whatcanGOwrong

go/pkg/mod/github.com/cilium/ebpf@v0.11.0/link/iter.go

@@ -0,0 +1,85 @@
+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
+}