmd line...]\n'
+        '\n'
+        'Example:\n'
+        '  ./strace_inputs.py base_unittests testing/xvfb.py out/Release '
+        'out/Release/base_unittests')
+    return 1
+  return strace_inputs(sys.argv[1], sys.argv[2:])
+
+
+if __name__ == '__main__':
+  sys.exit(main())