Add a helper script to be able to run "apt-get install" without running

the maintainer scripts on installed packages.

I've experimented with using this in the install_packages.sh that
runs from outside the targetfs. It is able to extract packages and
make them appear to be installed (for the most part) without
running the maintainer scripts.

This will allow us to start figuring out what problems we will
have when we no longer run the maintainer scripts.

In the long run it would be nice to add an option to "dpkg" to
skip maintainer scripts.

Review URL: http://codereview.chromium.org/517004

dpkg_no_scripts.sh

@@ -0,0 +1,83 @@
+#!/bin/bash
+
+# Copyright (c) 2009 The Chromium OS 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 can be used to replace the "dpkg" binary as far as the
+# "apt-get install" command is concerned. When "apt-get install foo"
+# runs it will make two calls to dpkg like:
+#   dpkg --status-fd ## --unpack --auto-deconfigure /path/to/foo.deb
+#   dpkg --status-fd ## --configure foo
+# This script will extract the .deb file and make it appear to be installed
+# successfully. It will skip the maintainer scripts and configure steps.
+#
+# As a one-off test, you can run like:
+#  apt-get -o="Dir::Bin::dpkg=/path/to/this" install foo
+
+# Load common constants.  This should be the first executable line.
+# The path to common.sh should be relative to your script's location.
+. "$(dirname "$0")/common.sh"
+
+# Flags
+DEFINE_string root "" \
+  "The target rootfs directory in which to install packages."
+DEFINE_string status_fd "" \
+  "The file descriptor to report status on; ignored."
+DEFINE_boolean unpack $FLAGS_FALSE "Is the action 'unpack'?"
+DEFINE_boolean configure $FLAGS_FALSE "Is the action 'configure'?"
+DEFINE_boolean auto_deconfigure $FLAGS_FALSE "Ignored"
+
+# Fix up the command line and parse with shflags.
+FIXED_FLAGS="$@"
+FIXED_FLAGS=${FIXED_FLAGS/status-fd/status_fd}
+FIXED_FLAGS=${FIXED_FLAGS/auto-deconfigure/auto_deconfigure}
+FLAGS $FIXED_FLAGS || exit 1
+eval set -- "${FLAGS_ARGV}"
+
+# Die on any errors.
+set -e
+
+if [ $FLAGS_configure -eq $FLAGS_TRUE ]; then
+  # We ignore configure requests.
+  exit 0
+fi
+if [ $FLAGS_unpack -ne $FLAGS_TRUE ]; then
+  # Ignore unknown command line.
+  echo "Unexpected command line: $@"
+  exit 0
+fi
+if [ -z "$FLAGS_root" ]; then
+  echo "Missing root directory."
+  exit 0
+fi
+
+DPKG_STATUS=""
+if [ -d "$FLAGS_root/var/lib/dpkg" ]; then
+  DPKG_STATUS="$FLAGS_root/var/lib/dpkg/status"
+  DPKG_INFO="$FLAGS_root/var/lib/dpkg/info/"
+fi
+
+for p in "$@"; do
+  echo "Extracting $p"
+  dpkg-deb --extract "$p" "$FLAGS_root"
+
+  if [ -n "$DPKG_STATUS" ]; then
+    TMPDIR=$(mktemp -d)
+    dpkg-deb --control "$p" "$TMPDIR"
+
+    # Copy the info files
+    PACKAGE=$(dpkg-deb --field "$p" Package)
+    FILES=$(ls "$TMPDIR" | grep -v control)
+    for f in $FILES; do
+      cp "${TMPDIR}/$f" "${DPKG_INFO}/$PACKAGE.$f"
+    done
+
+    # Mark the package as installed successfully.
+    echo "Status: install ok installed" >> "$DPKG_STATUS"
+    cat "${TMPDIR}/control" >> "$DPKG_STATUS"
+    echo "" >> "$DPKG_STATUS"
+
+    rm -rf "$TMPDIR"
+  fi
+done