1 files changed, 146 insertions, 0 deletions
diff --git a/src/syscall/dirent_test.go b/src/syscall/dirent_test.go
new file mode 100644
index 0000000..68e766e
--- /dev/null
+++ b/src/syscall/dirent_test.go
@@ -0,0 +1,146 @@
+// 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 := string(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)
+	}
+}