fix parsing s3 tag (#7069)

* fix parsing s3 tag

fix https://github.com/seaweedfs/seaweedfs/issues/7040#issuecomment-3145615630

* url.ParseQuery

test/s3/basic/object_tagging_test.go

@@ -2,6 +2,7 @@ package basic
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/aws/aws-sdk-go/aws"
@@ -147,3 +148,81 @@ func TestObjectTaggingWithEncodedValues(t *testing.T) {
 		Key:    aws.String("testDir/testObjectWithEncodedTags"),
 	})
 }
+
+// TestObjectUploadWithEncodedTags tests the specific issue reported in GitHub issue #7040
+// where tags sent via X-Amz-Tagging header during object upload are not URL decoded properly
+func TestObjectUploadWithEncodedTags(t *testing.T) {
+	// This test specifically addresses the issue where tags with special characters
+	// (like spaces, colons, slashes) sent during object upload are not URL decoded
+	// This tests the fix in filer_server_handlers_write_autochunk.go
+
+	objectKey := "testDir/testObjectUploadWithTags"
+
+	// Upload object with tags that contain special characters that would be URL encoded
+	// The AWS SDK will automatically URL encode these when sending the X-Amz-Tagging header
+	// Test edge cases that url.ParseQuery handles better than manual parsing:
+	// - Values containing "=" characters
+	// - Empty values
+	// - Complex special characters
+	_, err := svc.PutObject(&s3.PutObjectInput{
+		Bucket:  aws.String("theBucket"),
+		Key:     aws.String(objectKey),
+		Body:    aws.ReadSeekCloser(strings.NewReader("test content")),
+		Tagging: aws.String("Timestamp=2025-07-16 14:40:39&Path=/tmp/file.txt&Description=A test file with spaces&Equation=x=y+1&EmptyValue=&Complex=A%20tag%20with%20%26%20%3D%20chars"),
+	})
+
+	if err != nil {
+		t.Fatalf("Failed to upload object with tags: %v", err)
+	}
+
+	// Get the tags back to verify they were properly URL decoded during upload
+	response, err := svc.GetObjectTagging(&s3.GetObjectTaggingInput{
+		Bucket: aws.String("theBucket"),
+		Key:    aws.String(objectKey),
+	})
+
+	if err != nil {
+		t.Fatalf("Failed to get object tags: %v", err)
+	}
+
+	// Verify that the tags are properly decoded (not URL encoded)
+	tagMap := make(map[string]string)
+	for _, tag := range response.TagSet {
+		tagMap[*tag.Key] = *tag.Value
+	}
+
+	// Test cases for values that would be URL encoded in the X-Amz-Tagging header
+	testCases := []struct {
+		key           string
+		expectedValue string
+		description   string
+	}{
+		{"Timestamp", "2025-07-16 14:40:39", "timestamp with spaces and colons"},
+		{"Path", "/tmp/file.txt", "file path with slashes"},
+		{"Description", "A test file with spaces", "description with spaces"},
+	}
+
+	for _, tc := range testCases {
+		actualValue, exists := tagMap[tc.key]
+		if !exists {
+			t.Errorf("Expected tag key '%s' not found", tc.key)
+			continue
+		}
+
+		if actualValue != tc.expectedValue {
+			t.Errorf("Tag '%s' (%s): expected '%s', got '%s'",
+				tc.key, tc.description, tc.expectedValue, actualValue)
+		} else {
+			fmt.Printf("✓ Tag '%s' correctly decoded: '%s'\n", tc.key, actualValue)
+		}
+	}
+
+	// Clean up
+	_, err = svc.DeleteObject(&s3.DeleteObjectInput{
+		Bucket: aws.String("theBucket"),
+		Key:    aws.String(objectKey),
+	})
+	if err != nil {
+		t.Logf("Warning: Failed to clean up test object: %v", err)
+	}
+}