bash_dirtrack

#! /bin/bash
# BASH directory tracking
# See bash_dirtrack.md for details.
#
# Assumptions:
# - $MACH is set to the equivalent of $(hostname -s)
# - BASH 4.x or later

# Check the current directory for signs it is an ACL binary directory.
# If it is, then set up the the ACL build environment in BASH.
function __do_acl_build_env_setup {
    # This gives an easy way to short circuit the source'ing of env.sh
    [ "${ENV_SH_DEBUG-}" ] && return 0
    if [ -f makefile.m -a -f env.sh -a -f ../makefile.top ]; then
	source env.sh
    fi
    return 0
}

# usage: __my_localize_path path
#  return a local version of PATH if it uses NFS to access a resource
#  on the same machine, as given by $MACH.
function __my_localize_path {
    # lockf(3) doesn't work on FreeBSD on an NFS-mounted filesystem, so
    # remove the /net/<host> so ACL tests work on FreeBSD, when on
    # the <host>.  This solution works quite nicely with directory tracking
    # in Emacs.  See also scm-bin/fiemacsclient for hacks to handle the
    # case where emacs and emacsclient are run on different machines.
    local dir="$1"
    local temp

    if [ ! -e "$dir" ]; then
	echo $dir does not exist 1>&2
	return 1
    fi

    # Do some transformations, so locatization can happen.
    # The first is layer-specific and the 2nd is company wide.
    # Remember that ~/l/.. symlinks can turn into /fi/.. paths.

    if [[ "$dir" =~ ^$HOME/l/ ]]; then
	if [[ $dir =~ ^(.*)/$ ]]; then
	    dir="${BASH_REMATCH[1]}"
	fi
	temp="$(readlink -f "$dir")"
	if [ ! "$temp" ]; then
	    echo expansion of $dir was null 1>&2
	    return 1
	elif [ ! -e "$temp" ]; then
	    echo expansion of $dir does not exist: $temp 1>&2
	    return 1
	fi
	dir="$temp"
    fi

    if [[ "$dir" =~ ^/fi/ ]]; then
	temp="$(builtin cd "$dir"; pwd -P)"
	if [[ $temp =~ ^([a-zA-z0-9]+):(/.*) ]]; then
	    # autofs 'nobind' screws us again!
	    dir="/net/${BASH_REMATCH[1]}${BASH_REMATCH[2]}"
	else
	    dir="$temp"
	fi
    fi

    if [[ "$dir" =~ ^/net/([^/]+)(/.*) ]]; then
	if [ "${BASH_REMATCH[1]}" = "$MACH" ]; then
	    dir="${BASH_REMATCH[2]}"
	    echo "[ using local path: $dir ]" 1>&2
	fi
    fi
    echo "$dir"
}

function cd {
    local dir
    local args

    if [ $# -eq 0 ]; then
	# accessing $HOME via NFS sucks!
	dir="$HOME"
	args=
    else
	# separate the directory from the options
	local n=$(( ${#@} - 1 ))
	args="${@:1:$n}"
	dir="${@: -1}"
	if [[ $dir =~ ^/scp:[^:]+:(.*) ]]; then
	    # strip off the prefix, which is solely
	    # for Emacs to track the directory properly.
	    dir="${BASH_REMATCH[1]}"
	fi
    fi

    if dir="$(__my_localize_path "$dir")"; then
	builtin cd $args "$dir" && __do_acl_build_env_setup
    fi
}

function pushd {
    if [ $# -eq 0 ]; then
	builtin pushd && __do_acl_build_env_setup
    elif [[ $1 =~ ^[-+] ]]; then
	builtin pushd $1 && __do_acl_build_env_setup
    else
	local n=$(( ${#@} - 1 ))
	local args="${@:1:$n}"
	local dir="${@: -1}"
	if [[ $dir =~ ^/scp:[^:]+:(.*) ]]; then
	    # strip off the prefix, which is solely
	    # for Emacs to track the directory properly.
	    dir="${BASH_REMATCH[1]}"
	fi
	if dir="$(__my_localize_path "$dir")"; then
	    builtin pushd $args "$dir" && __do_acl_build_env_setup
	fi
    fi
}

function popd {
    builtin popd "$@" && __do_acl_build_env_setup
}