Allow RunShellCommand to work even with very large commands

build/android/pylib/device/device_utils.py

 # Copyright 2014 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.
 
 """Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
 # pylint: disable=W0613
 
@@ skipping 409 matching lines @@
         more lines.
       CommandTimeoutError on timeout.
       DeviceUnreachableError on missing device.
     """
     def env_quote(key, value):
       if not DeviceUtils._VALID_SHELL_VARIABLE.match(key):
         raise KeyError('Invalid shell variable name %r' % key)
       # using double quotes here to allow interpolation of shell variables
       return '%s=%s' % (key, cmd_helper.DoubleQuote(value))
 
+    def do_run(cmd):
+      try:
+        return self.adb.Shell(cmd)
+      except device_errors.AdbCommandFailedError as exc:
+        if check_return:
+          raise
+        else:
+          return exc.output
+
     if not isinstance(cmd, basestring):
       cmd = ' '.join(cmd_helper.SingleQuote(s) for s in cmd)
     if env:
       env = ' '.join(env_quote(k, v) for k, v in env.iteritems())
       cmd = '%s %s' % (env, cmd)
     if cwd:
       cmd = 'cd %s && %s' % (cmd_helper.SingleQuote(cwd), cmd)
     if as_root and self.NeedsSU():
       # "su -c sh -c" allows using shell features in |cmd|
       cmd = 'su -c sh -c %s' % cmd_helper.SingleQuote(cmd)
     if timeout is None:
       timeout = self._default_timeout
 
-    try:
-      output = self.adb.Shell(cmd)
-    except device_errors.AdbCommandFailedError as e:
-      if check_return:
-        raise
-      else:
-        output = e.output
+    if len(cmd) < 512:

[jbudorick, 2014/11/25 17:05:26]

We should de-magic 512. "MAX_ADB_COMMAND_LENGTH" or something like that.

+      output = do_run(cmd)
+    else:
+      with device_temp_file.DeviceTempFile(self, suffix='.sh') as script:
+        # |as_root| must be False, and |force_push| must be True,
+        # otherwise WriteFile may introduce infinite recursion

[jbudorick, 2014/11/25 17:05:26]

This worries me. It's the same kind of cyclical dependency we had in the
previous version of device_temp_file -- one that is correctly avoided _now_ and
well-commented, but is tricky to modify and liable to be sneakily broken by
changes elsewhere (in this case, in WriteFile). Maybe would should instead be
doing this with tempfile + device_temp_file + adb.Push?

+        self.WriteFile(script.name, cmd, as_root=False, force_push=True)

[perezju, 2014/11/25 16:25:33]

look, our first non-artificial use of force_push! :)

+        output = do_run('sh %s' % script.name_quoted)
 
     output = output.splitlines()
     if single_line:
       if not output:
         return ''
       elif len(output) == 1:
         return output[0]
       else:
         msg = 'one line of output was expected, but got: %s'
         raise device_errors.CommandFailedError(msg % output, str(self))
@@ skipping 696 matching lines @@
     Returns:
       A Parallelizer operating over |devices|.
     """
     if not devices or len(devices) == 0:
       devices = pylib.android_commands.GetAttachedDevices()
     parallelizer_type = (parallelizer.Parallelizer if async
                          else parallelizer.SyncParallelizer)
     return parallelizer_type([
         d if isinstance(d, DeviceUtils) else DeviceUtils(d)
         for d in devices])