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

     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 darwin || freebsd || netbsd || openbsd
     6  // +build darwin freebsd netbsd openbsd
     7  
     8  package syscall_test
     9  
    10  import (
    11  	"fmt"
    12  	"os"
    13  	"path/filepath"
    14  	"sort"
    15  	"strings"
    16  	"syscall"
    17  	"testing"
    18  	"unsafe"
    19  )
    20  
    21  func TestGetdirentries(t *testing.T) {
    22  	for _, count := range []int{10, 1000} {
    23  		t.Run(fmt.Sprintf("n=%d", count), func(t *testing.T) {
    24  			testGetdirentries(t, count)
    25  		})
    26  	}
    27  }
    28  func testGetdirentries(t *testing.T, count int) {
    29  	if count > 100 && testing.Short() && os.Getenv("GO_BUILDER_NAME") == "" {
    30  		t.Skip("skipping in -short mode")
    31  	}
    32  	d := t.TempDir()
    33  	var names []string
    34  	for i := 0; i < count; i++ {
    35  		names = append(names, fmt.Sprintf("file%03d", i))
    36  	}
    37  
    38  	// Make files in the temp directory
    39  	for _, name := range names {
    40  		err := os.WriteFile(filepath.Join(d, name), []byte("data"), 0)
    41  		if err != nil {
    42  			t.Fatalf("WriteFile: %v", err)
    43  		}
    44  	}
    45  
    46  	// Read files using Getdirentries
    47  	var names2 []string
    48  	fd, err := syscall.Open(d, syscall.O_RDONLY, 0)
    49  	if err != nil {
    50  		t.Fatalf("Open: %v", err)
    51  	}
    52  	defer syscall.Close(fd)
    53  	var base uintptr
    54  	var buf [2048]byte
    55  	for {
    56  		n, err := syscall.Getdirentries(fd, buf[:], &base)
    57  		if err != nil {
    58  			t.Fatalf("Getdirentries: %v", err)
    59  		}
    60  		if n == 0 {
    61  			break
    62  		}
    63  		data := buf[:n]
    64  		for len(data) > 0 {
    65  			// If multiple Dirents are written into buf, sometimes when we reach the final one,
    66  			// we have cap(buf) < Sizeof(Dirent). So use an appropriate slice to copy from data.
    67  			var dirent syscall.Dirent
    68  			copy((*[unsafe.Sizeof(dirent)]byte)(unsafe.Pointer(&dirent))[:], data)
    69  
    70  			data = data[dirent.Reclen:]
    71  			name := make([]byte, dirent.Namlen)
    72  			for i := 0; i < int(dirent.Namlen); i++ {
    73  				name[i] = byte(dirent.Name[i])
    74  			}
    75  			names2 = append(names2, string(name))
    76  		}
    77  	}
    78  
    79  	names = append(names, ".", "..") // Getdirentries returns these also
    80  	sort.Strings(names)
    81  	sort.Strings(names2)
    82  	if strings.Join(names, ":") != strings.Join(names2, ":") {
    83  		t.Errorf("names don't match\n names: %q\nnames2: %q", names, names2)
    84  	}
    85  }