compress: add comments to gzip and zlib.

Fixes #2939.

R=rsc, r
CC=golang-dev
https://golang.org/cl/5655050

diff --git a/src/pkg/compress/gzip/gunzip.go b/src/pkg/compress/gzip/gunzip.go
index 3828f41052f7cc55602611781771aebaea0702e2..33736f635082fd636fb07957803126993d7b88fe 100644 (file)
--- a/src/pkg/compress/gzip/gunzip.go
+++ b/src/pkg/compress/gzip/gunzip.go
@@ -34,8 +34,12 @@ func makeReader(r io.Reader) flate.Reader {
        return bufio.NewReader(r)
 }
 
-var ErrHeader = errors.New("invalid gzip header")
-var ErrChecksum = errors.New("gzip checksum error")
+var (
+       // ErrChecksum is returned when reading GZIP data that has an invalid checksum.
+       ErrChecksum = errors.New("gzip: invalid checksum")
+       // ErrHeader is returned when reading GZIP data that has an invalid header.
+       ErrHeader = errors.New("gzip: invalid header")
+)
 
 // The gzip file stores a header giving metadata about the compressed file.
 // That header is exposed as the fields of the Writer and Reader structs.

diff --git a/src/pkg/compress/gzip/gzip.go b/src/pkg/compress/gzip/gzip.go
index f9adc1bebe3c1a28388aecd90022fc037ec8be6f..3035dfffccf31ded5a87c7856b3e7177bb7275c0 100644 (file)
--- a/src/pkg/compress/gzip/gzip.go
+++ b/src/pkg/compress/gzip/gzip.go
@@ -130,6 +130,8 @@ func (z *Writer) writeString(s string) (err error) {
        return err
 }
 
+// Write writes a compressed form of p to the underlying io.Writer. The
+// compressed bytes are not necessarily flushed until the Writer is closed.
 func (z *Writer) Write(p []byte) (int, error) {
        if z.err != nil {
                return 0, z.err

diff --git a/src/pkg/compress/zlib/reader.go b/src/pkg/compress/zlib/reader.go
index 4638a6548425bb44bb86db2f5682a54472a42bdb..f38ef5a885e8107569d15d2ef3ab4e693c99d5df 100644 (file)
--- a/src/pkg/compress/zlib/reader.go
+++ b/src/pkg/compress/zlib/reader.go
@@ -34,9 +34,14 @@ import (
 
 const zlibDeflate = 8
 
-var ErrChecksum = errors.New("zlib checksum error")
-var ErrHeader = errors.New("invalid zlib header")
-var ErrDictionary = errors.New("invalid zlib dictionary")
+var (
+       // ErrChecksum is returned when reading ZLIB data that has an invalid checksum.
+       ErrChecksum = errors.New("zlib: invalid checksum")
+       // ErrDictionary is returned when reading ZLIB data that has an invalid dictionary.
+       ErrDictionary = errors.New("zlib: invalid dictionary")
+       // ErrHeader is returned when reading ZLIB data that has an invalid header.
+       ErrHeader = errors.New("zlib: invalid header")
+)
 
 type reader struct {
        r            flate.Reader

diff --git a/src/pkg/compress/zlib/writer.go b/src/pkg/compress/zlib/writer.go
index 6f70513e01956baa0dc9bd3b716c82189a4c721b..cd8dea460a4f868f296366d4160f61399e425692 100644 (file)
--- a/src/pkg/compress/zlib/writer.go
+++ b/src/pkg/compress/zlib/writer.go
@@ -119,6 +119,9 @@ func (z *Writer) writeHeader() (err error) {
        return nil
 }
 
+// Write writes a compressed form of p to the underlying io.Writer. The
+// compressed bytes are not necessarily flushed until the Writer is closed or
+// explicitly flushed.
 func (z *Writer) Write(p []byte) (n int, err error) {
        if !z.wroteHeader {
                z.err = z.writeHeader()
@@ -138,7 +141,7 @@ func (z *Writer) Write(p []byte) (n int, err error) {
        return
 }
 
-// Flush flushes the underlying compressor.
+// Flush flushes the Writer to its underlying io.Writer.
 func (z *Writer) Flush() error {
        if !z.wroteHeader {
                z.err = z.writeHeader()