174 lines
4.6 KiB
Plaintext
174 lines
4.6 KiB
Plaintext
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#!/bin/bash
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# Generates typedef from list of strings
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#
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# Copyright (C) 2018 R-T Specialty, LLC.
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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##
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# store unique names and values to detect collisions
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declare -A _unames=()
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declare -A _uvalues=()
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# Provide an error and abort if a name or value collision is found
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#
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# This function stores each name and value that it sees each time it is
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# invoked. If a duplicate is found, an error is output and the script
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# terminates.
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#
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# This is important because both values are transformed in a way that
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# the output space is a subset of the input. In the case of names,
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# characters are stripped and replaced; in the case of values, the range
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# of the hash function is determined by the number of bytes desired.
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#
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# Both will cause really bad bugs if left undetected.
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assert-collision()
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{
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local -r name="${1?Missing name (const)}"
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local -r value="${2?Missing value (hashed)}"
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test -z "${_unames[$name]}" || {
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echo "error: name collision: $name" >&2
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exit 1
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}
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test -z "${_uvalues[$value]}" || {
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echo "error: value collision: $name = $value" >&2
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exit 1
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}
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_unames["$name"]=1
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_uvalues["$value"]=1
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}
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# Generate typedef item from given string
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#
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# An item node will be output with the given string converted to a class
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# (see `constify'); a BYTES-byte decimal integer as the value (see
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# `hash-name'); and the original string as the description.
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output-item()
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{
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local -r typedef="${1?Missing typedef}"
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local -ri bytes="${2?Missing byte size}"
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local name; read -r name
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local -r const=$( constify "$typedef" <<< "$name" )
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local -r value=$( hash-name "$bytes" <<< "$name" )
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assert-collision "$const" "$value"
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printf ' <item name="%s" value="%s" desc="%s" />\n' \
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"$const" \
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"$value" \
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"$name"
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}
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# Convert a string into a constant
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#
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# The returned format will be "TYPE_NAME", where "TYPE" is the typedef
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# converted into uppercase and "NAME" is the string converted into
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# uppercase with all consecutive non-alphanumeric characters converted
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# into an underscore.
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constify()
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{
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local -r typedef="${1?Missing typedef}"
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local name; read -r name
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echo -n "${typedef^^}_"
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sed 's/[^a-zA-Z0-9 ]\+//g;
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s/ \+/_/g' <<< "${name^^}"
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}
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# Produce a decimal integer by taking the high BYTES bytes of the SHA256
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# hash of stdin
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#
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# Since the output of sha256sum is hexidecimal, two digits represent a
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# single byte. For example, let BYTES=4: taking the first 8 digits
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# gives us the high 4 bytes (32 bits). Another way to visualize this is
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# to convert a truncated hash to decimal.
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hash-name()
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{
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local -ri bytes="${1?Missing byte size}"
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local -ri digits=$(( bytes * 2 ))
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echo $(( 0x$( sha256sum | head -c"$digits" ) ))
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}
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# Usage information
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#
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# This function terminates the script with EX_USAGE.
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usage()
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{
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cat <<'EOF'
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Usage: $0 typename [bytes]
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Generate typedef of name TYPENAME using hashed standard input values
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Each input line will produce a single typedef item. Each item has a
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decimal value of the high BYTES of its SHA256 hash. If BYTES is not
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provided, it defaults to 4 (32 bits).
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Empty lines and lines beginning with a `#' are ignored.
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This script checks for collisions of both names and values. If a
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hash collision is found, the number of bytes BYTES must be
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increased or the input string changed. Collisions will immediate
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abort the script with a non-zero exit status.
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EOF
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return 64 # EX_USAGE
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}
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# Output typedef with hashed values
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main()
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{
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local -r typedef="${1?Missing typedef}"
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local -ri bytes="${2:-4}"
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test "$bytes" -gt 0 || {
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echo 'error: byte count must be greater than 0' >&2
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usage
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}
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cat <<EOF
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<?xml version="1.0"?>
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<package xmlns="http://www.lovullo.com/rater"
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title="$typedef Type">
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<typedef name="$typedef" desc="$typedef">
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<enum type="integer">
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EOF
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while read line; do
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# ignore empty and comment lines
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[[ "$line" && ! "$line" =~ ^\# ]] || continue
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output-item "$typedef" "$bytes" <<< "$line"
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done
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echo ' </enum>'
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echo ' </typedef>'
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echo '</package>'
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}
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test $# -gt 0 || usage || exit
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main "$@"
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