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ioutil.go
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ioutil.go
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// Copyright ©2015 The Go Authors
// Copyright ©2015 Steve Francia <spf@spf13.com>
//
// 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.
package afero
import (
"bytes"
"io"
"os"
"path/filepath"
"sort"
"strconv"
"strings"
"sync"
"time"
)
// byName implements sort.Interface.
type byName []os.FileInfo
func (f byName) Len() int { return len(f) }
func (f byName) Less(i, j int) bool { return f[i].Name() < f[j].Name() }
func (f byName) Swap(i, j int) { f[i], f[j] = f[j], f[i] }
// ReadDir reads the directory named by dirname and returns
// a list of sorted directory entries.
func (a Afero) ReadDir(dirname string) ([]os.FileInfo, error) {
return ReadDir(a.Fs, dirname)
}
func ReadDir(fs Fs, dirname string) ([]os.FileInfo, error) {
f, err := fs.Open(dirname)
if err != nil {
return nil, err
}
list, err := f.Readdir(-1)
f.Close()
if err != nil {
return nil, err
}
sort.Sort(byName(list))
return list, nil
}
// ReadFile reads the file named by filename and returns the contents.
// A successful call returns err == nil, not err == EOF. Because ReadFile
// reads the whole file, it does not treat an EOF from Read as an error
// to be reported.
func (a Afero) ReadFile(filename string) ([]byte, error) {
return ReadFile(a.Fs, filename)
}
func ReadFile(fs Fs, filename string) ([]byte, error) {
f, err := fs.Open(filename)
if err != nil {
return nil, err
}
defer f.Close()
// It's a good but not certain bet that FileInfo will tell us exactly how much to
// read, so let's try it but be prepared for the answer to be wrong.
var n int64
if fi, err := f.Stat(); err == nil {
// Don't preallocate a huge buffer, just in case.
if size := fi.Size(); size < 1e9 {
n = size
}
}
// As initial capacity for readAll, use n + a little extra in case Size is zero,
// and to avoid another allocation after Read has filled the buffer. The readAll
// call will read into its allocated internal buffer cheaply. If the size was
// wrong, we'll either waste some space off the end or reallocate as needed, but
// in the overwhelmingly common case we'll get it just right.
return readAll(f, n+bytes.MinRead)
}
// readAll reads from r until an error or EOF and returns the data it read
// from the internal buffer allocated with a specified capacity.
func readAll(r io.Reader, capacity int64) (b []byte, err error) {
buf := bytes.NewBuffer(make([]byte, 0, capacity))
// If the buffer overflows, we will get bytes.ErrTooLarge.
// Return that as an error. Any other panic remains.
defer func() {
e := recover()
if e == nil {
return
}
if panicErr, ok := e.(error); ok && panicErr == bytes.ErrTooLarge {
err = panicErr
} else {
panic(e)
}
}()
_, err = buf.ReadFrom(r)
return buf.Bytes(), err
}
// ReadAll reads from r until an error or EOF and returns the data it read.
// A successful call returns err == nil, not err == EOF. Because ReadAll is
// defined to read from src until EOF, it does not treat an EOF from Read
// as an error to be reported.
func ReadAll(r io.Reader) ([]byte, error) {
return readAll(r, bytes.MinRead)
}
// WriteFile writes data to a file named by filename.
// If the file does not exist, WriteFile creates it with permissions perm;
// otherwise WriteFile truncates it before writing.
func (a Afero) WriteFile(filename string, data []byte, perm os.FileMode) error {
return WriteFile(a.Fs, filename, data, perm)
}
func WriteFile(fs Fs, filename string, data []byte, perm os.FileMode) error {
f, err := fs.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
if err != nil {
return err
}
n, err := f.Write(data)
if err == nil && n < len(data) {
err = io.ErrShortWrite
}
if err1 := f.Close(); err == nil {
err = err1
}
return err
}
// Random number state.
// We generate random temporary file names so that there's a good
// chance the file doesn't exist yet - keeps the number of tries in
// TempFile to a minimum.
var randNum uint32
var randmu sync.Mutex
func reseed() uint32 {
return uint32(time.Now().UnixNano() + int64(os.Getpid()))
}
func nextRandom() string {
randmu.Lock()
r := randNum
if r == 0 {
r = reseed()
}
r = r*1664525 + 1013904223 // constants from Numerical Recipes
randNum = r
randmu.Unlock()
return strconv.Itoa(int(1e9 + r%1e9))[1:]
}
// TempFile creates a new temporary file in the directory dir,
// opens the file for reading and writing, and returns the resulting *os.File.
// The filename is generated by taking pattern and adding a random
// string to the end. If pattern includes a "*", the random string
// replaces the last "*".
// If dir is the empty string, TempFile uses the default directory
// for temporary files (see os.TempDir).
// Multiple programs calling TempFile simultaneously
// will not choose the same file. The caller can use f.Name()
// to find the pathname of the file. It is the caller's responsibility
// to remove the file when no longer needed.
func (a Afero) TempFile(dir, pattern string) (f File, err error) {
return TempFile(a.Fs, dir, pattern)
}
func TempFile(fs Fs, dir, pattern string) (f File, err error) {
if dir == "" {
dir = os.TempDir()
}
var prefix, suffix string
if pos := strings.LastIndex(pattern, "*"); pos != -1 {
prefix, suffix = pattern[:pos], pattern[pos+1:]
} else {
prefix = pattern
}
nconflict := 0
for i := 0; i < 10000; i++ {
name := filepath.Join(dir, prefix+nextRandom()+suffix)
f, err = fs.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
if os.IsExist(err) {
if nconflict++; nconflict > 10 {
randmu.Lock()
randNum = reseed()
randmu.Unlock()
}
continue
}
break
}
return
}
// TempDir creates a new temporary directory in the directory dir
// with a name beginning with prefix and returns the path of the
// new directory. If dir is the empty string, TempDir uses the
// default directory for temporary files (see os.TempDir).
// Multiple programs calling TempDir simultaneously
// will not choose the same directory. It is the caller's responsibility
// to remove the directory when no longer needed.
func (a Afero) TempDir(dir, prefix string) (name string, err error) {
return TempDir(a.Fs, dir, prefix)
}
func TempDir(fs Fs, dir, prefix string) (name string, err error) {
if dir == "" {
dir = os.TempDir()
}
nconflict := 0
for i := 0; i < 10000; i++ {
try := filepath.Join(dir, prefix+nextRandom())
err = fs.Mkdir(try, 0700)
if os.IsExist(err) {
if nconflict++; nconflict > 10 {
randmu.Lock()
randNum = reseed()
randmu.Unlock()
}
continue
}
if err == nil {
name = try
}
break
}
return
}