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WIP: wasm compatible patcher?

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This commit is contained in:
Nico Verbruggen
2026-03-15 21:43:16 +01:00
parent d646a4b766
commit 76d7e943e3
9 changed files with 1069 additions and 27 deletions
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17
.gitignore vendored
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@@ -1,5 +1,14 @@
firmware
kobo_usb_root
kobopatch-src
kobopatch
# Local device data
kobo_usb_root/
firmware/
# Pre-built kobopatch tool (reference only)
kobopatch/
# Kobopatch WASM build artifacts
kobopatch-wasm/kobopatch-src/
kobopatch-wasm/kobopatch.wasm
kobopatch-wasm/wasm_exec.js
# Claude
.claude

17
kobopatch-wasm/build.sh Executable file
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@@ -0,0 +1,17 @@
#!/bin/bash
set -euo pipefail
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
if [ ! -d "$SCRIPT_DIR/kobopatch-src" ]; then
echo "Error: kobopatch source not found. Run ./setup.sh first."
exit 1
fi
echo "Building kobopatch WASM..."
cd "$SCRIPT_DIR"
GOOS=js GOARCH=wasm go build -o kobopatch.wasm .
echo "WASM binary size: $(du -h kobopatch.wasm | cut -f1)"
echo ""
echo "Output: $SCRIPT_DIR/kobopatch.wasm"

21
kobopatch-wasm/go.mod Normal file
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@@ -0,0 +1,21 @@
module github.com/nicoverbruggen/kobopatch-wasm
go 1.23.12
require (
github.com/pgaskin/kobopatch v0.0.0
gopkg.in/yaml.v3 v3.0.1
)
replace github.com/pgaskin/kobopatch => ./kobopatch-src
replace gopkg.in/yaml.v3 => github.com/pgaskin/yaml v0.0.0-20190717135119-db0123c0912e // v3-node-decodestrict
require (
github.com/ianlancetaylor/demangle v0.0.0-20250628045327-2d64ad6b7ec5 // indirect
github.com/pgaskin/go-libz v0.0.2 // indirect
github.com/riking/cssparse v0.0.0-20180325025645-c37ded0aac89 // indirect
github.com/tetratelabs/wazero v1.9.0 // indirect
golang.org/x/text v0.3.2 // indirect
rsc.io/arm v0.0.0-20150420010332-9c32f2193064 // indirect
)

23
kobopatch-wasm/go.sum Normal file
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@@ -0,0 +1,23 @@
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/ianlancetaylor/demangle v0.0.0-20250628045327-2d64ad6b7ec5 h1:QCtizt3VTaANvnsd8TtD/eonx7JLIVdEKW1//ZNPZ9A=
github.com/ianlancetaylor/demangle v0.0.0-20250628045327-2d64ad6b7ec5/go.mod h1:gx7rwoVhcfuVKG5uya9Hs3Sxj7EIvldVofAWIUtGouw=
github.com/pgaskin/go-libz v0.0.2 h1:uTzyOb6qXvzTdofzq9RNzhpHzHl3fT88yM6wxzjrMFY=
github.com/pgaskin/go-libz v0.0.2/go.mod h1:zKOJy/NMDudfyiyGiA7r0jAKjEyu+/7MSBHAnarLvxY=
github.com/pgaskin/yaml v0.0.0-20190717135119-db0123c0912e h1:jIAOCdmm9VlOD9ezgGGiJOQofvz2mnLIH1sA1wyI8D4=
github.com/pgaskin/yaml v0.0.0-20190717135119-db0123c0912e/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/riking/cssparse v0.0.0-20180325025645-c37ded0aac89 h1:hMsoSMebpfpaDW7+B7gsxNnMBNChjekeqmK8wkzAlc0=
github.com/riking/cssparse v0.0.0-20180325025645-c37ded0aac89/go.mod h1:yc5MYwuNUGggTQ8++IDAbOYq/9PXxsg73+EHYgoG/4w=
github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
github.com/tetratelabs/wazero v1.9.0 h1:IcZ56OuxrtaEz8UYNRHBrUa9bYeX9oVY93KspZZBf/I=
github.com/tetratelabs/wazero v1.9.0/go.mod h1:TSbcXCfFP0L2FGkRPxHphadXPjo1T6W+CseNNY7EkjM=
golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
rsc.io/arm v0.0.0-20150420010332-9c32f2193064 h1:bBbas3KhLwE6f59Z9lUipY23xUX9qrvyLBdQzzV2Tko=
rsc.io/arm v0.0.0-20150420010332-9c32f2193064/go.mod h1:MVYPdlFruujBlzEY3x2Q3XBk7XLdYRNZ7zDbrzYFO7w=

325
kobopatch-wasm/main.go Normal file
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@@ -0,0 +1,325 @@
package main
import (
"archive/tar"
"archive/zip"
"bytes"
"compress/gzip"
"crypto/sha1"
"errors"
"fmt"
"io"
"path/filepath"
"strings"
"syscall/js"
"time"
"github.com/pgaskin/kobopatch/patchfile"
_ "github.com/pgaskin/kobopatch/patchfile/kobopatch"
_ "github.com/pgaskin/kobopatch/patchfile/patch32lsb"
"github.com/pgaskin/kobopatch/patchlib"
"gopkg.in/yaml.v3"
)
// Config mirrors the kobopatch config structure, but only the fields we need.
type Config struct {
Version string
In string // unused in WASM, but required by YAML schema
Out string // unused in WASM
Log string // unused in WASM
Patches map[string]string
Overrides map[string]map[string]bool
}
// patchResult holds the output of a patching operation.
type patchResult struct {
tgzBytes []byte
log string
}
func main() {
js.Global().Set("kobopatchVersion", js.ValueOf("wasm-1.0.0"))
js.Global().Set("patchFirmware", js.FuncOf(jsPatchFirmware))
// Keep the Go runtime alive.
select {}
}
// jsPatchFirmware is the JS-callable wrapper.
//
// Arguments:
//
// args[0]: configYAML (string) - the kobopatch.yaml config content
// args[1]: firmwareZip (Uint8Array) - the firmware zip file bytes
// args[2]: patchFiles (Object) - map of filename -> Uint8Array patch file contents
//
// Returns: a Promise that resolves to { tgz: Uint8Array, log: string } or rejects with an error.
func jsPatchFirmware(this js.Value, args []js.Value) interface{} {
handler := js.FuncOf(func(this js.Value, promiseArgs []js.Value) interface{} {
resolve := promiseArgs[0]
reject := promiseArgs[1]
go func() {
result, err := runPatch(args)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return
}
// Create Uint8Array for the tgz output.
tgzArray := js.Global().Get("Uint8Array").New(len(result.tgzBytes))
js.CopyBytesToJS(tgzArray, result.tgzBytes)
// Return { tgz: Uint8Array, log: string }
obj := js.Global().Get("Object").New()
obj.Set("tgz", tgzArray)
obj.Set("log", result.log)
resolve.Invoke(obj)
}()
return nil
})
return js.Global().Get("Promise").New(handler)
}
func runPatch(args []js.Value) (*patchResult, error) {
if len(args) < 3 {
return nil, errors.New("patchFirmware requires 3 arguments: configYAML, firmwareZip, patchFiles")
}
// Parse arguments.
configYAML := args[0].String()
firmwareZipLen := args[1].Get("length").Int()
firmwareZip := make([]byte, firmwareZipLen)
js.CopyBytesToGo(firmwareZip, args[1])
patchFilesJS := args[2]
patchFileKeys := js.Global().Get("Object").Call("keys", patchFilesJS)
patchFiles := make(map[string][]byte)
for i := 0; i < patchFileKeys.Length(); i++ {
key := patchFileKeys.Index(i).String()
val := patchFilesJS.Get(key)
buf := make([]byte, val.Get("length").Int())
js.CopyBytesToGo(buf, val)
patchFiles[key] = buf
}
return patchFirmware([]byte(configYAML), firmwareZip, patchFiles)
}
// patchFirmware runs the kobopatch patching pipeline entirely in memory.
func patchFirmware(configYAML []byte, firmwareZip []byte, patchFileContents map[string][]byte) (*patchResult, error) {
var logBuf bytes.Buffer
logf := func(format string, a ...interface{}) {
fmt.Fprintf(&logBuf, format+"\n", a...)
}
// Parse config.
var config Config
dec := yaml.NewDecoder(bytes.NewReader(configYAML))
if err := dec.Decode(&config); err != nil {
return nil, fmt.Errorf("could not parse config YAML: %w", err)
}
if config.Version == "" || len(config.Patches) == 0 {
return nil, errors.New("invalid config: version and patches are required")
}
logf("kobopatch wasm")
logf("Firmware version: %s", config.Version)
// Open the firmware zip from memory.
zipReader, err := zip.NewReader(bytes.NewReader(firmwareZip), int64(len(firmwareZip)))
if err != nil {
return nil, fmt.Errorf("could not open firmware zip: %w", err)
}
// Find and extract KoboRoot.tgz from the zip.
var koboRootTgz io.ReadCloser
for _, f := range zipReader.File {
if f.Name == "KoboRoot.tgz" {
koboRootTgz, err = f.Open()
if err != nil {
return nil, fmt.Errorf("could not open KoboRoot.tgz in firmware zip: %w", err)
}
break
}
}
if koboRootTgz == nil {
return nil, errors.New("could not find KoboRoot.tgz in firmware zip")
}
defer koboRootTgz.Close()
gzReader, err := gzip.NewReader(koboRootTgz)
if err != nil {
return nil, fmt.Errorf("could not decompress KoboRoot.tgz: %w", err)
}
defer gzReader.Close()
tarReader := tar.NewReader(gzReader)
// Prepare the output tar.gz in memory.
var outBuf bytes.Buffer
outGZ := gzip.NewWriter(&outBuf)
outTar := tar.NewWriter(outGZ)
var outTarExpectedSize int64
sums := map[string]string{}
// Iterate over firmware tar entries and apply patches.
for {
h, err := tarReader.Next()
if err == io.EOF {
break
}
if err != nil {
return nil, fmt.Errorf("could not read firmware tar entry: %w", err)
}
// Find which patch files target this entry.
var matchingPatchFiles []string
for patchFileName, targetPath := range config.Patches {
if h.Name == "./"+targetPath || h.Name == targetPath || filepath.Base(targetPath) == h.Name {
matchingPatchFiles = append(matchingPatchFiles, patchFileName)
}
}
if len(matchingPatchFiles) == 0 {
continue
}
if h.Typeflag != tar.TypeReg {
return nil, fmt.Errorf("could not patch '%s': not a regular file", h.Name)
}
logf("Patching %s", h.Name)
entryBytes, err := io.ReadAll(tarReader)
if err != nil {
return nil, fmt.Errorf("could not read '%s' from firmware: %w", h.Name, err)
}
pt := patchlib.NewPatcher(entryBytes)
for _, pfn := range matchingPatchFiles {
logf(" Loading patch file: %s", pfn)
patchData, ok := patchFileContents[pfn]
if !ok {
return nil, fmt.Errorf("patch file '%s' not provided", pfn)
}
format := detectFormat(pfn)
formatFn, ok := patchfile.GetFormat(format)
if !ok {
return nil, fmt.Errorf("unknown patch format '%s' for file '%s'", format, pfn)
}
ps, err := formatFn(patchData)
if err != nil {
return nil, fmt.Errorf("could not parse patch file '%s': %w", pfn, err)
}
// Apply overrides.
if overrides, ok := config.Overrides[pfn]; ok {
for name, enabled := range overrides {
if err := ps.SetEnabled(name, enabled); err != nil {
return nil, fmt.Errorf("could not set override '%s' in '%s': %w", name, pfn, err)
}
if enabled {
logf(" ENABLE %s", name)
} else {
logf(" DISABLE %s", name)
}
}
}
if err := ps.Validate(); err != nil {
return nil, fmt.Errorf("invalid patch file '%s': %w", pfn, err)
}
patchfile.Log = func(format string, a ...interface{}) {
logf(" "+format, a...)
}
if err := ps.ApplyTo(pt); err != nil {
return nil, fmt.Errorf("error applying patches from '%s': %w", pfn, err)
}
}
patchedBytes := pt.GetBytes()
outTarExpectedSize += h.Size
// Write patched file to output tar, preserving original attributes.
if err := outTar.WriteHeader(&tar.Header{
Typeflag: h.Typeflag,
Name: h.Name,
Mode: h.Mode,
Uid: h.Uid,
Gid: h.Gid,
ModTime: time.Now(),
Uname: h.Uname,
Gname: h.Gname,
PAXRecords: h.PAXRecords,
Size: int64(len(patchedBytes)),
Format: h.Format,
}); err != nil {
return nil, fmt.Errorf("could not write header for '%s': %w", h.Name, err)
}
if _, err := outTar.Write(patchedBytes); err != nil {
return nil, fmt.Errorf("could not write patched '%s': %w", h.Name, err)
}
sums[h.Name] = fmt.Sprintf("%x", sha1.Sum(patchedBytes))
}
// Finalize the output tar.gz.
if err := outTar.Close(); err != nil {
return nil, fmt.Errorf("could not finalize output tar: %w", err)
}
if err := outGZ.Close(); err != nil {
return nil, fmt.Errorf("could not finalize output gzip: %w", err)
}
// Verify consistency.
logf("\nVerifying output KoboRoot.tgz...")
verifyReader, err := gzip.NewReader(bytes.NewReader(outBuf.Bytes()))
if err != nil {
return nil, fmt.Errorf("could not verify output: %w", err)
}
verifyTar := tar.NewReader(verifyReader)
var verifySum int64
for {
vh, err := verifyTar.Next()
if err == io.EOF {
break
}
if err != nil {
return nil, fmt.Errorf("output verification failed: %w", err)
}
verifySum += vh.Size
}
if verifySum != outTarExpectedSize {
return nil, fmt.Errorf("output size mismatch: expected %d, got %d", outTarExpectedSize, verifySum)
}
logf("Output verified. Size: %d bytes", outBuf.Len())
for f, s := range sums {
logf(" sha1 %s %s", s, f)
}
return &patchResult{
tgzBytes: outBuf.Bytes(),
log: logBuf.String(),
}, nil
}
func detectFormat(filename string) string {
ext := strings.TrimLeft(filepath.Ext(filename), ".")
ext = strings.ReplaceAll(ext, "patch", "patch32lsb")
ext = strings.ReplaceAll(ext, "yaml", "kobopatch")
return ext
}

23
kobopatch-wasm/setup.sh Executable file
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@@ -0,0 +1,23 @@
#!/bin/bash
set -euo pipefail
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
KOBOPATCH_DIR="$SCRIPT_DIR/kobopatch-src"
if [ -d "$KOBOPATCH_DIR" ]; then
echo "Updating kobopatch source..."
cd "$KOBOPATCH_DIR"
git pull
else
echo "Cloning kobopatch source..."
git clone https://github.com/pgaskin/kobopatch.git "$KOBOPATCH_DIR"
fi
echo "Copying wasm_exec.js from Go SDK..."
cp "$(go env GOROOT)/lib/wasm/wasm_exec.js" "$SCRIPT_DIR/wasm_exec.js"
echo ""
echo "Done. kobopatch source is at: $KOBOPATCH_DIR"
echo "wasm_exec.js copied to: $SCRIPT_DIR/wasm_exec.js"
echo ""
echo "Run ./build.sh to compile the WASM binary."

575
kobopatch-wasm/wasm_exec.js Normal file
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@@ -0,0 +1,575 @@
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
"use strict";
(() => {
const enosys = () => {
const err = new Error("not implemented");
err.code = "ENOSYS";
return err;
};
if (!globalThis.fs) {
let outputBuf = "";
globalThis.fs = {
constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1, O_DIRECTORY: -1 }, // unused
writeSync(fd, buf) {
outputBuf += decoder.decode(buf);
const nl = outputBuf.lastIndexOf("\n");
if (nl != -1) {
console.log(outputBuf.substring(0, nl));
outputBuf = outputBuf.substring(nl + 1);
}
return buf.length;
},
write(fd, buf, offset, length, position, callback) {
if (offset !== 0 || length !== buf.length || position !== null) {
callback(enosys());
return;
}
const n = this.writeSync(fd, buf);
callback(null, n);
},
chmod(path, mode, callback) { callback(enosys()); },
chown(path, uid, gid, callback) { callback(enosys()); },
close(fd, callback) { callback(enosys()); },
fchmod(fd, mode, callback) { callback(enosys()); },
fchown(fd, uid, gid, callback) { callback(enosys()); },
fstat(fd, callback) { callback(enosys()); },
fsync(fd, callback) { callback(null); },
ftruncate(fd, length, callback) { callback(enosys()); },
lchown(path, uid, gid, callback) { callback(enosys()); },
link(path, link, callback) { callback(enosys()); },
lstat(path, callback) { callback(enosys()); },
mkdir(path, perm, callback) { callback(enosys()); },
open(path, flags, mode, callback) { callback(enosys()); },
read(fd, buffer, offset, length, position, callback) { callback(enosys()); },
readdir(path, callback) { callback(enosys()); },
readlink(path, callback) { callback(enosys()); },
rename(from, to, callback) { callback(enosys()); },
rmdir(path, callback) { callback(enosys()); },
stat(path, callback) { callback(enosys()); },
symlink(path, link, callback) { callback(enosys()); },
truncate(path, length, callback) { callback(enosys()); },
unlink(path, callback) { callback(enosys()); },
utimes(path, atime, mtime, callback) { callback(enosys()); },
};
}
if (!globalThis.process) {
globalThis.process = {
getuid() { return -1; },
getgid() { return -1; },
geteuid() { return -1; },
getegid() { return -1; },
getgroups() { throw enosys(); },
pid: -1,
ppid: -1,
umask() { throw enosys(); },
cwd() { throw enosys(); },
chdir() { throw enosys(); },
}
}
if (!globalThis.path) {
globalThis.path = {
resolve(...pathSegments) {
return pathSegments.join("/");
}
}
}
if (!globalThis.crypto) {
throw new Error("globalThis.crypto is not available, polyfill required (crypto.getRandomValues only)");
}
if (!globalThis.performance) {
throw new Error("globalThis.performance is not available, polyfill required (performance.now only)");
}
if (!globalThis.TextEncoder) {
throw new Error("globalThis.TextEncoder is not available, polyfill required");
}
if (!globalThis.TextDecoder) {
throw new Error("globalThis.TextDecoder is not available, polyfill required");
}
const encoder = new TextEncoder("utf-8");
const decoder = new TextDecoder("utf-8");
globalThis.Go = class {
constructor() {
this.argv = ["js"];
this.env = {};
this.exit = (code) => {
if (code !== 0) {
console.warn("exit code:", code);
}
};
this._exitPromise = new Promise((resolve) => {
this._resolveExitPromise = resolve;
});
this._pendingEvent = null;
this._scheduledTimeouts = new Map();
this._nextCallbackTimeoutID = 1;
const setInt64 = (addr, v) => {
this.mem.setUint32(addr + 0, v, true);
this.mem.setUint32(addr + 4, Math.floor(v / 4294967296), true);
}
const setInt32 = (addr, v) => {
this.mem.setUint32(addr + 0, v, true);
}
const getInt64 = (addr) => {
const low = this.mem.getUint32(addr + 0, true);
const high = this.mem.getInt32(addr + 4, true);
return low + high * 4294967296;
}
const loadValue = (addr) => {
const f = this.mem.getFloat64(addr, true);
if (f === 0) {
return undefined;
}
if (!isNaN(f)) {
return f;
}
const id = this.mem.getUint32(addr, true);
return this._values[id];
}
const storeValue = (addr, v) => {
const nanHead = 0x7FF80000;
if (typeof v === "number" && v !== 0) {
if (isNaN(v)) {
this.mem.setUint32(addr + 4, nanHead, true);
this.mem.setUint32(addr, 0, true);
return;
}
this.mem.setFloat64(addr, v, true);
return;
}
if (v === undefined) {
this.mem.setFloat64(addr, 0, true);
return;
}
let id = this._ids.get(v);
if (id === undefined) {
id = this._idPool.pop();
if (id === undefined) {
id = this._values.length;
}
this._values[id] = v;
this._goRefCounts[id] = 0;
this._ids.set(v, id);
}
this._goRefCounts[id]++;
let typeFlag = 0;
switch (typeof v) {
case "object":
if (v !== null) {
typeFlag = 1;
}
break;
case "string":
typeFlag = 2;
break;
case "symbol":
typeFlag = 3;
break;
case "function":
typeFlag = 4;
break;
}
this.mem.setUint32(addr + 4, nanHead | typeFlag, true);
this.mem.setUint32(addr, id, true);
}
const loadSlice = (addr) => {
const array = getInt64(addr + 0);
const len = getInt64(addr + 8);
return new Uint8Array(this._inst.exports.mem.buffer, array, len);
}
const loadSliceOfValues = (addr) => {
const array = getInt64(addr + 0);
const len = getInt64(addr + 8);
const a = new Array(len);
for (let i = 0; i < len; i++) {
a[i] = loadValue(array + i * 8);
}
return a;
}
const loadString = (addr) => {
const saddr = getInt64(addr + 0);
const len = getInt64(addr + 8);
return decoder.decode(new DataView(this._inst.exports.mem.buffer, saddr, len));
}
const testCallExport = (a, b) => {
this._inst.exports.testExport0();
return this._inst.exports.testExport(a, b);
}
const timeOrigin = Date.now() - performance.now();
this.importObject = {
_gotest: {
add: (a, b) => a + b,
callExport: testCallExport,
},
gojs: {
// Go's SP does not change as long as no Go code is running. Some operations (e.g. calls, getters and setters)
// may synchronously trigger a Go event handler. This makes Go code get executed in the middle of the imported
// function. A goroutine can switch to a new stack if the current stack is too small (see morestack function).
// This changes the SP, thus we have to update the SP used by the imported function.
// func wasmExit(code int32)
"runtime.wasmExit": (sp) => {
sp >>>= 0;
const code = this.mem.getInt32(sp + 8, true);
this.exited = true;
delete this._inst;
delete this._values;
delete this._goRefCounts;
delete this._ids;
delete this._idPool;
this.exit(code);
},
// func wasmWrite(fd uintptr, p unsafe.Pointer, n int32)
"runtime.wasmWrite": (sp) => {
sp >>>= 0;
const fd = getInt64(sp + 8);
const p = getInt64(sp + 16);
const n = this.mem.getInt32(sp + 24, true);
fs.writeSync(fd, new Uint8Array(this._inst.exports.mem.buffer, p, n));
},
// func resetMemoryDataView()
"runtime.resetMemoryDataView": (sp) => {
sp >>>= 0;
this.mem = new DataView(this._inst.exports.mem.buffer);
},
// func nanotime1() int64
"runtime.nanotime1": (sp) => {
sp >>>= 0;
setInt64(sp + 8, (timeOrigin + performance.now()) * 1000000);
},
// func walltime() (sec int64, nsec int32)
"runtime.walltime": (sp) => {
sp >>>= 0;
const msec = (new Date).getTime();
setInt64(sp + 8, msec / 1000);
this.mem.setInt32(sp + 16, (msec % 1000) * 1000000, true);
},
// func scheduleTimeoutEvent(delay int64) int32
"runtime.scheduleTimeoutEvent": (sp) => {
sp >>>= 0;
const id = this._nextCallbackTimeoutID;
this._nextCallbackTimeoutID++;
this._scheduledTimeouts.set(id, setTimeout(
() => {
this._resume();
while (this._scheduledTimeouts.has(id)) {
// for some reason Go failed to register the timeout event, log and try again
// (temporary workaround for https://github.com/golang/go/issues/28975)
console.warn("scheduleTimeoutEvent: missed timeout event");
this._resume();
}
},
getInt64(sp + 8),
));
this.mem.setInt32(sp + 16, id, true);
},
// func clearTimeoutEvent(id int32)
"runtime.clearTimeoutEvent": (sp) => {
sp >>>= 0;
const id = this.mem.getInt32(sp + 8, true);
clearTimeout(this._scheduledTimeouts.get(id));
this._scheduledTimeouts.delete(id);
},
// func getRandomData(r []byte)
"runtime.getRandomData": (sp) => {
sp >>>= 0;
crypto.getRandomValues(loadSlice(sp + 8));
},
// func finalizeRef(v ref)
"syscall/js.finalizeRef": (sp) => {
sp >>>= 0;
const id = this.mem.getUint32(sp + 8, true);
this._goRefCounts[id]--;
if (this._goRefCounts[id] === 0) {
const v = this._values[id];
this._values[id] = null;
this._ids.delete(v);
this._idPool.push(id);
}
},
// func stringVal(value string) ref
"syscall/js.stringVal": (sp) => {
sp >>>= 0;
storeValue(sp + 24, loadString(sp + 8));
},
// func valueGet(v ref, p string) ref
"syscall/js.valueGet": (sp) => {
sp >>>= 0;
const result = Reflect.get(loadValue(sp + 8), loadString(sp + 16));
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 32, result);
},
// func valueSet(v ref, p string, x ref)
"syscall/js.valueSet": (sp) => {
sp >>>= 0;
Reflect.set(loadValue(sp + 8), loadString(sp + 16), loadValue(sp + 32));
},
// func valueDelete(v ref, p string)
"syscall/js.valueDelete": (sp) => {
sp >>>= 0;
Reflect.deleteProperty(loadValue(sp + 8), loadString(sp + 16));
},
// func valueIndex(v ref, i int) ref
"syscall/js.valueIndex": (sp) => {
sp >>>= 0;
storeValue(sp + 24, Reflect.get(loadValue(sp + 8), getInt64(sp + 16)));
},
// valueSetIndex(v ref, i int, x ref)
"syscall/js.valueSetIndex": (sp) => {
sp >>>= 0;
Reflect.set(loadValue(sp + 8), getInt64(sp + 16), loadValue(sp + 24));
},
// func valueCall(v ref, m string, args []ref) (ref, bool)
"syscall/js.valueCall": (sp) => {
sp >>>= 0;
try {
const v = loadValue(sp + 8);
const m = Reflect.get(v, loadString(sp + 16));
const args = loadSliceOfValues(sp + 32);
const result = Reflect.apply(m, v, args);
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 56, result);
this.mem.setUint8(sp + 64, 1);
} catch (err) {
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 56, err);
this.mem.setUint8(sp + 64, 0);
}
},
// func valueInvoke(v ref, args []ref) (ref, bool)
"syscall/js.valueInvoke": (sp) => {
sp >>>= 0;
try {
const v = loadValue(sp + 8);
const args = loadSliceOfValues(sp + 16);
const result = Reflect.apply(v, undefined, args);
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 40, result);
this.mem.setUint8(sp + 48, 1);
} catch (err) {
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 40, err);
this.mem.setUint8(sp + 48, 0);
}
},
// func valueNew(v ref, args []ref) (ref, bool)
"syscall/js.valueNew": (sp) => {
sp >>>= 0;
try {
const v = loadValue(sp + 8);
const args = loadSliceOfValues(sp + 16);
const result = Reflect.construct(v, args);
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 40, result);
this.mem.setUint8(sp + 48, 1);
} catch (err) {
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 40, err);
this.mem.setUint8(sp + 48, 0);
}
},
// func valueLength(v ref) int
"syscall/js.valueLength": (sp) => {
sp >>>= 0;
setInt64(sp + 16, parseInt(loadValue(sp + 8).length));
},
// valuePrepareString(v ref) (ref, int)
"syscall/js.valuePrepareString": (sp) => {
sp >>>= 0;
const str = encoder.encode(String(loadValue(sp + 8)));
storeValue(sp + 16, str);
setInt64(sp + 24, str.length);
},
// valueLoadString(v ref, b []byte)
"syscall/js.valueLoadString": (sp) => {
sp >>>= 0;
const str = loadValue(sp + 8);
loadSlice(sp + 16).set(str);
},
// func valueInstanceOf(v ref, t ref) bool
"syscall/js.valueInstanceOf": (sp) => {
sp >>>= 0;
this.mem.setUint8(sp + 24, (loadValue(sp + 8) instanceof loadValue(sp + 16)) ? 1 : 0);
},
// func copyBytesToGo(dst []byte, src ref) (int, bool)
"syscall/js.copyBytesToGo": (sp) => {
sp >>>= 0;
const dst = loadSlice(sp + 8);
const src = loadValue(sp + 32);
if (!(src instanceof Uint8Array || src instanceof Uint8ClampedArray)) {
this.mem.setUint8(sp + 48, 0);
return;
}
const toCopy = src.subarray(0, dst.length);
dst.set(toCopy);
setInt64(sp + 40, toCopy.length);
this.mem.setUint8(sp + 48, 1);
},
// func copyBytesToJS(dst ref, src []byte) (int, bool)
"syscall/js.copyBytesToJS": (sp) => {
sp >>>= 0;
const dst = loadValue(sp + 8);
const src = loadSlice(sp + 16);
if (!(dst instanceof Uint8Array || dst instanceof Uint8ClampedArray)) {
this.mem.setUint8(sp + 48, 0);
return;
}
const toCopy = src.subarray(0, dst.length);
dst.set(toCopy);
setInt64(sp + 40, toCopy.length);
this.mem.setUint8(sp + 48, 1);
},
"debug": (value) => {
console.log(value);
},
}
};
}
async run(instance) {
if (!(instance instanceof WebAssembly.Instance)) {
throw new Error("Go.run: WebAssembly.Instance expected");
}
this._inst = instance;
this.mem = new DataView(this._inst.exports.mem.buffer);
this._values = [ // JS values that Go currently has references to, indexed by reference id
NaN,
0,
null,
true,
false,
globalThis,
this,
];
this._goRefCounts = new Array(this._values.length).fill(Infinity); // number of references that Go has to a JS value, indexed by reference id
this._ids = new Map([ // mapping from JS values to reference ids
[0, 1],
[null, 2],
[true, 3],
[false, 4],
[globalThis, 5],
[this, 6],
]);
this._idPool = []; // unused ids that have been garbage collected
this.exited = false; // whether the Go program has exited
// Pass command line arguments and environment variables to WebAssembly by writing them to the linear memory.
let offset = 4096;
const strPtr = (str) => {
const ptr = offset;
const bytes = encoder.encode(str + "\0");
new Uint8Array(this.mem.buffer, offset, bytes.length).set(bytes);
offset += bytes.length;
if (offset % 8 !== 0) {
offset += 8 - (offset % 8);
}
return ptr;
};
const argc = this.argv.length;
const argvPtrs = [];
this.argv.forEach((arg) => {
argvPtrs.push(strPtr(arg));
});
argvPtrs.push(0);
const keys = Object.keys(this.env).sort();
keys.forEach((key) => {
argvPtrs.push(strPtr(`${key}=${this.env[key]}`));
});
argvPtrs.push(0);
const argv = offset;
argvPtrs.forEach((ptr) => {
this.mem.setUint32(offset, ptr, true);
this.mem.setUint32(offset + 4, 0, true);
offset += 8;
});
// The linker guarantees global data starts from at least wasmMinDataAddr.
// Keep in sync with cmd/link/internal/ld/data.go:wasmMinDataAddr.
const wasmMinDataAddr = 4096 + 8192;
if (offset >= wasmMinDataAddr) {
throw new Error("total length of command line and environment variables exceeds limit");
}
this._inst.exports.run(argc, argv);
if (this.exited) {
this._resolveExitPromise();
}
await this._exitPromise;
}
_resume() {
if (this.exited) {
throw new Error("Go program has already exited");
}
this._inst.exports.resume();
if (this.exited) {
this._resolveExitPromise();
}
}
_makeFuncWrapper(id) {
const go = this;
return function () {
const event = { id: id, this: this, args: arguments };
go._pendingEvent = event;
go._resume();
return event.result;
};
}
}
})();

47
wip/todo.md
View File

@@ -4,43 +4,44 @@
- [x] Device detection proof of concept (File System Access API)
- [x] Serial prefix → model mapping (verified against official Kobo help page)
- [x] Architecture planning
- [x] Cloned kobopatch source (`kobopatch-src/`)
- [x] Architecture planning (updated: fully client-side, no PHP backend)
- [x] Installed Go via Homebrew (v1.26.1)
- [x] Verified all kobopatch tests pass natively
- [x] Verified all kobopatch tests pass under `GOOS=js GOARCH=wasm` (via Node.js)
- [x] Updated device identification doc with correct model list
- [x] Removed obsolete backend-api.md
- [x] Created `kobopatch-wasm/` with setup.sh, build.sh, go.mod, main.go
- [x] WASM wrapper compiles successfully (9.9MB)
- [x] All kobopatch tests still pass with our module's replace directives
- [x] Cleaned up .gitignore
## In Progress
### WASM Build of kobopatch
### Integration Testing
- [ ] Write Go WASM wrapper (`kobopatch-src/wasm/`) exposing `PatchFirmware()` to JS
- Accepts: config YAML (bytes), firmware zip (bytes), patch YAML files (bytes)
- Returns: KoboRoot.tgz (bytes) or error
- All I/O in-memory, no filesystem access
- [ ] Refactor `kobopatch/kobopatch.go` main logic into reusable function
- Strip `os.Open`/`os.Create` → use `io.Reader`/`io.Writer`
- Strip `os.Chdir` → resolve paths in memory
- Strip `exec.Command` (lrelease) → skip translations
- [ ] Compile with `GOOS=js GOARCH=wasm go build`
- [ ] Test WASM binary loads and runs in browser
- [ ] Test WASM binary in actual browser (load wasm_exec.js + kobopatch.wasm)
- [ ] Test `patchFirmware()` JS function end-to-end with real firmware zip + patches
### Frontend - Patch UI
- [ ] `patch-ui.js` - parse patch YAML client-side, render grouped toggles
- [ ] YAML parsing in JS (extract patch names, descriptions, enabled, PatchGroup)
- [ ] `patch-ui.js` — render grouped toggles per target file
- [ ] PatchGroup mutual exclusion (radio buttons)
- [ ] Bundle patch YAML files as static assets (or fetch from known URL)
- [ ] Generate kobopatch.yaml config from UI state
- [ ] Generate kobopatch.yaml config string from UI state
### Frontend - Build Flow
- [ ] User provides firmware zip (file input or drag-and-drop)
- [ ] Load WASM module, pass firmware + config + patches
- [ ] Receive KoboRoot.tgz blob from WASM
- [ ] Write KoboRoot.tgz to device via File System Access API
- [ ] Fallback: download KoboRoot.tgz if FS Access write fails
- [ ] User provides firmware zip (file input / drag-and-drop)
- [ ] Load WASM, call `patchFirmware()` with config + firmware + patch files
- [ ] Receive KoboRoot.tgz blob, write to `.kobo/` via File System Access API
- [ ] Fallback: download KoboRoot.tgz manually
- [ ] Bundle patch YAML files as static assets
## Future / Polish
- [ ] Browser compatibility warning with more detail
- [ ] Loading/progress states during WASM build (Web Worker?)
- [ ] Run WASM patching in a Web Worker (avoid blocking UI)
- [ ] Browser compatibility warning with detail
- [ ] Loading/progress states during build
- [ ] Error handling for common failure modes
- [ ] Host as static site (GitHub Pages / Netlify)
- [ ] NickelMenu install/uninstall support (bonus feature)

48
wip/wasm-feasibility.md Normal file
View File

@@ -0,0 +1,48 @@
# WASM Feasibility — Confirmed
## Test Results
All kobopatch tests pass under both native and WASM targets.
### Native (`go test ./...`)
```
ok github.com/pgaskin/kobopatch/kobopatch 0.003s
ok github.com/pgaskin/kobopatch/patchfile/kobopatch 0.003s
ok github.com/pgaskin/kobopatch/patchfile/patch32lsb 0.002s
ok github.com/pgaskin/kobopatch/patchlib 0.796s
```
### WASM (`GOOS=js GOARCH=wasm`, run via Node.js)
```
ok github.com/pgaskin/kobopatch/kobopatch 0.158s
ok github.com/pgaskin/kobopatch/patchfile/kobopatch 0.162s
ok github.com/pgaskin/kobopatch/patchfile/patch32lsb 0.133s
ok github.com/pgaskin/kobopatch/patchlib 9.755s
```
### Notes
- `patchlib` tests are ~12x slower under WASM (9.7s vs 0.8s) — expected overhead
- All pure Go dependencies compile to WASM without issues
- No CGO, no OS-specific syscalls in the core libraries
- Go WASM executor: `$(go env GOROOT)/lib/wasm/go_js_wasm_exec`
- Node.js v25.8.1 used for WASM test execution
## What Works in WASM
- Binary patching (`patchlib`)
- ARM Thumb-2 instruction assembly (`patchlib/asm`)
- ELF symbol table parsing (`patchlib/syms`)
- YAML patch format parsing (`patchfile/kobopatch`)
- Binary patch format parsing (`patchfile/patch32lsb`)
- CSS parsing (`patchlib/css`)
- Zlib compression/decompression
- tar.gz reading/writing
- ZIP extraction
## What Won't Work in WASM (and doesn't need to)
- `os.Open` / `os.Create` — replace with in-memory I/O
- `os.Chdir` — not needed, use in-memory paths
- `exec.Command` (lrelease for translations) — skip, rare use case
- `ioutil.TempDir` — not needed with in-memory approach