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 unix
6
7package syscall_test
8
9import (
10	"bytes"
11	"fmt"
12	"os"
13	"path/filepath"
14	"runtime"
15	"slices"
16	"strconv"
17	"strings"
18	"syscall"
19	"testing"
20	"unsafe"
21)
22
23func TestDirent(t *testing.T) {
24	const (
25		direntBufSize   = 2048 // arbitrary? See https://go.dev/issue/37323.
26		filenameMinSize = 11
27	)
28
29	d := t.TempDir()
30	t.Logf("tmpdir: %s", d)
31
32	for i, c := range []byte("0123456789") {
33		name := string(bytes.Repeat([]byte{c}, filenameMinSize+i))
34		err := os.WriteFile(filepath.Join(d, name), nil, 0644)
35		if err != nil {
36			t.Fatalf("writefile: %v", err)
37		}
38	}
39
40	names := make([]string, 0, 10)
41
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
48	buf := bytes.Repeat([]byte{0xCD}, direntBufSize)
49	for {
50		n, err := syscall.ReadDirent(fd, buf)
51		if err == syscall.EINVAL {
52			// On linux, 'man getdents64' says that EINVAL indicates “result buffer is too small”.
53			// Try a bigger buffer.
54			t.Logf("ReadDirent: %v; retrying with larger buffer", err)
55			buf = bytes.Repeat([]byte{0xCD}, len(buf)*2)
56			continue
57		}
58		if err != nil {
59			t.Fatalf("syscall.readdir: %v", err)
60		}
61		t.Logf("ReadDirent: read %d bytes", n)
62		if n == 0 {
63			break
64		}
65
66		var consumed, count int
67		consumed, count, names = syscall.ParseDirent(buf[:n], -1, names)
68		t.Logf("ParseDirent: %d new name(s)", count)
69		if consumed != n {
70			t.Fatalf("ParseDirent: consumed %d bytes; expected %d", consumed, n)
71		}
72	}
73
74	slices.Sort(names)
75	t.Logf("names: %q", names)
76
77	if len(names) != 10 {
78		t.Errorf("got %d names; expected 10", len(names))
79	}
80	for i, name := range names {
81		ord, err := strconv.Atoi(name[:1])
82		if err != nil {
83			t.Fatalf("names[%d] is non-integer %q: %v", i, names[i], err)
84		}
85		if expected := strings.Repeat(name[:1], filenameMinSize+ord); name != expected {
86			t.Errorf("names[%d] is %q (len %d); expected %q (len %d)", i, name, len(name), expected, len(expected))
87		}
88	}
89}
90
91func TestDirentRepeat(t *testing.T) {
92	const N = 100
93	// Note: the size of the buffer is small enough that the loop
94	// below will need to execute multiple times. See issue #31368.
95	size := N * unsafe.Offsetof(syscall.Dirent{}.Name) / 4
96	if runtime.GOOS == "freebsd" || runtime.GOOS == "netbsd" {
97		if size < 1024 {
98			size = 1024 // DIRBLKSIZ, see issue 31403.
99		}
100	}
101
102	// Make a directory containing N files
103	d := t.TempDir()
104
105	var files []string
106	for i := 0; i < N; i++ {
107		files = append(files, fmt.Sprintf("file%d", i))
108	}
109	for _, file := range files {
110		err := os.WriteFile(filepath.Join(d, file), []byte("contents"), 0644)
111		if err != nil {
112			t.Fatalf("writefile: %v", err)
113		}
114	}
115
116	// Read the directory entries using ReadDirent.
117	fd, err := syscall.Open(d, syscall.O_RDONLY, 0)
118	if err != nil {
119		t.Fatalf("syscall.open: %v", err)
120	}
121	defer syscall.Close(fd)
122	var files2 []string
123	for {
124		buf := make([]byte, size)
125		n, err := syscall.ReadDirent(fd, buf)
126		if err != nil {
127			t.Fatalf("syscall.readdir: %v", err)
128		}
129		if n == 0 {
130			break
131		}
132		buf = buf[:n]
133		for len(buf) > 0 {
134			var consumed int
135			consumed, _, files2 = syscall.ParseDirent(buf, -1, files2)
136			buf = buf[consumed:]
137		}
138	}
139
140	// Check results
141	slices.Sort(files)
142	slices.Sort(files2)
143	if strings.Join(files, "|") != strings.Join(files2, "|") {
144		t.Errorf("bad file list: want\n%q\ngot\n%q", files, files2)
145	}
146}
147