Initial commit
This commit is contained in:
gutmet
commit
a2f357eb33
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LaymansHex: A layman's hex editor.
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Copyright (C) 2020 Alexander Weinhold
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Unless explicitly stated otherwise, the following applies:
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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 version 2 as published by
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the Free Software Foundation.
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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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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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LaymansHex
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==========
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LaymansHex takes a (partial) file description and allows tinkering with
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the values in a binary file. It thus serves as a sort of layman's
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hex editor.
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File description format
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-----------------------
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In EBNF:
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```
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description =
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{ comment }
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endianness
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definition
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{ definition }
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.
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comment = '#' { LETTER | DIGIT } '\n'.
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endianness = ("little endian" | "big endian") '\n'.
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definition = name ':' type '\n'.
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name = { LETTER | DIGIT }.
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type = ( "byte[" INTEGER "]" )
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| int8 | int16 | int32 | int64
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| uint8 | uint16 | uint32 | uint64
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| float32 | float64
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```
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The name of a definition line can be left empty to ignore that particular value.
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Portions of the binary file not covered be the file description are ignored.
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Usage
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-----
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To get values: laymanshex FORMATFILE BINARY
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To set values: laymanshex -set "key123=value123" FORMATFILE BINARY
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TODO
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----
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There is no way to express offset values inside a file yet. Since this is
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relatively common, I will add it at some point.
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@ -0,0 +1,380 @@
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package main
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import (
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"bufio"
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"encoding/binary"
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"encoding/hex"
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"errors"
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"flag"
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"fmt"
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"io"
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"os"
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"strconv"
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"strings"
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"time"
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)
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func optPanic(msg string, err error) {
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if err != nil {
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panic(errors.New(msg + ": " + err.Error()))
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}
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}
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type handling struct {
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bytes int64
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readFrom func(io.Reader, binary.ByteOrder) string
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writeTo func(io.Writer, binary.ByteOrder, string)
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}
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func binaryRead(r io.Reader, order binary.ByteOrder, pointerTo interface{}) {
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err := binary.Read(r, order, pointerTo)
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optPanic(fmt.Sprintf("binary conversion failed (%T)", pointerTo), err)
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}
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func binaryWrite(w io.Writer, order binary.ByteOrder, pointerTo interface{}) {
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err := binary.Write(w, order, pointerTo)
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optPanic(fmt.Sprintf("binary write failed (%T)", pointerTo), err)
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}
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var handlings = map[string]handling{
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"int8": handling{1,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i int8
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binaryRead(r, bo, &i)
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return strconv.FormatInt(int64(i), 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseInt(s, 10, 8)
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optPanic("conversion of "+s+"to int8 failed", err)
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binaryWrite(w, bo, int8(i))
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}},
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"uint8": handling{1,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i uint8
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binaryRead(r, bo, &i)
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return strconv.FormatUint(uint64(i), 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseUint(s, 10, 8)
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optPanic("conversion of "+s+"to uint8 failed", err)
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binaryWrite(w, bo, uint8(i))
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}},
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"int16": handling{2,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i int16
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binaryRead(r, bo, &i)
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return strconv.FormatInt(int64(i), 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseInt(s, 10, 16)
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optPanic("conversion of "+s+"to int16 failed", err)
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binaryWrite(w, bo, int16(i))
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}},
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"uint16": handling{2,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i uint16
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binaryRead(r, bo, &i)
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return strconv.FormatUint(uint64(i), 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseUint(s, 10, 16)
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optPanic("conversion of "+s+"to uint16 failed", err)
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binaryWrite(w, bo, uint16(i))
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}},
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"int32": handling{4,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i int32
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binaryRead(r, bo, &i)
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return strconv.FormatInt(int64(i), 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseInt(s, 10, 32)
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optPanic("conversion of "+s+"to int32 failed", err)
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binaryWrite(w, bo, int32(i))
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}},
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"uint32": handling{4,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i uint32
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binaryRead(r, bo, &i)
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return strconv.FormatUint(uint64(i), 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseUint(s, 10, 32)
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optPanic("conversion of "+s+"to uint32 failed", err)
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binaryWrite(w, bo, uint32(i))
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}},
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"int64": handling{8,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i int64
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binaryRead(r, bo, &i)
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return strconv.FormatInt(i, 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseInt(s, 10, 64)
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optPanic("conversion of "+s+"to int64 failed", err)
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binaryWrite(w, bo, i)
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}},
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"uint64": handling{8,
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func(r io.Reader, bo binary.ByteOrder) string {
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var i uint64
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binaryRead(r, bo, &i)
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return strconv.FormatUint(i, 10)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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i, err := strconv.ParseUint(s, 10, 64)
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optPanic("conversion of "+s+"to uint64 failed", err)
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binaryWrite(w, bo, i)
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}},
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"float32": handling{4,
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func(r io.Reader, bo binary.ByteOrder) string {
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var f float32
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binaryRead(r, bo, &f)
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return strconv.FormatFloat(float64(f), 'f', -1, 64)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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f, err := strconv.ParseFloat(s, 32)
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optPanic("conversion of "+s+"to float32 failed", err)
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binaryWrite(w, bo, float32(f))
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}},
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"float64": handling{8,
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func(r io.Reader, bo binary.ByteOrder) string {
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var f float64
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binaryRead(r, bo, &f)
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return strconv.FormatFloat(f, 'f', -1, 64)
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},
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func(w io.Writer, bo binary.ByteOrder, s string) {
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f, err := strconv.ParseFloat(s, 64)
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optPanic("conversion of "+s+"to float64 failed", err)
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binaryWrite(w, bo, float64(f))
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}},
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}
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type filePart struct {
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name string
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parttype string
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handling handling
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}
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func (part *filePart) Line() string {
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return part.name + " : " + part.parttype
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}
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func (part *filePart) setHandling() {
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if strings.HasPrefix(part.parttype, "byte") {
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tmp := strings.TrimRight(strings.TrimLeft(part.parttype, "byte["), "]")
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bytes, err := strconv.ParseInt(tmp, 10, 64)
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optPanic(part.name, err)
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readFrom := func(r io.Reader, bo binary.ByteOrder) string {
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buf := make([]byte, bytes)
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var i int64
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for i = 0; i < bytes; i++ {
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binaryRead(r, bo, &buf[i])
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}
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return hex.EncodeToString(buf)
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}
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writeTo := func(w io.Writer, bo binary.ByteOrder, s string) {
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buf, err := hex.DecodeString(s)
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optPanic("invalid string of hex values: "+s, err)
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binaryWrite(w, bo, buf)
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}
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part.handling = handling{bytes, readFrom, writeTo}
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} else {
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if handling, ok := handlings[part.parttype]; !ok {
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panic(part.Line() + ": Don't know type")
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} else {
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part.handling = handling
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}
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}
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}
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type fileDescription struct {
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byteOrder binary.ByteOrder
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parts []filePart
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}
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func trim(s string) string {
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return strings.TrimSpace(s)
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}
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var debug bool
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func info(i string, s string) {
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if debug {
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fmt.Fprintln(os.Stderr, i, "-->", s)
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}
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}
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func readPart(line string) *filePart {
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part := &filePart{}
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splitline := strings.Split(line, ":")
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if len(splitline) != 2 {
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panic("invalid definition: " + line)
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}
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part.name = trim(splitline[0])
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part.parttype = trim(splitline[1])
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info("definition", part.Line())
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part.setHandling()
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return part
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}
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func readFileDescription(path string) fileDescription {
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errmsg := "read format file"
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descr := fileDescription{}
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f, err := os.Open(path)
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defer f.Close()
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optPanic("open format file", err)
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buf := bufio.NewReader(f)
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/*----------------------------------*/
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line, err := buf.ReadString('\n')
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optPanic(errmsg, err)
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line = trim(line)
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for strings.HasPrefix(line, "#") {
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info("comment", line)
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line, err = buf.ReadString('\n')
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optPanic(errmsg, err)
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line = trim(line)
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}
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/*----------------------------------*/
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line = trim(line)
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if line == "big endian" {
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descr.byteOrder = binary.BigEndian
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} else if line == "little endian" {
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descr.byteOrder = binary.LittleEndian
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} else {
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panic(errmsg + ": expected endianness ('little endian' or 'big endian'), got :" + line)
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}
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info("endianness", line)
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/*----------------------------------*/
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line, err = buf.ReadString('\n')
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optPanic(errmsg, err)
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line = trim(line)
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for err != io.EOF && line != "" {
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part := readPart(line)
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descr.parts = append(descr.parts, *part)
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line, err = buf.ReadString('\n')
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line = trim(line)
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}
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line = trim(line)
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if err == io.EOF && line != "" {
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descr.parts = append(descr.parts, *readPart(line))
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} else if err != io.EOF {
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optPanic(errmsg, err)
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}
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return descr
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}
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func readAssignments(descr fileDescription, s string) map[string]string {
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assignments := strings.Split(s, ",")
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m := make(map[string]string)
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for _, assignment := range assignments {
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kv := strings.Split(assignment, "=")
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if len(kv) != 2 {
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panic("weird parameters in set: " + assignment + "\nWant list of comma-separated key=value assignments")
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}
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key := trim(kv[0])
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value := trim(kv[1])
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found := false
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for _, part := range descr.parts {
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if key == part.name {
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found = true
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}
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}
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if found {
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m[key] = value
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} else {
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panic("unknown key: " + key)
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}
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}
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return m
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}
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func backup(binpath string) {
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bin, err := os.Open(binpath)
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defer bin.Close()
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optPanic("failed to open binary", err)
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timestamp := time.Now().Format("20060102150405")
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fi, err := bin.Stat()
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optPanic("failed to get permissions of binary", err)
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backuppath := binpath + ".bak" + timestamp
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backup, err := os.OpenFile(backuppath, os.O_RDWR|os.O_CREATE, fi.Mode())
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defer backup.Close()
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_, err = io.Copy(backup, bin)
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optPanic("failed to create backup", err)
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backup.Chmod(fi.Mode())
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fmt.Println("Created backup " + backuppath + "\n")
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}
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func setValues(descr fileDescription, binpath string, vals map[string]string) {
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backup(binpath)
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f, err := os.OpenFile(binpath, os.O_RDWR, 0666)
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optPanic("failed to write-open binary", err)
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defer f.Close()
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for _, part := range descr.parts {
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needSeek := true
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if part.name != "" {
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if val, ok := vals[part.name]; ok {
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part.handling.writeTo(f, descr.byteOrder, val)
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needSeek = false
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}
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}
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if needSeek {
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f.Seek(part.handling.bytes, 1)
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}
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}
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}
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func getValues(descr fileDescription, binpath string) map[string]string {
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vals := make(map[string]string)
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f, err := os.Open(binpath)
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defer f.Close()
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optPanic("failed to open binary", err)
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for _, part := range descr.parts {
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if part.name == "" {
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f.Seek(part.handling.bytes, 1)
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} else {
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vals[part.name] = part.handling.readFrom(f, descr.byteOrder)
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}
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}
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return vals
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}
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func padding(descr fileDescription) string {
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pad := 0
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for _, part := range descr.parts {
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if n := len(part.name); n > pad {
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pad = n
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}
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}
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return strconv.Itoa(pad)
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}
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func printValues(descr fileDescription, vals map[string]string) {
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for _, part := range descr.parts {
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if part.name != "" {
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fmt.Printf("%"+padding(descr)+"s = %s\n", part.name, vals[part.name])
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}
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}
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}
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func printUsage() {
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fmt.Fprintf(os.Stderr, "Usage: %s [Options] FORMATFILE BINARY\n", os.Args[0])
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flag.PrintDefaults()
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}
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func main() {
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var assignments string
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flag.StringVar(&assignments, "set", "", "key=value pairs (e.g. \"key1=value1,key2=value2\")")
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flag.BoolVar(&debug, "debug", false, "print recognized parts of the format file")
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flag.Parse()
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args := flag.Args()
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if len(args) != 2 {
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printUsage()
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os.Exit(-1)
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}
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descr := readFileDescription(args[0])
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if assignments != "" {
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setValues(descr, args[1], readAssignments(descr, assignments))
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}
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printValues(descr, getValues(descr, args[1]))
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}
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