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/*
* This is a simple program demonstrating the libx86emu usage.
*
* It lets you load a binary blob at some address and run the emulation.The
* emulation trace is logged to the console to show what it is doing.
*/
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <x86emu.h>
void help(void);
void flush_log(x86emu_t *emu, char *buf, unsigned size);
x86emu_t *emu_new(void);
int emu_init(x86emu_t *emu, char *file);
void emu_run(char *file);
struct option options[] = {
{ "help", 0, NULL, 'h' },
{ "load", 1, NULL, 'l' },
{ "start", 1, NULL, 's' },
{ "max", 1, NULL, 'm' },
{ "32", 0, NULL, 1001 },
{ }
};
struct {
struct {
unsigned segment;
unsigned offset;
} start;
unsigned load;
unsigned max_instructions;
unsigned bits_32:1;
char *file;
} opt;
/*
* Parse options, then run emulation.
*/
int main(int argc, char **argv)
{
int i;
char *str;
opt.start.segment = 0;
opt.start.offset = opt.load = 0x7c00;
opt.max_instructions = 10000000;
opterr = 0;
while((i = getopt_long(argc, argv, "hm:l:s:", options, NULL)) != -1) {
switch(i) {
case 'm':
opt.max_instructions = strtoul(optarg, NULL, 0);
break;
case 'l':
opt.load = strtoul(optarg, NULL, 0);
break;
case 's':
opt.start.offset = strtoul(optarg, &str, 0);
if(*str == ':') {
opt.start.segment = opt.start.offset;
opt.start.offset = strtoul(str + 1, NULL, 0);
}
break;
case 1001:
opt.bits_32 = 1;
break;
default:
help();
return i == 'h' ? 0 : 1;
}
}
if(argc == optind + 1) {
opt.file = argv[optind];
}
else {
help();
return 1;
}
emu_run(opt.file);
return 0;
}
/*
* Display short usage message.
*/
void help()
{
printf(
"Usage: x86emu-demo [OPTIONS] FILE\n"
"\n"
"Load FILE and run x86 emulation.\n"
"\n"
"Options:\n"
" -l, --load ADDRESS Load FILE at ADDRESS into memory (default 0x7c00).\n"
" -s, --start ADDRESS Start emulation at ADDRESS (default 0:0x7c00).\n"
" ADDRESS may contain a colon (':') to separate segment and\n"
" offset values. Without colon, segment 0 is assumed.\n"
" -m, --max N Stop after emulating N instructions.\n"
" --32 Start in 32-bit mode (default 16-bit mode).\n"
" -h, --help Show this text\n"
);
}
/*
* Write emulation log to console.
*/
void flush_log(x86emu_t *emu, char *buf, unsigned size)
{
if(!buf || !size) return;
fwrite(buf, size, 1, stdout);
}
/*
* Create new emulation object.
*/
x86emu_t *emu_new()
{
x86emu_t *emu = x86emu_new(X86EMU_PERM_R | X86EMU_PERM_W | X86EMU_PERM_X, 0);
/* log buf size of 1000000 is purely arbitrary */
x86emu_set_log(emu, 1000000, flush_log);
emu->log.trace = X86EMU_TRACE_DEFAULT;
return emu;
}
/*
* Setup registers and memory.
*/
int emu_init(x86emu_t *emu, char *file)
{
FILE *f;
unsigned addr;
int i;
addr = opt.load;
x86emu_set_seg_register(emu, emu->x86.R_CS_SEL, opt.start.segment);
emu->x86.R_EIP = opt.start.offset;
if(opt.bits_32) {
/* set default data/address size to 32 bit */
emu->x86.R_CS_ACC |= (1 << 10);
/* maximize descriptor limits */
emu->x86.R_CS_LIMIT =
emu->x86.R_DS_LIMIT =
emu->x86.R_ES_LIMIT =
emu->x86.R_FS_LIMIT =
emu->x86.R_GS_LIMIT =
emu->x86.R_SS_LIMIT = ~0;
}
if(!(f = fopen(file, "r"))) return 0;
while((i = fgetc(f)) != EOF) {
x86emu_write_byte(emu, addr++, i);
}
fclose(f);
return 1;
}
/*
* Run emulation.
*/
void emu_run(char *file)
{
x86emu_t *emu = emu_new();
unsigned flags = X86EMU_RUN_MAX_INSTR | X86EMU_RUN_NO_EXEC | X86EMU_RUN_NO_CODE | X86EMU_RUN_LOOP;
int ok = 0;
if(!file) return;
ok = emu_init(emu, file);
if(ok) {
printf("*** running %s ***\n\n", file);
x86emu_dump(emu, X86EMU_DUMP_MEM | X86EMU_DUMP_ASCII);
x86emu_reset_access_stats(emu);
emu->max_instr = opt.max_instructions;
x86emu_run(emu, flags);
x86emu_dump(emu, X86EMU_DUMP_DEFAULT | X86EMU_DUMP_ACC_MEM);
x86emu_clear_log(emu, 1);
}
x86emu_done(emu);
}
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