/
file.go
197 lines (158 loc) · 4.06 KB
/
file.go
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package s3fs
import (
"context"
"fmt"
"io"
"io/fs"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/feature/s3/manager"
"github.com/aws/aws-sdk-go-v2/service/s3"
"github.com/eikenb/pipeat"
)
var (
_ fs.File = (*File)(nil)
_ fs.DirEntry = (*File)(nil)
_ writerCloserAt = (*File)(nil)
)
type File struct {
reader readerCloserAt
writer writerCloserAt
fs *Fs
readerCancelFn context.CancelFunc
writerCancelFn context.CancelFunc
info FileInfo
offset int64
}
func (f *File) Name() string { return f.info.Name() }
func (f *File) IsDir() bool { return f.info.IsDir() }
func (f *File) Type() fs.FileMode { return f.info.Type() }
func (f *File) Info() (fs.FileInfo, error) { return f.info.Info() }
func (f *File) Stat() (fs.FileInfo, error) { return &f.info, nil }
func (f *File) Read(b []byte) (int, error) {
if f.reader == nil {
return 0, fmt.Errorf("file not open for reading: %w", fs.ErrClosed)
}
n, err := f.reader.Read(b)
if err != nil {
return n, err
}
f.offset += int64(n)
return n, nil
}
func (f *File) ReadAt(b []byte, offset int64) (int, error) {
if f.reader == nil {
return 0, fmt.Errorf("file not open for reading: %w", fs.ErrClosed)
}
return f.reader.ReadAt(b, offset)
}
func (f *File) Seek(offset int64, whence int) (int64, error) {
if f.reader == nil {
return 0, fmt.Errorf("seek only supported for reading: %w", fs.ErrClosed)
}
var start int64
switch whence {
case io.SeekStart:
start = offset
case io.SeekCurrent:
start = f.offset + offset
case io.SeekEnd:
start = f.info.Size() - offset
}
if start < 0 || start > f.info.Size() {
return 0, &fs.PathError{Op: "seek", Path: f.info.name, Err: fs.ErrInvalid}
}
return start, f.openReaderAt(context.Background(), start)
}
func (f *File) openReaderAt(ctx context.Context, offset int64) error {
if f.readerCancelFn != nil {
f.readerCancelFn()
}
if f.reader != nil {
if err := f.Close(); err != nil {
return err
}
}
r, w, err := pipeat.PipeInDir(f.fs.tempDir)
if err != nil {
return err
}
ctx, cancelFn := context.WithCancel(ctx)
downloader := manager.NewDownloader(f.fs.client, func(d *manager.Downloader) {
d.Concurrency = 1
d.PartSize = f.fs.partSize
})
var streamRange *string
if offset > 0 {
streamRange = aws.String(fmt.Sprintf("bytes=%d-", offset))
}
go func() {
defer cancelFn()
_, err := downloader.Download(ctx, w, &s3.GetObjectInput{
Bucket: aws.String(f.fs.bucket),
Key: aws.String(f.fs.withPrefix(f.Name())),
Range: streamRange,
})
_ = w.CloseWithError(err)
}()
f.offset = offset
f.reader = r
f.readerCancelFn = cancelFn
return nil
}
func (f *File) openWriter(ctx context.Context) error {
r, w, err := pipeat.PipeInDir(f.fs.tempDir)
if err != nil {
return err
}
ctx, cancel := context.WithCancel(ctx)
uploader := manager.NewUploader(f.fs.client, func(u *manager.Uploader) {
u.Concurrency = 1
u.PartSize = f.fs.partSize
})
go func() {
defer cancel()
_, err := uploader.Upload(ctx, &s3.PutObjectInput{
Bucket: aws.String(f.fs.bucket),
Key: aws.String(f.fs.withPrefix(f.Name())),
Body: r,
})
_ = r.CloseWithError(err)
}()
f.writer = w
f.writerCancelFn = cancel
return nil
}
// Write implements io.Writer interface.
func (f *File) Write(p []byte) (n int, err error) {
if f.writer == nil {
return 0, fmt.Errorf("file not open for writing: %w", fs.ErrClosed)
}
return f.writer.Write(p)
}
// WriteAt implements io.WriterAt interface.
func (f *File) WriteAt(p []byte, off int64) (n int, err error) {
if f.writer == nil {
return 0, fmt.Errorf("file not open for writing: %w", fs.ErrClosed)
}
return f.writer.WriteAt(p, off)
}
// Close implements io.Closer interface.
func (f *File) Close() error {
if f.reader != nil {
if err := f.reader.Close(); err != nil {
return err
}
}
if f.readerCancelFn != nil {
f.readerCancelFn()
}
if f.writer != nil {
if err := f.writer.Close(); err != nil {
return err
}
}
if f.writerCancelFn != nil {
f.writerCancelFn()
}
return nil
}