From 8b8658bd72e4e27b6ba86de60894bd67115b7ac0 Mon Sep 17 00:00:00 2001
From: Steve Hill <cheesy@google.com>
Date: Thu, 10 Nov 2016 11:54:08 -0500
Subject: [PATCH] Add scripts to setup 32-bit chroots for building.

---
 install/centos/build_env.sh     |   2 +
 install/centos/run_in_chroot.sh |  50 +++++++++++++
 install/centos/setup_chroot.sh  | 120 ++++++++++++++++++++++++++++++++
 install/install_from_source.sh  |  10 +++
 install/run_in_chroot.sh        |   1 +
 install/setup_chroot.sh         |   1 +
 install/shell_utils.sh          |  66 ++++++++++++++++++
 install/ubuntu/build_env.sh     |   3 +
 install/ubuntu/run_in_chroot.sh |   7 ++
 install/ubuntu/setup_chroot.sh  |  82 ++++++++++++++++++++++
 10 files changed, 342 insertions(+)
 create mode 100644 install/centos/run_in_chroot.sh
 create mode 100644 install/centos/setup_chroot.sh
 create mode 100755 install/install_from_source.sh
 create mode 120000 install/run_in_chroot.sh
 create mode 120000 install/setup_chroot.sh
 create mode 100644 install/ubuntu/run_in_chroot.sh
 create mode 100644 install/ubuntu/setup_chroot.sh

diff --git a/install/centos/build_env.sh b/install/centos/build_env.sh
index a93125cff..3e7db7ecc 100644
--- a/install/centos/build_env.sh
+++ b/install/centos/build_env.sh
@@ -17,6 +17,8 @@ if [ -f "$devtoolset_enable" ]; then
 
 fi
 
+export CHROOT_DIR=/var/chroot/centos_i386
+
 export SSL_CERT_DIR=/etc/pki/tls/certs
 export SSL_CERT_FILE=/etc/pki/tls/cert.pem
 
diff --git a/install/centos/run_in_chroot.sh b/install/centos/run_in_chroot.sh
new file mode 100644
index 000000000..de81d8548
--- /dev/null
+++ b/install/centos/run_in_chroot.sh
@@ -0,0 +1,50 @@
+#!/bin/bash
+# Copyright 2016 Google Inc. All Rights Reserved.
+# Author: cheesy@google.com (Steve Hill)
+#
+# This script emulates the behavior of schroot, which:
+# - Invokes chroot(2) as root (schroot is setuid).
+# - setuids back to the uid it was run as.
+# - chdirs to the directory it was run from.
+# - execs the command supplied as arguments, or starts an interactive shell.
+#
+# Trying to write a single command that can be passed to sudo that will do the
+# su, chdir, exec combination without breaking arg tokenisation is nigh
+# impossible. Instead, once the chrooting and setuiding (via sudo) has been
+# taken care of, the script execs itself with --chroot_done. This takes care
+# of the chdir and exec.
+
+# This comes from build_env.sh.
+if [ -z "${CHROOT_DIR:-}" ]; then
+  echo "This must be run via os_redirector.sh!" >&2
+  exit 1
+fi
+
+# When we re-invoke the script, it's called with:
+# --chroot_done <directory> [CMD]
+# It then chdirs to <directory> and invokes CMD or an interactive $SHELL
+if [ "${1-}" = "--chroot_done" ]; then
+  if [ $# -lt 2 ]; then
+    echo "Do not run this directly with --chroot_done" >&2
+    exit 1
+  fi
+
+  cd "$2"
+  shift 2
+
+  if [ $# -eq 0 ]; then
+    set -- "$SHELL" -l
+  fi
+  eval exec "$@"
+  exit 1  # NOTREACHED
+fi
+
+# We need the absolute path to re-exec the script after the chroot.
+this_script="$0"
+if [[ "$this_script" != /* ]]; then
+  this_script="$PWD/$this_script"
+fi
+
+# Note that here $0 is expected to be a symlink to os_redirector.sh.
+exec setarch i386 sudo /usr/sbin/chroot "$CHROOT_DIR" sudo -u "$USER" -i -- \
+  "$this_script" --chroot_done "$PWD" "$@"
diff --git a/install/centos/setup_chroot.sh b/install/centos/setup_chroot.sh
new file mode 100644
index 000000000..ea23ae4c8
--- /dev/null
+++ b/install/centos/setup_chroot.sh
@@ -0,0 +1,120 @@
+#!/bin/bash
+# Copyright 2016 Google Inc. All Rights Reserved.
+# Author: cheesy@google.com (Steve Hill)
+#
+# Setup a 32-bit chroot for CentOS.
+
+# This comes from build_env.sh.
+if [ -z "${CHROOT_DIR:-}" ]; then
+  echo "This must be run via os_redirector.sh!" >&2
+  exit 1
+fi
+
+if [ -d "$CHROOT_DIR" ]; then
+  "$install_dir/run_in_chroot.sh" /bin/true >/dev/null 2>&1
+  if [ $? -eq 0 ]; then
+    echo chroot already setup, nothing to do.
+    exit 0
+  else
+    echo "$CHROOT_DIR exists but doesn't seem to be setup correctly." >&2
+    echo "You're going to have to clean up manually." >&2
+    exit 1
+  fi
+fi
+
+if [ "$UID" != 0 ]; then
+  echo "This script needs to run as root, re-running with sudo"
+  exec sudo $0 "$@"
+  exit 1  # NOTREACHED
+fi
+
+# TODO(cheesy): The release_rpm stuff below is not especially robust, but
+# scraping the site is a pain. If this is a problem we can fix it later.
+
+centos_version="$(lsb_release -rs)"
+git_pkg=
+if version_compare "$centos_version" -lt 6; then
+  # CentOS 5
+  release_rpm_url=http://mirror.centos.org/centos/5/os/i386/CentOS/centos-release-5-11.el5.centos.i386.rpm
+elif version_compare "$centos_version" -lt 7; then
+  # CentOS 6
+  release_rpm_url=http://mirror.centos.org/centos/6/os/i386/Packages/centos-release-6-8.el6.centos.12.3.i686.rpm
+  # TODO(cheesy): Once gclient is gone, we may be able to use the git rpm.
+else
+  # CentOS 7
+  release_rpm_url=http://mirror.centos.org/altarch/7/os/i386/Packages/centos-release-7-2.1511.el7.centos.2.9.i686.rpm
+  git_pkg=git
+fi
+
+release_rpm="$(basename "$release_rpm_url")"
+wget -O "$release_rpm" "$release_rpm_url"
+
+mkdir -p "$CHROOT_DIR/var/lib/rpm"
+
+# Required to run the chroot in 32-bit mode.
+yum -y install setarch
+
+function cleanup_etc_rpm_platform() {
+  if [ -s /etc/rpm/platform.real ]; then
+    mv -f /etc/rpm/platform.real /etc/rpm/platform
+  elif [ -f /etc/rpm/platform.real ]; then
+    # Only do this if platform.real exists, otherwise we could delete a
+    # perfectly valid file.
+    rm -f /etc/rpm/platform /etc/rpm/platform.real
+  fi
+}
+
+# To force install a different architecture, we must put a fake arch into
+# /etc/rpm/platform. Older CentOSes will have the file, newer may not. Either
+# way, it's important that we don't leave the fake one lying around.
+trap 'cleanup_etc_rpm_platform'  EXIT
+if [ -e /etc/rpm/platform ]; then
+  mv /etc/rpm/platform /etc/rpm/platform.real
+else
+  touch /etc/rpm/platform.real
+fi
+
+echo i686-redhat-linux > /etc/rpm/platform
+rpm --root="$CHROOT_DIR" --rebuilddb
+rpm --root="$CHROOT_DIR" --nodeps -i "$release_rpm"
+
+yum -y --installroot="$CHROOT_DIR" update
+# redhat-lsb and sudo are required for run_in_chroot.sh
+yum -y --installroot="$CHROOT_DIR" install yum sudo redhat-lsb
+
+cleanup_etc_rpm_platform
+trap - EXIT
+
+for x in passwd shadow group gshadow hosts sudoers resolv.conf; do
+  ln -f "/etc/$x" "$CHROOT_DIR/etc/$x"
+done
+
+cp -p /etc/yum.repos.d/* "$CHROOT_DIR/etc/yum.repos.d/"
+# These don't work for 32-bit.
+if version_compare "$centos_version" -ge 6; then
+  rm -f "$CHROOT_DIR/etc/yum.repos.d"/CentOS-SCLo-scl[.-]*
+fi
+
+for dir in /proc /sys /dev /selinux /etc/selinux /home; do
+  [ -d "$dir" ] || continue
+  chroot_dir="${CHROOT_DIR}$dir"
+  if [ ! -d "$chroot_dir" ]; then
+    mkdir -p "$chroot_dir"
+    chown --reference "$dir" "$chroot_dir"
+    chmod --reference "$dir" "$chroot_dir"
+  fi
+  echo "$dir $chroot_dir none bind 0 0" >> /etc/fstab
+done
+
+echo "none $CHROOT_DIR/dev/shm tmpfs defaults 0 0" >> /etc/fstab
+
+mount -a
+
+# The previous yum install above probably did all the updates,
+# but it doesn't hurt to ask.
+install/run_in_chroot.sh yum -y update
+install/run_in_chroot.sh yum -y install which redhat-lsb curl wget $git_pkg
+
+if [ -z "$git_pkg" ]; then
+  install/run_in_chroot.sh install/install_from_source.sh git
+fi
diff --git a/install/install_from_source.sh b/install/install_from_source.sh
new file mode 100755
index 000000000..5a460b014
--- /dev/null
+++ b/install/install_from_source.sh
@@ -0,0 +1,10 @@
+#!/bin/bash
+# Copyright 2016 Google Inc. All Rights Reserved.
+# Author: cheesy@google.com (Steve Hill)
+#
+# Trivial wrapper for shell function that installs a package from source
+# tarball.
+
+source "$(dirname "$BASH_SOURCE")/build_env.sh" || exit 1
+
+install_from_src "$@"
diff --git a/install/run_in_chroot.sh b/install/run_in_chroot.sh
new file mode 120000
index 000000000..ede6c5b83
--- /dev/null
+++ b/install/run_in_chroot.sh
@@ -0,0 +1 @@
+os_redirector.sh
\ No newline at end of file
diff --git a/install/setup_chroot.sh b/install/setup_chroot.sh
new file mode 120000
index 000000000..ede6c5b83
--- /dev/null
+++ b/install/setup_chroot.sh
@@ -0,0 +1 @@
+os_redirector.sh
\ No newline at end of file
diff --git a/install/shell_utils.sh b/install/shell_utils.sh
index 0ecc673db..97b5a2df5 100644
--- a/install/shell_utils.sh
+++ b/install/shell_utils.sh
@@ -83,3 +83,69 @@ function run_with_log() {
   fi
   return $rc
 }
+
+# Compare version numbers in dotted notation.
+# Usage: version_compare <version_a> <comparator> <version_b>
+# For instance:
+# if version_compare $version -lt 4.2; then echo "Too old!"; fi
+#
+function version_compare() {
+  if [ $# -ne 3 ]; then
+    echo "Usage: version_compare <version_a> <comparator> <version_b>" >&2
+    exit 1
+  fi
+
+  local a=$1
+  local comparator=$2
+  local b=$3
+
+  if [[ "$a" == *[^.0-9]* ]]; then
+    echo "Non-numeric version: $a" >&2
+    exit 1
+  fi
+
+  if [[ "$b" == *[^.0-9]* ]]; then
+    echo "Non-numeric version: $b" >&2
+    exit 1
+  fi
+
+  # The computed difference. 0 means a == b, -1 means a < b, 1 means a > b.
+  local difference=0
+
+  while [ $difference -eq 0 ]; do
+    if [ -z "$a" -a -z "$b" ]; then
+      break
+    elif [ -z "$a" ]; then
+      # a="" and b != "", therefore a < b
+      difference=-1
+      break
+    elif [ -z "$b" ]; then
+      # a != "" and b="", therefore a > b
+      difference=1
+      break
+    fi
+
+    # $a is N[.N.N]. Extract the first N from the beginning into $a_tok
+    local a_tok="${a%%.*}"
+    # Make $a any remaining N.N.
+    a="${a#*.}"
+    [ "$a" = "$a_tok" ] && a=""  # Happens when there are no dots in $a
+
+    # Same for $b
+    local b_tok="${b%%.*}"
+    b="${b#*.}"
+    [ "$b" = "$b_tok" ] && b=""
+
+    # Now do the integer comparison between a and b.
+    if [ "$a_tok" -lt "$b_tok" ]; then
+      difference=-1
+    elif [ "$b_tok" -gt "$b_tok" ]; then
+      difference=1
+    fi
+  done
+
+  # Now do the actual comparison. We use the supplied comparator (say -le) to
+  # compare the computed difference with zero. This will return the expected
+  # result.
+  [ "$difference" "$comparator" 0 ]
+}
diff --git a/install/ubuntu/build_env.sh b/install/ubuntu/build_env.sh
index fc75f43e3..6ab0ad832 100644
--- a/install/ubuntu/build_env.sh
+++ b/install/ubuntu/build_env.sh
@@ -14,3 +14,6 @@ if [ -x "${compiler_path}/bin/gcc" ]; then
 fi
 
 export PATH=$HOME/bin:/usr/local/bin:$PATH
+
+# precise_i386, for instance.
+CHROOT_NAME="$(lsb_release -cs)_i386"
diff --git a/install/ubuntu/run_in_chroot.sh b/install/ubuntu/run_in_chroot.sh
new file mode 100644
index 000000000..3a4d60754
--- /dev/null
+++ b/install/ubuntu/run_in_chroot.sh
@@ -0,0 +1,7 @@
+#!/bin/sh
+# Copyright 2016 Google Inc. All Rights Reserved.
+# Author: cheesy@google.com (Steve Hill)
+#
+# Run a single command in a chroot via schroot.
+
+exec schroot -c "$CHROOT_NAME" -- "$@"
diff --git a/install/ubuntu/setup_chroot.sh b/install/ubuntu/setup_chroot.sh
new file mode 100644
index 000000000..b06a98154
--- /dev/null
+++ b/install/ubuntu/setup_chroot.sh
@@ -0,0 +1,82 @@
+#!/bin/bash
+# Copyright 2016 Google Inc. All Rights Reserved.
+# Author: cheesy@google.com (Steve Hill)
+#
+# Setup a 32-bit chroot for Ubuntu.
+
+install_dir="$(dirname "${BASH_SOURCE[0]}")/.."
+
+chroot_dir="/var/chroot/$CHROOT_NAME"
+
+if [ -d "$chroot_dir" ]; then
+  "$install_dir/run_in_chroot.sh" /bin/true >/dev/null 2>&1
+  if [ $? -eq 0 ]; then
+    echo chroot already setup, nothing to do.
+    exit 0
+  else
+    echo "$chroot_dir exists but doesn't seem to be setup correctly." >&2
+    echo "You're going to have to clean up manually." >&2
+    exit 1
+  fi
+fi
+
+if [ "$UID" -ne 0 ]; then
+  echo This script needs to run as root. Re-execing via sudo.
+  exec sudo $0 "$@"
+  exit 1  # NOTREACHED
+fi
+
+apt-get -y update
+# We have to install ssl-cert in the host because /etc/group is copied
+# into the chroot.
+apt-get -y install debootstrap dchroot ssl-cert
+
+distro_name="$(lsb_release -cs)"
+
+# Create the initial chroot.
+debootstrap --variant=buildd --arch i386 \
+  "$distro_name" "$chroot_dir" http://archive.ubuntu.com/ubuntu/
+
+# Stop daemons from starting in the chroot. Do this before updating any pkgs!
+# https://major.io/2016/05/05/preventing-ubuntu-16-04-starting-daemons-package-installed/
+cat > "$chroot_dir/usr/sbin/policy-rc.d" << EOF
+#!/bin/sh
+# Prevent all daemons from starting.
+# Created by $(basename $0) for mod_pagespeed.
+exit 101
+EOF
+chmod +x "$chroot_dir/usr/sbin/policy-rc.d"
+
+# Configure schroot
+
+cat >> /etc/schroot/schroot.conf << EOF
+[$CHROOT_NAME]
+description=Ubuntu $distro_name for i386
+directory=$chroot_dir
+type=directory
+personality=linux32
+preserve-environment=true
+root-groups=sudo
+groups=sudo
+EOF
+
+cat >> /etc/schroot/default/fstab << EOF
+# Don't add /dev/shm, weird things will happen. See:
+# https://bugs.launchpad.net/ubuntu/+source/schroot/+bug/1438942/comments/5
+none   /run/shm   tmpfs   rw,nosuid,nodev,noexec 0 0
+EOF
+
+cat >> /etc/schroot/default/copyfiles << EOF
+/etc/apt/sources.list
+EOF
+
+# schroot is now functional, so we can use run_in_chroot.sh to complete setup
+# of the chroot.
+
+"$install_dir/run_in_chroot.sh" apt-get -y update
+"$install_dir/run_in_chroot.sh" apt-get -y upgrade
+"$install_dir/run_in_chroot.sh" apt-get -y install locales sudo lsb-release
+"$install_dir/run_in_chroot.sh" locale-gen en_US.UTF-8
+
+# This must be done after we install sudo or dpkg gets cranky.
+echo /etc/sudoers >> /etc/schroot/default/copyfiles