From 7c15abd453664293a200801392bfcc87162fe5b4 Mon Sep 17 00:00:00 2001
From: Francisco Javier Honduvilla Coto <javierhonduco@gmail.com>
Date: Wed, 31 May 2023 11:42:06 +0100
Subject: [PATCH] Expose libbpf_num_possible_cpus

To fetch the number of "possible" (`/sys/devices/system/cpu/possible`)
CPUs.

This is needed in various PERCPU structures to compute the value size.
More details in https://github.com/parca-dev/parca-agent/issues/1696#issuecomment-1568736923

Signed-off-by: Francisco Javier Honduvilla Coto <javierhonduco@gmail.com>
---
 libbpfgo.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libbpfgo.go b/libbpfgo.go
index 5b7613c5..d13e16dc 100644
--- a/libbpfgo.go
+++ b/libbpfgo.go
@@ -2089,3 +2089,11 @@ func BPFProgramTypeIsSupported(progType BPFProgType) (bool, error) {
 	}
 	return cSupported == 1, nil
 }
+
+func NumPossibleCPUs() (int, error) {
+	numCPUs, _ := C.libbpf_num_possible_cpus()
+	if numCPUs < 0 {
+		return 0, fmt.Errorf("failed to retrieve the number of CPUs")
+	}
+	return int(numCPUs), nil
+}