Add a helper function for finding the git repo

packages/git/src/git-helpers.js

@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2024  Puter Technologies Inc.
+ *
+ * This file is part of Puter's Git client.
+ *
+ * Puter's Git client is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+import path from 'path-browserify';
+
+/**
+ * Attempt to locate the git repository directory.
+ * @throws Error If no git repository could be found, or another error occurred.
+ * @param fs Filesystem API
+ * @param pwd Directory to search from
+ * @returns {Promise<{repository_dir: (string|*), git_dir: (string|string)}>}
+ */
+export const find_repo_root = async (fs, pwd) => {
+    if (!path.isAbsolute(pwd))
+        throw new Error(`PWD is not absolute: ${pwd}`);
+
+    let current_path = path.normalize(pwd);
+    while (true) {
+        let stat;
+        const current_git_path = path.resolve(current_path, './.git');
+        try {
+            stat = await fs.promises.stat(current_git_path);
+        } catch (e) {
+            if (e.code === 'ENOENT') {
+                if (current_path === '/')
+                    break;
+
+                current_path = path.dirname(current_path);
+                continue;
+            }
+
+            throw e;
+        }
+
+        // If .git exists, we're probably in a git repo so call that good.
+        // TODO: The git cli seems to check other things, maybe try to match that behaviour.
+
+        const result = {
+            repository_dir: current_path,
+            git_dir: current_git_path,
+        };
+
+        // Non-default-git-folder repos have .git as a text file containing the git dir path.
+        if (stat.isFile()) {
+            const contents = await fs.promises.readFile(current_git_path, { encoding: 'utf8' });
+            // The format of .git is `gitdir: /path/to/git/dir`
+            const prefix = 'gitdir:';
+            if (!contents.startsWith(prefix))
+                throw new Error(`invalid gitfile format: ${current_git_path}`);
+            result.git_dir = contents.slice(prefix.length).trim();
+        }
+
+        return result;
+    }
+
+    throw new Error('not a git repository (or any of the parent directories): .git');
+}