// Copyright 2018 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. //go:build unix package syscall_test import ( "bytes" "fmt" "os" "path/filepath" "runtime" "sort" "strconv" "strings" "syscall" "testing" "unsafe" ) func TestDirent(t *testing.T) { const ( direntBufSize = 2048 // arbitrary? See https://go.dev/issue/37323. filenameMinSize = 11 ) d := t.TempDir() t.Logf("tmpdir: %s", d) for i, c := range []byte("0123456789") { name := string(bytes.Repeat([]byte{c}, filenameMinSize+i)) err := os.WriteFile(filepath.Join(d, name), nil, 0644) if err != nil { t.Fatalf("writefile: %v", err) } } names := make([]string, 0, 10) fd, err := syscall.Open(d, syscall.O_RDONLY, 0) if err != nil { t.Fatalf("syscall.open: %v", err) } defer syscall.Close(fd) buf := bytes.Repeat([]byte{0xCD}, direntBufSize) for { n, err := syscall.ReadDirent(fd, buf) if err == syscall.EINVAL { // On linux, 'man getdents64' says that EINVAL indicates “result buffer is too small”. // Try a bigger buffer. t.Logf("ReadDirent: %v; retrying with larger buffer", err) buf = bytes.Repeat([]byte{0xCD}, len(buf)*2) continue } if err != nil { t.Fatalf("syscall.readdir: %v", err) } t.Logf("ReadDirent: read %d bytes", n) if n == 0 { break } var consumed, count int consumed, count, names = syscall.ParseDirent(buf[:n], -1, names) t.Logf("ParseDirent: %d new name(s)", count) if consumed != n { t.Fatalf("ParseDirent: consumed %d bytes; expected %d", consumed, n) } } sort.Strings(names) t.Logf("names: %q", names) if len(names) != 10 { t.Errorf("got %d names; expected 10", len(names)) } for i, name := range names { ord, err := strconv.Atoi(name[:1]) if err != nil { t.Fatalf("names[%d] is non-integer %q: %v", i, names[i], err) } if expected := strings.Repeat(name[:1], filenameMinSize+ord); name != expected { t.Errorf("names[%d] is %q (len %d); expected %q (len %d)", i, name, len(name), expected, len(expected)) } } } func TestDirentRepeat(t *testing.T) { const N = 100 // Note: the size of the buffer is small enough that the loop // below will need to execute multiple times. See issue #31368. size := N * unsafe.Offsetof(syscall.Dirent{}.Name) / 4 if runtime.GOOS == "freebsd" || runtime.GOOS == "netbsd" { if size < 1024 { size = 1024 // DIRBLKSIZ, see issue 31403. } } // Make a directory containing N files d := t.TempDir() var files []string for i := 0; i < N; i++ { files = append(files, fmt.Sprintf("file%d", i)) } for _, file := range files { err := os.WriteFile(filepath.Join(d, file), []byte("contents"), 0644) if err != nil { t.Fatalf("writefile: %v", err) } } // Read the directory entries using ReadDirent. fd, err := syscall.Open(d, syscall.O_RDONLY, 0) if err != nil { t.Fatalf("syscall.open: %v", err) } defer syscall.Close(fd) var files2 []string for { buf := make([]byte, size) n, err := syscall.ReadDirent(fd, buf) if err != nil { t.Fatalf("syscall.readdir: %v", err) } if n == 0 { break } buf = buf[:n] for len(buf) > 0 { var consumed int consumed, _, files2 = syscall.ParseDirent(buf, -1, files2) buf = buf[consumed:] } } // Check results sort.Strings(files) sort.Strings(files2) if strings.Join(files, "|") != strings.Join(files2, "|") { t.Errorf("bad file list: want\n%q\ngot\n%q", files, files2) } }