Add TestDecodeLengthOffset.
diff --git a/snappy_test.go b/snappy_test.go
index 2c26930..1da01df 100644
--- a/snappy_test.go
+++ b/snappy_test.go
@@ -6,6 +6,7 @@
import (
"bytes"
+ "encoding/binary"
"flag"
"fmt"
"io"
@@ -278,6 +279,57 @@
}
}
+// TestDecodeLengthOffset tests decoding an encoding of the form literal +
+// copy-length-offset + literal. For example: "abcdefghijkl" + "efghij" + "AB".
+func TestDecodeLengthOffset(t *testing.T) {
+ const (
+ prefix = "abcdefghijkl"
+ suffix = "ABCDEFGHIJKL"
+ )
+ var gotBuf, wantBuf, inputBuf [256]byte
+ for length := 1; length < 12; length++ {
+ for offset := 1; offset < 12; offset++ {
+ for suffixLen := 0; suffixLen < 12; suffixLen++ {
+ inputLen := binary.PutUvarint(inputBuf[:], uint64(len(prefix)+length+suffixLen))
+ inputBuf[inputLen] = tagLiteral + 4*byte(len(prefix)-1)
+ inputLen++
+ inputLen += copy(inputBuf[inputLen:], prefix)
+ inputBuf[inputLen+0] = tagCopy2 + 4*byte(length-1)
+ inputBuf[inputLen+1] = byte(offset)
+ inputBuf[inputLen+2] = 0x00
+ inputLen += 3
+ if suffixLen > 0 {
+ inputBuf[inputLen] = tagLiteral + 4*byte(suffixLen-1)
+ inputLen++
+ inputLen += copy(inputBuf[inputLen:], suffix[:suffixLen])
+ }
+ input := inputBuf[:inputLen]
+
+ got, err := Decode(gotBuf[:], input)
+ if err != nil {
+ t.Errorf("length=%d, offset=%d; suffixLen=%d: %v", length, offset, suffixLen)
+ continue
+ }
+
+ wantLen := 0
+ wantLen += copy(wantBuf[wantLen:], prefix)
+ for i := 0; i < length; i++ {
+ wantBuf[wantLen] = wantBuf[wantLen-offset]
+ wantLen++
+ }
+ wantLen += copy(wantBuf[wantLen:], suffix[:suffixLen])
+ want := wantBuf[:wantLen]
+
+ if !bytes.Equal(got, want) {
+ t.Errorf("length=%d, offset=%d; suffixLen=%d:\ninput % x\ngot % x\nwant % x",
+ length, offset, suffixLen, input, got, want)
+ continue
+ }
+ }
+ }
+ }
+}
+
// TestEncodeNoiseThenRepeats encodes input for which the first half is very
// incompressible and the second half is very compressible. The encoded form's
// length should be closer to 50% of the original length than 100%.
