Blame view

tests/runcom.c 4.92 KB
bellard authored
1
2
3
4
5
/*
 * Simple example of use of vm86: launch a basic .com DOS executable
 */
#include <stdlib.h>
#include <stdio.h>
bellard authored
6
#include <string.h>
bellard authored
7
8
9
10
11
12
13
14
15
16
17
#include <inttypes.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <signal.h>

#include <linux/unistd.h>
#include <asm/vm86.h>

//#define SIGTEST
bellard authored
18
19
20
21
22
23
#undef __syscall_return
#define __syscall_return(type, res) \
do { \
	return (type) (res); \
} while (0)
bellard authored
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
_syscall2(int, vm86, int, func, struct vm86plus_struct *, v86)

#define COM_BASE_ADDR    0x10100

void usage(void)
{
    printf("runcom version 0.1 (c) 2003 Fabrice Bellard\n"
           "usage: runcom file.com\n"
           "VM86 Run simple .com DOS executables (linux vm86 test mode)\n");
    exit(1);
}

static inline void set_bit(uint8_t *a, unsigned int bit)
{
    a[bit / 8] |= (1 << (bit % 8));
}

static inline uint8_t *seg_to_linear(unsigned int seg, unsigned int reg)
{
    return (uint8_t *)((seg << 4) + (reg & 0xffff));
}

static inline void pushw(struct vm86_regs *r, int val)
{
    r->esp = (r->esp & ~0xffff) | ((r->esp - 2) & 0xffff);
    *(uint16_t *)seg_to_linear(r->ss, r->esp) = val;
}

void dump_regs(struct vm86_regs *r)
{
54
    fprintf(stderr,
bellard authored
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
            "EAX=%08lx EBX=%08lx ECX=%08lx EDX=%08lx\n"
            "ESI=%08lx EDI=%08lx EBP=%08lx ESP=%08lx\n"
            "EIP=%08lx EFL=%08lx\n"
            "CS=%04x DS=%04x ES=%04x SS=%04x FS=%04x GS=%04x\n",
            r->eax, r->ebx, r->ecx, r->edx, r->esi, r->edi, r->ebp, r->esp,
            r->eip, r->eflags,
            r->cs, r->ds, r->es, r->ss, r->fs, r->gs);
}

#ifdef SIGTEST
void alarm_handler(int sig)
{
    fprintf(stderr, "alarm signal=%d\n", sig);
    alarm(1);
}
#endif

int main(int argc, char **argv)
{
    uint8_t *vm86_mem;
    const char *filename;
    int fd, ret, seg;
    struct vm86plus_struct ctx;
    struct vm86_regs *r;

    if (argc != 2)
        usage();
    filename = argv[1];
83
84
85
    vm86_mem = mmap((void *)0x00000000, 0x110000,
                    PROT_WRITE | PROT_READ | PROT_EXEC,
bellard authored
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
                    MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
    if (vm86_mem == MAP_FAILED) {
        perror("mmap");
        exit(1);
    }
#ifdef SIGTEST
    {
        struct sigaction act;

        act.sa_handler = alarm_handler;
        sigemptyset(&act.sa_mask);
        act.sa_flags = 0;
        sigaction(SIGALRM, &act, NULL);
        alarm(1);
    }
#endif

    /* load the MSDOS .com executable */
    fd = open(filename, O_RDONLY);
    if (fd < 0) {
        perror(filename);
        exit(1);
    }
    ret = read(fd, vm86_mem + COM_BASE_ADDR, 65536 - 256);
    if (ret < 0) {
        perror("read");
        exit(1);
    }
    close(fd);

    memset(&ctx, 0, sizeof(ctx));
    /* init basic registers */
    r = &ctx.regs;
    r->eip = 0x100;
    r->esp = 0xfffe;
    seg = (COM_BASE_ADDR - 0x100) >> 4;
    r->cs = seg;
    r->ss = seg;
    r->ds = seg;
    r->es = seg;
    r->fs = seg;
    r->gs = seg;
bellard authored
128
    r->eflags = VIF_MASK;
bellard authored
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149

    /* put return code */
    set_bit((uint8_t *)&ctx.int_revectored, 0x21);
    *seg_to_linear(r->cs, 0) = 0xb4; /* mov ah, $0 */
    *seg_to_linear(r->cs, 1) = 0x00;
    *seg_to_linear(r->cs, 2) = 0xcd; /* int $0x21 */
    *seg_to_linear(r->cs, 3) = 0x21;
    pushw(&ctx.regs, 0x0000);

    /* the value of these registers seem to be assumed by pi_10.com */
    r->esi = 0x100;
    r->ecx = 0xff;
    r->ebp = 0x0900;
    r->edi = 0xfffe;

    for(;;) {
        ret = vm86(VM86_ENTER, &ctx);
        switch(VM86_TYPE(ret)) {
        case VM86_INTx:
            {
                int int_num, ah;
150
bellard authored
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
                int_num = VM86_ARG(ret);
                if (int_num != 0x21)
                    goto unknown_int;
                ah = (r->eax >> 8) & 0xff;
                switch(ah) {
                case 0x00: /* exit */
                    exit(0);
                case 0x02: /* write char */
                    {
                        uint8_t c = r->edx;
                        write(1, &c, 1);
                    }
                    break;
                case 0x09: /* write string */
                    {
                        uint8_t c;
                        for(;;) {
                            c = *seg_to_linear(r->ds, r->edx);
                            if (c == '$')
                                break;
                            write(1, &c, 1);
                        }
                        r->eax = (r->eax & ~0xff) | '$';
                    }
                    break;
                default:
                unknown_int:
                    fprintf(stderr, "unsupported int 0x%02x\n", int_num);
                    dump_regs(&ctx.regs);
                    //                    exit(1);
                }
            }
            break;
        case VM86_SIGNAL:
            /* a signal came, we just ignore that */
            break;
        case VM86_STI:
            break;
        default:
            fprintf(stderr, "unhandled vm86 return code (0x%x)\n", ret);
            dump_regs(&ctx.regs);
            exit(1);
        }
    }
}