Fix solink and add a postsolink hook (use the hook for android strip)

build/toolchain/android/BUILD.gn

 # Copyright 2013 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.
 
 import("//build/config/sysroot.gni")  # Imports android/config.gni.
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/goma.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 
 # The Android GCC toolchains share most of the same parameters, so we have this
@@ skipping 21 matching lines @@
     # The tools should be run relative to the build dir.
     tool_prefix = rebase_path(invoker.tool_prefix, root_build_dir)
 
     cc = tool_prefix + "gcc"
     cxx = tool_prefix + "g++"
     ar = tool_prefix + "ar"
     ld = cxx
 
     toolchain_os = "android"
     toolchain_cpu_arch = invoker.toolchain_cpu_arch
+
+    android_strip = "${tool_prefix}strip"
+    mkdir_command = "mkdir -p lib.stripped"

[cjhopman, 2014/07/07 23:00:50]

This mkdir isn't needed if ninja knows about the output file.

[brettw, 2014/07/08 22:06:54]

Can you add a comment above this line about why it's needed?

[Nico, 2014/07/08 23:02:29]

Can we not use mkdir? It's not available on Windows (well, it is, but not with a
'-p' flag I think), and I thought one of the points of gn was to make
chrome/android hostable on more platforms

[cjhopman, 2014/07/11 20:48:50]

The right way to do this is to tell ninja about the output file in that
directory.

The next most "correct" way would probably be to make a separate target that
creates this directory (or actually just a file in it), and then have these
toolchains depend on that target. That's a bit more complicated than I would
like to do just to potentially make it easier to support other platforms...

I really only need the -p so that it doesn't fail if the directory already
exists, can i do (mkdir lib.stripped || true)? How about (if [ ! -e
lib.stripped]; then mkdir lib.stripped; fi)?

Really, my preference for this postsolink hook would be that I could write it as
a normal gn action (or whatever else) that just run as part of solink and had
access to the outputs. Then it would be easy to correctly handle other platforms
(or rather, it wouldn't be a special case and could be handled like all the
other gn stuff).

+    strip_command = "$android_strip --strip-unneeded -o lib.stripped/\$soname.tmp \$lib"
+    replace_command = "if ! cmp -s lib.stripped/\${soname}.tmp lib.stripped/\${soname}; then mv lib.stripped/\${soname}.tmp lib.stripped/\${soname}; fi"
+    postsolink = "$mkdir_command && $strip_command && $replace_command"
   }
 }
 
 android_gcc_toolchain("x86") {
   android_ndk_sysroot = "$android_ndk_root/$x86_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib"
 
   tool_prefix = "$x86_android_toolchain_root/bin/i686-linux-android-"
   toolchain_cpu_arch = "x86"
 }
 
 android_gcc_toolchain("arm") {
   android_ndk_sysroot = "$android_ndk_root/$arm_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib"
 
   tool_prefix = "$arm_android_toolchain_root/bin/arm-linux-androideabi-"
   toolchain_cpu_arch = "arm"
 }
 
 android_gcc_toolchain("mipsel") {
   android_ndk_sysroot = "$android_ndk_root/$mips_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib"
 
   tool_prefix = "$mips_android_toolchain_root/bin/mipsel-linux-android-"
   toolchain_cpu_arch = "mipsel"
 }