From 5a7a745c2285cf6e2e2c698a9f2696549c7a3206 Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Fri, 14 Jan 2022 09:43:59 +0500
Subject: [PATCH] Add enum KernAux_Multiboot2_HTag_RelocatableHeader_Preference

---
 include/kernaux/multiboot2.h     | 14 ++++++++++----
 src/multiboot2/header_is_valid.c | 16 ++++++++++++++--
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/include/kernaux/multiboot2.h b/include/kernaux/multiboot2.h
index f98bbb8..edc915b 100644
--- a/include/kernaux/multiboot2.h
+++ b/include/kernaux/multiboot2.h
@@ -35,6 +35,12 @@ extern "C" {
 #define KERNAUX_MULTIBOOT2_HTAG_FLAGS_REQUIRE_CONSOLE (1 << 0)
 #define KERNAUX_MULTIBOOT2_HTAG_FLAGS_EGA_SUPPORT     (1 << 1)
 
+enum KernAux_Multiboot2_HTag_RelocatableHeader_Preference {
+    KERNAUX_MULTIBOOT2_HTAG_RELOCATABLE_HEADER_PREFERENCE_NONE    = 0,
+    KERNAUX_MULTIBOOT2_HTAG_RELOCATABLE_HEADER_PREFERENCE_LOWEST  = 1,
+    KERNAUX_MULTIBOOT2_HTAG_RELOCATABLE_HEADER_PREFERENCE_HIGHEST = 2,
+};
+
 /****************
  * Common types *
  ****************/
@@ -214,10 +220,10 @@ struct KernAux_Multiboot2_HTag_RelocatableHeader {
     // size = 24
     struct KernAux_Multiboot2_HTagBase base;
 
-    unsigned min_addr    : 32;
-    unsigned max_addr    : 32;
-    unsigned align       : 32;
-    unsigned preferences : 32;
+    unsigned min_addr                                                     : 32;
+    unsigned max_addr                                                     : 32;
+    unsigned align                                                        : 32;
+    enum KernAux_Multiboot2_HTag_RelocatableHeader_Preference preferences : 32;
 }
 __attribute__((packed));
 
diff --git a/src/multiboot2/header_is_valid.c b/src/multiboot2/header_is_valid.c
index f296c3a..0e0d924 100644
--- a/src/multiboot2/header_is_valid.c
+++ b/src/multiboot2/header_is_valid.c
@@ -238,10 +238,22 @@ bool KernAux_Multiboot2_HTag_EFIAmd64EntryAddr_is_valid(
 bool KernAux_Multiboot2_HTag_RelocatableHeader_is_valid(
     const struct KernAux_Multiboot2_HTag_RelocatableHeader *tag
 ) {
-    return (
+    if (!(
         tag->base.type == KERNAUX_MULTIBOOT2_HTAG_RELOCATABLE_HEADER &&
         tag->base.size == 24 &&
         // TODO: write this
         true
-    );
+    )) {
+        return false;
+    }
+
+    switch (tag->preferences) {
+    case KERNAUX_MULTIBOOT2_HTAG_RELOCATABLE_HEADER_PREFERENCE_NONE:    break;
+    case KERNAUX_MULTIBOOT2_HTAG_RELOCATABLE_HEADER_PREFERENCE_LOWEST:  break;
+    case KERNAUX_MULTIBOOT2_HTAG_RELOCATABLE_HEADER_PREFERENCE_HIGHEST: break;
+    default:
+        return false;
+    }
+
+    return true;
 }