From a7733cd4ab00b542d7e1afd53d9319b7f8b33674 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Thu, 15 Feb 2024 09:58:49 +0200
Subject: map sizes can be specified through flags

---
 internal/flags/flags.go | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

(limited to 'internal/flags')

diff --git a/internal/flags/flags.go b/internal/flags/flags.go
index 674f22f..1ba9d60 100644
--- a/internal/flags/flags.go
+++ b/internal/flags/flags.go
@@ -2,17 +2,22 @@ package flags
 
 import (
 	"flag"
+	"fmt"
 	"unsafe"
 
 	bpf "github.com/aquasecurity/libbpfgo"
 )
 
 type Flags struct {
-	UidFilter int
+	UidFilter        int
+	FdEventMapSize   int
+	OpenEventMapSize int
 }
 
 func New() (flags Flags) {
 	flag.IntVar(&flags.UidFilter, "uid", 0, "Filter for processes with UID")
+	flag.IntVar(&flags.FdEventMapSize, "fdMapSize", 4096, "BPF FD event map size")
+	flag.IntVar(&flags.OpenEventMapSize, "openMapSize", 1024, "BPF open event map size")
 	flag.Parse()
 	return flags
 }
@@ -32,3 +37,30 @@ func (flags Flags) SetBPF(bpfModule *bpf.Module) error {
 	key := uint32(1)
 	return flagsMap.Update(unsafe.Pointer(&key), unsafe.Pointer(&flagsValues))
 }
+
+func (flags Flags) ResizeBPFMaps(bpfModule *bpf.Module) error {
+	if err := resizeBPFMap(bpfModule, "open_event_map", uint32(flags.OpenEventMapSize)); err != nil {
+		return err
+	}
+	if err := resizeBPFMap(bpfModule, "fd_event_map", uint32(flags.FdEventMapSize)); err != nil {
+		return err
+	}
+	return nil
+}
+
+func resizeBPFMap(module *bpf.Module, name string, size uint32) error {
+	m, err := module.GetMap("open_event_map")
+	if err != nil {
+		return err
+	}
+
+	if err = m.SetMaxEntries(size); err != nil {
+		return err
+	}
+
+	if actual := m.MaxEntries(); actual != size {
+		return fmt.Errorf("map resize failed, expected %v, actual %v", size, actual)
+	}
+
+	return nil
+}
-- 
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