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os, syscall: refactor Unix directory parsing

Browse Source 
Moved the details of how to read a directory
and how to parse the results behind the new
syscall functions ReadDirent and ParseDirent.

Now os needs just one copy of Readdirnames
for the three Unix variants, and it no longer
imports "unsafe".

R=r, r2
CC=golang-dev
https://golang.org/cl/4368048
This commit is contained in:
Russ Cox 2011-04-06 15:44:40 -04:00
parent 1e1e2f0971
commit cf56f06ab6
7 changed files with 83 additions and 160 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/pkg/os/Makefile
View File

@ -6,7 +6,6 @@ include ../../Make.inc
TARG=os
GOFILES=\
dir_$(GOOS).go\
error.go\
env.go\
exec.go\
@ -19,6 +18,7 @@ GOFILES=\
types.go\
GOFILES_freebsd=\
dir_unix.go\
error_posix.go\
env_unix.go\
file_posix.go\
@ -28,6 +28,7 @@ GOFILES_freebsd=\
exec_unix.go\
GOFILES_darwin=\
dir_unix.go\
error_posix.go\
env_unix.go\
file_posix.go\
@ -37,6 +38,7 @@ GOFILES_darwin=\
exec_unix.go\
GOFILES_linux=\
dir_unix.go\
error_posix.go\
env_unix.go\
file_posix.go\
@ -46,6 +48,7 @@ GOFILES_linux=\
exec_unix.go\
GOFILES_windows=\
dir_windows.go\
error_posix.go\
env_windows.go\
file_posix.go\
@ -55,6 +58,7 @@ GOFILES_windows=\
exec_windows.go\
GOFILES_plan9=\
dir_plan9.go\
error_plan9.go\
env_plan9.go\
file_plan9.go\

65
src/pkg/os/dir_freebsd.go
View File

@ -1,65 +0,0 @@
// Copyright 2009 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 os
import (
"syscall"
"unsafe"
)
const (
blockSize = 4096
)
func (file *File) Readdirnames(count int) (names []string, err Error) {
// If this file has no dirinfo, create one.
if file.dirinfo == nil {
file.dirinfo = new(dirInfo)
// The buffer must be at least a block long.
file.dirinfo.buf = make([]byte, blockSize)
}
d := file.dirinfo
size := count
if size < 0 {
size = 100
}
names = make([]string, 0, size) // Empty with room to grow.
for count != 0 {
// Refill the buffer if necessary
if d.bufp >= d.nbuf {
var errno int
d.bufp = 0
// Final argument is (basep *uintptr) and the syscall doesn't take nil.
d.nbuf, errno = syscall.Getdirentries(file.fd, d.buf, new(uintptr))
if errno != 0 {
d.nbuf = 0
return names, NewSyscallError("getdirentries", errno)
}
if d.nbuf <= 0 {
break // EOF
}
}
// Drain the buffer
for count != 0 && d.bufp < d.nbuf {
dirent := (*syscall.Dirent)(unsafe.Pointer(&d.buf[d.bufp]))
if dirent.Reclen == 0 {
d.bufp = d.nbuf
break
}
d.bufp += int(dirent.Reclen)
if dirent.Fileno == 0 { // File absent in directory.
continue
}
bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
var name = string(bytes[0:dirent.Namlen])
if name == "." || name == ".." { // Useless names
continue
}
count--
names = append(names, name)
}
}
return names, nil
}

68
src/pkg/os/dir_linux.go
View File

@ -1,68 +0,0 @@
// Copyright 2009 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 os
import (
"syscall"
"unsafe"
)
const (
blockSize = 4096
)
func clen(n []byte) int {
for i := 0; i < len(n); i++ {
if n[i] == 0 {
return i
}
}
return len(n)
}
func (file *File) Readdirnames(count int) (names []string, err Error) {
// If this file has no dirinfo, create one.
if file.dirinfo == nil {
file.dirinfo = new(dirInfo)
// The buffer must be at least a block long.
file.dirinfo.buf = make([]byte, blockSize)
}
d := file.dirinfo
size := count
if size < 0 {
size = 100
}
names = make([]string, 0, size) // Empty with room to grow.
for count != 0 {
// Refill the buffer if necessary
if d.bufp >= d.nbuf {
var errno int
d.nbuf, errno = syscall.Getdents(file.fd, d.buf)
if errno != 0 {
return names, NewSyscallError("getdents", errno)
}
if d.nbuf <= 0 {
break // EOF
}
d.bufp = 0
}
// Drain the buffer
for count != 0 && d.bufp < d.nbuf {
dirent := (*syscall.Dirent)(unsafe.Pointer(&d.buf[d.bufp]))
d.bufp += int(dirent.Reclen)
if dirent.Ino == 0 { // File absent in directory.
continue
}
bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
var name = string(bytes[0:clen(bytes[0:])])
if name == "." || name == ".." { // Useless names
continue
}
count--
names = append(names, name)
}
}
return names, nil
}

32
src/pkg/os/dir_darwin.go → src/pkg/os/dir_unix.go
View File

@ -6,7 +6,6 @@ package os
import (
"syscall"
"unsafe"
)
const (
@ -34,37 +33,22 @@ func (file *File) Readdirnames(count int) (names []string, err Error) {
for count != 0 {
// Refill the buffer if necessary
if d.bufp >= d.nbuf {
var errno int
d.bufp = 0
// Final argument is (basep *uintptr) and the syscall doesn't take nil.
d.nbuf, errno = syscall.Getdirentries(file.fd, d.buf, new(uintptr))
var errno int
d.nbuf, errno = syscall.ReadDirent(file.fd, d.buf)
if errno != 0 {
d.nbuf = 0
return names, NewSyscallError("getdirentries", errno)
return names, NewSyscallError("readdirent", errno)
}
if d.nbuf <= 0 {
break // EOF
}
}
// Drain the buffer
for count != 0 && d.bufp < d.nbuf {
dirent := (*syscall.Dirent)(unsafe.Pointer(&d.buf[d.bufp]))
if dirent.Reclen == 0 {
d.bufp = d.nbuf
break
}
d.bufp += int(dirent.Reclen)
if dirent.Ino == 0 { // File absent in directory.
continue
}
bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
var name = string(bytes[0:dirent.Namlen])
if name == "." || name == ".." { // Useless names
continue
}
count--
names = append(names, name)
}
var nb, nc int
nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], count, names)
d.bufp += nb
count -= nc
}
return names, nil
}

3
src/pkg/os/os_test.go
View File

@ -17,8 +17,7 @@ import (
)
var dot = []string{
"dir_darwin.go",
"dir_linux.go",
"dir_unix.go",
"env_unix.go",
"error.go",
"file.go",

35
src/pkg/syscall/syscall_bsd.go
View File

@ -68,6 +68,41 @@ func Setgroups(gids []int) (errno int) {
return setgroups(len(a), &a[0])
}
func ReadDirent(fd int, buf []byte) (n int, errno int) {
// Final argument is (basep *uintptr) and the syscall doesn't take nil.
// TODO(rsc): Can we use a single global basep for all calls?
return Getdirentries(fd, buf, new(uintptr))
}
// ParseDirent parses up to max directory entries in buf,
// appending the names to names. It returns the number
// 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)
for max != 0 && len(buf) > 0 {
dirent := (*Dirent)(unsafe.Pointer(&buf[0]))
if dirent.Reclen == 0 {
buf = nil
break
}
buf = buf[dirent.Reclen:]
if dirent.Ino == 0 { // File absent in directory.
continue
}
bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
var name = string(bytes[0:dirent.Namlen])
if name == "." || name == ".." { // Useless names
continue
}
max--
count++
names = append(names, name)
}
return origlen - len(buf), count, names
}
// Wait status is 7 bits at bottom, either 0 (exited),
// 0x7F (stopped), or a signal number that caused an exit.
// The 0x80 bit is whether there was a core dump.

34
src/pkg/syscall/syscall_linux.go
View File

@ -679,6 +679,40 @@ func Reboot(cmd int) (errno int) {
return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
}
func clen(n []byte) int {
for i := 0; i < len(n); i++ {
if n[i] == 0 {
return i
}
}
return len(n)
}
func ReadDirent(fd int, buf []byte) (n int, errno int) {
return Getdents(fd, buf)
}
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 {
dirent := (*Dirent)(unsafe.Pointer(&buf[0]))
buf = buf[dirent.Reclen:]
if dirent.Ino == 0 { // File absent in directory.
continue
}
bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
var name = string(bytes[0:clen(bytes[:])])
if name == "." || name == ".." { // Useless names
continue
}
max--
count++
names = append(names, name)
}
return origlen - len(buf), count, names
}
// Sendto
// Recvfrom
// Socketpair