From fc4d9a51e73938bbb6198334a2a9be93a9c22a74 Mon Sep 17 00:00:00 2001
From: Pragyansh Chaturvedi <pragyansh.chaturvedi@canonical.com>
Date: Sun, 19 Oct 2025 04:06:35 +0530
Subject: [PATCH] Fix perf_buffer__new call

---
 src/core/bpf_perf_buffer.cpp | 59 +++++++++++++++++++-----------------
 src/core/bpf_perf_buffer.h   |  3 +-
 2 files changed, 34 insertions(+), 28 deletions(-)

diff --git a/src/core/bpf_perf_buffer.cpp b/src/core/bpf_perf_buffer.cpp
index a1e7276..dceb747 100644
--- a/src/core/bpf_perf_buffer.cpp
+++ b/src/core/bpf_perf_buffer.cpp
@@ -1,6 +1,38 @@
 #include "bpf_perf_buffer.h"
 #include "bpf_exception.h"
 
+BpfPerfBuffer::BpfPerfBuffer(int map_fd, int page_cnt, py::function callback,
+                             py::object lost_callback)
+    : pb_(nullptr), callback_(std::move(callback)),
+      lost_callback_(lost_callback) {
+
+  if (page_cnt <= 0 || (page_cnt & (page_cnt - 1)) != 0) {
+    throw BpfException("page_cnt must be a positive power of 2");
+  }
+
+  struct perf_buffer_opts pb_opts = {};
+  pb_opts.sz = sizeof(pb_opts); // Required for forward compatibility
+
+  pb_ = perf_buffer__new(
+      map_fd, page_cnt,
+      sample_callback_wrapper,                                   // sample_cb
+      lost_callback.is_none() ? nullptr : lost_callback_wrapper, // lost_cb
+      this,                                                      // ctx
+      &pb_opts                                                   // opts
+  );
+
+  if (!pb_) {
+    throw BpfException("Failed to create perf buffer: " +
+                       std::string(std::strerror(errno)));
+  }
+}
+
+BpfPerfBuffer::~BpfPerfBuffer() {
+  if (pb_) {
+    perf_buffer__free(pb_);
+  }
+}
+
 void BpfPerfBuffer::sample_callback_wrapper(void *ctx, int cpu, void *data,
                                             unsigned int size) {
   auto *self = static_cast<BpfPerfBuffer *>(ctx);
@@ -36,33 +68,6 @@ void BpfPerfBuffer::lost_callback_wrapper(void *ctx, int cpu,
   }
 }
 
-BpfPerfBuffer::BpfPerfBuffer(int map_fd, int page_cnt, py::function callback,
-                             py::object lost_callback)
-    : pb_(nullptr), callback_(std::move(callback)) {
-
-  if (!lost_callback.is_none()) {
-    lost_callback_ = lost_callback.cast<py::function>();
-  }
-
-  // Setup perf buffer options
-  perf_buffer_opts pb_opts = {};
-  pb_opts.sample_cb = sample_callback_wrapper;
-  pb_opts.lost_cb = lost_callback.is_none() ? nullptr : lost_callback_wrapper;
-  pb_opts.ctx = this;
-
-  // Create perf buffer
-  pb_ = perf_buffer__new(map_fd, page_cnt, &pb_opts);
-  if (!pb_) {
-    throw BpfException("Failed to create perf buffer");
-  }
-}
-
-BpfPerfBuffer::~BpfPerfBuffer() {
-  if (pb_) {
-    perf_buffer__free(pb_);
-  }
-}
-
 int BpfPerfBuffer::poll(int timeout_ms) {
   // Release GIL during blocking poll
   py::gil_scoped_release release;
diff --git a/src/core/bpf_perf_buffer.h b/src/core/bpf_perf_buffer.h
index 3794a2d..3f21213 100644
--- a/src/core/bpf_perf_buffer.h
+++ b/src/core/bpf_perf_buffer.h
@@ -20,11 +20,12 @@ private:
 
 public:
   BpfPerfBuffer(int map_fd, int page_cnt, py::function callback,
-                py::object lost_callback);
+                py::object lost_callback = py::none());
   ~BpfPerfBuffer();
 
   int poll(int timeout_ms);
   int consume();
+  [[nodiscard]] int fd() const;
 };
 
 #endif // PYLIBBPF_BPF_PERF_BUFFER_H