Commit e3c7ffcd authored by Keith Randall's avatar Keith Randall

os: reset dirinfo when seeking on Darwin

The first Readdirnames calls opendir and caches the result.
The behavior of that cached opendir result isn't specified on a seek
of the underlying fd. Free the opendir result on a seek so that
we'll allocate a new one the next time around.

Also fix wasm behavior in this regard, so that a seek to the
file start resets the Readdirnames position, regardless of platform.

p.s. I hate the Readdirnames API.

Fixes #35767.

Change-Id: Ieffb61b3c5cdd42591f69ab13f932003966f2297
Reviewed-on: https://go-review.googlesource.com/c/go/+/209961
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: default avatarEmmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: default avatarBrad Fitzpatrick <bradfitz@golang.org>
parent d72dce87
......@@ -24,6 +24,16 @@ func (d *dirInfo) close() {
d.dir = 0
}
func (f *File) seekInvalidate() {
if f.dirinfo == nil {
return
}
// Free cached dirinfo, so we allocate a new one if we
// access this file as a directory again. See #35767.
f.dirinfo.close()
f.dirinfo = nil
}
func (f *File) readdirnames(n int) (names []string, err error) {
if f.dirinfo == nil {
dir, call, errno := f.pfd.OpenDir()
......
......@@ -26,6 +26,8 @@ const (
func (d *dirInfo) close() {}
func (f *File) seekInvalidate() {}
func (f *File) readdirnames(n int) (names []string, err error) {
// If this file has no dirinfo, create one.
if f.dirinfo == nil {
......
......@@ -295,6 +295,7 @@ func (f *File) pwrite(b []byte, off int64) (n int, err error) {
// relative to the current offset, and 2 means relative to the end.
// It returns the new offset and an error, if any.
func (f *File) seek(offset int64, whence int) (ret int64, err error) {
f.seekInvalidate()
ret, err = f.pfd.Seek(offset, whence)
runtime.KeepAlive(f)
return ret, err
......
......@@ -34,6 +34,7 @@ var (
type jsFile struct {
path string
entries []string
dirIdx int // entries[:dirIdx] have already been returned in ReadDirent
pos int64
seeked bool
}
......@@ -141,8 +142,8 @@ func ReadDirent(fd int, buf []byte) (int, error) {
}
n := 0
for len(f.entries) > 0 {
entry := f.entries[0]
for f.dirIdx < len(f.entries) {
entry := f.entries[f.dirIdx]
l := 2 + len(entry)
if l > len(buf) {
break
......@@ -152,7 +153,7 @@ func ReadDirent(fd int, buf []byte) (int, error) {
copy(buf[2:], entry)
buf = buf[l:]
n += l
f.entries = f.entries[1:]
f.dirIdx++
}
return n, nil
......@@ -470,6 +471,7 @@ func Seek(fd int, offset int64, whence int) (int64, error) {
}
f.seeked = true
f.dirIdx = 0 // Reset directory read position. See issue 35767.
f.pos = newPos
return newPos, nil
}
......
// run
// Copyright 2019 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 main
import (
"log"
"os"
)
func main() {
wd, err := os.Getwd()
if err != nil {
log.Fatal(err)
}
f, err := os.Open(wd)
if err != nil {
log.Fatal(err)
}
dirnames1, err := f.Readdirnames(0)
if err != nil {
log.Fatal(err)
}
ret, err := f.Seek(0, 0)
if err != nil {
log.Fatal(err)
}
if ret != 0 {
log.Fatalf("seek result not zero: %d", ret)
}
dirnames2, err := f.Readdirnames(0)
if err != nil {
log.Fatal(err)
return
}
if len(dirnames1) != len(dirnames2) {
log.Fatalf("listings have different lengths: %d and %d\n", len(dirnames1), len(dirnames2))
}
for i, n1 := range dirnames1 {
n2 := dirnames2[i]
if n1 != n2 {
log.Fatalf("different name i=%d n1=%s n2=%s\n", i, n1, n2)
}
}
}
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