Merge pull request #428 from projectdiscovery/add_isempty_func

add IsEmpty func

file/file.go

@@ -15,6 +15,7 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"unicode"
 
 	"github.com/asaskevich/govalidator"
 	"github.com/mattn/go-isatty"
@@ -605,3 +606,36 @@ func DedupeLines(filename string) error {
 
 	return os.WriteFile(filename, []byte(strings.Join(deduplicatedLines, "\n")+"\n"), 0644)
 }
+
+// IsEmpty checks if the file is empty
+func IsEmpty(filename string) (bool, error) {
+	fileInfo, err := os.Stat(filename)
+	if err != nil {
+		return false, err
+	}
+
+	if fileInfo.Size() == 0 {
+		return true, nil
+	}
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return false, err
+	}
+	defer file.Close()
+
+	// Read up to 512 bytes to check for non-space characters
+	buffer := make([]byte, 16)
+	n, err := file.Read(buffer)
+	if err != nil && err != io.EOF {
+		return false, err
+	}
+
+	// Check if all read characters are spaces, null characters, new lines, or carriage returns
+	for i := 0; i < n; i++ {
+		if unicode.IsSpace(rune(buffer[i])) || buffer[i] == 0 || buffer[i] == '\n' || buffer[i] == '\r' {
+			return true, nil
+		}
+	}
+	return false, nil
+}

file/file_test.go

@@ -632,3 +632,38 @@ func TestFileExistsIn(t *testing.T) {
 		})
 	}
 }
+
+func TestIsEmpty(t *testing.T) {
+	// Create a temporary directory
+	tempDir := t.TempDir()
+
+	// Test case: File not existent
+	t.Run("file not existent", func(t *testing.T) {
+		nonExistentFile := filepath.Join(tempDir, "nonexistent.txt")
+		isEmpty, err := IsEmpty(nonExistentFile)
+		require.Error(t, err, "expected an error for non-existent file")
+		require.False(t, isEmpty, "non-existent file should not be considered empty")
+	})
+
+	// Test case: Empty file
+	t.Run("empty file", func(t *testing.T) {
+		emptyFile := filepath.Join(tempDir, "empty.txt")
+		err := os.WriteFile(emptyFile, []byte(""), 0644)
+		require.NoError(t, err, "failed to create empty file")
+		defer os.Remove(emptyFile) // Clean up the created file
+		isEmpty, err := IsEmpty(emptyFile)
+		require.NoError(t, err, "should not error for an empty file")
+		require.True(t, isEmpty, "empty file should be considered empty")
+	})
+
+	// Test case: File containing only spaces
+	t.Run("file with spaces", func(t *testing.T) {
+		spacesFile := filepath.Join(tempDir, "spaces.txt")
+		err := os.WriteFile(spacesFile, []byte("   "), 0644)
+		require.NoError(t, err, "failed to create file with spaces")
+		defer os.Remove(spacesFile) // Clean up the created file
+		isEmpty, err := IsEmpty(spacesFile)
+		require.NoError(t, err, "should not error for a file with only spaces")
+		require.True(t, isEmpty, "file with only spaces should be considered empty")
+	})
+}