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syscall-dos.c
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syscall-dos.c
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/* MSDOS system calls for 8086 emulator */
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>
#include "8086.h"
#include "exe.h"
#if BLINK16
#include "blink/machine.h"
#define f_verbose 0
#else
extern int f_verbose;
#endif
extern Word loadSegment;
static char* pathBuffers[2];
static int* fileDescriptors;
static int fileDescriptorCount = 6;
static void* alloc(size_t bytes)
{
void* r = malloc(bytes);
if (r == 0) {
runtimeError("Out of memory\n");
}
return r;
}
static void init()
{
pathBuffers[0] = (char*)alloc(0x10000);
pathBuffers[1] = (char*)alloc(0x10000);
fileDescriptors = (int*)alloc(6*sizeof(int));
fileDescriptors[0] = STDIN_FILENO;
fileDescriptors[1] = STDOUT_FILENO;
fileDescriptors[2] = STDERR_FILENO;
fileDescriptors[3] = STDOUT_FILENO;
fileDescriptors[4] = STDOUT_FILENO;
fileDescriptors[5] = -1;
}
static char* initString(Word offset, int seg, int write, int buffer, int bytes)
{
for (int i = 0; i < bytes; ++i) {
char p;
if (write) {
p = pathBuffers[buffer][i];
ram[physicalAddress(offset + i, seg, true)] = p;
}
else {
p = ram[physicalAddress(offset + i, seg, false)];
pathBuffers[buffer][i] = p;
}
if (p == 0 && bytes == 0x10000)
break;
}
if (!write)
pathBuffers[buffer][0xffff] = 0;
return pathBuffers[buffer];
}
static char* dsdxparms(int write, int bytes)
{
return initString(dx(), DS, write, 0, bytes);
}
static char *dsdx()
{
return dsdxparms(false, 0x10000);
}
static int dosError(int e)
{
if (e == ENOENT)
return 2;
runtimeError("%s\n", strerror(e));
return 0;
}
static int getDescriptor()
{
for (int i = 0; i < fileDescriptorCount; ++i)
if (fileDescriptors[i] == -1)
return i;
int newCount = fileDescriptorCount << 1;
int* newDescriptors = (int*)alloc(newCount*sizeof(int));
for (int i = 0; i < fileDescriptorCount; ++i)
newDescriptors[i] = fileDescriptors[i];
free(fileDescriptors);
int oldCount = fileDescriptorCount;
fileDescriptorCount = newCount;
fileDescriptors = newDescriptors;
return oldCount;
}
int checkStackDOS(struct exe *e)
{
return (e->t_stackLow && ((DWord)ss() << 4) + sp() <= e->t_stackLow);
}
static int SysExit(struct exe *e, int rc)
{
if (f_verbose) printf("EXIT %d\n", rc);
exit(rc);
return -1;
}
static int SysWrite(struct exe *e, int fd, char *buf, size_t n)
{
#if BLINK16
extern ssize_t ptyWrite(int fd, char *buf, int len);
SetWriteAddr(g_machine, physicalAddress(dx(), DS, false), n);
return ptyWrite(fd, buf, n);
#else
return write(fd, buf, n);
#endif
}
int handleSyscallDOS(struct exe *e, int intno)
{
int fileDescriptor;
char *p, *addr;
DWord data;
static int once = 0;
if (!once) {
init();
once = 1;
}
switch (intno << 8 | ah()) {
case 0x1a00:
data = es();
setES(0);
setDX(readWordSeg(0x046c, ES));
setCX(readWordSeg(0x046e, ES));
setAL(readByte(0x0470, ES));
setES(data);
break;
case 0x2109:
addr = dsdx();
p = strchr(addr, '$');
if (p) SysWrite(e, STDOUT_FILENO, addr, p-addr);
break;
case 0x2130:
setAX(0x1403);
setBX(0xff00);
setCX(0);
break;
case 0x2139:
if (mkdir(dsdx(), 0700) == 0)
setCF(false);
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x213a:
if (rmdir(dsdx()) == 0)
setCF(false);
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x213b:
if (chdir(dsdx()) == 0)
setCF(false);
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x213c:
fileDescriptor = creat(dsdx(), 0700);
if (fileDescriptor != -1) {
setCF(false);
int guestDescriptor = getDescriptor();
setAX(guestDescriptor);
fileDescriptors[guestDescriptor] = fileDescriptor;
}
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x213d:
fileDescriptor = open(dsdx(), al() & 3, 0700);
if (fileDescriptor != -1) {
setCF(false);
setAX(getDescriptor());
fileDescriptors[ax()] = fileDescriptor;
}
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x213e:
fileDescriptor = fileDescriptors[bx()];
if (fileDescriptor == -1) {
setCF(true);
setAX(6); // Invalid handle
break;
}
if (fileDescriptor >= 5 &&
close(fileDescriptor) != 0) {
setCF(true);
setAX(dosError(errno));
}
else {
fileDescriptors[bx()] = -1;
setCF(false);
}
break;
case 0x213f:
fileDescriptor = fileDescriptors[bx()];
if (fileDescriptor == -1) {
setCF(true);
setAX(6); // Invalid handle
break;
}
data = read(fileDescriptor, pathBuffers[0], cx());
dsdxparms(true, cx());
if (data == (DWord)-1) {
setCF(true);
setAX(dosError(errno));
}
else {
setCF(false);
setAX(data);
}
break;
case 0x2140:
fileDescriptor = fileDescriptors[bx()];
if (fileDescriptor == -1) {
setCF(true);
setAX(6); // Invalid handle
break;
}
data = SysWrite(e, fileDescriptor, dsdxparms(false, cx()), cx());
if (data == (DWord)-1) {
setCF(true);
setAX(dosError(errno));
}
else {
setCF(false);
setAX(data);
}
break;
case 0x2141:
if (unlink(dsdx()) == 0)
setCF(false);
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x2142:
fileDescriptor = fileDescriptors[bx()];
if (fileDescriptor == -1) {
setCF(true);
setAX(6); // Invalid handle
break;
}
data = lseek(fileDescriptor, (cx() << 16) + dx(),
al());
if (data != (DWord)-1) {
setCF(false);
setDX(data >> 16);
setAX(data);
}
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x2144:
if (al() != 0)
runtimeError("Unknown IOCTL 0x%02x", al());
fileDescriptor = fileDescriptors[bx()];
if (fileDescriptor == -1) {
setCF(true);
setAX(6); // Invalid handle
break;
}
data = isatty(fileDescriptor);
if (data == 1) {
setDX(0x80);
setCF(false);
}
else {
if (errno == ENOTTY) {
setDX(0);
setCF(false);
}
else {
setAX(dosError(errno));
setCF(true);
}
}
break;
case 0x2147:
if (getcwd(pathBuffers[0], 64) != 0) {
setCF(false);
initString(si(), DS, true, 0, 0x10000);
}
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x214a:
// Only allow attempts to "resize" the PSP segment,
// and check that CS:IP and SS:SP do not overshoot the
// segment end
if (es() == loadSegment - 0x10) {
DWord memEnd = (DWord)(es() + bx()) << 4;
if (physicalAddress(getIP(), CS, false) < memEnd &&
physicalAddress(sp() - 1, SS, true) < memEnd) {
setCF(false);
break;
}
}
runtimeError("Bad attempt to resize DOS memory "
"block: int 0x21, ah = 0x4a, bx = 0x%04x, "
"es = 0x%04x", (unsigned)bx(), (unsigned)es());
break;
case 0x214c:
//printf("*** Cycles: %i\n", ios);
SysExit(e, 0);
break;
case 0x2156:
if (rename(dsdx(), initString(di(), ES, false, 1, 0x10000)) == 0)
setCF(false);
else {
setCF(true);
setAX(dosError(errno));
}
break;
case 0x2157:
switch (al()) {
case 0x00:
fileDescriptor = fileDescriptors[bx()];
if (fileDescriptor == -1) {
setCF(true);
setAX(6); // Invalid handle
break;
}
setCX(0x0000); // Return a "reasonable" file
setDX(0x0021); // time and file date
setCF(false);
break;
default:
runtimeError("Unknown DOS call: int 0x21, "
"ax = 0x%04x", (unsigned)ax());
}
break;
default:
runtimeError("Unknown DOS/BIOS call: int 0x%02x, "
"ah = 0x%02x", intno, (unsigned)ah());
return 0;
}
return 1;
}