enter.in

#!/bin/sh

#
# This script runs a shell inside chroot as a 'build' user.  If any arguments
# supplied, those are the command to be run, otherwise the interactive shell
# will be invoked.
#

CHROOT_PATH=$0
case "$0" in
    /*) CHROOT_PATH=$(dirname "$0");;
    *)  CHROOT_PATH=$(dirname $(pwd)/"$0");;
esac

HTTP_PROXY=@@HTTP_PROXY@@
FTP_PROXY=@@FTP_PROXY@@

# Quote argument for shell.
# Usage example: eval "$var_name=\"$(quote_shell "$var_value")\""
quote_shell() {
	local out="$*"
	if [ -z "${out##*[\"\$\`\\\\]*}" ]; then
		out="$(printf %s "$out" |sed -e 's/["$`\\]/\\&/g')" ||
			return 1
	fi
	printf %s "$out"
    #` # Hey, Emacs, your syntax highlighter is wrooong!
    #'` # You too, gedit!
}

quote_args() {
    for i in "$@"; do
        echo -n \"$(quote_shell "$i")\"
        echo -n " "
    done
    echo
}

# A space-separated list of mounted repositories
mounted_repos=

# Unmount all mounted repositories
unmount_repos() {
    
    for _mounted_repo in $mounted_repos; do
        # Unmount repository no matter what.    
        sudo umount "$_mounted_repo" 2> /dev/null || :
        # Remove the repo directory and any empty parent directories
        sudo rmdir -p "$_mounted_repo" 2> /dev/null || :
    done
    exit
}

# Mount a repository directory
mount_repo() {
    _chroot_path=$1
    _local_rep=$2
    
    # Strip any meaningless trailing dots and slashes from the chroot path
    _trimmed_chroot_path=$(echo "$_chroot_path" | sed 's|/\.\?$||')
    
    # If the local repo directory isn't already mounted
    if ! fgrep -q "$_trimmed_chroot_path$_local_rep" < /etc/mtab; then
        
        # Make a mount dir within chroot and mount the local repo dir to it
        sudo mkdir -p "$_trimmed_chroot_path$_local_rep"
        sudo mount --bind "$_local_rep" "$_trimmed_chroot_path$_local_rep"
        
        # Add local repo to list of mounted repos
        mounted_repos=`echo "$mounted_repos $_trimmed_chroot_path$_local_rep"`
        
        # Call unmount_repos to clean up the local repos when the script is 
        # exited or interrupted
        trap unmount_repos TERM INT EXIT
    fi
}

if [ "$#" -eq 0 ]; then
    # Interactive shell
    SU_CMD="-i -l"
else
    # Single command. Double quoting to pass through two su(1) invocations. Blergh.
    S=$(quote_args "$@")
    QS=$(quote_args "$S")
    SU_CMD="-c $QS"
fi

if [ -n "$HTTP_PROXY" ]; then
    ENV_EXPORT="http_proxy=$HTTP_PROXY; export http_proxy;"
fi
if [ -n "$FTP_PROXY" ]; then
    ENV_EXPORT="$ENV_EXPORT ftp_proxy=$FTP_PROXY; export ftp_proxy;"
fi

if [ -f /proc/cpuinfo ]; then
    NCPUS=$(grep -c '^processor' /proc/cpuinfo)
    ENV_EXPORT="$ENV_EXPORT DEB_BUILD_OPTIONS=parallel=$NCPUS"
fi

# Mount every local repository in the chroot's sources.list file that doesn't 
# exist in the chroot file system.

# All the local repositories mentioned in chroot's sources.list file
local_repos=$(egrep -o '(file:[^[:space:]]+)' < "$CHROOT_PATH/etc/apt/sources.list" | sed 's/file://')

for local_repo in $local_repos; do
    # If the directory doesn't exist in the chroot file system
    if [ ! -e "$CHROOT_PATH$local_repo" ]; then
        
        # If the directory does exist in the exterior file system
        if [ -d "$local_repo" ]; then
            
            # Make a mount dir and mount the exterior repository dir to it
            mount_repo "$CHROOT_PATH" "$local_repo"
        fi
    fi
done

sudo chroot "$CHROOT_PATH" su -l -c "$ENV_EXPORT exec \$SHELL $SU_CMD" build