[#38059] Fix GCS glob matching to support ** and / in object names

CHANGES.md

@@ -80,6 +80,7 @@
 
 ## Bugfixes
 
+* Fixed GCS filesystem glob matching to correctly handle `/` in object names and support `**` for recursive matching (Go) ([#38059](https://github.com/apache/beam/issues/38059)).
 * Fixed BigQueryEnrichmentHandler batch mode dropping earlier requests when multiple requests share the same enrichment key (Python) ([#38035](https://github.com/apache/beam/issues/38035)).
 
 ## Security Fixes

sdks/go/pkg/beam/io/filesystem/gcs/gcs.go

@@ -21,7 +21,8 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"path/filepath"
+	"regexp"
+	"strings"
 	"time"
 
 	"cloud.google.com/go/storage"
@@ -38,6 +39,91 @@ const (
 	projectBillingHook = "beam:go:hook:filesystem:billingproject"
 )
 
+// globToRegex translates a glob pattern to a regular expression.
+// It differs from filepath.Match in that:
+//   - / is treated as a regular character (not a separator), since GCS object
+//     names are flat with / being just another character
+//   - ** matches any sequence of characters including / (zero or more)
+//   - **/  matches zero or more path segments (e.g., "" or "dir/" or "dir/subdir/")
+//   - * matches any sequence of characters except / (zero or more)
+//   - ? matches a single character (any character including /)
+//
+// This matches the behavior of the Python and Java SDKs.
+func globToRegex(pattern string) (*regexp.Regexp, error) {
+	var result strings.Builder
+	result.WriteString("^")
+
+	for i := 0; i < len(pattern); i++ {
+		c := pattern[i]
+		switch c {
+		case '*':
+			// Check for ** (double asterisk)
+			if i+1 < len(pattern) && pattern[i+1] == '*' {
+				// Check if followed by / (e.g., "**/" matches zero or more path segments)
+				if i+2 < len(pattern) && pattern[i+2] == '/' {
+					// **/ matches "" or "something/" or "a/b/c/"
+					result.WriteString("(.*/)?")
+					i += 2 // Skip the second * and the /
+				} else {
+					// ** at end or before non-slash matches any characters
+					result.WriteString(".*")
+					i++ // Skip the second *
+				}
+			} else {
+				result.WriteString("[^/]*")
+			}
+		case '?':
+			result.WriteString(".")
+		case '[':
+			// Character class - find the closing bracket
+			j := i + 1
+			if j < len(pattern) && pattern[j] == '!' {
+				j++
+			}
+			if j < len(pattern) && pattern[j] == ']' {
+				j++
+			}
+			for j < len(pattern) && pattern[j] != ']' {
+				j++
+			}
+			if j >= len(pattern) {
+				// No closing bracket, treat [ as literal
+				result.WriteString(regexp.QuoteMeta(string(c)))
+			} else {
+				// Copy the character class, converting ! to ^ for negation
+				result.WriteByte('[')
+				content := pattern[i+1 : j]
+				if len(content) > 0 && content[0] == '!' {
+					result.WriteByte('^')
+					content = content[1:]
+				}
+				result.WriteString(content)
+				result.WriteByte(']')
+				i = j
+			}
+		default:
+			// Escape regex special characters
+			if isRegexSpecial(c) {
+				result.WriteByte('\\')
+			}
+			result.WriteByte(c)
+		}
+	}
+
+	result.WriteString("$") // match end
+	return regexp.Compile(result.String())
+}
+
+// isRegexSpecial returns true if the character is a regex metacharacter
+// that needs to be escaped.
+func isRegexSpecial(c byte) bool {
+	switch c {
+	case '.', '+', '^', '$', '(', ')', '|', '{', '}', '\\':
+		return true
+	}
+	return false
+}
+
 var billingProject string = ""
 
 func init() {
@@ -107,6 +193,15 @@ func (f *fs) List(ctx context.Context, glob string) ([]string, error) {
 		return nil, err
 	}
 
+	// Compile the glob pattern to a regex. We use a custom glob-to-regex
+	// translation that treats / as a regular character (not a separator),
+	// since GCS object names are flat. This also supports ** for recursive
+	// matching, similar to the Java and Python SDKs.
+	re, err := globToRegex(object)
+	if err != nil {
+		return nil, fmt.Errorf("invalid glob pattern %q: %w", object, err)
+	}
+
 	var candidates []string
 
 	// We handle globs by list all candidates and matching them here.
@@ -125,11 +220,7 @@ func (f *fs) List(ctx context.Context, glob string) ([]string, error) {
 			return nil, err
 		}
 
-		match, err := filepath.Match(object, obj.Name)
-		if err != nil {
-			return nil, err
-		}
-		if match {
+		if re.MatchString(obj.Name) {
 			candidates = append(candidates, obj.Name)
 		}
 	}

sdks/go/pkg/beam/io/filesystem/gcs/gcs_test.go

@@ -271,6 +271,124 @@ func TestGCS_copy(t *testing.T) {
 	}
 }
 
+func TestGlobToRegex(t *testing.T) {
+	tests := []struct {
+		pattern string
+		name    string
+		want    bool
+	}{
+		// Single * should NOT match / in object names
+		{"*.txt", "file.txt", true},
+		{"*.txt", "dir/file.txt", false},
+		{"prefix*", "prefix123", true},
+		{"prefix*", "prefix/subdir", false},
+
+		// ** should match any characters including /
+		{"**", "file.txt", true},
+		{"**", "dir/file.txt", true},
+		{"**", "dir/subdir/file.txt", true},
+		{"prefix/**", "prefix/file.txt", true},
+		{"prefix/**", "prefix/subdir/file.txt", true},
+		{"**/file.txt", "file.txt", true},
+		{"**/file.txt", "dir/file.txt", true},
+		{"**/file.txt", "dir/subdir/file.txt", true},
+
+		// Mixed patterns
+		{"dir/*.txt", "dir/file.txt", true},
+		{"dir/*.txt", "dir/subdir/file.txt", false},
+		{"dir/**/*.txt", "dir/file.txt", true},
+		{"dir/**/*.txt", "dir/subdir/file.txt", true},
+		{"dir/**/file.txt", "dir/file.txt", true},
+		{"dir/**/file.txt", "dir/a/b/c/file.txt", true},
+
+		// ? should match any single character including /
+		{"file?.txt", "file1.txt", true},
+		{"file?.txt", "file12.txt", false},
+
+		// Character classes
+		{"file[0-9].txt", "file1.txt", true},
+		{"file[0-9].txt", "filea.txt", false},
+		{"file[!0-9].txt", "filea.txt", true},
+		{"file[!0-9].txt", "file1.txt", false},
+
+		// Exact match (no wildcards)
+		{"exact.txt", "exact.txt", true},
+		{"exact.txt", "notexact.txt", false},
+
+		// Regex special characters should be escaped
+		{"file.txt", "file.txt", true},
+		{"file.txt", "fileXtxt", false},
+		{"file(1).txt", "file(1).txt", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.pattern+"_"+tt.name, func(t *testing.T) {
+			re, err := globToRegex(tt.pattern)
+			if err != nil {
+				t.Fatalf("globToRegex(%q) error = %v", tt.pattern, err)
+			}
+			got := re.MatchString(tt.name)
+			if got != tt.want {
+				t.Errorf("globToRegex(%q).MatchString(%q) = %v, want %v", tt.pattern, tt.name, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestGCS_listWithSlashesInObjectNames(t *testing.T) {
+	ctx := context.Background()
+	bucket := "beamgogcsfilesystemtest"
+	dirPath := "gs://" + bucket
+
+	// Create server with objects that have / in their names
+	server := fakestorage.NewServer([]fakestorage.Object{
+		{ObjectAttrs: fakestorage.ObjectAttrs{BucketName: bucket, Name: "file.txt"}, Content: []byte("")},
+		{ObjectAttrs: fakestorage.ObjectAttrs{BucketName: bucket, Name: "dir/file.txt"}, Content: []byte("")},
+		{ObjectAttrs: fakestorage.ObjectAttrs{BucketName: bucket, Name: "dir/subdir/file.txt"}, Content: []byte("")},
+		{ObjectAttrs: fakestorage.ObjectAttrs{BucketName: bucket, Name: "other.txt"}, Content: []byte("")},
+	})
+	t.Cleanup(server.Stop)
+	c := &fs{client: server.Client()}
+
+	tests := []struct {
+		glob string
+		want []string
+	}{
+		// Single * should only match top-level files
+		{dirPath + "/*.txt", []string{dirPath + "/file.txt", dirPath + "/other.txt"}},
+		// ** should match all files recursively
+		{dirPath + "/**", []string{
+			dirPath + "/file.txt",
+			dirPath + "/dir/file.txt",
+			dirPath + "/dir/subdir/file.txt",
+			dirPath + "/other.txt",
+		}},
+		// dir/* should only match immediate children
+		{dirPath + "/dir/*", []string{dirPath + "/dir/file.txt"}},
+		// dir/** should match all descendants
+		{dirPath + "/dir/**", []string{
+			dirPath + "/dir/file.txt",
+			dirPath + "/dir/subdir/file.txt",
+		}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.glob, func(t *testing.T) {
+			got, err := c.List(ctx, tt.glob)
+			if err != nil {
+				t.Fatalf("List(%q) error = %v", tt.glob, err)
+			}
+
+			sort.Strings(got)
+			sort.Strings(tt.want)
+
+			if !cmp.Equal(got, tt.want) {
+				t.Errorf("List(%q) = %v, want %v", tt.glob, got, tt.want)
+			}
+		})
+	}
+}
+
 func createFakeGCSServer(tb testing.TB) *fakestorage.Server {
 	tb.Helper()