Initial commit of native dependency building.

.gitignore

@@ -6,3 +6,5 @@
 /node_modules
 /docker_node_modules
 /pkg/control
+/.hak
+/.yarnrc

hak/matrix-seshat/build.js

@@ -0,0 +1,109 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+const child_process = require('child_process');
+
+module.exports = async function(hakEnv, moduleInfo) {
+    if (hakEnv.isWin()) await buildOpenSsl(hakEnv, moduleInfo);
+    await buildSqlCipher(hakEnv, moduleInfo);
+    await buildMatrixSeshat(hakEnv, moduleInfo);
+}
+
+async function buildOpenSsl(hakEnv, moduleInfo) {
+    const openSslDir = path.join(moduleInfo.moduleHakDir, 'openssl-1.1.1d');
+}
+
+async function buildSqlCipher(hakEnv, moduleInfo) {
+    const sqlCipherDir = path.join(moduleInfo.moduleHakDir, 'sqlcipher-4.3.0');
+
+    const args = [
+        '--prefix=' + moduleInfo.depPrefix + '',
+        '--enable-tempstore=yes',
+        '--enable-shared=no',
+    ];
+
+    if (hakEnv.isMac()) {
+        args.push('--with-crypto-lib=commoncrypto');
+    }
+    args.push('CFLAGS=-DSQLITE_HAS_CODEC');
+    if (hakEnv.isMac()) {
+        args.push('LDFLAGS=-framework Security -framework Foundation');
+    }
+
+    await new Promise((resolve, reject) => {
+        const proc = child_process.spawn(
+            path.join(sqlCipherDir, 'configure'),
+            args,
+            {
+                cwd: sqlCipherDir,
+                stdio: 'inherit',
+            },
+        );
+        proc.on('exit', (code) => {
+            code ? reject(code) : resolve();
+        });
+    });
+
+    await new Promise((resolve, reject) => {
+        const proc = child_process.spawn(
+            'make',
+            [],
+            {
+                cwd: sqlCipherDir,
+                stdio: 'inherit',
+            },
+        );
+        proc.on('exit', (code) => {
+            code ? reject(code) : resolve();
+        });
+    });
+
+    await new Promise((resolve, reject) => {
+        const proc = child_process.spawn(
+            'make',
+            ['install'],
+            {
+                cwd: sqlCipherDir,
+                stdio: 'inherit',
+            },
+        );
+        proc.on('exit', (code) => {
+            code ? reject(code) : resolve();
+        });
+    });
+}
+
+async function buildMatrixSeshat(hakEnv, moduleInfo) {
+    await new Promise((resolve) => {
+        const proc = child_process.spawn(
+            path.join(moduleInfo.nodeModuleBinDir, 'neon'),
+            ['build', '--release'],
+            {
+                cwd: moduleInfo.moduleBuildDir,
+                env: Object.assign({
+                    SQLCIPHER_STATIC: 1,
+                    SQLCIPHER_LIB_DIR: path.join(moduleInfo.depPrefix, 'lib'),
+                    SQLCIPHER_INCLUDE_DIR: path.join(moduleInfo.depPrefix, 'include'),
+                }, hakEnv.makeGypEnv()),
+                stdio: 'inherit',
+            },
+        );
+        proc.on('exit', (code) => {
+            code ? reject(code) : resolve();
+        });
+    });
+}

hak/matrix-seshat/fetchDeps.js

@@ -0,0 +1,98 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+
+const fsProm = require('fs').promises;
+const needle = require('needle');
+const tar = require('tar');
+
+module.exports = async function(hakEnv, moduleInfo) {
+    await getSqlCipher(hakEnv, moduleInfo);
+
+    if (hakEnv.isWin()) {
+        getOpenSsl(hakEnv, moduleInfo);
+    }
+}
+
+async function getSqlCipher(hakEnv, moduleInfo) {
+    const sqlCipherDir = path.join(moduleInfo.moduleHakDir, 'sqlcipher-4.3.0');
+
+    let haveSqlcipher;
+    try {
+        await fsProm.stat(sqlCipherDir);
+        haveSqlcipher = true;
+    } catch (e) {
+        haveSqlcipher = false;
+    }
+
+    if (haveSqlcipher) return;
+
+    const sqlCipherTarball = path.join(moduleInfo.moduleHakDir, 'sqlcipher-4.3.0.tar.gz');
+    let haveSqlcipherTar;
+    try {
+        await fsProm.stat(sqlCipherTarball);
+        haveSqlcipherTar = true;
+    } catch (e) {
+        haveSqlcipherTar = false;
+    }
+    if (!haveSqlcipherTar) {
+        const bob =  needle('get', 'https://github.com/sqlcipher/sqlcipher/archive/v4.3.0.tar.gz', {
+            follow: 10,
+            output: sqlCipherTarball,
+        });
+        await bob;
+    }
+
+    await tar.x({
+        file: sqlCipherTarball,
+        cwd: moduleInfo.moduleHakDir,
+    });
+}
+
+async function getOpenSsl(hakEnv, moduleInfo) {
+    const openSslDir = path.join(moduleInfo.moduleHakDir, 'openssl-1.1.1d');
+
+    let haveOpenSsl;
+    try {
+        await fsProm.stat(openSslDir);
+        haveOpenSsl = true;
+    } catch (e) {
+        haveOpenSsl = false;
+    }
+
+    if (haveOpenSsl) return;
+
+    const openSslTarball = path.join(moduleInfo.depDir, 'openssl-1.1.1d.tar.gz');
+    let haveOpenSslTar;
+    try {
+        await fsProm.stat(openSslTarball);
+        haveOpenSslTar = true;
+    } catch (e) {
+        haveOpenSslTar = false;
+    }
+    if (!haveOpenSslTar) {
+        await needle('get', 'https://www.openssl.org/source/openssl-1.1.1d.tar.gz', {
+            follow: 10,
+            output: openSslTarball,
+        });
+    }
+
+    await tar.x({
+        file: openSslTarball,
+        cwd: moduleInfo.depDir,
+    });
+}

hak/matrix-seshat/hak.json

@@ -0,0 +1,9 @@
+{
+    "scripts": {
+        "check": "check.js",
+        "fetchDeps": "fetchDeps.js",
+        "build": "build.js"
+    },
+    "prune": "native",
+    "copy": "native/index.node"
+}

package.json

@@ -16,13 +16,14 @@
     "fetch": "yarn run mkdirs && node scripts/fetch-package.js",
     "setversion": "node scripts/set-version.js",
     "start": "electron .",
-    "lint": "eslint src/",
+    "lint": "eslint src/ scripts/",
     "build": "yarn run setversion && electron-builder",
     "in-docker": "scripts/in-docker.sh",
     "docker:build": "yarn run in-docker yarn run build",
     "docker:install": "yarn run in-docker yarn install",
     "debrepo": "scripts/mkrepo.sh",
-    "clean": "rimraf webapp.asar dist packages deploys"
+    "clean": "rimraf webapp.asar dist packages deploys",
+    "hak": "node scripts/hak/index.js"
   },
   "dependencies": {
     "auto-launch": "^5.0.1",
@@ -40,11 +41,20 @@
     "eslint": "^5.8.0",
     "eslint-config-google": "^0.7.1",
     "eslint-plugin-babel": "^4.1.2",
+    "find-npm-prefix": "^1.0.2",
     "follow-redirects": "^1.9.0",
+    "glob": "^7.1.6",
     "matrix-js-sdk": "^2.4.6-rc.1",
-    "mkdirp": "^0.5.1",
+    "mkdirp": "^1.0.3",
-    "rimraf": "^3.0.0",
+    "needle": "^2.3.2",
-    "tar": "^5.0.5"
+    "node-pre-gyp": "^0.14.0",
+    "npm": "^6.13.7",
+    "rimraf": "^3.0.2",
+    "semver": "^7.1.3",
+    "tar": "^6.0.1"
+  },
+  "hakDependencies": {
+    "matrix-seshat": "^1.0.0"
   },
   "build": {
     "appId": "im.riot.app",

scripts/hak/README.md

@@ -0,0 +1,78 @@
+hak
+===
+
+This tool builds native dependencies for riot-desktop. Here follows dome very minimal
+documentation for it.
+
+Goals:
+ * Must build compiled native node modules in a shippable state
+   (ie. only dynamically linked against libraries that will be on the
+   target system, all unnecessary files removed).
+ * Must be able to build any native module, no matter what build system
+   it uses (electron-rebuild is supposed to do this job but only works
+   for modules that use gyp).
+
+It's also loosely designed to be a general tool and agnostic to what it's
+actually building. It's used here to build modules for the electron app
+but should work equally well for building modules for normal node.
+
+Running
+=======
+Hak is invoked with a command and a dependency, eg. `yarn run hak fetch matrix-seshat`.
+If no dependencies are given, hak runs the command on all dependencies.
+
+Files
+=====
+There are a lot of files involved:
+
+ * scripts/hak/... - The tool itself
+ * hak/[dependency] - Files provided by the app that tell hak how to build each of its native dependencies.
+       Contains a hak.json file and also some script files, each of which must be referenced in hak.json.
+ * .hak/ - Files generated by hak in the course of doing its job. Includes the dependency module itself and
+       any of the native dependency's native dependencies.
+ * .hak/[dependency]/build - An extracted copy of the dependency's node module used to build it.
+ * .hak/[dependency]/out - Another extracted copy of the dependency, this one contains only what will be shipped.
+
+Workings
+========
+Hak works around native node modules that try to fetch or build their native component in
+the npm 'install' phase - modules that do this will typically end up with native components
+targeted to the build platform and the node that npm/yarn is using, which is no good for an]
+electron app.
+
+It does this by installing it with `--ignore-scripts` and then using `yarn link` to keep the
+dependency module separate so yarn doesn't try to run its install / postinstall script
+at other points (eg. whenever you `yarn add` a random other dependency).
+
+This also means that the dependencies cannot be listed in `dependencies` or
+`devDependencies` in the project, since this would cause npm / yarn to install them and
+trey to fetch their native parts. Instead, they are listed in `hakDependencies` which
+hak reads to install them for you.
+
+Hak will *not* install dependencies for the copy of the module it links into your
+project, so if your native module has javascript dependencies that are actually needed at
+runtime (and not just to fetch / build the native parts), it won't work.
+
+Hak will generate a `.yarnrc` in the project directory to set the link directory to its
+own in the .hak directory (unless one already exists, in which case this is your problem).
+
+Lifecycle
+=========
+Hak is divided into lifecycle stages, in order:
+ * fetch - Download and extract the source of the dependency
+ * link - Link the copy of the dependency into your node_modules directory
+ * fetchDeps - Fetch & extract any native dependencies required to build the module.
+ * build - The Good Stuff. Configure and build any native dependencies, then the module itself.
+ * copy - Copy the built artifact from the module build dorectory to the module output directory.
+
+hak.json
+========
+The scripts section contains scripts used for lifecycle stages that need them (fetch, fetchDeps, build).
+It also contains 'prune' and 'copy' which are globs of files to delete from the output module directory
+and copy over from the module build directory to the output module directory, respectively.
+
+Shortcomings
+============
+Hak doesn't know about dependencies between lifecycle stages, ie. it doesn't know that you need to
+'fetch' and 'fetchDeps' before you can 'build', etc. You get to run each individually, and remember
+the right order.

scripts/hak/build.js

@@ -0,0 +1,26 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+const url = require('url');
+const fsProm = require('fs').promises;
+const child_process = require('child_process');
+
+async function build(hakEnv, moduleInfo) {
+    moduleInfo.scripts.build(hakEnv, moduleInfo);
+};
+
+module.exports = build;

scripts/hak/clean.js

@@ -0,0 +1,53 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+
+const rimraf = require('rimraf');
+
+async function clean(hakEnv, moduleInfo) {
+    await new Promise((resolve, reject) => {
+        rimraf(moduleInfo.moduleHakDir, (err) => {
+            if (err) {
+                reject(err);
+            } else {
+                resolve();
+            }
+        });
+    });
+
+    await new Promise((resolve, reject) => {
+        rimraf(path.join(hakEnv.dotHakDir, 'links', moduleInfo.name), (err) => {
+            if (err) {
+                reject(err);
+            } else {
+                resolve();
+            }
+        });
+    });
+
+    await new Promise((resolve, reject) => {
+        rimraf(path.join(hakEnv.projectRoot, 'node_modules', moduleInfo.name), (err) => {
+            if (err) {
+                reject(err);
+            } else {
+                resolve();
+            }
+        });
+    });
+}
+
+module.exports = clean;

scripts/hak/copy.js

@@ -0,0 +1,67 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+const fsProm = require('fs').promises;
+
+const rimraf = require('rimraf');
+const glob = require('glob');
+const mkdirp = require('mkdirp');
+
+async function copy(hakEnv, moduleInfo) {
+    if (moduleInfo.cfg.prune) {
+        console.log("Removing " + moduleInfo.cfg.prune + " from " + moduleInfo.moduleOutDir);
+        // rimraf doesn't have a 'cwd' option: it always uses process.cwd()
+        // (and if you set glob.cwd it just breaks because it can't find the files)
+        const oldCwd = process.cwd();
+        try {
+            process.chdir(moduleInfo.moduleOutDir);
+            await new Promise((resolve, reject) => {
+                rimraf(moduleInfo.cfg.prune, {}, err => {
+                    err ? reject(err) : resolve();
+                });
+            });
+        } finally {
+            process.chdir(oldCwd);
+        }
+    }
+
+    if (moduleInfo.cfg.copy) {
+        console.log(
+            "Copying " + moduleInfo.cfg.prune + " from " +
+            moduleInfo.moduleOutDir + " to " + moduleInfo.moduleOutDir,
+        );
+        const files = await new Promise(async (resolve, reject) => {
+            glob(moduleInfo.cfg.copy, {
+                nosort: true,
+                silent: true,
+                cwd: moduleInfo.moduleBuildDir,
+            }, (err, files) => {
+                err ? reject(err) : resolve(files);
+            });
+        });
+        for (const f of files) {
+            console.log("\t" + f);
+            const src = path.join(moduleInfo.moduleBuildDir, f);
+            const dst = path.join(moduleInfo.moduleOutDir, f);
+
+            await mkdirp(path.dirname(dst));
+            await fsProm.copyFile(src, dst);
+        }
+    }
+};
+
+module.exports = copy;

scripts/hak/fetch.js

@@ -0,0 +1,116 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+const url = require('url');
+const fsProm = require('fs').promises;
+const child_process = require('child_process');
+
+const npm = require('npm');
+const semver = require('semver');
+const needle = require('needle');
+const mkdirp = require('mkdirp');
+const tar = require('tar');
+
+async function fetch(hakEnv, moduleInfo) {
+    let haveModuleBuildDir;
+    try {
+        const stats = await fsProm.stat(moduleInfo.moduleBuildDir);
+        haveModuleBuildDir = stats.isDirectory();
+    } catch (e) {
+        haveModuleBuildDir = false;
+    }
+
+    if (haveModuleBuildDir) return;
+
+    await new Promise((resolve) => {
+        npm.load({'loglevel': 'silent'}, resolve);
+    });
+
+    console.log("Fetching " + moduleInfo.name + " at version " + moduleInfo.version);
+    const versions = await new Promise((resolve, reject) => {
+        npm.view([
+            moduleInfo.name + '@' + moduleInfo.version,
+            'dist.tarball',
+            (err, versions) => {
+                if (err) {
+                    reject(err);
+                } else {
+                    resolve(versions);
+                }
+            },
+        ]);
+    });
+
+    const orderedVersions = Object.keys(versions);
+    semver.sort(orderedVersions);
+
+    console.log("Resolved version " + orderedVersions[0] + " for " + moduleInfo.name);
+
+    const tarballUrl = versions[orderedVersions[0]]['dist.tarball'];
+
+    await mkdirp(moduleInfo.moduleHakDir);
+
+    const parsedUrl = url.parse(tarballUrl);
+    const tarballFile = path.join(moduleInfo.moduleHakDir, path.basename(parsedUrl.path));
+
+    let haveTarball;
+    try {
+        await fsProm.stat(tarballFile);
+        haveTarball = true;
+    } catch (e) {
+        haveTarball = false;
+    }
+    if (!haveTarball) {
+        console.log("Downloading " + tarballUrl);
+        await needle('get', tarballUrl, { output: tarballFile });
+    } else {
+        console.log(tarballFile + " already exists.");
+    }
+
+    await mkdirp(moduleInfo.moduleBuildDir);
+
+    await tar.x({
+        file: tarballFile,
+        cwd: moduleInfo.moduleBuildDir,
+        strip: 1,
+    });
+
+    await new Promise((resolve, reject) => {
+        const proc = child_process.spawn(
+            'yarn',
+            ['install', '--ignore-scripts'],
+            {
+                stdio: 'inherit',
+                cwd: moduleInfo.moduleBuildDir,
+            },
+        );
+        proc.on('exit', code => {
+            code ? reject(code) : resolve();
+        });
+    });
+
+    // also extract another copy to the output directory at this point
+    // nb. we do not yarn install in the output copy
+    await mkdirp(moduleInfo.moduleOutDir);
+    await tar.x({
+        file: tarballFile,
+        cwd: moduleInfo.moduleOutDir,
+        strip: 1,
+    });
+}
+
+module.exports = fetch;

scripts/hak/fetchDeps.js

@@ -0,0 +1,23 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+async function fetchDeps(hakEnv, moduleInfo) {
+    if (moduleInfo.scripts.fetchDeps) {
+        await moduleInfo.scripts.fetchDeps(hakEnv, moduleInfo);
+    }
+};
+
+module.exports = fetchDeps;

scripts/hak/hakEnv.js

@@ -0,0 +1,100 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+const os = require('os');
+
+const nodePreGypVersioning = require('node-pre-gyp/lib/util/versioning');
+
+function getElectronVersion(packageJson) {
+    // should we pick the version of an installed electron
+    // dependency, and if so, before or after electronVersion?
+    if (packageJson.build && packageJson.build.electronVersion) {
+        return packageJson.build.electronVersion;
+    }
+    return null;
+}
+
+function getRuntime(packageJson) {
+    const electronVersion = getElectronVersion(packageJson);
+    return electronVersion ? 'electron' : 'node-webkit';
+}
+
+function getTarget(packageJson) {
+    const electronVersion = getElectronVersion(packageJson);
+    if (electronVersion) {
+        return electronVersion;
+    } else {
+        return process.version.substr(1);
+    }
+}
+
+
+module.exports = class HakEnv {
+    constructor(prefix, packageJson) {
+        Object.assign(this, {
+            // what we're targeting
+            runtime: getRuntime(packageJson),
+            target: getTarget(packageJson),
+            platform: process.platform,
+            arch: process.arch,
+
+            // paths
+            projectRoot: prefix,
+            dotHakDir: path.join(prefix, '.hak'),
+        });
+    }
+
+    getRuntimeAbi() {
+        return nodePreGypVersioning.get_runtime_abi(
+            this.runtime,
+            this.target,
+        );
+    }
+
+    // {node_abi}-{platform}-{arch}
+    getNodeTriple() {
+        return this.getRuntimeAbi() + '-' + this.platform + '-' + this.arch;
+    }
+
+    isWin() {
+        return this.platform === 'win32';
+    }
+
+    isMac() {
+        return this.platform === 'darwin';
+    }
+
+    isLinux() {
+        return this.platform === 'linux';
+    }
+
+    makeGypEnv() {
+        return Object.assign({}, process.env, {
+            npm_config_target: this.target,
+            npm_config_arch: this.arch,
+            npm_config_target_arch: this.arch,
+            npm_config_disturl: 'https://atom.io/download/electron',
+            npm_config_runtime: this.runtime,
+            npm_config_build_from_source: true,
+            npm_config_devdir: path.join(os.homedir(), ".electron-gyp"),
+        });
+    }
+
+    getNodeModuleBin(name) {
+        return path.join(this.projectRoot, 'node_modules', '.bin', name);
+    }
+};

scripts/hak/index.js

@@ -0,0 +1,131 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+const fsProm = require('fs').promises;
+
+const findNpmPrefix = require('find-npm-prefix');
+
+const HakEnv = require('./hakEnv');
+
+const GENERALCOMMANDS = [
+    'target',
+];
+
+// These can only be run on specific modules
+const MODULECOMMANDS = [
+    'fetch',
+    'link',
+    'fetchDeps',
+    'build',
+    'copy',
+    'clean',
+];
+
+const HAKSCRIPTS = [
+    'fetch',
+    'fetchDeps',
+    'build',
+];
+
+async function main() {
+    const prefix = await findNpmPrefix(process.cwd());
+    let packageJson;
+    try {
+        packageJson = require(path.join(prefix, "package.json"));
+    } catch (e) {
+        console.error("Can't find a package.json!");
+        process.exit(1);
+    }
+
+    const hakEnv = new HakEnv(prefix, packageJson);
+
+    const deps = {};
+
+    const hakDepsCfg = packageJson.hakDependencies || {};
+
+    for (const dep of Object.keys(hakDepsCfg)) {
+        const hakJsonPath = path.join(prefix, 'hak', dep, 'hak.json');
+        let hakJson;
+        try {
+            hakJson = await require(hakJsonPath);
+        } catch (e) {
+            console.error("No hak.json found for " + dep + ".");
+            console.log("Expecting " + hakJsonPath);
+            process.exit(1);
+        }
+        deps[dep] = {
+            name: dep,
+            version: hakDepsCfg[dep],
+            cfg: hakJson,
+            moduleHakDir: path.join(hakEnv.dotHakDir, dep),
+            moduleBuildDir: path.join(hakEnv.dotHakDir, dep, 'build'),
+            moduleOutDir: path.join(hakEnv.dotHakDir, dep, 'out'),
+            nodeModuleBinDir: path.join(hakEnv.dotHakDir, dep, 'build', 'node_modules', '.bin'),
+            depPrefix: path.join(hakEnv.dotHakDir, dep, 'opt'),
+            scripts: {},
+        };
+
+        for (const s of HAKSCRIPTS) {
+            if (hakJson.scripts && hakJson.scripts[s]) {
+                deps[dep].scripts[s] = require(path.join(prefix, 'hak', dep, hakJson.scripts[s]));
+            }
+        }
+    }
+
+    if (process.argv.length < 3) {
+        console.log("Usage: hak <command> [modules...]");
+        process.exit(1);
+    }
+
+    const cmd = process.argv[2];
+    if (GENERALCOMMANDS.includes(cmd)) {
+        if (cmd === 'target') {
+            console.log(hakEnv.getNodeTriple());
+        }
+        return;
+    }
+
+    if (!MODULECOMMANDS.includes(cmd)) {
+        console.error("Unknown command: " + cmd);
+        console.log("Commands I know about:");
+        for (const cmd of MODULECOMMANDS) {
+            console.log("\t" + cmd);
+        }
+        process.exit(1);
+    }
+
+    const cmdFunc = require('./' + cmd);
+
+    let modules = process.argv.slice(3);
+
+    if (modules.length === 0) modules = Object.keys(deps);
+
+    for (const mod of modules) {
+        const depInfo = deps[mod];
+        if (depInfo === undefined) {
+            console.log(
+                "Module " + mod + " not found - is it in hakDependencies " +
+                "in your package.json?",
+            );
+            process.exit(1);
+        }
+        console.log("hak " + cmd + ": " + mod);
+        await cmdFunc(hakEnv, depInfo);
+    }
+}
+
+main();

scripts/hak/link.js

@@ -0,0 +1,60 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+const path = require('path');
+const os = require('os');
+const fsProm = require('fs').promises;
+const child_process = require('child_process');
+
+async function link(hakEnv, moduleInfo) {
+    const yarnrc = path.join(hakEnv.projectRoot, '.yarnrc');
+    // this is fairly terrible but it's reasonably clunky to either parse a yarnrc
+    // properly or get yarn to do it, so this will probably suffice for now.
+    // We just check to see if there is a local .yarnrc at all, and assume that
+    // if you've put one there yourself, you probably know what you're doing and
+    // we won't meddle with it.
+    // Also we do this for each module which is unnecessary, but meh.
+    try {
+        await fsProm.stat(yarnrc);
+    } catch (e) {
+        await fsProm.writeFile(
+            yarnrc, 
+            '--link-folder ' + path.join(hakEnv.dotHakDir, 'links') + os.EOL,
+        );
+    }
+
+    await new Promise((resolve, reject) => {
+        const proc = child_process.spawn('yarn', ['link'], {
+            cwd: moduleInfo.moduleOutDir,
+            stdio: 'inherit',
+        });
+        proc.on('exit', code => {
+            code ? reject(code) : resolve();
+        });
+    });
+
+    await new Promise((resolve, reject) => {
+        const proc = child_process.spawn('yarn', ['link', moduleInfo.name], {
+            cwd: hakEnv.projectRoot,
+            stdio: 'inherit',
+        });
+        proc.on('exit', code => {
+            code ? reject(code) : resolve();
+        });
+    });
+};
+
+module.exports = link;