#!/usr/bin/env bash

# This scripts present a friendly interface to the fiu remote control
# capabilities. Currently, it supports only the named pipe method (the only
# one implemented).

# default remote control over named pipes prefix; we use the same one as
# fiu-run so it's easier to use
FIFO_PREFIX="${TMPDIR:-/tmp}/fiu-ctrl"

# commands to send, will be filled by options processing; must be in the
# format supported by the fiu remote control (see fiu-rc.c for more details)
declare -a CMDS


HELP_MSG="
Usage: fiu-ctrl [options] PID [PID ...]

The following options are supported:

  -c command	Run the given libfiu remote control command before executing
		the program (see below for reference).
  -f ctrlpath	Enable remote control over named pipes with the given path as
		base name, the process id will be appended (defaults to
		\"$FIFO_PREFIX\", set to \"\" to disable).

Remote control commands are of the form 'command param1=value1,param2=value2'.
Valid commands are:

 - 'enable name=NAME'
     Enables the NAME failure point unconditionally.
 - 'enable_random name=NAME,probability=P'
     Enables the NAME failure point with a probability of P.
 - 'disable name=NAME'
     Disables the NAME failure point.

All of the enable\* can also optionally take 'failnum' and 'failinfo'
parameters, analogous to the ones taken by the C functions.

The following options existed in the past but are deprecated and WILL BE
REMOVED in future releases: -e, -p, -u, -i, and -d.


Examples:

  fiu-ctrl -c 'enable_random name=posix/io/*,probability=0.25' \\
           -c 'enable_random name=libc/mm/*,probability=0.05' 12345

Tell the process with pid 12345 to enable the failure point 'posix/io/read'
with a 25% of probability to fail, and the failure point 'libc/mm/malloc' with
a 5% of probability to fail.

  fiu-ctrl -c 'disable name=posix/io/read' 12345

Tell the same process to disable the previously enabled failure point.

You can control multiple processes at once by specifiying more than one
process ID.
"


#
# Parse the options
#

if [ $# -lt 1 ]; then
	echo "$HELP_MSG"
	exit 1
fi

function opts_reset() {
	# variables to store what we know so far; after a new name is found
	# the old one is added to $CMD
	DEP_NAME=""
	DEP_PROB=-1
	DEP_FAILNUM=1
	DEP_FAILINFO=0
}

function add_deprecated_enable() {
	if [ "$DEP_NAME" == "" ]; then
		return
	fi;

	PARAMS="name=$DEP_NAME,failnum=$DEP_FAILNUM,failinfo=$DEP_FAILINFO"
	if [ "$DEP_PROB" -ge 0 ]; then
		C="enable_random $PARAMS,probability=0.$DEP_PROB"
	else
		C="enable $PARAMS"
	fi

	CMDS[${#CMDS[*]}]="$C"
}

function deprecated_warning() {
	echo "Warning: this option is deprecated and will be removed." >&2
}

opts_reset;
while getopts "+c:e:p:u:i:d:f:h" opt; do
	case $opt in
	c)
		CMDS[${#CMDS[*]}]="$OPTARG"
		;;
	e)
		# add the current one, if any
		deprecated_warning;
		add_deprecated_enable;
		opts_reset;
		DEP_NAME="$OPTARG"
		;;
	p)
		deprecated_warning;
		DEP_PROB="$OPTARG"
		;;
	u)
		deprecated_warning;
		DEP_FAILNUM="$OPTARG"
		;;
	i)
		deprecated_warning;
		DEP_FAILINFO="$OPTARG"
		;;
	f)
		FIFO_PREFIX="$OPTARG"
		;;
	d)
		deprecated_warning;
		CMDS[${#CMDS[*]}]="disable name=$OPTARG"
		opts_reset;
		;;
	h|*)
		echo "$HELP_MSG"
		exit 1
		;;
	esac;
done

# add leftovers
if [ "$DEP_NAME" != "" ]; then
	add_deprecated_enable;
fi

# eat the parameters we already processed
shift $(( $OPTIND - 1 ))

PIDS=""
PREFIXES=""

for i in "$@"; do
	if test -p "$i.out"; then
		PREFIXES="$PREFIXES $i"
	elif kill -0 $i > /dev/null 2> /dev/null && \
			test -p	"$FIFO_PREFIX-$i.out"; then
		PIDS="$PIDS $i"
	else
		echo "Error: unknown pid or named pipe $i, skipping"
		echo "Note that options must come before the PID"
	fi
done

#
# Send the commands
#

function send_cmd_fifo() {
	# $1 = complete fifo prefix
	# $2+ = command to send
	# echoes the reply
	P=$1
	shift 1
	echo "$@" > $P.in
	REPLY=$(cat "$P.out")
	if [ "$REPLY" == "-1" ]; then
		echo "$P: Command '$@' returned error ($REPLY)"
	fi
	#echo "$P: $@ -> $REPLY"
}

for c in "${CMDS[@]}"; do
	for i in $PIDS; do
		send_cmd_fifo $FIFO_PREFIX-$i "$c"
	done
	for i in $PREFIXES; do
		send_cmd_fifo $i "$c"
	done
done