makelog.sh

makelog.sh

#!/bin/bash

# usage: ./makelog.sh -m make.log /usr/bin/make all

startdate=$(date +"%F %T.%3N%z")

makemode=
servermode=
target=
prereqs=()

while [ $# != 0 ]; do
case $1 in
'--')
  shift
  break
  ;;
'-s')
  servermode=x
  shift
  ;;
'-m')
  makemode=x
  export MAKELOG=${2:?}
  shift 2
  ;;
'-t')
  target=${2:?}
  shift 2
  ;;
'-p')
  prereqs+=("${2:?}")
  shift 2
  ;;
'-c')
  break
  ;;
-*)
  >&2 echo "unknown option $1"
  exit 1
  ;;
*)
  break
  ;;
esac
done

if [ "$servermode" ]; then
  exec 2>&4
  trap '' HUP                # although we are detached, parent bash may still HUP us
  cat >"${MAKELOG:?}"        # wait pipe EOF
  >&2 printf '\nfinished\n'
  exit 0
fi

if [ "$makemode" ]; then
  set -e

  THISDIR=$(cd -- "$(dirname -- "$MAKELOG")" && pwd)
  THISFILE=${MAKELOG##*/}
  export MAKELOG_LOCK="$THISDIR/$THISFILE.lck"

  THISDIR=$(cd -- "$(dirname -- "$0")" && pwd)
  THISFILE=${0##*/}

  exec 4>&2

  # create pipe handle to share across all processes
  coproc (
      read s # to avoid race condition do not die until we disown/do stuff with $COPROC
      # detach from tty
      setsid "$THISDIR/$THISFILE" -s <&0 # create grandchild and die
  )

  disown

  export MAKELOG_FD=${COPROC[1]}

  # clear FD_CLOEXEC for write side of the pipe and unblock the child
  eval "exec ${COPROC[0]}>&-; exec ${COPROC[0]}>&1 1>&${COPROC[1]} ${COPROC[1]}>&-; exec ${COPROC[1]}>&1 1>&${COPROC[0]} ${COPROC[0]}>&-; echo >&${COPROC[1]}"

  export MAKELOG_STOP_AT_PID=$$
  exec -- "$@" SHELL="$THISDIR/$THISFILE"' $(@:%=-t %) $(^:%=-p %) --'
fi

fn_now() {
  # linux,cygwin,msys
  read ms x </proc/uptime
  ms=${ms/./}0
}

fn_now
old_ms=$ms

# output consists of name:value pairs and lists
# the colon is chosen to not interfere with the equal sign in environ
# each token is separated by nul character
# values may contain newlines
# lists with unknown number of elements end with a name:value pair with an empty name
# a whole record also ends with a name:value pair with an empty name, but the value contains double newline for cosmetic purpose

LF='
'


pid=$$

  ${MAKELOG_SHELL:-/bin/sh} "$@"
  ret=$?

  set -e

  exec 41>>"${MAKELOG_LOCK:?}"
  flock 41

  exec 1>&"${MAKELOG_FD:?}"

  printf 'date:%s\0' "$startdate"

  printf 'target:%s\0' "$target"

  # nprereqs followed by n prereqs delimited by nul
  printf 'nprereqs:%s\0' ${#prereqs[@]}
  if [ ${#prereqs[@]} != 0 ]; then
    printf '%s\0' "${prereqs[@]}"
  fi

  printf 'cwd:%s\0' "$PWD"

  # TODO: currently, args are always: -c "cmd1 && cmd2 && cmd3 && ..."
  # nargs followed by n args delimited by nul
  printf 'nargs:%s\0' $#
  if [ $# != 0 ]; then
    printf '%s\0' "$@"
  fi

  # process hierarchy list with unknown number of elements; terminated with just a colon
  savepid=$pid
  printf 'pidstack:\0'
  # in /proc/self/status command can contain spaces, but newlines are escaped
  while true; do
    name=
    ppid=

    shouldbreak=": : break"
    while read -r key val; do
    case $key in
    'Name:')
      name=$val
      ;;
    'PPid:')
      ppid=$val
      ;;
    *) continue;;
    esac
    shouldbreak=${shouldbreak:2}
    $shouldbreak
    done </proc/${pid:?}/status

    printf '%s:%s\0' "${pid}" "$name"

    [ 0 != "$ppid" -a x"$MAKELOG_STOP_AT_PID" != "x$pid" ] || break

    pid=$ppid
  done
  printf ':\0'
  pid=$savepid

  printf 'environ:\0'
  # env var list with unknown number of elements; terminated with just a colon
  cat /proc/${pid:?}/environ
  printf ':\0'

fn_now
ms=$((ms - old_ms))

printf 'millis:%s\0' $ms
printf 'ret:%s\0' $ret

printf ':\n\n\0'

exit $ret