AOSP build error: use of undeclared identifier 'pipe2'

[matthew]

I modified a file under frameworks/base/core/java/android/content/ and I try to compile it to see the change

here is what I did:

source build/envsetup.sh
lunch 22
mmm frameworks/base

But then I got the following error message:

frameworks/base/cmds/idmap2/tests/FileUtilsTests.cpp:73:13: error: use of undeclared identifier 'pipe2'

  ASSERT_EQ(pipe2(pipefd, O_CLOEXEC), 0);

I am trying to build it on mac and run it on the emulator, and it can runs perfectly before I try to build this module. Does anyone know how this issue happens?