Source file src/io/ioutil/ioutil.go

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package ioutil implements some I/O utility functions.
     6  //
     7  // Deprecated: As of Go 1.16, the same functionality is now provided
     8  // by package [io] or package [os], and those implementations
     9  // should be preferred in new code.
    10  // See the specific function documentation for details.
    11  package ioutil
    12  
    13  import (
    14  	"io"
    15  	"io/fs"
    16  	"os"
    17  	"sort"
    18  )
    19  
    20  // ReadAll reads from r until an error or EOF and returns the data it read.
    21  // A successful call returns err == nil, not err == EOF. Because ReadAll is
    22  // defined to read from src until EOF, it does not treat an EOF from Read
    23  // as an error to be reported.
    24  //
    25  // Deprecated: As of Go 1.16, this function simply calls [io.ReadAll].
    26  func ReadAll(r io.Reader) ([]byte, error) {
    27  	return io.ReadAll(r)
    28  }
    29  
    30  // ReadFile reads the file named by filename and returns the contents.
    31  // A successful call returns err == nil, not err == EOF. Because ReadFile
    32  // reads the whole file, it does not treat an EOF from Read as an error
    33  // to be reported.
    34  //
    35  // Deprecated: As of Go 1.16, this function simply calls [os.ReadFile].
    36  func ReadFile(filename string) ([]byte, error) {
    37  	return os.ReadFile(filename)
    38  }
    39  
    40  // WriteFile writes data to a file named by filename.
    41  // If the file does not exist, WriteFile creates it with permissions perm
    42  // (before umask); otherwise WriteFile truncates it before writing, without changing permissions.
    43  //
    44  // Deprecated: As of Go 1.16, this function simply calls [os.WriteFile].
    45  func WriteFile(filename string, data []byte, perm fs.FileMode) error {
    46  	return os.WriteFile(filename, data, perm)
    47  }
    48  
    49  // ReadDir reads the directory named by dirname and returns
    50  // a list of fs.FileInfo for the directory's contents,
    51  // sorted by filename. If an error occurs reading the directory,
    52  // ReadDir returns no directory entries along with the error.
    53  //
    54  // Deprecated: As of Go 1.16, [os.ReadDir] is a more efficient and correct choice:
    55  // it returns a list of [fs.DirEntry] instead of [fs.FileInfo],
    56  // and it returns partial results in the case of an error
    57  // midway through reading a directory.
    58  //
    59  // If you must continue obtaining a list of [fs.FileInfo], you still can:
    60  //
    61  //	entries, err := os.ReadDir(dirname)
    62  //	if err != nil { ... }
    63  //	infos := make([]fs.FileInfo, 0, len(entries))
    64  //	for _, entry := range entries {
    65  //		info, err := entry.Info()
    66  //		if err != nil { ... }
    67  //		infos = append(infos, info)
    68  //	}
    69  func ReadDir(dirname string) ([]fs.FileInfo, error) {
    70  	f, err := os.Open(dirname)
    71  	if err != nil {
    72  		return nil, err
    73  	}
    74  	list, err := f.Readdir(-1)
    75  	f.Close()
    76  	if err != nil {
    77  		return nil, err
    78  	}
    79  	sort.Slice(list, func(i, j int) bool { return list[i].Name() < list[j].Name() })
    80  	return list, nil
    81  }
    82  
    83  // NopCloser returns a ReadCloser with a no-op Close method wrapping
    84  // the provided Reader r.
    85  //
    86  // Deprecated: As of Go 1.16, this function simply calls [io.NopCloser].
    87  func NopCloser(r io.Reader) io.ReadCloser {
    88  	return io.NopCloser(r)
    89  }
    90  
    91  // Discard is an io.Writer on which all Write calls succeed
    92  // without doing anything.
    93  //
    94  // Deprecated: As of Go 1.16, this value is simply [io.Discard].
    95  var Discard io.Writer = io.Discard
    96  

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