BEAM-13231: Add glob wildcard escaping utilities to FileSystems

sdks/java/core/src/main/java/org/apache/beam/sdk/io/FileSystems.java

@@ -78,6 +78,8 @@ public class FileSystems {
   private static final Pattern FILE_SCHEME_PATTERN =
       Pattern.compile("(?<scheme>[a-zA-Z][-a-zA-Z0-9+.]*):/.*");
   private static final Pattern GLOB_PATTERN = Pattern.compile("[*?{}]");
+  private static final Pattern ESCAPED_GLOB_PATTERN = Pattern.compile("\\\\[*?{}]");
+  private static final String GLOB_ESCAPE_PREFIX = "\\";
 
   private static final AtomicReference<KV<Long, Integer>> FILESYSTEM_REVISION =
       new AtomicReference<>();
@@ -92,6 +94,40 @@ public static boolean hasGlobWildcard(String spec) {
     return GLOB_PATTERN.matcher(spec).find();
   }
 
+  /**
+   * Escapes glob wildcard characters in the given spec so they are treated as literals.
+   *
+   * <p>This method escapes the characters '*', '?', '{', and '}' by prefixing them with a
+   * backslash, allowing them to be treated as literal characters in a file path rather than as
+   * glob wildcards.
+   *
+   * <p>Example: {@code escapeGlobWildcards("file*.txt")} returns {@code "file\\*.txt"}
+   *
+   * @param spec the file path specification to escape
+   * @return the escaped specification
+   */
+  public static String escapeGlobWildcards(String spec) {
+    checkNotNull(spec, "spec cannot be null");
+    return spec.replaceAll("([*?{}])", "\\\\$1");
+  }
+
+  /**
+   * Unescapes glob wildcard characters in the given spec that were previously escaped with {@link
+   * #escapeGlobWildcards(String)}.
+   *
+   * <p>This method removes the backslash prefix from escaped glob characters ('*', '?', '{', '}'),
+   * restoring them to their unescaped form.
+   *
+   * <p>Example: {@code unescapeGlobWildcards("file\\*.txt")} returns {@code "file*.txt"}
+   *
+   * @param spec the file path specification to unescape
+   * @return the unescaped specification
+   */
+  public static String unescapeGlobWildcards(String spec) {
+    checkNotNull(spec, "spec cannot be null");
+    return spec.replaceAll("\\\\([*?{}])", "$1");
+  }
+
   /**
    * This is the entry point to convert user-provided specs to {@link ResourceId ResourceIds}.
    * Callers should use {@link #match} to resolve users specs ambiguities before calling other

sdks/java/core/src/test/java/org/apache/beam/sdk/io/FileSystemsTest.java

@@ -354,6 +354,56 @@ private void createFileWithContent(Path path, String content) throws Exception {
     }
   }
 
+  @Test
+  public void testEscapeGlobWildcards() {
+    // Test escaping asterisk
+    assertEquals("file\\*.txt", FileSystems.escapeGlobWildcards("file*.txt"));
+
+    // Test escaping question mark
+    assertEquals("file\\?.txt", FileSystems.escapeGlobWildcards("file?.txt"));
+
+    // Test escaping braces
+    assertEquals("file\\{1,2\\}.txt", FileSystems.escapeGlobWildcards("file{1,2}.txt"));
+
+    // Test escaping multiple characters
+    assertEquals("\\*\\?\\{\\}.txt", FileSystems.escapeGlobWildcards("*?{}.txt"));
+
+    // Test string with no glob characters
+    assertEquals("file.txt", FileSystems.escapeGlobWildcards("file.txt"));
+
+    // Test empty string
+    assertEquals("", FileSystems.escapeGlobWildcards(""));
+  }
+
+  @Test
+  public void testUnescapeGlobWildcards() {
+    // Test unescaping asterisk
+    assertEquals("file*.txt", FileSystems.unescapeGlobWildcards("file\\*.txt"));
+
+    // Test unescaping question mark
+    assertEquals("file?.txt", FileSystems.unescapeGlobWildcards("file\\?.txt"));
+
+    // Test unescaping braces
+    assertEquals("file{1,2}.txt", FileSystems.unescapeGlobWildcards("file\\{1,2\\}.txt"));
+
+    // Test unescaping multiple characters
+    assertEquals("*?{}.txt", FileSystems.unescapeGlobWildcards("\\*\\?\\{\\}.txt"));
+
+    // Test string with no escaped characters
+    assertEquals("file.txt", FileSystems.unescapeGlobWildcards("file.txt"));
+
+    // Test empty string
+    assertEquals("", FileSystems.unescapeGlobWildcards(""));
+  }
+
+  @Test
+  public void testEscapeUnescapeRoundTrip() {
+    String original = "file*test?.txt";
+    String escaped = FileSystems.escapeGlobWildcards(original);
+    String unescaped = FileSystems.unescapeGlobWildcards(escaped);
+    assertEquals(original, unescaped);
+  }
+
   private LocalResourceId toLocalResourceId(String str) throws Exception {
     boolean isDirectory;
     if (SystemUtils.IS_OS_WINDOWS) {