fs: add followSymlinks option to glob methods and tests for symlink handling

Author: MatricalDefunkt

doc/api/fs.md

@@ -1115,6 +1115,8 @@ changes:
     If a string array is provided, each string should be a glob pattern that
     specifies paths to exclude. Note: Negation patterns (e.g., '!foo.js') are
     not supported.
+  * `followSymlinks` {boolean} `true` if the glob should traverse symbolic
+    links to directories, `false` otherwise. **Default:** `false`.
   * `withFileTypes` {boolean} `true` if the glob should return paths as Dirents,
     `false` otherwise. **Default:** `false`.
 * Returns: {AsyncIterator} An AsyncIterator that yields the paths of files
@@ -3215,6 +3217,8 @@ changes:
   * `exclude` {Function|string\[]} Function to filter out files/directories or a
     list of glob patterns to be excluded. If a function is provided, return
     `true` to exclude the item, `false` to include it. **Default:** `undefined`.
+  * `followSymlinks` {boolean} `true` if the glob should traverse symbolic
+    links to directories, `false` otherwise. **Default:** `false`.
   * `withFileTypes` {boolean} `true` if the glob should return paths as Dirents,
     `false` otherwise. **Default:** `false`.
 
@@ -5772,6 +5776,8 @@ changes:
   * `exclude` {Function|string\[]} Function to filter out files/directories or a
     list of glob patterns to be excluded. If a function is provided, return
     `true` to exclude the item, `false` to include it. **Default:** `undefined`.
+  * `followSymlinks` {boolean} `true` if the glob should traverse symbolic
+    links to directories, `false` otherwise. **Default:** `false`.
   * `withFileTypes` {boolean} `true` if the glob should return paths as Dirents,
     `false` otherwise. **Default:** `false`.
 * Returns: {string\[]} paths of files that match the pattern.

lib/internal/fs/glob.js

@@ -16,8 +16,8 @@ const {
   StringPrototypeEndsWith,
 } = primordials;
 
-const { lstatSync, readdirSync } = require('fs');
-const { lstat, readdir } = require('fs/promises');
+const { lstatSync, readdirSync, statSync } = require('fs');
+const { lstat, readdir, stat } = require('fs/promises');
 const { join, resolve, basename, isAbsolute, dirname } = require('path');
 
 const {
@@ -48,28 +48,46 @@ function lazyMinimatch() {
 
 /**
  * @param {string} path
+ * @param {boolean} followSymlinks
  * @returns {Promise<DirentFromStats|null>}
  */
-async function getDirent(path) {
-  let stat;
+async function getDirent(path, followSymlinks = false) {
+  let statResult;
   try {
-    stat = await lstat(path);
+    statResult = await lstat(path);
+    // If it's a symlink and followSymlinks is true, use stat to follow it
+    if (followSymlinks && statResult.isSymbolicLink()) {
+      try {
+        statResult = await stat(path);
+      } catch {
+        // If stat fails (e.g., broken symlink), keep the lstat result
+      }
+    }
   } catch {
     return null;
   }
-  return new DirentFromStats(basename(path), stat, dirname(path));
+  return new DirentFromStats(basename(path), statResult, dirname(path));
 }
 
 /**
  * @param {string} path
+ * @param {boolean} followSymlinks
  * @returns {DirentFromStats|null}
  */
-function getDirentSync(path) {
-  const stat = lstatSync(path, { throwIfNoEntry: false });
-  if (stat === undefined) {
+function getDirentSync(path, followSymlinks = false) {
+  let statResult = lstatSync(path, { throwIfNoEntry: false });
+  if (statResult === undefined) {
     return null;
   }
-  return new DirentFromStats(basename(path), stat, dirname(path));
+  // If it's a symlink and followSymlinks is true, use statSync to follow it
+  if (followSymlinks && statResult.isSymbolicLink()) {
+    const followedStat = statSync(path, { throwIfNoEntry: false });
+    if (followedStat !== undefined) {
+      statResult = followedStat;
+    }
+    // If followedStat is undefined (broken symlink), keep the lstat result
+  }
+  return new DirentFromStats(basename(path), statResult, dirname(path));
 }
 
 /**
@@ -115,13 +133,22 @@ class Cache {
   #cache = new SafeMap();
   #statsCache = new SafeMap();
   #readdirCache = new SafeMap();
+  #followSymlinks = false;
+
+  setFollowSymlinks(followSymlinks) {
+    this.#followSymlinks = followSymlinks;
+  }
+
+  isFollowSymlinks() {
+    return this.#followSymlinks;
+  }
 
   stat(path) {
     const cached = this.#statsCache.get(path);
     if (cached) {
       return cached;
     }
-    const promise = getDirent(path);
+    const promise = getDirent(path, this.#followSymlinks);
     this.#statsCache.set(path, promise);
     return promise;
   }
@@ -131,7 +158,7 @@ class Cache {
     if (cached && !(cached instanceof Promise)) {
       return cached;
     }
-    const val = getDirentSync(path);
+    const val = getDirentSync(path, this.#followSymlinks);
     this.#statsCache.set(path, val);
     return val;
   }
@@ -267,9 +294,12 @@ class Glob {
   #isExcluded = () => false;
   constructor(pattern, options = kEmptyObject) {
     validateObject(options, 'options');
-    const { exclude, cwd, withFileTypes } = options;
+    const { exclude, cwd, withFileTypes, followSymlinks } = options;
     this.#root = toPathIfFileURL(cwd) ?? '.';
     this.#withFileTypes = !!withFileTypes;
+    if (followSymlinks === true) {
+      this.#cache.setFollowSymlinks(true);
+    }
     if (exclude != null) {
       validateStringArrayOrFunction(exclude, 'options.exclude');
       if (ArrayIsArray(exclude)) {
@@ -427,7 +457,18 @@ class Glob {
     for (let i = 0; i < children.length; i++) {
       const entry = children[i];
       const entryPath = join(path, entry.name);
-      this.#cache.addToStatCache(join(fullpath, entry.name), entry);
+
+      // If followSymlinks is enabled and entry is a symlink, resolve it
+      let resolvedEntry = entry;
+      if (this.#cache.isFollowSymlinks() && entry.isSymbolicLink()) {
+        const resolved = this.#cache.statSync(join(fullpath, entry.name));
+        if (resolved && !resolved.isSymbolicLink()) {
+          resolvedEntry = resolved;
+          resolvedEntry.name = entry.name;
+        }
+      }
+
+      this.#cache.addToStatCache(join(fullpath, entry.name), resolvedEntry);
 
       const subPatterns = new SafeSet();
       const nSymlinks = new SafeSet();
@@ -453,10 +494,10 @@ class Glob {
           const matchesDot = isDot && pattern.test(nextNonGlobIndex, entry.name);
 
           if ((isDot && !matchesDot) ||
-              (this.#exclude && this.#exclude(this.#withFileTypes ? entry : entry.name))) {
+              (this.#exclude && this.#exclude(this.#withFileTypes ? resolvedEntry : entry.name))) {
             continue;
           }
-          if (!fromSymlink && entry.isDirectory()) {
+          if (!fromSymlink && resolvedEntry.isDirectory()) {
             // If directory, add ** to its potential patterns
             subPatterns.add(index);
           } else if (!fromSymlink && index === last) {
@@ -469,24 +510,24 @@ class Glob {
           if (nextMatches && nextIndex === last && !isLast) {
             // If next pattern is the last one, add to results
             this.#results.add(entryPath);
-          } else if (nextMatches && entry.isDirectory()) {
+          } else if (nextMatches && resolvedEntry.isDirectory()) {
             // Pattern matched, meaning two patterns forward
             // are also potential patterns
             // e.g **/b/c when entry is a/b - add c to potential patterns
             subPatterns.add(index + 2);
           }
           if ((nextMatches || pattern.at(0) === '.') &&
-           (entry.isDirectory() || entry.isSymbolicLink()) && !fromSymlink) {
+           (resolvedEntry.isDirectory() || resolvedEntry.isSymbolicLink()) && !fromSymlink) {
             // If pattern after ** matches, or pattern starts with "."
             // and entry is a directory or symlink, add to potential patterns
             subPatterns.add(nextIndex);
           }
 
-          if (entry.isSymbolicLink()) {
+          if (resolvedEntry.isSymbolicLink()) {
             nSymlinks.add(index);
           }
 
-          if (next === '..' && entry.isDirectory()) {
+          if (next === '..' && resolvedEntry.isDirectory()) {
             // In case pattern is "**/..",
             // both parent and current directory should be added to the queue
             // if this is the last pattern, add to results instead
@@ -529,7 +570,7 @@ class Glob {
           // add next pattern to potential patterns, or to results if it's the last pattern
           if (index === last) {
             this.#results.add(entryPath);
-          } else if (entry.isDirectory()) {
+          } else if (resolvedEntry.isDirectory()) {
             subPatterns.add(nextIndex);
           }
         }
@@ -637,7 +678,18 @@ class Glob {
     for (let i = 0; i < children.length; i++) {
       const entry = children[i];
       const entryPath = join(path, entry.name);
-      this.#cache.addToStatCache(join(fullpath, entry.name), entry);
+
+      // If followSymlinks is enabled and entry is a symlink, resolve it
+      let resolvedEntry = entry;
+      if (this.#cache.isFollowSymlinks() && entry.isSymbolicLink()) {
+        const resolved = await this.#cache.stat(join(fullpath, entry.name));
+        if (resolved && !resolved.isSymbolicLink()) {
+          resolvedEntry = resolved;
+          resolvedEntry.name = entry.name;
+        }
+      }
+
+      this.#cache.addToStatCache(join(fullpath, entry.name), resolvedEntry);
 
       const subPatterns = new SafeSet();
       const nSymlinks = new SafeSet();
@@ -663,16 +715,16 @@ class Glob {
           const matchesDot = isDot && pattern.test(nextNonGlobIndex, entry.name);
 
           if ((isDot && !matchesDot) ||
-              (this.#exclude && this.#exclude(this.#withFileTypes ? entry : entry.name))) {
+              (this.#exclude && this.#exclude(this.#withFileTypes ? resolvedEntry : entry.name))) {
             continue;
           }
-          if (!fromSymlink && entry.isDirectory()) {
+          if (!fromSymlink && resolvedEntry.isDirectory()) {
             // If directory, add ** to its potential patterns
             subPatterns.add(index);
           } else if (!fromSymlink && index === last) {
             // If ** is last, add to results
             if (!this.#results.has(entryPath) && this.#results.add(entryPath)) {
-              yield this.#withFileTypes ? entry : entryPath;
+              yield this.#withFileTypes ? resolvedEntry : entryPath;
             }
           }
 
@@ -681,26 +733,26 @@ class Glob {
           if (nextMatches && nextIndex === last && !isLast) {
             // If next pattern is the last one, add to results
             if (!this.#results.has(entryPath) && this.#results.add(entryPath)) {
-              yield this.#withFileTypes ? entry : entryPath;
+              yield this.#withFileTypes ? resolvedEntry : entryPath;
             }
-          } else if (nextMatches && entry.isDirectory()) {
+          } else if (nextMatches && resolvedEntry.isDirectory()) {
             // Pattern matched, meaning two patterns forward
             // are also potential patterns
             // e.g **/b/c when entry is a/b - add c to potential patterns
             subPatterns.add(index + 2);
           }
           if ((nextMatches || pattern.at(0) === '.') &&
-           (entry.isDirectory() || entry.isSymbolicLink()) && !fromSymlink) {
+           (resolvedEntry.isDirectory() || resolvedEntry.isSymbolicLink()) && !fromSymlink) {
             // If pattern after ** matches, or pattern starts with "."
             // and entry is a directory or symlink, add to potential patterns
             subPatterns.add(nextIndex);
           }
 
-          if (entry.isSymbolicLink()) {
+          if (resolvedEntry.isSymbolicLink()) {
             nSymlinks.add(index);
           }
 
-          if (next === '..' && entry.isDirectory()) {
+          if (next === '..' && resolvedEntry.isDirectory()) {
             // In case pattern is "**/..",
             // both parent and current directory should be added to the queue
             // if this is the last pattern, add to results instead
@@ -742,7 +794,7 @@ class Glob {
             if (nextIndex === last) {
               if (!this.#results.has(entryPath)) {
                 if (this.#results.add(entryPath)) {
-                  yield this.#withFileTypes ? entry : entryPath;
+                  yield this.#withFileTypes ? resolvedEntry : entryPath;
                 }
               }
             } else {
@@ -756,10 +808,10 @@ class Glob {
           if (index === last) {
             if (!this.#results.has(entryPath)) {
               if (this.#results.add(entryPath)) {
-                yield this.#withFileTypes ? entry : entryPath;
+                yield this.#withFileTypes ? resolvedEntry : entryPath;
               }
             }
-          } else if (entry.isDirectory()) {
+          } else if (resolvedEntry.isDirectory()) {
             subPatterns.add(nextIndex);
           }
         }