Follow symbolic links during glob expansion

nkakouros-nordsnipe · nkakouros-nordsnipe · commit 86c5772ae381 · 2026-04-27T19:19:57.000+03:00
FileResolver.listElements() unconditionally skipped all symlinks to
prevent cyclical globs from directory symlinks. As a side effect,
import*() and read*() silently dropped symlinks to regular files from
their results, returning partial output with no warning, and skipped
symlinks to directories even when no cycle existed.

Stop filtering symlinks. Switch the directory check from
Files.isDirectory(), which silently returns false on errors, to
Files.readAttributes(), which lets I/O errors propagate. This way the
existing OS-level symlink-resolution limit surfaces a clear "Too many
levels of symbolic links" error on cycles instead of a silent
truncation. Broken symlinks are still surfaced as non-directory entries
via a NoSuchFileException catch.
diff --git a/docs/modules/release-notes/pages/changelog.adoc b/docs/modules/release-notes/pages/changelog.adoc
@@ -4,6 +4,11 @@ include::ROOT:partial$component-attributes.adoc[]
 [[release-0.32.0]]
 == 0.32.0 (UNRELEASED)
 
+=== Fixes
+
+* Follow symbolic links during `import*` and `read*` glob expansion; symlink cycles now surface as a clear I/O error
+(pr:https://github.com/apple/pkl/pull/XXXX[]).
+
 [[release-0.31.1]]
 == 0.31.1 (2026-03-26)
 
diff --git a/pkl-core/src/main/java/org/pkl/core/module/FileResolver.java b/pkl-core/src/main/java/org/pkl/core/module/FileResolver.java
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@
 import java.nio.file.NoSuchFileException;
 import java.nio.file.NotDirectoryException;
 import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -37,11 +38,16 @@ public static List<PathElement> listElements(Path path) throws IOException {
     try (var stream = Files.newDirectoryStream(path)) {
       var ret = new ArrayList<PathElement>();
       for (var entry : stream) {
-        // skip symlinks to prevent cyclical globs
-        if (Files.isSymbolicLink(entry)) {
-          continue;
+        // Use readAttributes (rather than Files.isDirectory) so that errors like
+        // "Too many levels of symbolic links" surface as IOException instead of being
+        // silently swallowed. Broken symlinks still go through as non-directory entries.
+        boolean isDirectory;
+        try {
+          isDirectory = Files.readAttributes(entry, BasicFileAttributes.class).isDirectory();
+        } catch (NoSuchFileException ignored) {
+          isDirectory = false;
         }
-        ret.add(new PathElement(entry.getFileName().toString(), Files.isDirectory(entry)));
+        ret.add(new PathElement(entry.getFileName().toString(), isDirectory));
       }
       return ret;
     } catch (NotDirectoryException | NoSuchFileException ignored) {
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/linked-dir b/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/linked-dir
@@ -0,0 +1 @@
+subdir
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/linked.pkl b/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/linked.pkl
@@ -0,0 +1 @@
+real-target.pkl
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/real-target.pkl b/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/real-target.pkl
@@ -0,0 +1 @@
+name = "real-target"
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/subdir/inner.pkl b/pkl-core/src/test/files/LanguageSnippetTests/input-helper/globtest-symlink/subdir/inner.pkl
@@ -0,0 +1 @@
+name = "inner"
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/input/basic/importGlobSymlink.pkl b/pkl-core/src/test/files/LanguageSnippetTests/input/basic/importGlobSymlink.pkl
@@ -0,0 +1,19 @@
+amends ".../snippetTest.pkl"
+
+examples {
+  ["symlink to file is included"] {
+    import*("../../input-helper/globtest-symlink/*.pkl").keys.toListing()
+  }
+
+  ["symlink target content is read through symlink"] {
+    import*("../../input-helper/globtest-symlink/*.pkl")
+      .toMap()
+      .values
+      .map((it) -> it.name)
+      .toListing()
+  }
+
+  ["directory symlink is followed"] {
+    import*("../../input-helper/globtest-symlink/**.pkl").keys.toListing()
+  }
+}
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/output/basic/importGlob.pcf b/pkl-core/src/test/files/LanguageSnippetTests/output/basic/importGlob.pcf
@@ -19,6 +19,7 @@ examples {
       "../../input-helper/globtest/moduleA.pkl"
       "../../input-helper/globtest/moduleB.pkl"
       "../../input-helper/globtest/child/moduleC.pkl"
+      "../../input-helper/globtest/childlinked/moduleC.pkl"
     }
   }
   ["amended"] {
@@ -34,13 +35,19 @@ examples {
     ---
     name: child/moduleC
     
+    ---
+    name: child/moduleC
+    
     """
   }
   ["globstar then up one level"] {
     new {
       "../../input-helper/globtest/child/../module with [weird] ~!characters.pkl"
       "../../input-helper/globtest/child/../moduleA.pkl"
       "../../input-helper/globtest/child/../moduleB.pkl"
+      "../../input-helper/globtest/childlinked/../module with [weird] ~!characters.pkl"
+      "../../input-helper/globtest/childlinked/../moduleA.pkl"
+      "../../input-helper/globtest/childlinked/../moduleB.pkl"
     }
   }
   ["empty glob matches current directory"] {
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/output/basic/importGlobSymlink.pcf b/pkl-core/src/test/files/LanguageSnippetTests/output/basic/importGlobSymlink.pcf
@@ -0,0 +1,22 @@
+examples {
+  ["symlink to file is included"] {
+    new {
+      "../../input-helper/globtest-symlink/linked.pkl"
+      "../../input-helper/globtest-symlink/real-target.pkl"
+    }
+  }
+  ["symlink target content is read through symlink"] {
+    new {
+      "real-target"
+      "real-target"
+    }
+  }
+  ["directory symlink is followed"] {
+    new {
+      "../../input-helper/globtest-symlink/linked.pkl"
+      "../../input-helper/globtest-symlink/real-target.pkl"
+      "../../input-helper/globtest-symlink/linked-dir/inner.pkl"
+      "../../input-helper/globtest-symlink/subdir/inner.pkl"
+    }
+  }
+}
diff --git a/pkl-core/src/test/files/LanguageSnippetTests/output/basic/readGlob.pcf b/pkl-core/src/test/files/LanguageSnippetTests/output/basic/readGlob.pcf
@@ -27,6 +27,14 @@ examples {
         text = """
           name = "child/moduleC"
           
+          """
+        base64 = "bmFtZSA9ICJjaGlsZC9tb2R1bGVDIgo="
+      }
+      ["../../input-helper/globtest/childlinked/moduleC.pkl"] {
+        uri = "file:///$snippetsDir/input-helper/globtest/childlinked/moduleC.pkl"
+        text = """
+          name = "child/moduleC"
+          
           """
         base64 = "bmFtZSA9ICJjaGlsZC9tb2R1bGVDIgo="
       }
@@ -72,6 +80,11 @@ examples {
         text = "hi"
         base64 = "bmFtZSA9ICJjaGlsZC9tb2R1bGVDIgo="
       }
+      ["../../input-helper/globtest/childlinked/moduleC.pkl"] {
+        uri = "file:///$snippetsDir/input-helper/globtest/childlinked/moduleC.pkl"
+        text = "hi"
+        base64 = "bmFtZSA9ICJjaGlsZC9tb2R1bGVDIgo="
+      }
     }
   }
   ["env:"] {
diff --git a/pkl-core/src/test/kotlin/org/pkl/core/module/FileResolverTest.kt b/pkl-core/src/test/kotlin/org/pkl/core/module/FileResolverTest.kt
@@ -0,0 +1,83 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * 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
+ *
+ *     https://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.
+ */
+package org.pkl.core.module
+
+import java.nio.file.Files
+import java.nio.file.Path
+import kotlin.io.path.createDirectory
+import kotlin.io.path.createFile
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatCode
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import org.pkl.commons.writeString
+import org.pkl.core.EvaluatorBuilder
+import org.pkl.core.ModuleSource
+
+class FileResolverTest {
+  @Test
+  fun `includes symlink whose target is a regular file`(@TempDir tempDir: Path) {
+    val listedDir = tempDir.resolve("listed").createDirectory()
+    val otherDir = tempDir.resolve("other").createDirectory()
+    listedDir.resolve("real.pkl").createFile()
+    val target = otherDir.resolve("target.pkl").createFile()
+    Files.createSymbolicLink(listedDir.resolve("linked.pkl"), target)
+
+    val elements = FileResolver.listElements(listedDir)
+
+    assertThat(elements)
+      .containsExactlyInAnyOrder(PathElement("real.pkl", false), PathElement("linked.pkl", false))
+  }
+
+  @Test
+  fun `includes symlink whose target is a directory`(@TempDir tempDir: Path) {
+    val listedDir = tempDir.resolve("listed").createDirectory()
+    val otherDir = tempDir.resolve("other").createDirectory()
+    listedDir.resolve("real.pkl").createFile()
+    Files.createSymbolicLink(listedDir.resolve("linked-dir"), otherDir)
+
+    val elements = FileResolver.listElements(listedDir)
+
+    assertThat(elements)
+      .containsExactlyInAnyOrder(PathElement("real.pkl", false), PathElement("linked-dir", true))
+  }
+
+  @Test
+  fun `includes broken symlink as non-directory entry`(@TempDir tempDir: Path) {
+    tempDir.resolve("real.pkl").createFile()
+    Files.createSymbolicLink(tempDir.resolve("broken.pkl"), tempDir.resolve("missing.pkl"))
+
+    val elements = FileResolver.listElements(tempDir)
+
+    assertThat(elements)
+      .containsExactlyInAnyOrder(PathElement("real.pkl", false), PathElement("broken.pkl", false))
+  }
+
+  @Test
+  fun `glob expansion surfaces symlink cycle`(@TempDir tempDir: Path) {
+    val sources = tempDir.resolve("sources").createDirectory()
+    sources.resolve("real.pkl").createFile()
+    Files.createSymbolicLink(sources.resolve("loop"), sources)
+
+    val main = tempDir.resolve("main.pkl")
+    main.writeString("""result = import*("sources/**.pkl")""")
+
+    EvaluatorBuilder.preconfigured().build().use { evaluator ->
+      assertThatCode { evaluator.evaluateOutputText(ModuleSource.uri(main.toUri())) }
+        .hasMessageContaining("Too many levels of symbolic links")
+    }
+  }
+}

Original file line number	Diff line number	Diff line change
`@@ -19,6 +19,7 @@ examples {`
`19`	`19`	`"../../input-helper/globtest/moduleA.pkl"`
`20`	`20`	`"../../input-helper/globtest/moduleB.pkl"`
`21`	`21`	`"../../input-helper/globtest/child/moduleC.pkl"`
	`22`	`+ "../../input-helper/globtest/childlinked/moduleC.pkl"`
`22`	`23`	`}`
`23`	`24`	`}`
`24`	`25`	`["amended"] {`
`@@ -34,13 +35,19 @@ examples {`
`34`	`35`	`---`
`35`	`36`	`name: child/moduleC`
`36`	`37`
	`38`	`+ ---`
	`39`	`+ name: child/moduleC`
	`40`	`+`
`37`	`41`	`"""`
`38`	`42`	`}`
`39`	`43`	`["globstar then up one level"] {`
`40`	`44`	`new {`
`41`	`45`	`"../../input-helper/globtest/child/../module with [weird] ~!characters.pkl"`
`42`	`46`	`"../../input-helper/globtest/child/../moduleA.pkl"`
`43`	`47`	`"../../input-helper/globtest/child/../moduleB.pkl"`
	`48`	`+ "../../input-helper/globtest/childlinked/../module with [weird] ~!characters.pkl"`
	`49`	`+ "../../input-helper/globtest/childlinked/../moduleA.pkl"`
	`50`	`+ "../../input-helper/globtest/childlinked/../moduleB.pkl"`
`44`	`51`	`}`
`45`	`52`	`}`
`46`	`53`	`["empty glob matches current directory"] {`