a27bda0eb9
We currently import the C package solely for a single value: the FICLONE ioctl, which is a constant. Since this is a constant and also part of the Linux kernel ABI, there's no reason we need to have the C compiler generate it for us every time we build. We can instead hard-code the constant in place, since it will never change. This avoids the need for cgo in order to have a functional invocation of git lfs dedup on Linux.
67 lines
1.5 KiB
Go
67 lines
1.5 KiB
Go
// +build linux
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package tools
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import (
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"io"
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"io/ioutil"
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"os"
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"syscall"
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)
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const (
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// This is the FICLONE ioctl value found in linux/fs.h on a typical
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// system. It's equivalent to the older BTRFS_IOC_CLONE. We hard-code
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// the value here to avoid a dependency on cgo.
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ioctlFiClone = 0x40049409
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)
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// CheckCloneFileSupported runs explicit test of clone file on supplied directory.
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// This function creates some (src and dst) file in the directory and remove after test finished.
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//
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// If check failed (e.g. directory is read-only), returns err.
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func CheckCloneFileSupported(dir string) (supported bool, err error) {
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src, err := ioutil.TempFile(dir, "src")
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if err != nil {
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return false, err
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}
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defer os.Remove(src.Name())
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dst, err := ioutil.TempFile(dir, "dst")
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if err != nil {
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return false, err
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}
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defer os.Remove(dst.Name())
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if ok, err := CloneFile(dst, src); err != nil {
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return false, err
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} else {
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return ok, nil
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}
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}
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func CloneFile(writer io.Writer, reader io.Reader) (bool, error) {
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fdst, fdstFound := writer.(*os.File)
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fsrc, fsrcFound := reader.(*os.File)
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if fdstFound && fsrcFound {
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if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fdst.Fd(), ioctlFiClone, fsrc.Fd()); err != 0 {
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return false, err
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}
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return true, nil
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}
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return false, nil
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}
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func CloneFileByPath(dst, src string) (bool, error) {
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srcFile, err := os.Open(src)
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if err != nil {
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return false, err
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}
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dstFile, err := os.Create(dst) //truncating, it if it already exists.
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if err != nil {
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return false, err
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}
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return CloneFile(dstFile, srcFile)
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}
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