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kernel/utils/exeflat.c

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/****************************************************************/
/* */
/* exeflat.c */
/* */
/* EXE flattening program */
/* */
/* Copyright (c) 2001 */
/* Bart E. Oldeman */
/* All Rights Reserved */
/* */
/* This file is part of DOS-C. */
/* */
/* DOS-C is free software; you can redistribute it and/or */
/* modify it under the terms of the GNU General Public License */
/* as published by the Free Software Foundation; either version */
/* 2, or (at your option) any later version. */
/* */
/* DOS-C is distributed in the hope that it will be useful, but */
/* WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See */
/* the GNU General Public License for more details. */
/* */
/* You should have received a copy of the GNU General Public */
/* License along with DOS-C; see the file COPYING. If not, */
/* write to the Free Software Foundation, 675 Mass Ave, */
/* Cambridge, MA 02139, USA. */
/****************************************************************/
/*
Usage: exeflat (src.exe) (dest.sys) (relocation-factor)
large portions copied from task.c
*/
/* history
10/??/01 - Bart Oldeman
primary release
11/28/01 - tom ehlert
added -UPX option to make the kernel compressable with UPX
*/
#include "portab.h"
#include "exe.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define BUFSIZE 32768u
#define KERNEL_START 0x16 /* the kernel code really starts here at 60:16 */
typedef struct {
UWORD off, seg;
} farptr;
static int compReloc(const void *p1, const void *p2)
{
farptr *r1 = (farptr *) p1;
farptr *r2 = (farptr *) p2;
if (r1->seg > r2->seg)
return 1;
if (r1->seg < r2->seg)
return -1;
if (r1->off > r2->off)
return 1;
if (r1->off < r2->off)
return -1;
return 0;
}
static void usage(void)
{
printf("usage: exeflat (src.exe) (dest.sys) (relocation-factor)\n");
printf
(" -S10 - Silent relocate segment 10 (down list)\n");
exit(1);
}
static int exeflat(const char *srcfile, const char *dstfile,
const char *start, short *silentSegments, short silentcount,
int UPX, exe_header *header)
{
int i, j;
size_t bufsize;
farptr *reloc;
UWORD start_seg;
ULONG size, to_xfer;
UBYTE **buffers;
UBYTE **curbuf;
FILE *src, *dest;
short silentdone = 0;
int compress_sys_file;
UWORD realentry;
if ((src = fopen(srcfile, "rb")) == NULL)
{
printf("Source file %s could not be opened\n", srcfile);
exit(1);
}
if (fread(header, sizeof(*header), 1, src) != 1)
{
printf("Error reading header from %s\n", srcfile);
fclose(src);
exit(1);
}
if (header->exSignature != MAGIC)
{
printf("Source file %s is not a valid .EXE\n", srcfile);
fclose(src);
exit(1);
}
start_seg = (UWORD)strtol(start, NULL, 0);
if (header->exExtraBytes == 0)
header->exExtraBytes = 0x200;
printf("header len = %lu = 0x%lx\n", header->exHeaderSize * 16UL,
header->exHeaderSize * 16UL);
size =
((DWORD) (header->exPages - 1) << 9) + header->exExtraBytes -
header->exHeaderSize * 16UL;
printf("image size (less header) = %lu = 0x%lx\n", size, size);
printf("first relocation offset = %u = 0x%u\n", header->exOverlay,
header->exOverlay);
/* first read file into memory chunks */
fseek(src, header->exHeaderSize * 16UL, SEEK_SET);
buffers = malloc((size_t)((size + BUFSIZE - 1) / BUFSIZE) * sizeof(char *));
if (buffers == NULL)
{
printf("Allocation error\n");
exit(1);
}
bufsize = BUFSIZE;
for (to_xfer = size, curbuf = buffers; to_xfer > 0;
to_xfer -= bufsize, curbuf++)
{
if (to_xfer < BUFSIZE)
bufsize = (size_t)to_xfer;
*curbuf = malloc(bufsize);
if (*curbuf == NULL)
{
printf("Allocation error\n");
exit(1);
}
if (fread(*curbuf, sizeof(char), bufsize, src) != bufsize)
{
printf("Source file read error %ld %d\n", to_xfer, bufsize);
exit(1);
}
}
if (header->exRelocTable && header->exRelocItems)
{
fseek(src, header->exRelocTable, SEEK_SET);
reloc = malloc(header->exRelocItems * sizeof(farptr));
if (reloc == NULL)
{
printf("Allocation error\n");
exit(1);
}
if (fread(reloc, sizeof(farptr), header->exRelocItems, src) !=
header->exRelocItems)
{
printf("Source file read error\n");
exit(1);
}
}
fclose(src);
qsort(reloc, header->exRelocItems, sizeof(reloc[0]), compReloc);
for (i = 0; i < header->exRelocItems; i++)
{
ULONG spot = ((ULONG) reloc[i].seg << 4) + reloc[i].off;
UBYTE *spot0 = &buffers[(size_t)(spot / BUFSIZE)][(size_t)(spot % BUFSIZE)];
UBYTE *spot1 = &buffers[(size_t)((spot + 1) / BUFSIZE)][(size_t)((spot + 1) % BUFSIZE)];
UWORD segment = ((UWORD) * spot1 << 8) + *spot0;
for (j = 0; j < silentcount; j++)
if (segment == silentSegments[j])
{
silentdone++;
goto dontPrint;
}
printf("relocation at 0x%04x:0x%04x ->%04x\n", reloc[i].seg,
reloc[i].off, segment);
dontPrint:
segment += start_seg;
*spot0 = segment & 0xff;
*spot1 = segment >> 8;
}
printf("\nProcessed %d relocations, %d not shown\n",
header->exRelocItems, silentdone);
realentry = KERNEL_START;
if (buffers[0][0] == 0xeb /* jmp short */)
{
realentry = buffers[0][1] + 2;
}
else if (buffers[0][0] == 0xe9 /* jmp near */)
{
realentry = ((UWORD)(buffers[0][2]) << 8) + buffers[0][1] + 3;
}
if ((dest = fopen(dstfile, "wb+")) == NULL)
{
printf("Destination file %s could not be created\n", dstfile);
exit(1);
}
/* The biggest .sys file that UPX accepts seems to be 65419 bytes long */
compress_sys_file = size < 65420;
if (UPX) {
printf("Compressing kernel - %s format\n", (compress_sys_file)?"sys":"exe");
}
if (UPX && !compress_sys_file) {
ULONG realsize;
/* write header without relocations to file */
exe_header nheader = *header;
nheader.exRelocItems = 0;
nheader.exHeaderSize = 2;
realsize = size + 32;
nheader.exPages = (UWORD)(realsize >> 9);
nheader.exExtraBytes = (UWORD)realsize & 511;
if (nheader.exExtraBytes)
nheader.exPages++;
if (fwrite(&nheader, sizeof(nheader), 1, dest) != 1) {
printf("Destination file write error\n");
exit(1);
}
fseek(dest, 32UL, SEEK_SET);
}
/* write dest file from memory chunks */
bufsize = BUFSIZE;
for (to_xfer = size, curbuf = buffers; to_xfer > 0;
to_xfer -= bufsize, curbuf++)
{
if (to_xfer < BUFSIZE)
bufsize = (size_t)to_xfer;
if (fwrite(*curbuf, sizeof(char), bufsize, dest) != bufsize)
{
printf("Destination file write error\n");
exit(1);
}
free(*curbuf);
}
if (UPX && compress_sys_file) {
/* overwrite first 8 bytes with SYS header */
UWORD dhdr[4];
fseek(dest, 0, SEEK_SET);
for (i = 0; i < 3; i++)
dhdr[i] = 0xffff;
/* strategy will jump to us, interrupt never called */
dhdr[3] = realentry; /* KERNEL_START; */
fwrite(dhdr, sizeof(dhdr), 1, dest);
printf("KERNEL_START = 0x%04x\n", realentry);
}
fclose(dest);
return compress_sys_file;
}
static void write_header(FILE *dest, size_t size)
{
/* UPX HEADER jump $+2+size */
static char JumpBehindCode[] = {
/* kernel config header - 32 bytes */
0xeb, 0x1b, /* jmp short realentry */
'C', 'O', 'N', 'F', 'I', 'G', 6, 0, /* WORD */
0, /* DLASortByDriveNo db 0 */
1, /* InitDiskShowDriveAssignment db 1 */
2, /* SkipConfigSeconds db 2 */
0, /* ForceLBA db 0 */
1, /* GlobalEnableLBAsupport db 1 */
0, /* BootHarddiskSeconds */
'n', 'u', 's', 'e', 'd', /* unused filler bytes */
8, 7, 6, 5, 4, 3, 2, 1,
/* real-entry: jump over the 'real' image do the trailer */
0xe9, 0, 0 /* 100: jmp 103 */
};
struct x {
char y[sizeof(JumpBehindCode) == 0x20 ? 1 : -1];
};
fseek(dest, 0, SEEK_SET);
/* this assumes <= 0xfe00 code in kernel */
*(short *)&JumpBehindCode[0x1e] += (short)size;
fwrite(JumpBehindCode, 1, 0x20, dest);
}
static void write_trailer(FILE *dest, size_t size, int compress_sys_file,
exe_header *header)
{
/* UPX trailer */
/* hand assembled - so this remains ANSI C ;-) */
/* well almost: we still need packing and assume little endian ... */
/* move kernel down to place CONFIG-block, which added above,
at start_seg-2:0 (e.g. 0x5e:0) instead of
start_seg:0 (e.g. 0x60:0) and store there boot drive number
from BL; kernel.asm will then check presence of additional
CONFIG-block at this address. */
static char trailer[] = { /* shift down everything by sizeof JumpBehindCode */
0xB9, 0x00, 0x00, /* 0 mov cx,offset trailer */
0x0E, /* 3 push cs */
0x1F, /* 4 pop ds (=60) */
0x8C, 0xC8, /* 5 mov ax,cs */
0x48, /* 7 dec ax */
0x48, /* 8 dec ax */
0x8E, 0xC0, /* 9 mov es,ax */
0x93, /* 11 xchg ax,bx (to get al=bl) */
0x31, 0xFF, /* 12 xor di,di */
0xFC, /* 14 cld */
0xAA, /* 15 stosb (store drive number)*/
0x8B, 0xF7, /* 16 mov si,di */
0xF3, 0xA4, /* 18 rep movsb */
0x1E, /* 20 push ds */
0x58, /* 21 pop ax */
0x05, 0x00, 0x00, /* 22 add ax,... */
0x8E, 0xD0, /* 25 mov ss,ax */
0xBC, 0x00, 0x00, /* 27 mov sp,... */
0x31, 0xC0, /* 30 xor ax,ax */
0xFF, 0xE0 /* 32 jmp ax */
};
*(short *)&trailer[1] = (short)size + 0x20;
*(short *)&trailer[23] = header->exInitSS;
*(short *)&trailer[28] = header->exInitSP;
if (compress_sys_file) {
/* replace by jmp word ptr [6]: ff 26 06 00
(the .SYS strategy handler which will unpack) */
*(long *)&trailer[30] = 0x000626ffL;
/* set up a 4K stack for the UPX decompressor to work with */
*(short *)&trailer[23] = 0x1000;
*(short *)&trailer[28] = 0x1000;
}
fwrite(trailer, 1, sizeof trailer, dest);
}
int main(int argc, char **argv)
{
short silentSegments[20], silentcount = 0;
static exe_header header; /* must be initialized to zero */
int UPX = FALSE;
int i;
size_t sz, len, len2, n;
int compress_sys_file;
char *buffer, *tmpexe, *cmdbuf;
FILE *dest;
long size;
/* if no arguments provided, show usage and exit */
if (argc < 4) usage();
/* do optional argument processing here */
for (i = 4; i < argc && !UPX; i++)
{
char *argptr = argv[i];
if (argptr[0] != '-' && argptr[0] != '/')
usage();
argptr++;
switch (toupper(argptr[0]))
{
case 'U':
UPX = i;
break;
case 'S':
if (silentcount >= LENGTH(silentSegments))
{
printf("can't handle more then %d silent's\n",
LENGTH(silentSegments));
exit(1);
}
silentSegments[silentcount++] = (short)strtol(argptr + 1, NULL, 0);
break;
default:
usage();
}
}
/* arguments left :
infile outfile relocation offset */
compress_sys_file = exeflat(argv[1], argv[2], argv[3],
silentSegments, silentcount,
UPX, &header);
if (!UPX)
exit(0);
/* move kernel.sys tmp.exe */
tmpexe = argv[2];
if (!compress_sys_file)
{
tmpexe = "tmp.exe";
rename(argv[2], tmpexe);
}
len2 = strlen(tmpexe) + 1;
sz = len2;
if (sz < 256) sz = 256;
cmdbuf = malloc(sz);
len = 0;
for (i = UPX+1; i < argc; i++)
{
n = strlen(argv[i]);
if (len + len2 + n + 2 >= sz) {
sz *= 2;
cmdbuf = realloc(cmdbuf, sz);
}
if (i > UPX+1)
cmdbuf[len++] = ' ';
memcpy(cmdbuf + len, argv[i], n + 1);
len += n;
}
cmdbuf[len++] = ' ';
/* if tmpexe is tmpfile set above no quotes needed, if user needs quotes should add on cmd line */
memcpy(cmdbuf + len, tmpexe, len2);
cmdbuf[len + len2] = '\0';
printf("%s\n", cmdbuf);
if (system(cmdbuf))
{
printf("Problems executing %s\n", cmdbuf);
printf("Removing [%s]\n", tmpexe);
remove(tmpexe);
exit(1);
}
free(cmdbuf);
if (!compress_sys_file)
{
exeflat(tmpexe, argv[2], argv[3],
silentSegments, silentcount,
FALSE, &header);
remove(tmpexe);
}
/* argv[2] now contains the final flattened file: just
header and trailer need to be added */
/* the compressed file has two chunks max */
if ((dest = fopen(argv[2], "rb+")) == NULL)
{
printf("Destination file %s could not be opened\n", argv[2]);
exit(1);
}
buffer = malloc(0xfe01);
fread(buffer, 0xfe01, 1, dest);
size = ftell(dest);
if (size >= 0xfe00u)
{
printf("kernel; size too large - must be <= 0xfe00\n");
exit(1);
}
fseek(dest, 0, SEEK_SET);
write_header(dest, (size_t)size);
fwrite(buffer, (size_t)size, 1, dest);
write_trailer(dest, (size_t)size, compress_sys_file, &header);
return 0;
}
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