From 7c05eed48798c0d4c349c19858b9c46c34dd579f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?kleines=20Filmr=C3=B6llchen?= <filmroellchen@serenityos.org>
Date: Tue, 30 Aug 2022 12:44:33 +0200
Subject: [PATCH] Kernel: Bake version information into the Kernel

This is done by generating a Kernel/Version.h header with major version,
minor version, and git hash.
---
 Kernel/CMakeLists.txt           | 13 ++++++++++++
 Kernel/generate-version-file.sh | 37 +++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100755 Kernel/generate-version-file.sh

diff --git a/Kernel/CMakeLists.txt b/Kernel/CMakeLists.txt
index 56104ff750..cf30b1cd20 100644
--- a/Kernel/CMakeLists.txt
+++ b/Kernel/CMakeLists.txt
@@ -410,6 +410,18 @@ set(ELF_SOURCES
     ../Userland/Libraries/LibELF/Validation.cpp
 )
 
+add_custom_command(
+    COMMAND "${SerenityOS_SOURCE_DIR}/Kernel/generate-version-file.sh" "${CMAKE_CURRENT_BINARY_DIR}/Version.h.tmp"
+    COMMAND "${CMAKE_COMMAND}" -E copy_if_different "${CMAKE_CURRENT_BINARY_DIR}/Version.h.tmp" "${CMAKE_CURRENT_BINARY_DIR}/Version.h"
+    COMMAND "${CMAKE_COMMAND}" -E remove "${CMAKE_CURRENT_BINARY_DIR}/Version.h.tmp"
+    WORKING_DIRECTORY "${SerenityOS_SOURCE_DIR}"
+    COMMENT "Generating SerenityOS version information"
+    OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/Version.h"
+    VERBATIM
+)
+add_custom_target(generate_version_header ALL DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/Version.h")
+set(GENERATED_SOURCES "${CMAKE_CURRENT_BINARY_DIR}/Version.h")
+
 generate_state_machine(../Userland/Libraries/LibVT/StateMachine.txt ../Userland/Libraries/LibVT/EscapeSequenceStateMachine.h)
 
 set(VT_SOURCES
@@ -437,6 +449,7 @@ set(SOURCES
 if (NOT "${SERENITY_ARCH}" STREQUAL "aarch64")
     set(SOURCES
         ${KERNEL_SOURCES}
+        ${GENERATED_SOURCES}
         ${SOURCES}
         ${EDID_SOURCES}
         ${ELF_SOURCES}
diff --git a/Kernel/generate-version-file.sh b/Kernel/generate-version-file.sh
new file mode 100755
index 0000000000..98d02b7ae5
--- /dev/null
+++ b/Kernel/generate-version-file.sh
@@ -0,0 +1,37 @@
+#!/bin/sh
+
+set -e
+
+OUTPUT_FILE=$1
+
+if command -v git >/dev/null; then
+    if git status >/dev/null 2>&1; then
+        GIT_HASH=$( (git log --pretty=format:'%h' -n 1 | cut -c1-7) || true )
+        # There is at least one modified file as reported by git.
+        if git status --porcelain=v2 | head | grep -Ei '^1' >/dev/null; then
+            GIT_HASH="${GIT_HASH}-modified"
+        fi
+    else
+        GIT_HASH=unknown
+    fi
+else
+    GIT_HASH=unknown
+fi
+
+
+cat << EOF > "$OUTPUT_FILE"
+/*
+ * Automatically generated by Kernel/generate-version-file.sh
+ */
+
+#pragma once
+#include <AK/StringView.h>
+
+namespace Kernel {
+
+constexpr unsigned SERENITY_MAJOR_REVISION = 1;
+constexpr unsigned SERENITY_MINOR_REVISION = 0;
+constexpr StringView SERENITY_VERSION = "${GIT_HASH}"sv;
+
+}
+EOF