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55 lines
1.5 KiB
Go
55 lines
1.5 KiB
Go
package bpffs
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import (
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"fmt"
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"syscall"
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"unsafe"
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)
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const BPFFSPath = "/sys/fs/bpf"
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var FsMagicBPFFS int32
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func init() {
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// https://github.com/coreutils/coreutils/blob/v8.27/src/stat.c#L275
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// https://github.com/torvalds/linux/blob/v4.8/include/uapi/linux/magic.h#L80
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magic := uint32(0xCAFE4A11)
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// 0xCAFE4A11 overflows an int32, which is what's expected by Statfs_t.Type in 32bit platforms.
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// To avoid conditional compilation for all 32bit/64bit platforms, we use an unsafe cast
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FsMagicBPFFS = *(*int32)(unsafe.Pointer(&magic))
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}
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// IsMountedAt checks if the BPF fs is mounted already in the custom location
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func IsMountedAt(mountpoint string) (bool, error) {
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var data syscall.Statfs_t
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if err := syscall.Statfs(mountpoint, &data); err != nil {
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return false, fmt.Errorf("cannot statfs %q: %v", mountpoint, err)
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}
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return int32(data.Type) == FsMagicBPFFS, nil
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}
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// IsMounted checks if the BPF fs is mounted already in the default location
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func IsMounted() (bool, error) {
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return IsMountedAt(BPFFSPath)
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}
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// MountAt mounts the BPF fs in the custom location (if not already mounted)
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func MountAt(mountpoint string) error {
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mounted, err := IsMountedAt(mountpoint)
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if err != nil {
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return err
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}
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if mounted {
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return nil
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}
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if err := syscall.Mount(mountpoint, mountpoint, "bpf", 0, ""); err != nil {
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return fmt.Errorf("error mounting %q: %v", mountpoint, err)
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}
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return nil
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}
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// Mount mounts the BPF fs in the default location (if not already mounted)
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func Mount() error {
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return MountAt(BPFFSPath)
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}
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