dirent_test.go

Documentation: golang.org/x/sys/unix

     1  // Copyright 2019 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  //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
     6  
     7  package unix_test
     8  
     9  import (
    10  	"bytes"
    11  	"fmt"
    12  	"os"
    13  	"path/filepath"
    14  	"runtime"
    15  	"sort"
    16  	"strconv"
    17  	"strings"
    18  	"testing"
    19  	"unsafe"
    20  
    21  	"golang.org/x/sys/unix"
    22  )
    23  
    24  func TestDirent(t *testing.T) {
    25  	const (
    26  		direntBufSize   = 2048 // arbitrary? See https://go.dev/issue/37323.
    27  		filenameMinSize = 11
    28  	)
    29  
    30  	d := t.TempDir()
    31  	t.Logf("tmpdir: %s", d)
    32  
    33  	for i, c := range []byte("0123456789") {
    34  		name := string(bytes.Repeat([]byte{c}, filenameMinSize+i))
    35  		err := os.WriteFile(filepath.Join(d, name), nil, 0644)
    36  		if err != nil {
    37  			t.Fatal(err)
    38  		}
    39  	}
    40  
    41  	names := make([]string, 0, 10)
    42  
    43  	fd, err := unix.Open(d, unix.O_RDONLY, 0)
    44  	if err != nil {
    45  		t.Fatalf("Open: %v", err)
    46  	}
    47  	defer unix.Close(fd)
    48  
    49  	buf := bytes.Repeat([]byte{0xCD}, direntBufSize)
    50  	for {
    51  		n, err := unix.ReadDirent(fd, buf)
    52  		if err == unix.EINVAL {
    53  			// On linux, 'man getdents64' says that EINVAL indicates result buffer is too small.
    54  			// Try a bigger buffer.
    55  			t.Logf("ReadDirent: %v; retrying with larger buffer", err)
    56  			buf = bytes.Repeat([]byte{0xCD}, len(buf)*2)
    57  			continue
    58  		}
    59  		if err != nil {
    60  			t.Fatalf("ReadDirent: %v", err)
    61  		}
    62  		t.Logf("ReadDirent: read %d bytes", n)
    63  		if n == 0 {
    64  			break
    65  		}
    66  
    67  		var consumed, count int
    68  		consumed, count, names = unix.ParseDirent(buf[:n], -1, names)
    69  		t.Logf("ParseDirent: %d new name(s)", count)
    70  		if consumed != n {
    71  			t.Fatalf("ParseDirent: consumed %d bytes; expected %d", consumed, n)
    72  		}
    73  	}
    74  
    75  	sort.Strings(names)
    76  	t.Logf("names: %q", names)
    77  
    78  	if len(names) != 10 {
    79  		t.Errorf("got %d names; expected 10", len(names))
    80  	}
    81  	for i, name := range names {
    82  		ord, err := strconv.Atoi(name[:1])
    83  		if err != nil {
    84  			t.Fatalf("names[%d] is non-integer %q: %v", i, names[i], err)
    85  		}
    86  		if expected := string(strings.Repeat(name[:1], filenameMinSize+ord)); name != expected {
    87  			t.Errorf("names[%d] is %q (len %d); expected %q (len %d)", i, name, len(name), expected, len(expected))
    88  		}
    89  	}
    90  }
    91  
    92  func TestDirentRepeat(t *testing.T) {
    93  	const N = 100
    94  	// Note: the size of the buffer is small enough that the loop
    95  	// below will need to execute multiple times. See issue #31368.
    96  	size := N * unsafe.Offsetof(unix.Dirent{}.Name) / 4
    97  	if runtime.GOOS == "freebsd" || runtime.GOOS == "netbsd" {
    98  		if size < 1024 {
    99  			size = 1024 // DIRBLKSIZ, see issue 31403.
   100  		}
   101  		if runtime.GOOS == "freebsd" {
   102  			t.Skip("need to fix issue 31416 first")
   103  		}
   104  	}
   105  
   106  	// Make a directory containing N files
   107  	d := t.TempDir()
   108  
   109  	var files []string
   110  	for i := 0; i < N; i++ {
   111  		files = append(files, fmt.Sprintf("file%d", i))
   112  	}
   113  	for _, file := range files {
   114  		err := os.WriteFile(filepath.Join(d, file), []byte("contents"), 0644)
   115  		if err != nil {
   116  			t.Fatal(err)
   117  		}
   118  	}
   119  
   120  	// Read the directory entries using ReadDirent.
   121  	fd, err := unix.Open(d, unix.O_RDONLY, 0)
   122  	if err != nil {
   123  		t.Fatalf("Open: %v", err)
   124  	}
   125  	defer unix.Close(fd)
   126  	var files2 []string
   127  	for {
   128  		buf := make([]byte, size)
   129  		n, err := unix.ReadDirent(fd, buf)
   130  		if err != nil {
   131  			t.Fatalf("ReadDirent: %v", err)
   132  		}
   133  		if n == 0 {
   134  			break
   135  		}
   136  		buf = buf[:n]
   137  		for len(buf) > 0 {
   138  			var consumed int
   139  			consumed, _, files2 = unix.ParseDirent(buf, -1, files2)
   140  			if consumed == 0 && len(buf) > 0 {
   141  				t.Fatal("no progress")
   142  			}
   143  			buf = buf[consumed:]
   144  		}
   145  	}
   146  
   147  	// Check results
   148  	sort.Strings(files)
   149  	sort.Strings(files2)
   150  	if strings.Join(files, "|") != strings.Join(files2, "|") {
   151  		t.Errorf("bad file list: want\n%q\ngot\n%q", files, files2)
   152  	}
   153  }
   154
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