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/
zipper.go
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/
zipper.go
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// Copyright 2020 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
////////////////////////////////////////////////
// This package performs gzip operations.
package main
import (
"compress/gzip"
"flag"
"io"
"log"
"os"
)
var (
src = flag.String("src", "", "The source location of the file to zip/unzip.")
dst = flag.String("dst", "", "The destination location of the file, after zip/unzip.")
decompress = flag.Bool("decompress", false, "If true, perform gunzip. If false, gzip.")
fast = flag.Bool("fast", false, "If true, use the fastest compression level.")
)
func main() {
flag.Parse()
if *src == "" {
log.Fatalln("Required option -src was not specified.")
}
if *dst == "" {
log.Fatalln("Required option -dst was not specified.")
}
var copy_from io.Reader
var copy_to io.Writer
f, err := os.Open(*src)
if err != nil {
log.Fatalf("Unable to read input file: %v", err)
}
t, err := os.Create(*dst)
if err != nil {
log.Fatalf("Unable to create output file: %v", err)
}
if *decompress {
zr, err := gzip.NewReader(f)
if err != nil {
log.Fatalf("Unable to read: %v", err)
}
defer func() {
if err := zr.Close(); err != nil {
log.Fatalf("Unable to close gzip reader: %v", err)
}
}()
copy_from = zr
copy_to = t
} else {
level := gzip.DefaultCompression
if *fast {
level = gzip.BestSpeed
}
zw, err := gzip.NewWriterLevel(t, level)
if err != nil {
log.Fatalf("Unable to create gzip writer: %v", err)
}
defer func() {
if err := zw.Close(); err != nil {
log.Fatalf("Unable to close gzip writer: %v", err)
}
}()
copy_from = f
copy_to = zw
}
if _, err := io.Copy(copy_to, copy_from); err != nil {
log.Fatalf("Unable to perform the gzip operation from %q to %q: %v", *src, *dst, err)
}
}