fix: upgrade cross-spawn (ReDoS), harden hook install and spawn handling

.gitignore

@@ -1,4 +1,5 @@
 node_modules
 npm-debug.log
 coverage
+.nyc_output
 .tern-port

hook

@@ -37,6 +37,15 @@ elif [[ -x "$LOCAL" ]]; then
   BINARY="$LOCAL"
 fi
 
+#
+# Run from the repository root so `require.resolve('pre-commit')` works for Yarn PnP,
+# and GUI git clients that invoke hooks with an unexpected cwd still resolve deps.
+#
+REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null)" || REPO_ROOT=""
+if [[ -n "$REPO_ROOT" ]]; then
+  cd "$REPO_ROOT" || exit 1
+fi
+
 #
 # Add --dry-run cli flag support so we can execute this hook without side effects
 # and see if it works in the current environment
@@ -46,5 +55,5 @@ if [[ $* == *--dry-run* ]]; then
     exit 1
   fi
 else
-  "$BINARY" "$("$BINARY" -e "console.log(require.resolve('pre-commit'))")"
+  exec "$BINARY" "$("$BINARY" -e "console.log(require.resolve('pre-commit'))")"
 fi

index.js

@@ -1,5 +1,16 @@
 'use strict';
 
+//
+// cross-spawn.spawnSync returns the same shape as child_process.spawnSync
+// (`status`, not `code`).
+//
+function failedSpawn(result) {
+  if (!result) return true;
+  if (result.error) return true;
+  if (result.signal) return true;
+  return result.status !== 0;
+}
+
 var spawn = require('cross-spawn')
   , which = require('which')
   , path = require('path')
@@ -173,8 +184,8 @@ Hook.prototype.initialize = function initialize() {
   this.root = this.exec(this.git, ['rev-parse', '--show-toplevel']);
   this.status = this.exec(this.git, ['status', '--porcelain']);
 
-  if (this.status.code) return this.log(Hook.log.status, 0);
-  if (this.root.code) return this.log(Hook.log.root, 0);
+  if (failedSpawn(this.status)) return this.log(Hook.log.status, 0);
+  if (failedSpawn(this.root)) return this.log(Hook.log.root, 0);
 
   this.status = this.status.stdout.toString().trim();
   this.root = this.root.stdout.toString().trim();
@@ -229,8 +240,11 @@ Hook.prototype.run = function runner() {
       env: process.env,
       cwd: hooked.root,
       stdio: [0, 1, 2]
-    }).once('close', function closed(code) {
-      if (code) return hooked.log(hooked.format(Hook.log.failure, script, code));
+    }).once('close', function closed(code, signal) {
+      var exitCode = typeof code === 'number' ? code : (signal ? 1 : 0);
+      if (exitCode !== 0) {
+        return hooked.log(hooked.format(Hook.log.failure, script, exitCode));
+      }
 
       again(scripts);
     });

install.js

@@ -7,9 +7,17 @@ var fs = require('fs')
   , path = require('path')
   , os = require('os')
   , hook = path.join(__dirname, 'hook')
+  , hookAbs = path.resolve(hook)
   , root = path.resolve(__dirname, '..', '..')
   , exists = fs.existsSync || path.existsSync;
 
+//
+// POSIX single-quoted string for embedding paths in generated shell scripts.
+//
+function shellSingleQuote(str) {
+  return '\'' + str.replace(/'/g, '\'\\\'\'') + '\'';
+}
+
 //
 // Gather the location of the possible hidden .git directory, the hooks
 // directory which contains all git hooks and the absolute location of the
@@ -45,10 +53,10 @@ function getGitFolderPath(currentPath) {
 //
 // Resolve git directory for submodules
 //
-if (exists(git) && fs.lstatSync(git).isFile()) {
+if (git && exists(git) && fs.lstatSync(git).isFile()) {
   var gitinfo = fs.readFileSync(git).toString()
     , gitdirmatch = /gitdir: (.+)/.exec(gitinfo)
-    , gitdir = gitdirmatch.length == 2 ? gitdirmatch[1] : null;
+    , gitdir = gitdirmatch && gitdirmatch.length === 2 ? gitdirmatch[1].trim() : null;
 
   if (gitdir !== null) {
     git = path.resolve(root, gitdir);
@@ -92,20 +100,17 @@ if (exists(precommit) && !fs.lstatSync(precommit).isSymbolicLink()) {
 try { fs.unlinkSync(precommit); }
 catch (e) {}
 
-// Create generic precommit hook that launches this modules hook (as well
-// as stashing - unstashing the unstaged changes)
-// TODO: we could keep launching the old pre-commit scripts
-var hookRelativeUnixPath = hook.replace(root, '.');
-
-if(os.platform() === 'win32') {
-  hookRelativeUnixPath = hookRelativeUnixPath.replace(/[\\\/]+/g, '/');
+// Delegate to this package's `hook` script using an absolute path so Yarn Plug'n'Play
+// and other layouts without `node_modules/pre-commit` still work. The hook script
+// changes to the git root before resolving `pre-commit` via Node.
+//
+var hookLauncher = hookAbs;
+if (os.platform() === 'win32') {
+  hookLauncher = hookLauncher.replace(/\\/g, '/');
 }
 
 var precommitContent = '#!/usr/bin/env bash' + os.EOL
-  +  hookRelativeUnixPath + os.EOL
-  + 'RESULT=$?' + os.EOL
-  + '[ $RESULT -ne 0 ] && exit 1' + os.EOL
-  + 'exit 0' + os.EOL;
+  + 'exec bash ' + shellSingleQuote(hookLauncher) + ' "$@"' + os.EOL;
 
 //
 // It could be that we do not have rights to this folder which could cause the
@@ -121,10 +126,10 @@ catch (e) {
   console.error('pre-commit:');
 }
 
-try { fs.chmodSync(precommit, '777'); }
+try { fs.chmodSync(precommit, 0o755); }
 catch (e) {
   console.error('pre-commit:');
-  console.error('pre-commit: chmod 0777 the pre-commit file in your .git/hooks folder because:');
+  console.error('pre-commit: chmod 0755 the pre-commit file in your .git/hooks folder because:');
   console.error('pre-commit: '+ e.message);
   console.error('pre-commit:');
 }