From 3f0ea72ac985a7ff4803f72487d53b8e04ca09d1 Mon Sep 17 00:00:00 2001
From: Bernd Boeckmann <bernd-freedos@boeckmann.io>
Date: Wed, 22 May 2024 19:45:04 +0200
Subject: [PATCH] fix #85 FDISK not modifying partition type

---
 doc/fdisk/CHANGES.md    | 16 ++++++++++++++++
 source/fdisk/pcompute.c |  2 +-
 source/fdisk/ui.c       |  7 ++++---
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/doc/fdisk/CHANGES.md b/doc/fdisk/CHANGES.md
index 7a1245b..157fd25 100644
--- a/doc/fdisk/CHANGES.md
+++ b/doc/fdisk/CHANGES.md
@@ -8,6 +8,22 @@ Bug classification:
  - LOW: Cosmetic bugs, like display issues etc.
 
 
+Version 1.3.15 (2024-??-??)
+---------------------------
+Fixes:
+ - HIGH: Fix FDISK not modifying partition type via command line /MODIFY
+     and via UI if FDISK is started in extended options mode /XO.
+ - HIGH: respect selected video page instead of hardcoding it to zero when
+     calling INT 10 routines.
+
+Changes:
+ - FDISK provided MBR bootloader does not require more than 128k of RAM
+   anymore. In fact it should run with as low as 64k of RAM (untested).
+ - Work around Xi8088 and Book8088 BIOS bug (bootloader and FDISK itself).
+ - Assume BIOS drive number of 0x80 to boot from if BIOS tells us it is
+     unit 0. This should be an error, because we boot from hard disk.
+
+
 Version 1.3.14 (2024-02-05)
 ---------------------------
 Fixes:
diff --git a/source/fdisk/pcompute.c b/source/fdisk/pcompute.c
index c6ce3c5..a0304a3 100644
--- a/source/fdisk/pcompute.c
+++ b/source/fdisk/pcompute.c
@@ -809,7 +809,7 @@ int Modify_Partition_Type( int partition_number, int type_number )
 {
    Partition_Table *pDrive = &part_table[flags.drive_number - 0x80];
 
-   if ( pDrive->usable ) {
+   if ( !pDrive->usable ) {
       return 99;
    }
 
diff --git a/source/fdisk/ui.c b/source/fdisk/ui.c
index c17ab04..f3cc070 100644
--- a/source/fdisk/ui.c
+++ b/source/fdisk/ui.c
@@ -1640,7 +1640,7 @@ void Display_Partition_Information( void )
          input = (int)Input( 1, -1, -1, YN, 0, 0, ESCR, 1, 0, '1', '4' );
 
          if ( ( ( input - 48 ) >= 1 ) && ( ( input - 48 ) <= 4 ) ) {
-            Modify_Primary_Partition_Information( ( input - 48 ) );
+            Modify_Primary_Partition_Information( input - 48 );
             goto Beginning;
          }
       }
@@ -1982,9 +1982,10 @@ void Modify_Primary_Partition_Information( int partition_number )
 
    unsigned long usage;
    Partition_Table *pDrive = &part_table[flags.drive_number - 0x80];
-   Partition *p = &pDrive->pri_part[partition_number];
+   Partition *p = NULL;
 
    partition_number--; /* Adjust partition number to start with 0. */
+   p = &pDrive->pri_part[partition_number];
 
    do {
       Clear_Screen( 0 );
@@ -1999,7 +2000,7 @@ void Modify_Primary_Partition_Information( int partition_number )
       Print_At( 4, 8, svarlang_str( 10, 11 ) );
 
       /* Drive Letter of Partition */
-      if ( IsRecognizedFatPartition( p->num_type == 1 ) ) {
+      if ( IsRecognizedFatPartition( p->num_type ) ) {
          Print_At( 5, 9, "%c:",
                    drive_lettering_buffer[( flags.drive_number - 128 )]
                                          [partition_number] );