Add env var support for home dir

packages/safe-chain/src/config/environmentVariables.js

@@ -55,3 +55,14 @@ export function getMinimumPackageAgeExclusions() {
 export function getMalwareListBaseUrl() {
   return process.env.SAFE_CHAIN_MALWARE_LIST_BASE_URL;
 }
+
+/**
+ * Gets the safe-chain base directory from environment variable.
+ * When set, all safe-chain data (bin, shims, scripts) will be placed under this directory
+ * instead of the default ~/.safe-chain, enabling system-wide installations.
+ * Example: "/usr/local/.safe-chain"
+ * @returns {string | undefined}
+ */
+export function getSafeChainDir() {
+  return process.env.SAFE_CHAIN_DIR;
+}

packages/safe-chain/src/config/environmentVariables.spec.js

@@ -0,0 +1,30 @@
+import { describe, it, beforeEach, afterEach } from "node:test";
+import assert from "node:assert";
+
+const { getSafeChainDir } = await import("./environmentVariables.js");
+
+describe("getSafeChainDir", () => {
+  let original;
+
+  beforeEach(() => {
+    original = process.env.SAFE_CHAIN_DIR;
+  });
+
+  afterEach(() => {
+    if (original !== undefined) {
+      process.env.SAFE_CHAIN_DIR = original;
+    } else {
+      delete process.env.SAFE_CHAIN_DIR;
+    }
+  });
+
+  it("returns undefined when SAFE_CHAIN_DIR is not set", () => {
+    delete process.env.SAFE_CHAIN_DIR;
+    assert.strictEqual(getSafeChainDir(), undefined);
+  });
+
+  it("returns the value of SAFE_CHAIN_DIR when set", () => {
+    process.env.SAFE_CHAIN_DIR = "/usr/local/.safe-chain";
+    assert.strictEqual(getSafeChainDir(), "/usr/local/.safe-chain");
+  });
+});

packages/safe-chain/src/shell-integration/helpers.js

@@ -3,6 +3,7 @@ import * as os from "os";
 import fs from "fs";
 import path from "path";
 import { ECOSYSTEM_JS, ECOSYSTEM_PY } from "../config/settings.js";
+import { getSafeChainDir } from "../config/environmentVariables.js";
 import { safeSpawn } from "../utils/safeSpawn.js";
 import { ui } from "../environment/userInteraction.js";
 
@@ -121,18 +122,34 @@ export function getPackageManagerList() {
   return `${tools.join(", ")}, and ${lastTool} commands`;
 }
 
+/**
+ * Returns the safe-chain base directory.
+ * Uses SAFE_CHAIN_DIR environment variable when set, otherwise defaults to ~/.safe-chain.
+ * @returns {string}
+ */
+export function getSafeChainBaseDir() {
+  return getSafeChainDir() ?? path.join(os.homedir(), ".safe-chain");
+}
+
+/**
+ * @returns {string}
+ */
+export function getBinDir() {
+  return path.join(getSafeChainBaseDir(), "bin");
+}
+
 /**
  * @returns {string}
  */
 export function getShimsDir() {
-  return path.join(os.homedir(), ".safe-chain", "shims");
+  return path.join(getSafeChainBaseDir(), "shims");
 }
 
 /**
  * @returns {string}
  */
 export function getScriptsDir() {
-  return path.join(os.homedir(), ".safe-chain", "scripts");
+  return path.join(getSafeChainBaseDir(), "scripts");
 }
 
 /**

packages/safe-chain/src/shell-integration/helpers.spec.js

@@ -1,6 +1,6 @@
 import { describe, it, beforeEach, afterEach, mock } from "node:test";
 import assert from "node:assert";
-import { tmpdir } from "node:os";
+import { tmpdir, homedir } from "node:os";
 import fs from "node:fs";
 import path from "path";
 
@@ -15,6 +15,7 @@ describe("removeLinesMatchingPatternTests", () => {
     mock.module("node:os", {
       namedExports: {
         EOL: "\r\n", // Simulate Windows line endings
+        homedir,
         tmpdir: tmpdir,
         platform: () => "linux",
       },
@@ -182,3 +183,66 @@ describe("removeLinesMatchingPatternTests", () => {
     assert.strictEqual(resultLines.length, 5, "Should have exactly 5 lines");
   });
 });
+
+describe("getSafeChainBaseDir / getBinDir / getShimsDir / getScriptsDir", () => {
+  const customDir = "/usr/local/.safe-chain";
+
+  let originalSafeChainDir;
+
+  beforeEach(() => {
+    originalSafeChainDir = process.env.SAFE_CHAIN_DIR;
+    delete process.env.SAFE_CHAIN_DIR;
+  });
+
+  afterEach(() => {
+    if (originalSafeChainDir !== undefined) {
+      process.env.SAFE_CHAIN_DIR = originalSafeChainDir;
+    } else {
+      delete process.env.SAFE_CHAIN_DIR;
+    }
+  });
+
+  it("defaults base dir to ~/.safe-chain when SAFE_CHAIN_DIR is not set", async () => {
+    const { getSafeChainBaseDir } = await import("./helpers.js");
+    assert.strictEqual(getSafeChainBaseDir(), path.join(homedir(), ".safe-chain"));
+  });
+
+  it("uses SAFE_CHAIN_DIR as base dir when set", async () => {
+    process.env.SAFE_CHAIN_DIR = customDir;
+    const { getSafeChainBaseDir } = await import("./helpers.js");
+    assert.strictEqual(getSafeChainBaseDir(), customDir);
+  });
+
+  it("getBinDir returns ~/.safe-chain/bin by default", async () => {
+    const { getBinDir } = await import("./helpers.js");
+    assert.strictEqual(getBinDir(), path.join(homedir(), ".safe-chain", "bin"));
+  });
+
+  it("getBinDir returns custom dir + /bin when SAFE_CHAIN_DIR is set", async () => {
+    process.env.SAFE_CHAIN_DIR = customDir;
+    const { getBinDir } = await import("./helpers.js");
+    assert.strictEqual(getBinDir(), `${customDir}/bin`);
+  });
+
+  it("getShimsDir returns ~/.safe-chain/shims by default", async () => {
+    const { getShimsDir } = await import("./helpers.js");
+    assert.strictEqual(getShimsDir(), path.join(homedir(), ".safe-chain", "shims"));
+  });
+
+  it("getShimsDir returns custom dir + /shims when SAFE_CHAIN_DIR is set", async () => {
+    process.env.SAFE_CHAIN_DIR = customDir;
+    const { getShimsDir } = await import("./helpers.js");
+    assert.strictEqual(getShimsDir(), `${customDir}/shims`);
+  });
+
+  it("getScriptsDir returns ~/.safe-chain/scripts by default", async () => {
+    const { getScriptsDir } = await import("./helpers.js");
+    assert.strictEqual(getScriptsDir(), path.join(homedir(), ".safe-chain", "scripts"));
+  });
+
+  it("getScriptsDir returns custom dir + /scripts when SAFE_CHAIN_DIR is set", async () => {
+    process.env.SAFE_CHAIN_DIR = customDir;
+    const { getScriptsDir } = await import("./helpers.js");
+    assert.strictEqual(getScriptsDir(), `${customDir}/scripts`);
+  });
+});