syscall: swap src, dest arguments in convertFromDirents11 for FreeBSD

make fixedSize, oldFixedSize constants.
use st instead of stat for function arg so that we do not shadow the stat() function.

dstPos+reclen == len(buf) is a valid write location, update the break condition.

Change-Id: I55f9210f54d24a3f9cda1ebab52437436254f8f4
Reviewed-on: https://go-review.googlesource.com/c/143637
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/syscall/export_freebsd_test.go b/src/syscall/export_freebsd_test.go
new file mode 100644 (file)
index 0000000..d47f090
--- /dev/null
+++ b/src/syscall/export_freebsd_test.go
@@ -0,0 +1,12 @@
+// 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.
+
+package syscall
+
+type Dirent_freebsd11 = dirent_freebsd11
+
+var (
+       Roundup              = roundup
+       ConvertFromDirents11 = convertFromDirents11
+)

diff --git a/src/syscall/syscall_freebsd.go b/src/syscall/syscall_freebsd.go
index 9ae024131dbe60d9156a3efc71a9d1d756753556..d6f75098c0981f43c9e77572d52eda5b57577f44 100644 (file)
--- a/src/syscall/syscall_freebsd.go
+++ b/src/syscall/syscall_freebsd.go
@@ -223,31 +223,31 @@ func Fstat(fd int, st *Stat_t) (err error) {
        return nil
 }
 
-func Statfs(path string, stat *Statfs_t) (err error) {
+func Statfs(path string, st *Statfs_t) (err error) {
        var oldStatfs statfs_freebsd11_t
        if supportsABI(_ino64First) {
-               return statfs_freebsd12(path, stat)
+               return statfs_freebsd12(path, st)
        }
        err = statfs(path, &oldStatfs)
        if err != nil {
                return err
        }
 
-       stat.convertFrom(&oldStatfs)
+       st.convertFrom(&oldStatfs)
        return nil
 }
 
-func Fstatfs(fd int, stat *Statfs_t) (err error) {
+func Fstatfs(fd int, st *Statfs_t) (err error) {
        var oldStatfs statfs_freebsd11_t
        if supportsABI(_ino64First) {
-               return fstatfs_freebsd12(fd, stat)
+               return fstatfs_freebsd12(fd, st)
        }
        err = fstatfs(fd, &oldStatfs)
        if err != nil {
                return err
        }
 
-       stat.convertFrom(&oldStatfs)
+       st.convertFrom(&oldStatfs)
        return nil
 }
 
@@ -262,7 +262,7 @@ func Getdirentries(fd int, buf []byte, basep *uintptr) (n int, err error) {
        oldBuf := make([]byte, oldBufLen)
        n, err = getdirentries(fd, oldBuf, basep)
        if err == nil && n > 0 {
-               n = convertFromDirents11(oldBuf[:n], buf)
+               n = convertFromDirents11(buf, oldBuf[:n])
        }
        return
 }
@@ -344,17 +344,20 @@ func (s *Statfs_t) convertFrom(old *statfs_freebsd11_t) {
        copy(s.Mntonname[:], old.Mntonname[:n])
 }
 
-func convertFromDirents11(old []byte, buf []byte) int {
-       oldFixedSize := int(unsafe.Offsetof((*dirent_freebsd11)(nil).Name))
-       fixedSize := int(unsafe.Offsetof((*Dirent)(nil).Name))
-       srcPos := 0
+func convertFromDirents11(buf []byte, old []byte) int {
+       const (
+               fixedSize    = int(unsafe.Offsetof(Dirent{}.Name))
+               oldFixedSize = int(unsafe.Offsetof(dirent_freebsd11{}.Name))
+       )
+
        dstPos := 0
+       srcPos := 0
        for dstPos+fixedSize < len(buf) && srcPos+oldFixedSize < len(old) {
-               srcDirent := (*dirent_freebsd11)(unsafe.Pointer(&old[srcPos]))
                dstDirent := (*Dirent)(unsafe.Pointer(&buf[dstPos]))
+               srcDirent := (*dirent_freebsd11)(unsafe.Pointer(&old[srcPos]))
 
                reclen := roundup(fixedSize+int(srcDirent.Namlen)+1, 8)
-               if dstPos+reclen >= len(buf) {
+               if dstPos+reclen > len(buf) {
                        break
                }
 

diff --git a/src/syscall/syscall_freebsd_test.go b/src/syscall/syscall_freebsd_test.go
new file mode 100644 (file)
index 0000000..3ccfe5d
--- /dev/null
+++ b/src/syscall/syscall_freebsd_test.go
@@ -0,0 +1,54 @@
+// 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.
+
+// +build freebsd
+
+package syscall_test
+
+import (
+       "fmt"
+       "syscall"
+       "testing"
+       "unsafe"
+)
+
+func TestConvertFromDirent11(t *testing.T) {
+       const (
+               filenameFmt  = "%04d"
+               numFiles     = 64
+               fixedHdrSize = int(unsafe.Offsetof(syscall.Dirent_freebsd11{}.Name))
+       )
+
+       namlen := len(fmt.Sprintf(filenameFmt, 0))
+       reclen := syscall.Roundup(fixedHdrSize+namlen+1, 4)
+       old := make([]byte, numFiles*reclen)
+       for i := 0; i < numFiles; i++ {
+               dent := syscall.Dirent_freebsd11{
+                       Fileno: uint32(i + 1),
+                       Reclen: uint16(reclen),
+                       Type:   syscall.DT_REG,
+                       Namlen: uint8(namlen),
+               }
+               rec := make([]byte, reclen)
+               copy(rec, (*[fixedHdrSize]byte)(unsafe.Pointer(&dent))[:])
+               copy(rec[fixedHdrSize:], fmt.Sprintf(filenameFmt, i+1))
+               copy(old[i*reclen:], rec)
+       }
+
+       buf := make([]byte, 2*len(old))
+       n := syscall.ConvertFromDirents11(buf, old)
+
+       names := make([]string, 0, numFiles)
+       _, _, names = syscall.ParseDirent(buf[:n], -1, names)
+
+       if len(names) != numFiles {
+               t.Errorf("expected %d files, have %d; names: %q", numFiles, len(names), names)
+       }
+
+       for i, name := range names {
+               if expected := fmt.Sprintf(filenameFmt, i+1); name != expected {
+                       t.Errorf("expected names[%d] to be %q; got %q", i, expected, name)
+               }
+       }
+}