source: trunk/TOOLS/INTERNAL/FIXCODE.ASM@ 41

Last change on this file since 41 was 37, checked in by Ben Rietbroek, 12 years ago

Reworked Build Environment [2012-02-15]

WARNING!!

All commits upto and including the commit of [2012-05-13] contain
a severe bug!! Building from these sources and then disabling
the 'force LBA' feature while also using the drive-letter feature or
editing the label can DESTROY THE MBR on ALL ATTACHED DISKS!!
DO NOT DISABLE 'FORCE LBA USAGE' WHEN BUILT FROM THE THESE COMMITS!!

Changes

o Reworked build environment
o Start made with coding FIXCODE in C
o Moved MBR protection image
o New overlap macro
o Protect type 0x35 from edit (user popup)
o Protect type 0x35 from adding to menu (user popup)
o More...
! No LVM Label change yet

Note

o Changed license to GPL v3

See file COPYING in trunk.
File size: 10.4 KB
Line 
1; AiR-BOOT (c) Copyright 1998-2009 M. Kiewitz
2;
3; This file is part of AiR-BOOT
4;
5; AiR-BOOT is free software: you can redistribute it and/or modify it under
6; the terms of the GNU General Public License as published by the Free
7; Software Foundation, either version 3 of the License, or (at your option)
8; any later version.
9;
10; AiR-BOOT is distributed in the hope that it will be useful, but WITHOUT ANY
11; WARRANTY: without even the implied warranty of MERCHANTABILITY or FITNESS
12; FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13; details.
14;
15; You should have received a copy of the GNU General Public License along with
16; AiR-BOOT. If not, see <http://www.gnu.org/licenses/>.
17;
18
19; This program fixes air-boot.com image.
20; a) it includes MBR protection image from mbr-prot\mbr_prot.com
21; b) it writes totally used sectors to byte at offset 10h in the image
22
23;JUMPS
24
25Include ../../INCLUDE/ASM.INC
26
27 .286p
28 .model small, basic
29
30fixcode group code_seg,bss_data
31
32code_seg segment use16 public 'CODE'
33 ;assume cs:code_seg, ds:code_seg, es:nothing, ss:nothing
34 assume cs:fixcode, ds:fixcode, es:nothing, ss:nothing
35 org 100h
36COM_StartUp: jmp COM_Init
37
38COM_Copyright db 'AiR-BOOT Bootcode Image Fix', 13, 10
39 db ' - (c) Copyright 2009 by M. Kiewitz', 13, 10, '$'
40COM_LoadCode db ' - Loading bootcode from file...$'
41COM_CodeName db 'air-boot.com', 0
42COM_LoadMBR db ' - Loading MBR-protection from file...$'
43COM_MBRName db 'mbr-prot\mbr_prot.com', 0
44COM_MergeMBR db ' - Merging MBR-protection into bootcode...$'
45COM_CountCode db ' - Count code in bootcode-image...$'
46COM_WriteCode db ' - Saving bootcode to file...$'
47COM_Okay db 'ok', 13, 10, '$'
48COM_Failed db 'failed', 13, 10, '$'
49
50COM_FailedOpenCode db 'air-boot.com not found', 13, 10, '$'
51COM_FailedReadCode db 'Read air-boot.com failed', 13, 10, '$'
52COM_FailedInvalidCode db 'Invalid air-boot.com', 13, 10, '$'
53COM_FailedOpenMBR db 'mbr-prot\mbr_prot.com not found', 13, 10, '$'
54COM_FailedReadMBR db 'Read mbr-prot\mbr_prot.com failed', 13, 10, '$'
55COM_FailedInvalidMBR db 'Invalid mbr-prot\mbr_prot.com', 13, 10, '$'
56COM_FailedWriteCode db 'Write air-boot.com failed', 13, 10, '$'
57
58MBRProtectionSignature db 'AiR-BOOT MBR-Protection Image'
59MBRProtectionSignatureLen equ 29
60
61ShowMessage Proc Near Uses ax
62 mov ah, 09h
63 int 21h ; DOS: WRITE STRING DS:DX TO CONSOLE
64 ret
65ShowMessage EndP
66
67ShowError Proc Near
68 mov ah, 09h
69 int 21h ; DOS: WRITE STRING DS:DX TO CONSOLE
70 jmp EndProgram
71 ret
72ShowError EndP
73
74COM_Init:
75 ; Setup and Copyright.
76 mov ax, cs
77 mov ds, ax
78 mov es, ax ; CS==DS==ES
79 mov dx, offset COM_Copyright
80 call ShowMessage
81
82 ; Open AIR-BOOT.COM
83 mov dx, offset COM_LoadCode
84 call ShowMessage
85 mov ax, 3D00h
86 mov dx, offset COM_CodeName
87 xor cl, cl
88 int 21h ; DOS: OPEN EXISTING FILE
89 jnc DoneOpenCode
90 mov dx, offset COM_FailedOpenCode
91 call ShowError
92
93DoneOpenCode: mov bx, ax ; BX = Filehandle
94
95 ; Load AIR-BOOT.COM
96 mov ah, 3Fh
97 mov cx, image_size ; Image size
98 mov dx, offset BootCode
99 int 21h ; DOS: READ FILE
100 jnc DoneReadCode
101 mov dx, offset COM_FailedReadCode
102 call ShowError
103
104
105DoneReadCode:
106 ; See if at least 'image-size' is loaded.
107 cmp ax, image_size
108 je DoneReadCode2
109InvalidCode: mov dx, offset COM_FailedInvalidCode
110 call ShowError
111
112 ; Try to read again which is expected to fail.
113 ; Otherwise image is too large.
114DoneReadCode2: mov ah, 3Fh
115 mov cx, 1
116 mov dx, offset BootCode
117 int 21h ; DOS: READ FILE
118 jc DoneReadCode3
119 or ax, ax
120 jz DoneReadCode3 ; EOF -> is now expected
121 jmp InvalidCode
122
123 ; It's loaded now, close it.
124DoneReadCode3: mov ah, 3Eh
125 int 21h ; DOS: CLOSE FILE
126
127 mov dx, offset COM_Okay
128 call ShowMessage
129
130 ; Open MBR_PROT.COM
131 mov dx, offset COM_LoadMBR
132 call ShowMessage
133 mov ax, 3D00h
134 mov dx, offset COM_MBRName
135 xor cl, cl
136 int 21h ; DOS: OPEN EXISTING FILE
137 jnc DoneOpenMBR
138 mov dx, offset COM_FailedOpenMBR
139 call ShowError
140
141DoneOpenMBR: mov bx, ax ; BX = Filehandle
142
143 ; Load MBR_PROT.COM
144 mov ah, 3Fh
145 mov cx, 1024 ; Image size
146 mov dx, offset MBRProtection
147 int 21h ; DOS: READ FILE
148 jnc DoneReadMBR
149 mov dx, offset COM_FailedReadMBR
150 call ShowError
151
152DoneReadMBR:
153 ; See if at least 1kB is loaded.
154 cmp ax, 1024
155 je DoneReadMBR2
156InvalidMBR: mov dx, offset COM_FailedInvalidMBR
157 call ShowError
158
159 ; Try to read again which is expected to fail.
160 ; Otherwise image is too large.
161DoneReadMBR2: mov ah, 3Fh
162 mov cx, 1
163 mov dx, offset MBRProtection
164 int 21h ; DOS: READ FILE
165 jc DoneReadMBR3
166 or ax, ax
167 jz DoneReadMBR3 ; EOF -> is now expected
168 jmp InvalidMBR
169
170 ; It's loaded now, close file.
171DoneReadMBR3: mov ah, 3Eh
172 int 21h ; DOS: CLOSE FILE
173
174 mov dx, offset COM_Okay
175 call ShowMessage
176
177
178
179 ; ========================== Merge MBR-Protection into Bootcode
180 mov dx, offset COM_MergeMBR
181 call ShowMessage
182
183 ; Search for signature in Bootcode
184 ; Note the search is with sector granularity.
185 ; This means the signature must be 512 bytes aligned.
186 mov si, offset BootCode
187 mov di, offset MBRProtectionSignature
188 mov cx, MBRProtectionSignatureLen
189 ; 54 sectors where signature may be.
190 ; (all sectors preceding config sector)
191 mov dx, 54
192COM_SignatureLoop:
193 push cx
194 push si
195 push di
196 repe cmpsb
197 pop di
198 pop si
199 pop cx
200 je COM_GotSignature
201 add si, 512
202 dec dx
203 jnz COM_SignatureLoop
204 mov dx, offset COM_Failed
205 call ShowMessage
206 jmp EndProgram
207
208COM_GotSignature:
209 ; Now copy MBR-protection into bootcode
210 mov di, si
211 mov si, offset MBRProtection
212 mov cx, 512
213 rep movsw
214 mov dx, offset COM_Okay
215 call ShowMessage
216
217 ; ====================== Count code sectors and adjust bootcode
218 mov dx, offset COM_CountCode
219 call ShowMessage
220
221 mov si, offset BootCode
222 add si, 512*53
223 mov cx, 256
224 mov dx, 53
225COM_CodeEndLoop:push cx
226 push si
227 push di
228COM_CodeEndLoop2:
229 cmp wptr ds:[si], 0
230 jne COM_ExitCodeEndLoop
231 add si, 2
232 dec cx
233 jnz COM_CodeEndLoop2
234COM_ExitCodeEndLoop:
235 pop di
236 pop si
237 pop cx
238 jne COM_FoundCodeEnd
239 sub si, 512
240 dec dx
241 jnz COM_CodeEndLoop
242 mov dx, offset COM_Failed
243 call ShowError
244
245COM_FoundCodeEnd:
246 mov [BootCode+10h], dl
247 mov dx, offset COM_Okay
248 call ShowMessage
249
250 ; ================================ Save bootcode back into file
251 mov dx, offset COM_WriteCode
252 call ShowMessage
253 mov ax, 3D02h
254 mov dx, offset COM_CodeName
255 xor cl, cl
256 int 21h ; DOS: OPEN EXISTING FILE
257 jnc DoneOpenCode2
258 mov dx, offset COM_FailedOpenCode
259 call ShowError
260
261DoneOpenCode2: mov bx, ax ; BX = Filehandle
262
263 mov ah, 40h
264 mov cx, image_size ; Image size
265 mov dx, offset BootCode
266 int 21h ; DOS: WRITE FILE
267 jnc DoneWriteCode
268FailedWriteCode:mov dx, offset COM_FailedWriteCode
269 call ShowError
270
271DoneWriteCode: cmp ax, image_size
272 jne FailedWriteCode
273
274 mov ah, 3Eh
275 int 21h ; DOS: CLOSE FILE
276
277 mov dx, offset COM_Okay
278 call ShowMessage
279 jmp EndProgram
280
281
282EndProgram:
283 ; DOS: TERMINATE PROGRAM
284 mov ax, 4C00h
285 int 21h
286
287
288
289COM_EndOfSegment:
290
291code_seg ends
292
293bss_data segment use16 public 'BSS'
294; Buffers for files
295BootCode db image_size dup (?)
296MBRProtection db 1024 dup (?)
297bss_data ends
298
299 end COM_StartUp
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