Add a flag to control deb-srcs and only add host bins to the chroot if the distro matches.

build/install-chroot.sh

 #!/bin/bash -e
 
 # Copyright (c) 2010 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 installs Debian-derived distributions in a chroot environment.
 # It can for example be used to have an accurate 32bit build and test
 # environment when otherwise working on a 64bit machine.
 # N. B. it is unlikely that this script will ever work on anything other than a
 # Debian-derived system.
 
 usage() {
-  echo "usage: ${0##*/} [-m mirror] [-g group,...]"
+  echo "usage: ${0##*/} [-m mirror] [-g group,...] [-s] [-c]"
   echo "-g group,... groups that can use the chroot unauthenticated"
   echo "             Default: 'admin' and current user's group ('$(id -gn)')"
   echo "-m mirror    an alternate repository mirror for package downloads"
+  echo "-s           configure default deb-srcs"
+  echo "-c           always copy 64bit helper binaries to 32bit chroot"
   echo "-h           this help message"
 }
 
 process_opts() {
   local OPTNAME OPTIND OPTERR OPTARG
-  while getopts ":g:m:h" OPTNAME; do
+  while getopts ":g:m:sch" OPTNAME; do
     case "$OPTNAME" in
       g)
         [ -n "${OPTARG}" ] &&
           chroot_groups="${chroot_groups}${chroot_groups:+,}${OPTARG}"
         ;;
       m)
         if [ -n "${mirror}" ]; then
           echo "You can only specify exactly one mirror location"
           usage
           exit 1
         fi
         mirror="$OPTARG"
         ;;
+      s)
+        add_srcs="y"
+        ;;
+      c)
+        copy_64="y"
+        ;;
       h)
         usage
         exit 0
         ;;
       \:)
         echo "'-$OPTARG' needs an argument."
         usage
         exit 1
         ;;
       *)
@@ skipping 161 matching lines @@
 else
   p="\$1"; shift
   exec schroot -c ${target%bit} -p "\$p" -- "\$@"
 fi
 exit 1
 EOF
 sudo chown root:root /usr/local/bin/"${target%bit}"
 sudo chmod 755 /usr/local/bin/"${target%bit}"
 
 # Add the standard Ubuntu update repositories if requested.
-[ "${alt_repos}" = "y" -a -r "/var/lib/chroot/${target}/etc/apt/sources.list" ] &&
+[ "${alt_repos}" = "y" -a \
+  -r "/var/lib/chroot/${target}/etc/apt/sources.list" ] &&
 sudo sed -i '/^deb .* [^ -]\+ main$/p
              s/^\(deb .* [^ -]\+\) main/\1-security main/
              p
              t1
              d
              :1;s/-security main/-updates main/
              t
              d' "/var/lib/chroot/${target}/etc/apt/sources.list"
 
 # Add a few more repositories to the chroot
-[ -r "/var/lib/chroot/${target}/etc/apt/sources.list" ] &&
+[ "${add_srcs}" = "y" -a \
+  -r "/var/lib/chroot/${target}/etc/apt/sources.list" ] &&
 sudo sed -i 's/ main$/ main restricted universe multiverse/
              p
              t1
              d
           :1;s/^deb/deb-src/
              t
              d' "/var/lib/chroot/${target}/etc/apt/sources.list"
 
 # Update packages
 sudo schroot -c "${target%bit}" -p -- /bin/sh -c '
@@ skipping 16 matching lines @@
 sudo schroot -c "${target%bit}" -p -- /bin/sh -c '
   egrep '"'^$(id -nu) '"' /etc/sudoers >/dev/null 2>&1 ||
   echo '"'$(id -nu) ALL=(ALL) ALL'"' >>/etc/sudoers'
 
 # Install a few more commonly used packages
 sudo schroot -c "${target%bit}" -p -- apt-get -y install                       \
   autoconf automake1.9 dpkg-dev g++-multilib gcc-multilib gdb less libtool     \
   strace
 
 # If running a 32bit environment on a 64bit machine, install a few binaries
-# as 64bit.
-if [ "${arch}" = 32bit ] && file /bin/bash 2>/dev/null | grep -q x86-64; then
+# as 64bit. This is only done automatically if the chroot distro is the same as
+# the host, otherwise there might be incompatibilities in build settings or
+# runtime dependencies. The user can force it with the '-c' flag.
+host_distro=$(grep DISTRIB_CODENAME /etc/lsb-release 2>/dev/null | \
+  cut -d "=" -f 2)
+if [ "${copy_64}" = "y" -o \
+    "${host_distro}" = "${distname}" -a "${arch}" = 32bit ] && \
+    file /bin/bash 2>/dev/null | grep -q x86-64; then
   readlinepkg=$(sudo schroot -c "${target%bit}" -p -- sh -c \
     'apt-cache search "lib64readline.\$" | sort | tail -n 1 | cut -d " " -f 1')
   sudo schroot -c "${target%bit}" -p -- apt-get -y install                     \
     lib64expat1 lib64ncurses5 ${readlinepkg} lib64z1
   dep=
   for i in binutils gdb strace; do
     [ -d /usr/share/doc/"$i" ] || dep="$dep $i"
   done
   [ -n "$dep" ] && sudo apt-get -y install $dep
   sudo cp /usr/bin/gdb "/var/lib/chroot/${target}/usr/local/bin/"
@@ skipping 22 matching lines @@
 
 Successfully installed ${distname} ${arch}
 
 You can run programs inside of the chroot by invoking the "${target%bit}"
 command.
 
 Your home directory is shared between the host and the chroot. But I configured
 $HOME/chroot to be private to the chroot environment. You can use it
 for files that need to differ between environments.
 EOF