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#!/usr/bin/env bash

# This script aims to make the use of the fiu_run_preload library a little
# easier by providing a more friendly user interface, and abstracting the
# environment variables used to communicate with it.

# default remote control over named pipes prefix
FIFO_PREFIX="${TMPDIR:-/tmp}/fiu-ctrl"

# default library path to look for preloader libraries
PLIBPATH="@@PLIBPATH@@"

# the enable string to pass to the preload library (via the FIU_ENABLE
# environment variable)
ENABLE=""

# additional preloader libraries to use
PRELOAD_LIBS=""

# use the POSIX preload library?
USE_POSIX_PRELOAD=0

# don't run, but show the command line instead
DRY_RUN=0

HELP_MSG="
Usage: fiu-run [options] program [arguments]

The following options are supported:

  -x		Use POSIX libfiu preload library, allows simulate failures in
		the POSIX and C standard library functions.
  -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).
  -l path	Path where to find the libfiu preload libraries, defaults to
		$PLIBPATH (which is usually correct).

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.

All of them 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 and -i.


Example:

  fiu-run -x -c 'enable_random name=posix/io/*,probability=0.25' \\
             -c 'enable_random name=libc/mm/*,probability=0.05' ls -l

Run \"ls -l\" enabling all failure points that begin with 'posix/io/' with a
25% of probability to fail, and the failure point libc/mm/malloc with a 5% of
probability to fail.
"


#
# 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 $ENABLE
	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 $PARAMS,probability=$DEP_PROB"
	else
		C="enable $PARAMS"
	fi

	ENABLE="$ENABLE
		$C"
}

opts_reset;
while getopts "+c:f:l:xne:p:u:i:h" opt; do
	case $opt in
	c)
		# Note we use the newline as a command separator.
		ENABLE="$ENABLE
			$OPTARG"
		;;
	f)
		FIFO_PREFIX="$OPTARG"
		;;
	l)
		PLIBPATH="$OPTARG"
		;;
	x)
		USE_POSIX_PRELOAD=1
		;;
	n)
		DRY_RUN=1
		;;

	# Deprecated options
	e)
		add_deprecated_enable
		opts_reset
		DEP_NAME="$OPTARG"
		;;
	p)
		DEP_PROB="$OPTARG"
		;;
	u)
		DEP_FAILNUM="$OPTARG"
		;;
	i)
		DEP_FAILINFO="$OPTARG"
		;;

	h|*)
		echo "$HELP_MSG"
		exit 1
		;;
	esac;
done

# add leftovers
add_deprecated_enable
opts_reset;

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

# Allow user to give -l and -x in any order.
if [ $USE_POSIX_PRELOAD -eq 1 ] ; then
	PRELOAD_LIBS="$PRELOAD_LIBS $PLIBPATH/fiu_posix_preload.so"
fi

#
# Run the application
#

export FIU_ENABLE="$ENABLE"
export FIU_CTRL_FIFO="$FIFO_PREFIX"
export LD_PRELOAD="$PLIBPATH/fiu_run_preload.so $PRELOAD_LIBS"

if [ $DRY_RUN -eq 1 ] ; then
	echo "FIU_ENABLE=\"$ENABLE\"" \\
	echo "FIU_CTRL_FIFO=\"$FIFO_PREFIX\"" \\
	echo "LD_PRELOAD=\"$PLIBPATH/fiu_run_preload.so $PRELOAD_LIBS\"" \\
	echo "$@"
else
	exec "$@"
fi