github.com/code-reading/golang@v0.0.0-20220303082512-ba5bc0e589a3/go/src/syscall/dirent_test.go (about)

     1  // Copyright 2018 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
     6  // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
     7  
     8  package syscall_test
     9  
    10  import (
    11  	"bytes"
    12  	"fmt"
    13  	"os"
    14  	"path/filepath"
    15  	"runtime"
    16  	"sort"
    17  	"strconv"
    18  	"strings"
    19  	"syscall"
    20  	"testing"
    21  	"unsafe"
    22  )
    23  
    24  func TestDirent(t *testing.T) {
    25  	const (
    26  		direntBufSize   = 2048
    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.Fatalf("writefile: %v", err)
    38  		}
    39  	}
    40  
    41  	buf := bytes.Repeat([]byte("DEADBEAF"), direntBufSize/8)
    42  	fd, err := syscall.Open(d, syscall.O_RDONLY, 0)
    43  	if err != nil {
    44  		t.Fatalf("syscall.open: %v", err)
    45  	}
    46  	defer syscall.Close(fd)
    47  	n, err := syscall.ReadDirent(fd, buf)
    48  	if err != nil {
    49  		t.Fatalf("syscall.readdir: %v", err)
    50  	}
    51  	buf = buf[:n]
    52  
    53  	names := make([]string, 0, 10)
    54  	for len(buf) > 0 {
    55  		var bc int
    56  		bc, _, names = syscall.ParseDirent(buf, -1, names)
    57  		buf = buf[bc:]
    58  	}
    59  
    60  	sort.Strings(names)
    61  	t.Logf("names: %q", names)
    62  
    63  	if len(names) != 10 {
    64  		t.Errorf("got %d names; expected 10", len(names))
    65  	}
    66  	for i, name := range names {
    67  		ord, err := strconv.Atoi(name[:1])
    68  		if err != nil {
    69  			t.Fatalf("names[%d] is non-integer %q: %v", i, names[i], err)
    70  		}
    71  		if expected := string(strings.Repeat(name[:1], filenameMinSize+ord)); name != expected {
    72  			t.Errorf("names[%d] is %q (len %d); expected %q (len %d)", i, name, len(name), expected, len(expected))
    73  		}
    74  	}
    75  }
    76  
    77  func TestDirentRepeat(t *testing.T) {
    78  	const N = 100
    79  	// Note: the size of the buffer is small enough that the loop
    80  	// below will need to execute multiple times. See issue #31368.
    81  	size := N * unsafe.Offsetof(syscall.Dirent{}.Name) / 4
    82  	if runtime.GOOS == "freebsd" || runtime.GOOS == "netbsd" {
    83  		if size < 1024 {
    84  			size = 1024 // DIRBLKSIZ, see issue 31403.
    85  		}
    86  		if runtime.GOOS == "freebsd" {
    87  			t.Skip("need to fix issue 31416 first")
    88  		}
    89  	}
    90  
    91  	// Make a directory containing N files
    92  	d := t.TempDir()
    93  
    94  	var files []string
    95  	for i := 0; i < N; i++ {
    96  		files = append(files, fmt.Sprintf("file%d", i))
    97  	}
    98  	for _, file := range files {
    99  		err := os.WriteFile(filepath.Join(d, file), []byte("contents"), 0644)
   100  		if err != nil {
   101  			t.Fatalf("writefile: %v", err)
   102  		}
   103  	}
   104  
   105  	// Read the directory entries using ReadDirent.
   106  	fd, err := syscall.Open(d, syscall.O_RDONLY, 0)
   107  	if err != nil {
   108  		t.Fatalf("syscall.open: %v", err)
   109  	}
   110  	defer syscall.Close(fd)
   111  	var files2 []string
   112  	for {
   113  		buf := make([]byte, size)
   114  		n, err := syscall.ReadDirent(fd, buf)
   115  		if err != nil {
   116  			t.Fatalf("syscall.readdir: %v", err)
   117  		}
   118  		if n == 0 {
   119  			break
   120  		}
   121  		buf = buf[:n]
   122  		for len(buf) > 0 {
   123  			var consumed int
   124  			consumed, _, files2 = syscall.ParseDirent(buf, -1, files2)
   125  			buf = buf[consumed:]
   126  		}
   127  	}
   128  
   129  	// Check results
   130  	sort.Strings(files)
   131  	sort.Strings(files2)
   132  	if strings.Join(files, "|") != strings.Join(files2, "|") {
   133  		t.Errorf("bad file list: want\n%q\ngot\n%q", files, files2)
   134  	}
   135  }