From 7f062e35a4c34454be180fd2e53e02e229cba91d Mon Sep 17 00:00:00 2001
From: Stephan Unverwerth <s.unverwerth@serenityos.org>
Date: Sun, 28 Aug 2022 11:47:58 +0200
Subject: [PATCH] LibGL: Implement glAttachShader

---
 Userland/Libraries/LibGL/Shader.cpp          | 12 ++++++--
 Userland/Libraries/LibGL/Shaders/Program.cpp | 32 ++++++++++++++++++--
 Userland/Libraries/LibGL/Shaders/Program.h   |  2 ++
 Userland/Libraries/LibGL/Shaders/Shader.h    |  1 +
 4 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/Userland/Libraries/LibGL/Shader.cpp b/Userland/Libraries/LibGL/Shader.cpp
index 5e9c8f39de..01b1bbfd78 100644
--- a/Userland/Libraries/LibGL/Shader.cpp
+++ b/Userland/Libraries/LibGL/Shader.cpp
@@ -95,8 +95,16 @@ void GLContext::gl_delete_program(GLuint program)
 
 void GLContext::gl_attach_shader(GLuint program, GLuint shader)
 {
-    dbgln("gl_attach_shader({}, {}) unimplemented ", program, shader);
-    TODO();
+    auto program_it = m_allocated_programs.find(program);
+    auto shader_it = m_allocated_shaders.find(shader);
+    // FIXME: implement check "GL_INVALID_VALUE is generated if either program or shader is not a value generated by OpenGL."
+    RETURN_WITH_ERROR_IF(program_it == m_allocated_programs.end(), GL_INVALID_OPERATION);
+    RETURN_WITH_ERROR_IF(shader_it == m_allocated_shaders.end(), GL_INVALID_OPERATION);
+
+    // NOTE: attach_result is Error if the shader is already attached to this program
+    auto attach_result = program_it->value->attach_shader(*shader_it->value);
+    RETURN_WITH_ERROR_IF(attach_result.is_error() && attach_result.error().is_errno() && attach_result.error().code() == ENOMEM, GL_OUT_OF_MEMORY);
+    RETURN_WITH_ERROR_IF(attach_result.is_error(), GL_INVALID_OPERATION);
 }
 
 void GLContext::gl_link_program(GLuint program)
diff --git a/Userland/Libraries/LibGL/Shaders/Program.cpp b/Userland/Libraries/LibGL/Shaders/Program.cpp
index e432b24680..e6ad8fc6ef 100644
--- a/Userland/Libraries/LibGL/Shaders/Program.cpp
+++ b/Userland/Libraries/LibGL/Shaders/Program.cpp
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibGL/GL/gl.h>
 #include <LibGL/Shaders/Program.h>
 
 namespace GL {
@@ -13,9 +14,36 @@ NonnullRefPtr<Program> Program::create()
     return adopt_ref(*new Program());
 }
 
-ErrorOr<void> Program::attach_shader(Shader&)
+bool Program::is_shader_attached(Shader const& shader) const
 {
-    TODO();
+    switch (shader.type()) {
+    case GL_VERTEX_SHADER:
+        return m_vertex_shaders.contains_slow(shader);
+    case GL_FRAGMENT_SHADER:
+        return m_fragment_shaders.contains_slow(shader);
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+ErrorOr<void> Program::attach_shader(Shader& shader)
+{
+    if (is_shader_attached(shader))
+        return Error::from_string_literal("Trying to attach a shader that is already attached");
+
+    switch (shader.type()) {
+    case GL_VERTEX_SHADER:
+        TRY(m_vertex_shaders.try_append(shader));
+        break;
+
+    case GL_FRAGMENT_SHADER:
+        TRY(m_fragment_shaders.try_append(shader));
+        break;
+
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
     return {};
 }
 
diff --git a/Userland/Libraries/LibGL/Shaders/Program.h b/Userland/Libraries/LibGL/Shaders/Program.h
index 3e619c3b2f..338149b9ca 100644
--- a/Userland/Libraries/LibGL/Shaders/Program.h
+++ b/Userland/Libraries/LibGL/Shaders/Program.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/Error.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
 #include <AK/Vector.h>
@@ -17,6 +18,7 @@ class Program final : public RefCounted<Program> {
 public:
     static NonnullRefPtr<Program> create();
 
+    bool is_shader_attached(Shader const&) const;
     ErrorOr<void> attach_shader(Shader&);
     ErrorOr<void> link();
 
diff --git a/Userland/Libraries/LibGL/Shaders/Shader.h b/Userland/Libraries/LibGL/Shaders/Shader.h
index 9b5c30c8ef..af1575b6e8 100644
--- a/Userland/Libraries/LibGL/Shaders/Shader.h
+++ b/Userland/Libraries/LibGL/Shaders/Shader.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <AK/Error.h>
+#include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
 #include <AK/RefPtr.h>
 #include <AK/String.h>