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// +build linux
package elf
import (
"fmt"
"os"
"path/filepath"
"strings"
"unsafe"
"github.com/iovisor/gobpf/pkg/bpffs"
)
/*
#include <linux/unistd.h>
#include <linux/bpf.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
extern __u64 ptr_to_u64(void *);
int bpf_pin_object(int fd, const char *pathname)
{
union bpf_attr attr;
memset(&attr, 0, sizeof(attr));
attr.pathname = ptr_to_u64((void *)pathname);
attr.bpf_fd = fd;
return syscall(__NR_bpf, BPF_OBJ_PIN, &attr, sizeof(attr));
}
*/
import "C"
const (
BPFDirGlobals = "globals" // as in iproute2's BPF_DIR_GLOBALS
BPFFSPath = "/sys/fs/bpf/"
)
func validPinPath(PinPath string) bool {
if !strings.HasPrefix(PinPath, BPFFSPath) {
return false
}
return filepath.Clean(PinPath) == PinPath
}
func pinObject(fd int, pinPath string) error {
mounted, err := bpffs.IsMounted()
if err != nil {
return fmt.Errorf("error checking if %q is mounted: %v", BPFFSPath, err)
}
if !mounted {
return fmt.Errorf("bpf fs not mounted at %q", BPFFSPath)
}
err = os.MkdirAll(filepath.Dir(pinPath), 0755)
if err != nil {
return fmt.Errorf("error creating directory %q: %v", filepath.Dir(pinPath), err)
}
_, err = os.Stat(pinPath)
if err == nil {
return fmt.Errorf("aborting, found file at %q", pinPath)
}
if err != nil && !os.IsNotExist(err) {
return fmt.Errorf("failed to stat %q: %v", pinPath, err)
}
pinPathC := C.CString(pinPath)
defer C.free(unsafe.Pointer(pinPathC))
ret, err := C.bpf_pin_object(C.int(fd), pinPathC)
if ret != 0 {
return fmt.Errorf("error pinning object to %q: %v", pinPath, err)
}
return nil
}
// PinObjectGlobal pins and object to a name in a namespaces
// e.g. `/sys/fs/bpf/my-namespace/globals/my-name`
func PinObjectGlobal(fd int, namespace, name string) error {
pinPath := filepath.Join(BPFFSPath, namespace, BPFDirGlobals, name)
return pinObject(fd, pinPath)
}
// PinObject pins an object to a path
func PinObject(fd int, pinPath string) error {
if !validPinPath(pinPath) {
return fmt.Errorf("not a valid pin path: %s", pinPath)
}
return pinObject(fd, pinPath)
}
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