Janne Beate BakengandNick Craig-Wood
00bd00d83d
With cmd/mount2, reading a directory more than once returned the correct entries on the first read but nothing on subsequent reads. Plain `ls` triggers this: it does lseek(fd, 0, SEEK_SET) to rewind the directory before a second getdents. go-fuse v2.9.0 rewinds a directory stream by calling Seekdir on the FileSeekdirer interface. dirStream did not implement it, so go-fuse returned ENOTSUP and produced an empty listing on every read after the first. This implements Seekdir on dirStream: a rewind to offset 0 resets the stream to the start, restoring correct listings on re-read. Non-zero offsets are uncommon for in-memory listings and still return ENOTSUP, matching go-fuse's own default. A compile-time interface assertion is added so signature drift on future go-fuse updates is caught at build time. Before: second and subsequent reads of a directory returned no entries. After: directories list correctly on every read. See: https://github.com/hanwen/go-fuse/issues/549 Co-authored-by: Nick Craig-Wood <nick@craig-wood.com>
76 lines
2.1 KiB
Go
76 lines
2.1 KiB
Go
//go:build linux || darwin || freebsd
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package vfstest
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import (
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"syscall"
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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)
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// countDirFd reads the directory referred to by fd to end-of-stream using
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// raw getdents syscalls and returns the number of entries (excluding "." and
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// ".." which ParseDirent skips).
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//
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// This deliberately uses syscall.ReadDirent rather than (*os.File).Readdir so
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// that it exercises the kernel readdir path directly on a single file
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// descriptor, the same way an in-process rewinddir does.
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func countDirFd(t *testing.T, fd int) int {
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buf := make([]byte, 8192)
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var names []string
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for {
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n, err := syscall.ReadDirent(fd, buf)
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require.NoError(t, err)
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if n <= 0 {
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break
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}
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_, _, names = syscall.ParseDirent(buf[:n], -1, names)
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}
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return len(names)
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}
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// TestDirRewind checks that re-reading a directory after rewinding the
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// directory stream (lseek(fd, 0, SEEK_SET), as rewinddir(3) does) returns the
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// same entries as the first read.
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//
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// This reproduces the bug where the mount2 backend returned an empty listing
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// on every read after the first because go-fuse v2.9.0 rewinds a directory by
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// calling Seekdir, which dirStream did not implement. See PR #9469 and
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// https://github.com/hanwen/go-fuse/issues/549
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func TestDirRewind(t *testing.T) {
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run.skipIfVFS(t)
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run.skipIfNoFUSE(t)
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run.mkdir(t, "dir")
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run.createFile(t, "dir/f1", "1")
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run.createFile(t, "dir/f2", "2")
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run.createFile(t, "dir/f3", "3")
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run.checkDir(t, "dir/|dir/f1 1|dir/f2 1|dir/f3 1")
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fh, err := run.os.Open(run.path("dir"))
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require.NoError(t, err)
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defer func() {
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_ = fh.Close()
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}()
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fd := int(fh.Fd())
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first := countDirFd(t, fd)
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assert.Equal(t, 3, first, "first read should see all entries")
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// rewinddir == lseek(fd, 0, SEEK_SET)
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_, err = syscall.Seek(fd, 0, 0)
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require.NoError(t, err)
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second := countDirFd(t, fd)
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assert.Equal(t, first, second, "re-read after rewind should match first read")
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require.NoError(t, fh.Close())
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run.rm(t, "dir/f1")
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run.rm(t, "dir/f2")
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run.rm(t, "dir/f3")
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run.rmdir(t, "dir")
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run.checkDir(t, "")
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}
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