lzw: fix Write returning the wrong number of bytes written.
Fixes #4160.
R=rsc, r
CC=golang-dev
https://golang.org/cl/6564060
diff --git a/src/pkg/compress/lzw/writer.go b/src/pkg/compress/lzw/writer.go
index 488ba64..c6f891b 100644
--- a/src/pkg/compress/lzw/writer.go
+++ b/src/pkg/compress/lzw/writer.go
@@ -131,13 +131,14 @@
}
// Write writes a compressed representation of p to e's underlying writer.
-func (e *encoder) Write(p []byte) (int, error) {
+func (e *encoder) Write(p []byte) (n int, err error) {
if e.err != nil {
return 0, e.err
}
if len(p) == 0 {
return 0, nil
}
+ n = len(p)
litMask := uint32(1<<e.litWidth - 1)
code := e.savedCode
if code == invalidCode {
@@ -167,11 +168,11 @@
code = literal
// Increment e.hi, the next implied code. If we run out of codes, reset
// the encoder state (including clearing the hash table) and continue.
- if err := e.incHi(); err != nil {
- if err == errOutOfCodes {
+ if err1 := e.incHi(); err1 != nil {
+ if err1 == errOutOfCodes {
continue
}
- e.err = err
+ e.err = err1
return 0, e.err
}
// Otherwise, insert key -> e.hi into the map that e.table represents.
@@ -184,7 +185,7 @@
}
}
e.savedCode = code
- return len(p), nil
+ return n, nil
}
// Close closes the encoder, flushing any pending output. It does not close or
diff --git a/src/pkg/compress/lzw/writer_test.go b/src/pkg/compress/lzw/writer_test.go
index 97daf14..3e4e6de 100644
--- a/src/pkg/compress/lzw/writer_test.go
+++ b/src/pkg/compress/lzw/writer_test.go
@@ -96,6 +96,14 @@
}
}
+func TestWriterReturnValues(t *testing.T) {
+ w := NewWriter(ioutil.Discard, LSB, 8)
+ n, err := w.Write([]byte("asdf"))
+ if n != 4 || err != nil {
+ t.Errorf("got %d, %v, want 4, nil", n, err)
+ }
+}
+
func benchmarkEncoder(b *testing.B, n int) {
b.StopTimer()
b.SetBytes(int64(n))
