Add Go build support for GN.

build/go/go.py

+#!/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.
+
+"""
+This script invokes the go build tool.
+Must be called as follows:
+python go.py <go-binary> <build directory> <output file> <src directory>
+<CGO_CFLAGS> <CGO_LDFLAGS> <go-binary options>
+eg.
+python go.py /usr/lib/google-golang/bin/go out/build out/a.out .. "-I."
+"-L. -ltest" test -c test/test.go
+"""
+
+import os
+import shutil
+import string
+import sys
+
+def main():
+  args = sys.argv
+  go_binary = args[1]
+  build_dir = args[2]
+  out_file = os.path.abspath(args[3])
+  # The src directory specified is relative. We will later need this as an
+  # absolute path.
+  src_root = os.path.abspath(args[4]) + "/"
+  # GOPATH must be absolute, and point to one directory up from |src_Root|
+  go_path = os.path.abspath(src_root + "..")
+  # CGO_CFLAGS and CGO_LDFLAGS contain a paths relative to |src_root|
+  # We need to make these absolute paths by prepending the (absolute) |src_root|
+  cgo_cflags = string.replace(" " + args[5], " -I", " -I" + src_root)[1:]
+  cgo_ldflags = string.replace(" " + args[6], " -L", " -L" + src_root)[1:]
+  go_options = args[7:]
+  try:
+    shutil.rmtree(build_dir, True)
+    os.mkdir(build_dir)
+  except:
+    pass
+  old_directory = os.getcwd()
+  os.chdir(build_dir)
+  os.environ["GOPATH"] = go_path
+  os.environ["CGO_CFLAGS"] = cgo_cflags
+  os.environ["CGO_LDFLAGS"] = cgo_ldflags
+  os.system("%s %s" % (go_binary, " ".join(go_options)))
+  out_files = [ f for f in os.listdir(".") if os.path.isfile(f)]
+  if (len(out_files) > 0):
+    shutil.move(out_files[0], out_file)
+  os.chdir(old_directory)
+  try:
+    shutil.rmtree(build_dir, True)
+  except:
+    pass
+
+if __name__ == '__main__':
+  sys.exit(main())