78 lines
1.8 KiB
Go
78 lines
1.8 KiB
Go
package internal
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import (
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"errors"
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"fmt"
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"os"
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"path/filepath"
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"runtime"
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"unsafe"
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"github.com/cilium/ebpf/internal/sys"
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"github.com/cilium/ebpf/internal/unix"
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)
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func Pin(currentPath, newPath string, fd *sys.FD) error {
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const bpfFSType = 0xcafe4a11
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if newPath == "" {
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return errors.New("given pinning path cannot be empty")
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}
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if currentPath == newPath {
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return nil
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}
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var statfs unix.Statfs_t
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if err := unix.Statfs(filepath.Dir(newPath), &statfs); err != nil {
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return err
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}
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fsType := int64(statfs.Type)
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if unsafe.Sizeof(statfs.Type) == 4 {
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// We're on a 32 bit arch, where statfs.Type is int32. bpfFSType is a
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// negative number when interpreted as int32 so we need to cast via
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// uint32 to avoid sign extension.
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fsType = int64(uint32(statfs.Type))
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}
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if fsType != bpfFSType {
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return fmt.Errorf("%s is not on a bpf filesystem", newPath)
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}
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defer runtime.KeepAlive(fd)
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if currentPath == "" {
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return sys.ObjPin(&sys.ObjPinAttr{
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Pathname: sys.NewStringPointer(newPath),
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BpfFd: fd.Uint(),
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})
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}
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// Renameat2 is used instead of os.Rename to disallow the new path replacing
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// an existing path.
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err := unix.Renameat2(unix.AT_FDCWD, currentPath, unix.AT_FDCWD, newPath, unix.RENAME_NOREPLACE)
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if err == nil {
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// Object is now moved to the new pinning path.
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return nil
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}
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if !os.IsNotExist(err) {
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return fmt.Errorf("unable to move pinned object to new path %v: %w", newPath, err)
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}
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// Internal state not in sync with the file system so let's fix it.
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return sys.ObjPin(&sys.ObjPinAttr{
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Pathname: sys.NewStringPointer(newPath),
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BpfFd: fd.Uint(),
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})
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}
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func Unpin(pinnedPath string) error {
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if pinnedPath == "" {
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return nil
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}
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err := os.Remove(pinnedPath)
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if err == nil || os.IsNotExist(err) {
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return nil
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}
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return err
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}
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