1 files changed, 159 insertions, 0 deletions
diff --git a/vendor/github.com/hashicorp/vault/helper/compressutil/compress.go b/vendor/github.com/hashicorp/vault/helper/compressutil/compress.go
new file mode 100644
index 0000000..e485f2f
--- /dev/null
+++ b/vendor/github.com/hashicorp/vault/helper/compressutil/compress.go
@@ -0,0 +1,159 @@
+package compressutil
+
+import (
+	"bytes"
+	"compress/gzip"
+	"compress/lzw"
+	"fmt"
+	"io"
+)
+
+const (
+	// A byte value used as a canary prefix for the compressed information
+	// which is used to distinguish if a JSON input is compressed or not.
+	// The value of this constant should not be a first character of any
+	// valid JSON string.
+
+	// Byte value used as canary when using Gzip format
+	CompressionCanaryGzip byte = 'G'
+
+	// Byte value used as canary when using Lzw format
+	CompressionCanaryLzw byte = 'L'
+
+	CompressionTypeLzw = "lzw"
+
+	CompressionTypeGzip = "gzip"
+)
+
+// CompressionConfig is used to select a compression type to be performed by
+// Compress and Decompress utilities.
+// Supported types are:
+// * CompressionTypeLzw
+// * CompressionTypeGzip
+//
+// When using CompressionTypeGzip, the compression levels can also be chosen:
+// * gzip.DefaultCompression
+// * gzip.BestSpeed
+// * gzip.BestCompression
+type CompressionConfig struct {
+	// Type of the compression algorithm to be used
+	Type string
+
+	// When using Gzip format, the compression level to employ
+	GzipCompressionLevel int
+}
+
+// Compress places the canary byte in a buffer and uses the same buffer to fill
+// in the compressed information of the given input. The configuration supports
+// two type of compression: LZW and Gzip. When using Gzip compression format,
+// if GzipCompressionLevel is not specified, the 'gzip.DefaultCompression' will
+// be assumed.
+func Compress(data []byte, config *CompressionConfig) ([]byte, error) {
+	var buf bytes.Buffer
+	var writer io.WriteCloser
+	var err error
+
+	if config == nil {
+		return nil, fmt.Errorf("config is nil")
+	}
+
+	// Write the canary into the buffer and create writer to compress the
+	// input data based on the configured type
+	switch config.Type {
+	case CompressionTypeLzw:
+		buf.Write([]byte{CompressionCanaryLzw})
+
+		writer = lzw.NewWriter(&buf, lzw.LSB, 8)
+	case CompressionTypeGzip:
+		buf.Write([]byte{CompressionCanaryGzip})
+
+		switch {
+		case config.GzipCompressionLevel == gzip.BestCompression,
+			config.GzipCompressionLevel == gzip.BestSpeed,
+			config.GzipCompressionLevel == gzip.DefaultCompression:
+			// These are valid compression levels
+		default:
+			// If compression level is set to NoCompression or to
+			// any invalid value, fallback to Defaultcompression
+			config.GzipCompressionLevel = gzip.DefaultCompression
+		}
+		writer, err = gzip.NewWriterLevel(&buf, config.GzipCompressionLevel)
+	default:
+		return nil, fmt.Errorf("unsupported compression type")
+	}
+	if err != nil {
+		return nil, fmt.Errorf("failed to create a compression writer; err: %v", err)
+	}
+
+	if writer == nil {
+		return nil, fmt.Errorf("failed to create a compression writer")
+	}
+
+	// Compress the input and place it in the same buffer containing the
+	// canary byte.
+	if _, err = writer.Write(data); err != nil {
+		return nil, fmt.Errorf("failed to compress input data; err: %v", err)
+	}
+
+	// Close the io.WriteCloser
+	if err = writer.Close(); err != nil {
+		return nil, err
+	}
+
+	// Return the compressed bytes with canary byte at the start
+	return buf.Bytes(), nil
+}
+
+// Decompress checks if the first byte in the input matches the canary byte.
+// If the first byte is a canary byte, then the input past the canary byte
+// will be decompressed using the method specified in the given configuration.
+// If the first byte isn't a canary byte, then the utility returns a boolean
+// value indicating that the input was not compressed.
+func Decompress(data []byte) ([]byte, bool, error) {
+	var err error
+	var reader io.ReadCloser
+	if data == nil || len(data) == 0 {
+		return nil, false, fmt.Errorf("'data' being decompressed is empty")
+	}
+
+	switch {
+	case data[0] == CompressionCanaryGzip:
+		// If the first byte matches the canary byte, remove the canary
+		// byte and try to decompress the data that is after the canary.
+		if len(data) < 2 {
+			return nil, false, fmt.Errorf("invalid 'data' after the canary")
+		}
+		data = data[1:]
+		reader, err = gzip.NewReader(bytes.NewReader(data))
+	case data[0] == CompressionCanaryLzw:
+		// If the first byte matches the canary byte, remove the canary
+		// byte and try to decompress the data that is after the canary.
+		if len(data) < 2 {
+			return nil, false, fmt.Errorf("invalid 'data' after the canary")
+		}
+		data = data[1:]
+		reader = lzw.NewReader(bytes.NewReader(data), lzw.LSB, 8)
+	default:
+		// If the first byte doesn't match the canary byte, it means
+		// that the content was not compressed at all. Indicate the
+		// caller that the input was not compressed.
+		return nil, true, nil
+	}
+	if err != nil {
+		return nil, false, fmt.Errorf("failed to create a compression reader; err: %v", err)
+	}
+	if reader == nil {
+		return nil, false, fmt.Errorf("failed to create a compression reader")
+	}
+
+	// Close the io.ReadCloser
+	defer reader.Close()
+
+	// Read all the compressed data into a buffer
+	var buf bytes.Buffer
+	if _, err = io.Copy(&buf, reader); err != nil {
+		return nil, false, err
+	}
+
+	return buf.Bytes(), false, nil
+}