#!/bin/bash
# A quick-hack drop-in replacement for "make" which recursively
# searches upwards in the dir hierarchy for a makefile, and runs the
# real "make" from the first such directory.
#
# The problem this solves is: it's common for me to work in emacs in
# source trees which don't have makefiles in every directory.  Tapping
# (ctrl-x m) to run make annoyingly (but rightfully) fails in such
# directories. By mapping this script to emacs's compile-command var,
# that problem disappears. i should have done this two decades ago :|.

# Reminder: we can't find the real make with "which make" because that
# might, depending on how this script is named, resolve to this
# script. Thus we unfortunately hard-code the make path here:
theMake=/usr/bin/make

# According to the GNU make docs, it looks for makefiles with these
# names in this order:
# https://www.gnu.org/software/make/manual/html_node/Makefile-Names.html
mfiles="GNUmakefile makefile Makefile"

# Returns 0 if any file in the list of $mfiles is found in the current
# directory, else returns non-0.
function cwdHasMakefile(){
    for f in $mfiles; do
        [[ -f "$f" ]] && return 0
    done
    return 1
}

prev= # previous directory
while true; do
    if [[ "x/" = "x$prev" ]]; then
        # Interestingly, "cd .." from / does not fail, so we
        # check for that case here.
        break
    fi
    if cwdHasMakefile; then
        exec "$theMake" "$@"
    fi
    prev=${PWD}
    # If cd fails for any reason, simply bail. This can happen
    # if, e.g., /home is not accessible on a shared hoster.
    cd .. >/dev/null || break
done
echo "$0: no makefile found." 1>&2
exit 127