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Adds Truncate to platform.File (#1428)

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Signed-off-by: Adrian Cole <adrian@tetrate.io>
This commit is contained in:
Crypt Keeper
2023-05-04 15:07:18 +08:00
committed by GitHub
parent 6dd0cef551
commit 5380321eea
6 changed files with 140 additions and 29 deletions
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23
imports/wasi_snapshot_preview1/fs.go
View File

@@ -20,12 +20,6 @@ import (
"github.com/tetratelabs/wazero/internal/wasm"
)
// The following interfaces are used until we finalize our own FD-scoped file.
type (
// truncateFile is implemented by os.File in file_posix.go
truncateFile interface{ Truncate(size int64) error }
)
// fdAdvise is the WASI function named FdAdviseName which provides file
// advisory information on a file descriptor.
//
@@ -101,16 +95,10 @@ func fdAllocateFn(_ context.Context, mod api.Module, params []uint64) syscall.Er
}
if st.Size >= tail {
// We already have enough space.
return 0
return 0 // We already have enough space.
}
osf, ok := f.File.File().(truncateFile)
if !ok {
return syscall.EBADF
}
return platform.UnwrapOSError(osf.Truncate(tail))
return f.File.Truncate(tail)
}
// fdClose is the WASI function named FdCloseName which closes a file
@@ -436,12 +424,9 @@ func fdFilestatSetSizeFn(_ context.Context, mod api.Module, params []uint64) sys
// Check to see if the file descriptor is available
if f, ok := fsc.LookupFile(fd); !ok {
return syscall.EBADF
} else if truncateFile, ok := f.File.File().(truncateFile); !ok {
return syscall.EBADF // possibly a fake file
} else if err := truncateFile.Truncate(int64(size)); err != nil {
return platform.UnwrapOSError(err)
} else {
return f.File.Truncate(int64(size))
}
return 0
}
// fdFilestatSetTimes is the WASI function named functionFdFilestatSetTimes

10
internal/gojs/fs.go
View File

@@ -48,12 +48,6 @@ var (
oEXCL = float64(os.O_EXCL)
)
// The following interfaces are used until we finalize our own FD-scoped file.
type (
// truncateFile is implemented by os.File in file_posix.go
truncateFile interface{ Truncate(size int64) error }
)
// jsfs = js.Global().Get("fs") // fs_js.go init
//
// js.fsCall conventions:
@@ -594,10 +588,8 @@ func (jsfsFtruncate) invoke(ctx context.Context, mod api.Module, args ...interfa
var errno syscall.Errno
if f, ok := fsc.LookupFile(fd); !ok {
errno = syscall.EBADF
} else if truncateFile, ok := f.File.File().(truncateFile); !ok {
errno = syscall.EBADF // possibly a fake file
} else {
errno = platform.UnwrapOSError(truncateFile.Truncate(length))
errno = f.File.Truncate(length)
}
return jsfsInvoke(ctx, mod, callback, errno)

49
internal/platform/file.go
View File

@@ -95,6 +95,7 @@ type File interface {
// https://pubs.opengroup.org/onlinepubs/9699919799/functions/fsync.html
// - This returns with no error instead of syscall.ENOSYS when
// unimplemented. This prevents fake filesystems from erring.
// - Windows does not error when calling Sync on a closed file.
Sync() syscall.Errno
// Datasync synchronizes the data of a file.
@@ -110,8 +111,26 @@ type File interface {
// https://pubs.opengroup.org/onlinepubs/9699919799/functions/fdatasync.html
// - This returns with no error instead of syscall.ENOSYS when
// unimplemented. This prevents fake filesystems from erring.
// - As this is commonly missing, some implementations dispatch to Sync.
Datasync() syscall.Errno
// Truncate truncates a file to a specified length.
//
// # Errors
//
// A zero syscall.Errno is success. The below are expected otherwise:
// - syscall.ENOSYS: the implementation does not support this function.
// - syscall.EBADF: the file or directory was closed.
// - syscall.EINVAL: the `size` is negative.
// - syscall.EISDIR: the file was a directory.
//
// # Notes
//
// - This is like syscall.Ftruncate and `ftruncate` in POSIX. See
// https://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html
// - Windows does not error when calling Truncate on a closed file.
Truncate(size int64) syscall.Errno
// Close closes the underlying file.
//
// A zero syscall.Errno is success. The below are expected otherwise:
@@ -156,6 +175,11 @@ func (UnimplementedFile) Datasync() syscall.Errno {
return 0 // not syscall.ENOSYS
}
// Truncate implements File.Truncate
func (UnimplementedFile) Truncate(int64) syscall.Errno {
return syscall.ENOSYS
}
func NewFsFile(path string, f fs.File) File {
return &fsFile{path, f}
}
@@ -205,6 +229,24 @@ func (f *fsFile) Datasync() syscall.Errno {
return datasync(f.file)
}
// Truncate implements File.Truncate
func (f *fsFile) Truncate(size int64) syscall.Errno {
if tf, ok := f.file.(truncateFile); ok {
errno := UnwrapOSError(tf.Truncate(size))
if errno == 0 {
return 0
}
// Operating systems return different syscall.Errno instead of EISDIR
// double-check on any err until we can assure this per OS.
if isOpenDir(f) {
return syscall.EISDIR
}
return errno
}
return syscall.ENOSYS
}
// Close implements File.Close
func (f *fsFile) Close() syscall.Errno {
return UnwrapOSError(f.file.Close())
@@ -258,3 +300,10 @@ type (
// truncateFile is implemented by os.File in file_posix.go
truncateFile interface{ Truncate(size int64) error }
)
func isOpenDir(f File) bool {
if st, statErrno := f.Stat(); statErrno == 0 && st.Mode.IsDir() {
return true
}
return false
}

80
internal/platform/file_test.go
View File

@@ -137,6 +137,77 @@ func testSync(t *testing.T, sync func(File) syscall.Errno) {
}
}
func TestFsFileTruncate(t *testing.T) {
content := []byte("123456")
tests := []struct {
name string
size int64
expectedContent []byte
expectedErr error
}{
{
name: "one less",
size: 5,
expectedContent: []byte("12345"),
},
{
name: "same",
size: 6,
expectedContent: content,
},
{
name: "zero",
size: 0,
expectedContent: []byte(""),
},
{
name: "larger",
size: 106,
expectedContent: append(content, make([]byte, 100)...),
},
}
for _, tt := range tests {
tc := tt
t.Run(tc.name, func(t *testing.T) {
tmpDir := t.TempDir()
f := openForWrite(t, path.Join(tmpDir, tc.name), content)
defer f.Close()
errno := f.Truncate(tc.size)
require.EqualErrno(t, 0, errno)
actual, err := os.ReadFile(f.Path())
require.NoError(t, err)
require.Equal(t, tc.expectedContent, actual)
})
}
truncateToZero := func(f File) syscall.Errno {
return f.Truncate(0)
}
if runtime.GOOS != "windows" {
// TODO: os.Truncate on windows can create the file even when it
// doesn't exist.
testEBADFIfFileClosed(t, truncateToZero)
}
testEISDIR(t, truncateToZero)
t.Run("negative", func(t *testing.T) {
tmpDir := t.TempDir()
f := openForWrite(t, path.Join(tmpDir, "truncate"), content)
defer f.Close()
errno := f.Truncate(-1)
require.EqualErrno(t, syscall.EINVAL, errno)
})
}
func testEBADFIfFileClosed(t *testing.T, fn func(File) syscall.Errno) bool {
return t.Run("EBADF if file closed", func(t *testing.T) {
tmpDir := t.TempDir()
@@ -150,6 +221,15 @@ func testEBADFIfFileClosed(t *testing.T, fn func(File) syscall.Errno) bool {
})
}
func testEISDIR(t *testing.T, fn func(File) syscall.Errno) bool {
return t.Run("EISDIR if directory", func(t *testing.T) {
f := openFsFile(t, os.TempDir(), os.O_RDONLY|O_DIRECTORY, 0o666)
defer f.Close()
require.EqualErrno(t, syscall.EISDIR, fn(f))
})
}
func openForWrite(t *testing.T, path string, content []byte) File {
require.NoError(t, os.WriteFile(path, content, 0o0600))
return openFsFile(t, path, os.O_RDWR, 0o666)

2
internal/platform/stat_test.go
View File

@@ -192,7 +192,7 @@ func TestStatFile(t *testing.T) {
require.NotEqual(t, uint64(0), st.Ino)
})
t.Run("closed file", func(t *testing.T) {
t.Run("closed fsFile", func(t *testing.T) {
require.Zero(t, fileF.Close())
_, errno := fileF.Stat()
require.EqualErrno(t, syscall.EBADF, errno)

5
internal/sys/fs.go
View File

@@ -210,6 +210,11 @@ func (r *lazyDir) Datasync() syscall.Errno {
}
}
// Truncate implements the same method as documented on platform.File
func (r *lazyDir) Truncate(int64) syscall.Errno {
return syscall.EISDIR
}
// File implements the same method as documented on platform.File
func (r *lazyDir) File() fs.File {
if f, ok := r.file(); !ok {