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Do not double close reader #29354

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merged 3 commits into from
Feb 24, 2024
Merged

Do not double close reader #29354

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2fc6583
Do not double close reader.
KN4CK3R Feb 23, 2024
e50392b
Return `nil` when calling `Close` multiple times.
KN4CK3R Feb 24, 2024
b1e0610
Merge branch 'main' into fix-double-close
wxiaoguang Feb 24, 2024
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13 changes: 12 additions & 1 deletion modules/git/blob_nogogit.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ import (
"bufio"
"bytes"
"io"
"io/fs"

"code.gitea.io/gitea/modules/log"
)
Expand Down Expand Up @@ -102,7 +103,17 @@ func (b *blobReader) Read(p []byte) (n int, err error) {

// Close implements io.Closer
func (b *blobReader) Close() error {
if b.rd == nil {
return fs.ErrClosed
}
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Should it panic here instead? Calling Close multiple times is a coding error. I checked all calls to DataAsync and could not find another double close. A panic could prevent double closes in future while returning a (most of time) ignored error could hide it.

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No. None of Golang's other "Close" methods panics.

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Could it simply return "nil"? Most (all) errors for a Close method are meanless .... no caller cares about it.

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I think double Close should be supported. i.e. It's safe to invoke file.Close twice. So I think we should also allow invoking Close twice. It's convenient for some situations.

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Should we then add this rule to our coding guidelines?

If a type implements io.Closer, calling Close multiple times must not fail and return a nil error.

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I guess it depends, for most cases: yes, nil is good enough.

But I guess there could be some special cases that the caller might be interested in the result.

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Then maybe relax the nil but specify that calling Close multiple times must not be undefined behaviour and must not panic?


defer b.cancel()

return DiscardFull(b.rd, b.n+1)
if err := DiscardFull(b.rd, b.n+1); err != nil {
return err
}

b.rd = nil

return nil
}
3 changes: 0 additions & 3 deletions routers/web/repo/editor.go
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Expand Up @@ -161,9 +161,6 @@ func editFile(ctx *context.Context, isNewFile bool) {
}

d, _ := io.ReadAll(dataRc)
if err := dataRc.Close(); err != nil {
log.Error("Error whilst closing blob data: %v", err)
}

buf = append(buf, d...)
if content, err := charset.ToUTF8(buf, charset.ConvertOpts{KeepBOM: true}); err != nil {
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