Add dependency installation files for x86_64

* The installation script installs the necessary dependencies based on
  host OS version on Ubuntu OS
* clang toolchain BUILD.gn will only use clang-3.5 or above
* Update documentation

Test: gn gen out/Default; ninja -C out/Default
Change-Id: Ibc732ebc68009af25e9a911a724a888e008d45ac

README.md

@@ -8,47 +8,6 @@ Just build AOSP - Fluoride is there by default.
 Instructions for Ubuntu, tested on 14.04 with Clang 3.5.0 and 16.10 with Clang
  3.8.0
 
-### Install required libraries
-
-```sh
-sudo apt-get install libevent-dev libc++-dev libc++abi-dev
-```
-
-### Install build tools
-
-  - Install [ninja](https://ninja-build.org/) build system
-
-```sh
-sudo apt-get install ninja-build
-```
-
-or download binary from https://github.com/ninja-build/ninja/releases
-
-  - Install [gn](https://chromium.googlesource.com/chromium/src/tools/gn/) -
- meta-build system that generates NinjaBuild files.
-
-Get sha1 of current version from [here](
-https://chromium.googlesource.com/chromium/buildtools/+/master/linux64/gn.sha1)
- and then download corresponding executable:
-
-```sh
-wget -O gn http://storage.googleapis.com/chromium-gn/<gn.sha1>
-```
-
-i.e. if sha1 is "3491f6687bd9f19946035700eb84ce3eed18c5fa" (value from 24 Feb
- 2016) do
-
-```sh
-wget -O gn http://storage.googleapis.com/chromium-gn/3491f6687bd9f19946035700eb84ce3eed18c5fa
-```
-
-Then make binary executable and put it on your PATH, i.e.:
-
-```sh
-chmod a+x ./gn
-sudo mv ./gn /usr/bin
-```
-
 ### Download source
 
 ```sh
@@ -57,6 +16,13 @@ cd ~/fluoride
 git clone https://android.googlesource.com/platform/system/bt
 ```
 
+Install dependencies (require sudo access):
+
+```sh
+cd ~/fluoride/bt
+build/install_deps.sh
+```
+
 Then fetch third party dependencies:
 
 ```sh

build/install_deps.sh

@@ -0,0 +1,57 @@
+#!/bin/bash
+CLANG_PACKAGE=clang
+GNSHA1_URL="https://chromium.googlesource.com/chromium/buildtools/\
++/master/linux64/gn.sha1?format=TEXT"
+
+# Check if clang is already installed on current system
+clang_path=`which clang`
+if [ -f "$clang_path" ]; then
+  # if clang binary is avalable, check its version
+  clang_version=$($clang_path --version | grep clang | sed "s/.*version\s*\([0-9]*\.[0-9]*\).*/\1/")
+  IFS="." read -ra clang_version_array <<< "$clang_version"
+  clang_version_major=${clang_version_array[0]}
+  clang_version_minor=${clang_version_array[1]}
+  # if the version is greater than 3.5 then do not install clang here
+  if [ $clang_version_major -ge 3 ] && [ $clang_version_minor -ge 5 ]; then
+    echo "Detected clang $clang_version"
+    CLANG_PACKAGE=""
+  fi
+fi
+
+if [ ! -z "$CLANG_PACKAGE" ]; then
+  # Try to find clang from a known list
+  for clang_version in 3.9 3.8 3.7 3.6 3.5
+  do
+    clang_path=`which clang-$clang_version`
+    if [ -f "$clang_path" ]; then
+      echo "Detected clang-$clang_version"
+      CLANG_PACKAGE=""
+      break
+    fi
+  done
+fi
+
+if [ ! -z "$CLANG_PACKAGE" ]; then
+  echo "clang not found on current system, installing"
+  if [ -f /etc/lsb-release ]; then
+	  # Ubuntu
+	  ubuntu_version=$(lsb_release --release --short)
+	  IFS="." read -ra ubuntu_version_array <<< "$ubuntu_version"
+	  ubuntu_version_major=${ubuntu_version_array[0]}
+	  ubuntu_version_minor=${ubuntu_version_array[1]}
+	  if [ $ubuntu_version_major -lt 15 ]; then
+	    echo "Choose clang-3.8 for Ubuntu 14 and below"
+	    CLANG_PACKAGE=clang-3.8
+	  fi
+  fi
+fi
+
+sudo apt-get -y install $CLANG_PACKAGE libevent-dev libc++-dev libc++abi-dev \
+                        ninja-build
+gn_path=`which gn`
+if [ -z $gn_path ]; then
+  gnsha1=$(curl $GNSHA1_URL | base64 -d)
+  wget -O gn http://storage.googleapis.com/chromium-gn/$gnsha1
+  chmod a+x ./gn
+  sudo mv ./gn /usr/bin/
+fi

build/toolchain/clang/BUILD.gn

@@ -13,8 +13,15 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
-clang = "clang"
-clangxx = "clang++"
+clang_suffix = exec_script("get_clang_suffix.py", [], "list lines")
+clang_suffix = clang_suffix[0]
+assert(clang_suffix != "None",
+      "Cannot find clang, please install clang 3.5 or above")
+if (clang_suffix != "") {
+  clang_suffix = "-" + clang_suffix
+}
+clang = "clang$clang_suffix"
+clangxx = "clang++$clang_suffix"
 
 config("clang_config") {
   include_dirs = [

build/toolchain/clang/get_clang_suffix.py

@@ -0,0 +1,43 @@
+import os
+import subprocess
+import re
+import sys
+
+def which(cmd):
+  for p in os.environ["PATH"].split(os.pathsep):
+    clang_path = os.path.join(p, cmd)
+    if os.path.exists(clang_path):
+      return clang_path
+  return None
+
+CLANG_VERSION_REGEX=".*version\s*([0-9]*\.[0-9]*)\.*"
+clang_path = which("clang++")
+clang_version_major = 0
+clang_version_minor = 0
+
+if clang_path:
+  clang_version_out = subprocess.Popen([clang_path, "--version"],
+    stdout=subprocess.PIPE).communicate()[0]
+  clang_version_match = re.search(CLANG_VERSION_REGEX, clang_version_out)
+  clang_version_str = clang_version_match.group(1)
+  clang_version_array = clang_version_str.split('.')
+  clang_version_major = int(clang_version_array[0])
+  clang_version_minor = int(clang_version_array[1])
+
+if clang_version_major >= 3 and clang_version_minor >= 5:
+  print ""
+else:
+  # Loop in support clang version only
+  clang_version_major = 3
+  clang_version_minor = 9
+  while clang_version_major >= 3 and clang_version_minor >= 5:
+    clang_version_str = "%d.%d" % (clang_version_major, clang_version_minor)
+    clang_path = which("clang++-" + clang_version_str)
+    if clang_path:
+      print clang_version_str
+      sys.exit(0)
+    clang_version_minor -= 1
+    if clang_version_minor < 0:
+      clang_version_minor = 9
+      clang_version_major -= 1
+  print "None"