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34 lines
708 B
Go
34 lines
708 B
Go
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package restorer
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import (
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"os"
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"runtime"
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"unsafe"
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"golang.org/x/sys/unix"
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)
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func preallocateFile(wr *os.File, size int64) error {
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// try contiguous first
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fst := unix.Fstore_t{
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Flags: unix.F_ALLOCATECONTIG | unix.F_ALLOCATEALL,
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Posmode: unix.F_PEOFPOSMODE,
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Offset: 0,
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Length: size,
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}
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_, err := unix.FcntlInt(wr.Fd(), unix.F_PREALLOCATE, int(uintptr(unsafe.Pointer(&fst))))
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if err == nil {
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return nil
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}
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// just take preallocation in any form, but still ask for everything
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fst.Flags = unix.F_ALLOCATEALL
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_, err = unix.FcntlInt(wr.Fd(), unix.F_PREALLOCATE, int(uintptr(unsafe.Pointer(&fst))))
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// Keep struct alive until fcntl has returned
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runtime.KeepAlive(fst)
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return err
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}
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