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Allow partial writes for gofer.specialFileFD. 

Originally, we avoided partial writes in case it caused us to write a partial
packet to a socket-backed specialFileFD. However, this check causes splicing
from a pipe to specialFileFD to fail if we hit EOF on the pipe.

PiperOrigin-RevId: 333016216
This commit is contained in:
Dean Deng 2020-09-21 23:42:47 -07:00 committed by gVisor bot
parent 059d90b9f1
commit 742e58b873
1 changed files with 9 additions and 5 deletions
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14
pkg/sentry/fsimpl/gofer/special_file.go
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@ -246,11 +246,12 @@ func (fd *specialFileFD) pwrite(ctx context.Context, src usermem.IOSequence, off
d.touchCMtime()
}
buf := make([]byte, src.NumBytes())
// Don't do partial writes if we get a partial read from src.
if _, err := src.CopyIn(ctx, buf); err != nil {
return 0, offset, err
copied, copyErr := src.CopyIn(ctx, buf)
if copied == 0 && copyErr != nil {
// Only return the error if we didn't get any data.
return 0, offset, copyErr
}
n, err := fd.handle.writeFromBlocksAt(ctx, safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf)), uint64(offset))
n, err := fd.handle.writeFromBlocksAt(ctx, safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf[:copied])), uint64(offset))
if err == syserror.EAGAIN {
err = syserror.ErrWouldBlock
}
@ -267,7 +268,10 @@ func (fd *specialFileFD) pwrite(ctx context.Context, src usermem.IOSequence, off
atomic.StoreUint64(&d.size, uint64(offset))
}
}
return int64(n), offset, err
if err != nil {
return int64(n), offset, err
}
return int64(n), offset, copyErr
}
// Write implements vfs.FileDescriptionImpl.Write.