79 lines
1.8 KiB
Go
79 lines
1.8 KiB
Go
// Copyright 2021 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package util
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import (
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"bytes"
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"errors"
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"io"
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)
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// ReadAtMost reads at most len(buf) bytes from r into buf.
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// It returns the number of bytes copied. n is only less than len(buf) if r provides fewer bytes.
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// If EOF or ErrUnexpectedEOF occurs while reading, err will be nil.
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func ReadAtMost(r io.Reader, buf []byte) (n int, err error) {
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n, err = io.ReadFull(r, buf)
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if err == io.EOF || err == io.ErrUnexpectedEOF {
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err = nil
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}
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return n, err
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}
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// ReadWithLimit reads at most "limit" bytes from r into buf.
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// If EOF or ErrUnexpectedEOF occurs while reading, err will be nil.
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func ReadWithLimit(r io.Reader, n int) (buf []byte, err error) {
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return readWithLimit(r, 1024, n)
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}
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func readWithLimit(r io.Reader, batch, limit int) ([]byte, error) {
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if limit <= batch {
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buf := make([]byte, limit)
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n, err := ReadAtMost(r, buf)
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if err != nil {
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return nil, err
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}
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return buf[:n], nil
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}
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res := bytes.NewBuffer(make([]byte, 0, batch))
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bufFix := make([]byte, batch)
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eof := false
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for res.Len() < limit && !eof {
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bufTmp := bufFix
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if res.Len()+batch > limit {
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bufTmp = bufFix[:limit-res.Len()]
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}
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n, err := io.ReadFull(r, bufTmp)
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if err == io.EOF || err == io.ErrUnexpectedEOF {
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eof = true
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} else if err != nil {
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return nil, err
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}
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if _, err = res.Write(bufTmp[:n]); err != nil {
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return nil, err
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}
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}
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return res.Bytes(), nil
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}
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// ErrNotEmpty is an error reported when there is a non-empty reader
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var ErrNotEmpty = errors.New("not-empty")
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// IsEmptyReader reads a reader and ensures it is empty
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func IsEmptyReader(r io.Reader) (err error) {
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var buf [1]byte
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for {
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n, err := r.Read(buf[:])
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if err != nil {
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if err == io.EOF {
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return nil
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}
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return err
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}
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if n > 0 {
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return ErrNotEmpty
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}
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}
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}
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