From e97d9eb1751623e5434aac08a5746350be2a7341 Mon Sep 17 00:00:00 2001
From: PancakeTAS <pancake@mgnet.work>
Date: Thu, 25 Jun 2026 11:13:16 +0200
Subject: Bug fixes all across the project

---
 src/gem.cpp | 65 +++++++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 46 insertions(+), 19 deletions(-)

(limited to 'src/gem.cpp')

diff --git a/src/gem.cpp b/src/gem.cpp
index 0572c3b..b6b3d38 100644
--- a/src/gem.cpp
+++ b/src/gem.cpp
@@ -4,8 +4,11 @@
 #include "drm++/helper.hpp"
 #include "drm++/ioctl.hpp"
 
+#include <cassert>
 #include <cerrno>
+#include <stdexcept>
 #include <system_error>
+#include <utility>
 
 #include <drm.h>
 #include <drm_mode.h>
@@ -18,14 +21,15 @@ using namespace drm::gem;
 
 /* GEM object class */
 
-Object::Object(int fd, int dmabuf_fd, bool close) : m_fd(fd) {
+Object::Object(ObjectManager& manager, int dmabuf_fd, bool close) : m_manager(&manager) {
     try {
         drm_prime_handle args{
             .fd = dmabuf_fd
         };
-        ioctl::perform(this->m_fd, DRM_IOCTL_PRIME_FD_TO_HANDLE, args);
+        ioctl::perform(this->m_manager->m_fd, DRM_IOCTL_PRIME_FD_TO_HANDLE, args);
 
         this->m_handle = args.handle;
+        this->m_manager->m_refcounts[this->m_handle]++;
     } catch (...) {
         if (close) {
             ::close(dmabuf_fd);
@@ -44,22 +48,36 @@ int Object::exportFd(ExportFlags flags) const {
         .handle = this->m_handle,
         .flags = static_cast<u32>(flags)
     };
-    ioctl::perform(this->m_fd, DRM_IOCTL_PRIME_HANDLE_TO_FD, args);
+    ioctl::perform(this->m_manager->m_fd, DRM_IOCTL_PRIME_HANDLE_TO_FD, args);
 
     return args.fd;
 }
 
 void Object::changeHandle(u32 handle) {
-    drm_gem_close args{
-        .handle = this->m_handle
+    auto& refcounts{this->m_manager->m_refcounts};
+    if (refcounts[handle] > 0 || refcounts[this->m_handle] > 1) {
+        throw std::logic_error("GEM handle is still in use");
+    }
+
+    drm_gem_change_handle args{
+        .handle = this->m_handle,
+        .new_handle = handle
     };
-    ioctl::perform(this->m_fd, DRM_IOCTL_GEM_CLOSE, args);
+    ioctl::perform(this->m_manager->m_fd, DRM_IOCTL_GEM_CHANGE_HANDLE, args);
 
+    std::exchange(refcounts[handle], refcounts[this->m_handle]);
     this->m_handle = handle;
 }
 
 void Object::destruct() noexcept {
-    if (this->m_fd < 0) {
+    if (this->m_manager == nullptr) {
+        return;
+    }
+
+    auto& refcounts{this->m_manager->m_refcounts};
+    if (refcounts[this->m_handle] > 1) {
+        refcounts[this->m_handle]--;
+        this->m_manager = nullptr;
         return;
     }
 
@@ -67,26 +85,28 @@ void Object::destruct() noexcept {
         .handle = this->m_handle
     };
     try {
-        ioctl::perform(this->m_fd, DRM_IOCTL_GEM_CLOSE, args);
+        ioctl::perform(this->m_manager->m_fd, DRM_IOCTL_GEM_CLOSE, args);
     } catch(...) {
-        (void) 0; // not much we can do about the leak
+        assert(false && "GEM close failed, memory leak likely");
     }
 
-    this->m_fd = -1;
+    this->m_manager = nullptr;
 }
 
 /* Dumb buffer class */
 
-DumbBuffer::DumbBuffer(int fd, u32 width, u32 height, u32 bpp)
-        : Object(fd), m_width(width), m_height(height), m_bpp(bpp) {
+DumbBuffer::DumbBuffer(ObjectManager& manager, u32 width, u32 height, u32 bpp)
+        : Object(manager), m_width(width), m_height(height), m_bpp(bpp) {
     drm_mode_create_dumb args{
         .height = height,
         .width = width,
         .bpp = bpp
     };
-    ioctl::perform(this->m_fd, DRM_IOCTL_MODE_CREATE_DUMB, args);
+    ioctl::perform(this->m_manager->m_fd, DRM_IOCTL_MODE_CREATE_DUMB, args);
 
     this->m_handle = args.handle;
+    this->m_manager->m_refcounts[this->m_handle]++;
+
     this->m_pitch = args.pitch;
     this->m_size = args.size;
 }
@@ -99,10 +119,10 @@ void* DumbBuffer::map() {
     drm_mode_map_dumb args{
         .handle = this->m_handle
     };
-    ioctl::perform(this->m_fd, DRM_IOCTL_MODE_MAP_DUMB, args);
+    ioctl::perform(this->m_manager->m_fd, DRM_IOCTL_MODE_MAP_DUMB, args);
 
     void* map{::mmap(nullptr, this->m_size, PROT_READ | PROT_WRITE, MAP_SHARED,
-        this->m_fd, static_cast<off_t>(args.offset))};
+        this->m_manager->m_fd, static_cast<off_t>(args.offset))};
     if (map == MAP_FAILED) {
         throw std::system_error(errno, std::generic_category(), "mmap failed");
     }
@@ -112,7 +132,14 @@ void* DumbBuffer::map() {
 }
 
 void DumbBuffer::destruct() noexcept {
-    if (this->m_fd < 0) {
+    if (this->m_manager == nullptr) {
+        return;
+    }
+
+    auto& refcounts{this->m_manager->m_refcounts};
+    if (refcounts[this->m_handle] > 1) {
+        refcounts[this->m_handle]--;
+        this->m_manager = nullptr;
         return;
     }
 
@@ -125,10 +152,10 @@ void DumbBuffer::destruct() noexcept {
         .handle = this->m_handle
     };
     try {
-        ioctl::perform(this->m_fd, DRM_IOCTL_MODE_DESTROY_DUMB, args);
+        ioctl::perform(this->m_manager->m_fd, DRM_IOCTL_MODE_DESTROY_DUMB, args);
     } catch(...) {
-        (void) 0; // not much we can do about the leak
+        assert(false && "Dumb buffer destroy failed, memory leak likely");
     }
 
-    this->m_fd = -1;
+    this->m_manager = nullptr;
 }
-- 
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