#!/bin/sh -u
# Validate a single command line argument (file or directory).
#------------------------------------------------------------
# Syntax:
#    $0 pathname
#------------------------------------------------------------
# Purpose:
#    If the pathname is a file, make sure it is readable, writable,
#    and non-zero size.
#    If the pathname is a directory, make sure it is readable and
#    searchable.
#    Otherwise, print an error message and exit non-zero.
#-------------------------------------------------------------
# -IAN! idallen@idallen.ca

# Use standard search path, friendly umask, ASCII collating and sorting.
# Set the language and character set to be ASCII/C standard.
#
PATH=/bin:/usr/bin ; export PATH
LC_COLLATE=C ; export LC_COLLATE
LANG=C ; export LANG
umask 022

# Make sure we have exactly one argument.
# If not, echo the count and incorrect input back to the user on stderr.
#
if [ $# -ne 1 ] ; then
    echo 1>&2 "$0: Expecting 1 pathname argument, found $# ($*)"
    exit 1
fi

# Optional: Echo the user's input argument back to the user before using it.
#
echo "Your pathname is: $1"

# Check for file or directory; do appropriate tests for each.
#
if [ -f "$1" ] ; then
    if [ ! -r "$1" ] ; then
        echo 1>&2 "$0: file '$1' is not readable."
        exit 1
    fi
    if [ ! -w "$1" ] ; then
        echo 1>&2 "$0: file '$1' is not writable."
        exit 1
    fi
    if [ ! -s "$1" ] ; then
        echo 1>&2 "$0: file '$1' is empty."
        exit 1
    fi
elif [ -d "$1" ] ; then
    if [ ! -r "$1" ] ; then
        echo 1>&2 "$0: directory '$1' is not readable."
        exit 1
    fi
    if [ ! -x "$1" ] ; then
        echo 1>&2 "$0: directory '$1' is not searchable."
        exit 1
    fi
else
    # If we get here, it is not a plain file or a directory.
    # (It might be a special file such as /dev/null or /dev/zero)
    #
    echo 1>&2 "$0: argument '$1' is not a plain file or a directory."
    exit 1
fi

# If we get here, it must have passed all the tests.
# Optional: Print a confirmation message. (not required)
#
echo "All tests passed."

exit 0