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@@ -1,9 +1,33 @@
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package docker
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package docker
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+/*
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+#include <sys/ioctl.h>
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+#include <linux/fs.h>
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+#include <errno.h>
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+
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+// See linux.git/fs/btrfs/ioctl.h
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+#define BTRFS_IOCTL_MAGIC 0x94
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+#define BTRFS_IOC_CLONE _IOW(BTRFS_IOCTL_MAGIC, 9, int)
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+
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+int
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+btrfs_reflink(int fd_out, int fd_in)
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+{
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+ int res;
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+ res = ioctl(fd_out, BTRFS_IOC_CLONE, fd_in);
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+ if (res < 0)
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+ return errno;
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+ return 0;
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+}
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+
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+*/
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+import "C"
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import (
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import (
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"fmt"
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"fmt"
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+ "io"
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"io/ioutil"
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"io/ioutil"
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+ "os"
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"strings"
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"strings"
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+ "syscall"
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)
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)
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// Compare two Config struct. Do not compare the "Image" nor "Hostname" fields
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// Compare two Config struct. Do not compare the "Image" nor "Hostname" fields
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@@ -182,3 +206,22 @@ func RootIsShared() bool {
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// No idea, probably safe to assume so
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// No idea, probably safe to assume so
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return true
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return true
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}
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}
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+
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+func BtrfsReflink(fd_out, fd_in uintptr) error {
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+ res := C.btrfs_reflink(C.int(fd_out), C.int(fd_in))
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+ if res != 0 {
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+ return syscall.Errno(res)
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+ }
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+ return nil
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+}
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+
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+func CopyFile(dstFile, srcFile *os.File) error {
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+ err := BtrfsReflink(dstFile.Fd(), srcFile.Fd())
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+ if err == nil {
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+ return nil
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+ }
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+
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+ // Fall back to normal copy
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+ _, err = io.Copy(dstFile, srcFile)
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+ return err
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+}
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