Dropping in software construction toolkit.

site_scons/site_tools/command_output.py

Index: site_scons/site_tools/command_output.py
===================================================================
--- site_scons/site_tools/command_output.py	(revision 0)
+++ site_scons/site_tools/command_output.py	(revision 0)
@@ -0,0 +1,130 @@
+#!/usr/bin/python2.4
+# Copyright 2008, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Command output builder for SCons."""
+
+
+import os
+import SCons.Script
+import subprocess
+
+
+def RunCommand(cmdargs, cwdir=None, env=None, echo_output=True):
+  """Runs an external command.
+
+  Args:
+    cmdargs: A command string, or a tuple containing the command and its
+        arguments.
+    cwdir: Working directory for the command, if not None.
+    env: Environment variables dict, if not None.
+    echo_output: If True, output will be echoed to stdout.
+
+  Returns:
+    The integer errorlevel from the command.
+    The combined stdout and stderr as a string.
+  """
+
+  # Force unicode string in the environment to strings.
+  if env:
+    env = dict([(k, str(v)) for k, v in env.items()])
+  child = subprocess.Popen(cmdargs, cwd=cwdir, env=env, shell=True,
+                           stdin=subprocess.PIPE,
+                           stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+  child_out = []
+  child_retcode = None
+
+  # Need to poll the child process, since the stdout pipe can fill.
+  while child_retcode is None:
+    child_retcode = child.poll()
+    new_out = child.stdout.read()
+    if echo_output:
+      print new_out,
+    child_out.append(new_out)
+
+  if echo_output:
+    print   # end last line of output
+  return child_retcode, ''.join(child_out)
+
+
+def CommandOutputBuilder(target, source, env):
+  """Command output builder.
+
+  Args:
+    self: Environment in which to build
+    target: List of target nodes
+    source: List of source nodes
+
+  Returns:
+    None or 0 if successful; nonzero to indicate failure.
+
+  Runs the command specified in the COMMAND_OUTPUT_CMDLINE environment variable
+  and stores its output in the first target file.  Additional target files
+  should be specified if the command creates additional output files.
+
+  Runs the command in the COMMAND_OUTPUT_RUN_DIR subdirectory.
+  """
+  env = env.Clone()
+
+  cmdline = env.subst('$COMMAND_OUTPUT_CMDLINE', target=target, source=source)
+  cwdir = env.subst('$COMMAND_OUTPUT_RUN_DIR', target=target, source=source)
+  if cwdir:
+    cwdir = os.path.normpath(cwdir)
+    env.AppendENVPath('PATH', cwdir)
+    env.AppendENVPath('LD_LIBRARY_PATH', cwdir)
+  else:
+    cwdir = None
+
+  retcode, output = RunCommand(cmdline, cwdir=cwdir, env=env['ENV'])
+
+  # Save command line output
+  output_file = open(str(target[0]), 'w')
+  output_file.write(output)
+  output_file.close()
+
+  return retcode
+
+
+def generate(env):
+  # NOTE: SCons requires the use of this name, which fails gpylint.
+  """SCons entry point for this tool."""
+
+  # Add the builder and tell it which build environment variables we use.
+  action = SCons.Script.Action(CommandOutputBuilder, varlist=[
+      'COMMAND_OUTPUT_CMDLINE',
+      'COMMAND_OUTPUT_RUN_DIR',
+  ])
+  builder = SCons.Script.Builder(action = action)
+  env.Append(BUILDERS={'CommandOutput': builder})
+
+  # Default command line is to run the first input
+  env['COMMAND_OUTPUT_CMDLINE'] = '$SOURCE'
+
+  # TODO(rspangler): add a pseudo-builder which takes an additional command
+  # line as an argument.