复制项目

tools/url2im/pkg/buffer.go

@@ -0,0 +1,110 @@
+// Copyright © 2023 OpenIM. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pkg
+
+import (
+	"bytes"
+	"io"
+	"os"
+)
+
+type ReadSeekSizeCloser interface {
+	io.ReadSeekCloser
+	Size() int64
+}
+
+func NewReader(r io.Reader, max int64, path string) (ReadSeekSizeCloser, error) {
+	buf := make([]byte, max+1)
+	n, err := io.ReadFull(r, buf)
+	if err == nil {
+		f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o666)
+		if err != nil {
+			return nil, err
+		}
+		var ok bool
+		defer func() {
+			if !ok {
+				_ = f.Close()
+				_ = os.Remove(path)
+			}
+		}()
+		if _, err := f.Write(buf[:n]); err != nil {
+			return nil, err
+		}
+		cn, err := io.Copy(f, r)
+		if err != nil {
+			return nil, err
+		}
+		if _, err := f.Seek(0, io.SeekStart); err != nil {
+			return nil, err
+		}
+		ok = true
+		return &fileBuffer{
+			f: f,
+			n: cn + int64(n),
+		}, nil
+	} else if err == io.EOF || err == io.ErrUnexpectedEOF {
+		return &memoryBuffer{
+			r: bytes.NewReader(buf[:n]),
+		}, nil
+	} else {
+		return nil, err
+	}
+}
+
+type fileBuffer struct {
+	n int64
+	f *os.File
+}
+
+func (r *fileBuffer) Read(p []byte) (n int, err error) {
+	return r.f.Read(p)
+}
+
+func (r *fileBuffer) Seek(offset int64, whence int) (int64, error) {
+	return r.f.Seek(offset, whence)
+}
+
+func (r *fileBuffer) Size() int64 {
+	return r.n
+}
+
+func (r *fileBuffer) Close() error {
+	name := r.f.Name()
+	if err := r.f.Close(); err != nil {
+		return err
+	}
+	return os.Remove(name)
+}
+
+type memoryBuffer struct {
+	r *bytes.Reader
+}
+
+func (r *memoryBuffer) Read(p []byte) (n int, err error) {
+	return r.r.Read(p)
+}
+
+func (r *memoryBuffer) Seek(offset int64, whence int) (int64, error) {
+	return r.r.Seek(offset, whence)
+}
+
+func (r *memoryBuffer) Close() error {
+	return nil
+}
+
+func (r *memoryBuffer) Size() int64 {
+	return r.r.Size()
+}