package link
import (
"fmt"
"io"
"unsafe"
"github.com/cilium/ebpf"
"github.com/cilium/ebpf/internal/sys"
)
type IterOptions struct {
// Program must be of type Tracing with attach type
// AttachTraceIter. The kind of iterator to attach to is
// determined at load time via the AttachTo field.
//
// AttachTo requires the kernel to include BTF of itself,
// and it to be compiled with a recent pahole (>= 1.16).
Program *ebpf.Program
// Map specifies the target map for bpf_map_elem and sockmap iterators.
// It may be nil.
Map *ebpf.Map
}
// AttachIter attaches a BPF seq_file iterator.
func AttachIter(opts IterOptions) (*Iter, error) {
if err := haveBPFLink(); err != nil {
return nil, err
}
progFd := opts.Program.FD()
if progFd < 0 {
return nil, fmt.Errorf("invalid program: %s", sys.ErrClosedFd)
}
var info bpfIterLinkInfoMap
if opts.Map != nil {
mapFd := opts.Map.FD()
if mapFd < 0 {
return nil, fmt.Errorf("invalid map: %w", sys.ErrClosedFd)
}
info.map_fd = uint32(mapFd)
}
attr := sys.LinkCreateIterAttr{
ProgFd: uint32(progFd),
AttachType: sys.AttachType(ebpf.AttachTraceIter),
IterInfo: sys.NewPointer(unsafe.Pointer(&info)),
IterInfoLen: uint32(unsafe.Sizeof(info)),
}
fd, err := sys.LinkCreateIter(&attr)
if err != nil {
return nil, fmt.Errorf("can't link iterator: %w", err)
}
return &Iter{RawLink{fd, ""}}, err
}
// Iter represents an attached bpf_iter.
type Iter struct {
RawLink
}
// Open creates a new instance of the iterator.
//
// Reading from the returned reader triggers the BPF program.
func (it *Iter) Open() (io.ReadCloser, error) {
attr := &sys.IterCreateAttr{
LinkFd: it.fd.Uint(),
}
fd, err := sys.IterCreate(attr)
if err != nil {
return nil, fmt.Errorf("can't create iterator: %w", err)
}
return fd.File("bpf_iter"), nil
}
// union bpf_iter_link_info.map
type bpfIterLinkInfoMap struct {
map_fd uint32
}