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#!/usr/bin/env bash
#
# @license Apache-2.0
#
# Copyright (c) 2017 The Stdlib Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Verify the checksum of one or more files.
#
# Usage: checksum <filepath> <hash> <filepath> <hash> ...
#
# Arguments:
#
# filepath File to verify.
# hash Expected checksum.
#
# shellcheck disable=SC2181
# VARIABLES #
# Checksum type:
checksum_type='sha256'
# Program used to compute a checksum:
checksum_program=
# Command to compute a checksum:
cmd=
# FUNCTIONS #
# Prints usage information.
usage() {
echo '' >&2
echo 'Usage: checksum <filepath> <hash> <filepath> <hash> ...' >&2
echo '' >&2
}
# Defines an error handler.
#
# $1 - error status
on_error() {
echo 'ERROR: An error was encountered during execution.' >&2
cleanup
exit "$1"
}
# Runs clean-up tasks.
cleanup() {
echo '' >&2
}
# Prints a success message.
print_success() {
echo 'Success.' >&2
}
# Prints a checksum.
#
# $1 - checksum
print_checksum() {
local num_lines
local width
local lines
local str
local len
local pos
width=64 # characters
len="${#1}"
if [[ "${len}" -gt "${width}" ]]; then
str="$1"
num_lines=$((len / width)) # floored
lines=$(seq 0 1 "${num_lines}") # total_lines = num_lines + 1
for i in ${lines}; do
pos=$((i * width))
echo " ${str:${pos}:${width}}"
done
else
echo " $1" >&2
fi
}
# Prints a checksum error.
#
# $1 - file
# $2 - checksum type
# $3 - checksum program
# $4 - expected checksum
# $5 - actual checksum
print_checksum_error() {
echo '' >&2
echo "ERROR: $2 checksum failure for $1. Expected:" >&2
echo '' >&2
print_checksum "$4"
echo '' >&2
echo "But \`$3\` results in:" >&2
echo '' >&2
print_checksum "$5"
echo '' >&2
echo "This may be due to bad downloads or network proxies. Check your network proxy/" >&2
echo "firewall settings and try downloading and verifying again." >&2
echo '' >&2
}
# Verifies a checksum.
#
# $1 - file
# $2 - expected checksum
verify() {
local curr_checksum
curr_checksum=$(eval "${cmd} $1 | awk '{ print \$1; }'")
if [[ "${curr_checksum}" != "$2" ]]; then
print_checksum_error "$1" "${checksum_type}" "${checksum_program}" "$2" "${curr_checksum}"
return 1
fi
return 0
}
# Main execution sequence.
main() {
local args
local len
args=("$@")
len="${#args[@]}"
for (( i=0; i<${len}; i+=2 )) ; do
verify "${args[i]}" "${args[i+1]}"
if [[ "$?" -ne 0 ]]; then
on_error 1
fi
done
print_success
cleanup
exit 0
}
# MAIN #
# Handle arguments...
if [[ "$#" -eq 0 ]]; then
usage
exit 0
elif [[ $(($#%2)) -eq 1 ]]; then
echo 'ERROR: invalid arguments. Each file to verify must be followed by an expected checksum.' >&2
exit 1
fi
# Find a program for computing a SHA256 checksum...
if [[ -n "$(command -v sha256sum)" ]]; then
checksum_program="sha256sum"
cmd='sha256sum'
elif [[ -n "$(command -v shasum)" ]]; then
checksum_program="shasum"
cmd='shasum -a 256'
fi
# Run main:
main "$@"
|
