unix: use ParseDirent from syscall

Just call syscall's implementation instead of duplicating ParseDirent
and the GOOS-specific private functions needed by it.

Change-Id: Icf49769390929463323608e093dd2a3d1c0ae4d3
Reviewed-on: https://go-review.googlesource.com/88475
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/dirent.go

@@ -6,97 +6,12 @@
 
 package unix
 
-import "unsafe"
-
-// readInt returns the size-bytes unsigned integer in native byte order at offset off.
-func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
-	if len(b) < int(off+size) {
-		return 0, false
-	}
-	if isBigEndian {
-		return readIntBE(b[off:], size), true
-	}
-	return readIntLE(b[off:], size), true
-}
-
-func readIntBE(b []byte, size uintptr) uint64 {
-	switch size {
-	case 1:
-		return uint64(b[0])
-	case 2:
-		_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
-		return uint64(b[1]) | uint64(b[0])<<8
-	case 4:
-		_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
-		return uint64(b[3]) | uint64(b[2])<<8 | uint64(b[1])<<16 | uint64(b[0])<<24
-	case 8:
-		_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
-		return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
-			uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
-	default:
-		panic("syscall: readInt with unsupported size")
-	}
-}
-
-func readIntLE(b []byte, size uintptr) uint64 {
-	switch size {
-	case 1:
-		return uint64(b[0])
-	case 2:
-		_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
-		return uint64(b[0]) | uint64(b[1])<<8
-	case 4:
-		_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
-		return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24
-	case 8:
-		_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
-		return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
-			uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
-	default:
-		panic("syscall: readInt with unsupported size")
-	}
-}
+import "syscall"
 
 // ParseDirent parses up to max directory entries in buf,
 // appending the names to names. It returns the number of
 // bytes consumed from buf, the number of entries added
 // to names, and the new names slice.
 func ParseDirent(buf []byte, max int, names []string) (consumed int, count int, newnames []string) {
-	origlen := len(buf)
-	count = 0
-	for max != 0 && len(buf) > 0 {
-		reclen, ok := direntReclen(buf)
-		if !ok || reclen > uint64(len(buf)) {
-			return origlen, count, names
-		}
-		rec := buf[:reclen]
-		buf = buf[reclen:]
-		ino, ok := direntIno(rec)
-		if !ok {
-			break
-		}
-		if ino == 0 { // File absent in directory.
-			continue
-		}
-		const namoff = uint64(unsafe.Offsetof(Dirent{}.Name))
-		namlen, ok := direntNamlen(rec)
-		if !ok || namoff+namlen > uint64(len(rec)) {
-			break
-		}
-		name := rec[namoff : namoff+namlen]
-		for i, c := range name {
-			if c == 0 {
-				name = name[:i]
-				break
-			}
-		}
-		// Check for useless names before allocating a string.
-		if string(name) == "." || string(name) == ".." {
-			continue
-		}
-		max--
-		count++
-		names = append(names, string(name))
-	}
-	return origlen - len(buf), count, names
+	return syscall.ParseDirent(buf, max, names)
 }

unix/syscall_darwin.go

@@ -76,18 +76,6 @@ func nametomib(name string) (mib []_C_int, err error) {
 	return buf[0 : n/siz], nil
 }
 
-func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
-}
-
-func direntReclen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
-}
-
-func direntNamlen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
-}
-
 //sys   ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
 func PtraceAttach(pid int) (err error) { return ptrace(PT_ATTACH, pid, 0, 0) }
 func PtraceDetach(pid int) (err error) { return ptrace(PT_DETACH, pid, 0, 0) }

unix/syscall_dragonfly.go

@@ -56,22 +56,6 @@ func nametomib(name string) (mib []_C_int, err error) {
 	return buf[0 : n/siz], nil
 }
 
-func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
-}
-
-func direntReclen(buf []byte) (uint64, bool) {
-	namlen, ok := direntNamlen(buf)
-	if !ok {
-		return 0, false
-	}
-	return (16 + namlen + 1 + 7) &^ 7, true
-}
-
-func direntNamlen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
-}
-
 //sysnb pipe() (r int, w int, err error)
 
 func Pipe(p []int) (err error) {

unix/syscall_freebsd.go

@@ -54,18 +54,6 @@ func nametomib(name string) (mib []_C_int, err error) {
 	return buf[0 : n/siz], nil
 }
 
-func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
-}
-
-func direntReclen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
-}
-
-func direntNamlen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
-}
-
 //sysnb pipe() (r int, w int, err error)
 
 func Pipe(p []int) (err error) {

unix/syscall_linux.go

@@ -1197,22 +1197,6 @@ func ReadDirent(fd int, buf []byte) (n int, err error) {
 	return Getdents(fd, buf)
 }
 
-func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
-}
-
-func direntReclen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
-}
-
-func direntNamlen(buf []byte) (uint64, bool) {
-	reclen, ok := direntReclen(buf)
-	if !ok {
-		return 0, false
-	}
-	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
-}
-
 //sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
 
 func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {

unix/syscall_netbsd.go

@@ -92,18 +92,6 @@ func nametomib(name string) (mib []_C_int, err error) {
 	return mib, nil
 }
 
-func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
-}
-
-func direntReclen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
-}
-
-func direntNamlen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
-}
-
 //sysnb pipe() (fd1 int, fd2 int, err error)
 func Pipe(p []int) (err error) {
 	if len(p) != 2 {

unix/syscall_openbsd.go

@@ -42,18 +42,6 @@ func nametomib(name string) (mib []_C_int, err error) {
 	return nil, EINVAL
 }
 
-func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
-}
-
-func direntReclen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
-}
-
-func direntNamlen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
-}
-
 //sysnb pipe(p *[2]_C_int) (err error)
 func Pipe(p []int) (err error) {
 	if len(p) != 2 {

unix/syscall_solaris.go

@@ -34,22 +34,6 @@ type SockaddrDatalink struct {
 	raw    RawSockaddrDatalink
 }
 
-func direntIno(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
-}
-
-func direntReclen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
-}
-
-func direntNamlen(buf []byte) (uint64, bool) {
-	reclen, ok := direntReclen(buf)
-	if !ok {
-		return 0, false
-	}
-	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
-}
-
 //sysnb	pipe(p *[2]_C_int) (n int, err error)
 
 func Pipe(p []int) (err error) {