?? dos.c
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#include <io.h>
#include <dos.h>
#include <errno.h>
#include <fcntl.h>
#include "stdio.h"
#include "global.h"
/* Table for mapping MS-DOS errors to UNIX errno values */
static int _ioerr[] = {
0, /* 0 - OK */
EINVAL, /* 1 - e_badFunction */
ENOENT, /* 2 - e_fileNotFound */
ENOENT, /* 3 - e_pathNotFound */
EMFILE, /* 4 - e_tooManyOpen */
EACCES, /* 5 - e_accessDenied */
EBADF, /* 6 - e_badHandle */
ENOMEM, /* 7 - e_mcbDestroyed */
ENOMEM, /* 8 - e_outOfMemory */
ENOMEM, /* 9 - e_badBlock */
E2BIG, /* 10 e_badEnviron */
ENOEXEC, /* 11 e_badFormat */
EACCES, /* 12 e_badAccess */
EINVAL, /* 13 e_badData */
EFAULT, /* 14 reserved */
EXDEV, /* 15 e_badDrive */
EACCES, /* 16 e_isCurrentDir */
ENOTSAM, /* 17 e_notSameDevice */
ENOENT, /* 18 e_noMoreFiles */
EROFS, /* 19 e_readOnly */
ENXIO, /* 20 e_unknownUnit */
EBUSY, /* 21 e_notReady */
EIO, /* 22 e_unknownCommand */
EIO, /* 23 e_dataError */
EIO, /* 24 e_badRequestLength */
EIO, /* 25 e_seekError */
EIO, /* 26 e_unknownMedia */
ENXIO, /* 27 e_sectorNotFound */
EBUSY, /* 28 e_outOfPaper */
EIO, /* 29 e_writeFault */
EIO, /* 30 e_readFault */
EIO, /* 31 e_generalFault */
EACCES, /* 32 e_sharing */
EACCES, /* 33 e_lock */
ENXIO, /* 34 e_diskChange */
ENFILE, /* 35 e_FCBunavailable */
ENFILE, /* 36 e_sharingOverflow */
EFAULT, EFAULT,
EFAULT, EFAULT,
EFAULT, EFAULT,
EFAULT, EFAULT,
EFAULT, EFAULT,
EFAULT, EFAULT,
EFAULT, /* 37-49 reserved */
ENODEV, /* 50 e_networkUnsupported */
EBUSY, /* 51 e_notListening */
EEXIST, /* 52 e_dupNameOnNet */
ENOENT, /* 53 e_nameNotOnNet */
EBUSY, /* 54 e_netBusy */
ENODEV, /* 55 e_netDeviceGone */
EAGAIN, /* 56 e_netCommandLimit */
EIO, /* 57 e_netHardError */
EIO, /* 58 e_wrongNetResponse */
EIO, /* 59 e_netError */
EINVAL, /* 60 e_remoteIncompatible */
EFBIG, /* 61 e_printQueueFull */
ENOSPC, /* 62 e_printFileSpace */
ENOENT, /* 63 e_printFileDeleted */
ENOENT, /* 64 e_netNameDeleted */
EACCES, /* 65 e_netAccessDenied */
ENODEV, /* 66 e_netDeviceWrong */
ENOENT, /* 67 e_netNameNotFound */
ENFILE, /* 68 e_netNameLimit */
EIO, /* 69 e_netBIOSlimit */
EAGAIN, /* 70 e_paused */
EINVAL, /* 71 e_netRequestRefused */
EAGAIN, /* 72 e_redirectionPaused */
EFAULT, EFAULT,
EFAULT, EFAULT,
EFAULT, EFAULT,
EFAULT, /* 73- 79 reserved */
EEXIST, /* 80 e_fileExists */
EFAULT, /* 81 reserved */
ENOSPC, /* 82 e_cannotMake */
EIO, /* 83 e_failInt24 */
ENFILE, /* 84 e_redirectionLimit */
EEXIST, /* 85 e_dupRedirection */
EPERM, /* 86 e_password */
EINVAL, /* 87 e_parameter */
EIO, /* 88 e_netDevice */
};
#define NERROR 89
/* Reference count table for open file descriptors */
unsigned *Refcnt;
int
_creat(file,mode)
const char *file; /* File name to create */
int mode; /* Ignored */
{
union REGS regs;
struct SREGS segregs;
int fd;
segregs.ds = FP_SEG(file);
regs.x.dx = FP_OFF(file);
regs.x.cx = 0; /* Normal attributes */
regs.h.ah = 0x3c;
intdosx(®s,®s,&segregs);
fd = regs.x.ax;
if(regs.x.cflag){
if(fd < NERROR)
errno = _ioerr[fd];
return -1;
}
Refcnt[fd] = 1;
return fd; /* Return handle */
}
int
_open(file,mode)
const char *file;
int mode;
{
union REGS regs;
struct SREGS segregs;
int dosmode,fd;
if(mode & O_TRUNC){
remove(file);
mode |= O_CREAT;
}
/* Translate unix to MS-DOS open modes */
switch(mode & (O_RDONLY|O_WRONLY|O_RDWR)){
case O_RDONLY:
dosmode = 0;
break;
case O_WRONLY:
dosmode = 1;
break;
case O_RDWR:
dosmode = 2;
break;
default:
errno = EINVAL;
return -1;
}
if(mode & O_EXCL)
dosmode |= 0x10;
segregs.ds = FP_SEG(file);
regs.x.dx = FP_OFF(file);
regs.h.al = dosmode;
regs.h.ah = 0x3d;
intdosx(®s,®s,&segregs);
fd = regs.x.ax;
if(regs.x.cflag){
if(fd < NERROR){
errno = _ioerr[fd];
if(errno == ENOENT && (mode & O_CREAT))
return _creat(file,0);
}
return -1;
}
Refcnt[fd] = 1;
return fd; /* Return handle */
}
/* Dup a file descriptor. Rather than allocating a new descriptor,
* as in UNIX or MS-DOS, we maintain a reference count table so we
* can return the same descriptor that is passed. This saves precious
* file descriptor space.
*/
int
dup(fd)
int fd;
{
if(fd < 0 || _fd_type(fd) != _FL_FILE){
errno = EINVAL; /* Valid only on files */
return -1;
}
fd = _fd_seq(fd);
if(fd >= Nfiles || Refcnt[fd] == 0){
errno = EINVAL;
return -1;
}
Refcnt[fd]++;
return fd;
}
int
_close(fd)
int fd;
{
union REGS regs;
if(fd < 0 || _fd_type(fd) != _FL_FILE){
errno = EINVAL; /* Valid only on files */
return -1;
}
fd = _fd_seq(fd);
if(fd >= Nfiles || Refcnt[fd] == 0){
errno = EINVAL;
return -1;
}
if(--Refcnt[fd] != 0)
return 0; /* Somebody else is still using it */
regs.x.bx = fd;
regs.h.ah = 0x3e;
intdos(®s,®s);
if(regs.x.cflag){
if(regs.x.ax < NERROR)
errno = _ioerr[regs.x.ax];
return -1;
}
return 0;
}
int
_read(fd,buf,cnt)
int fd;
void *buf;
unsigned cnt;
{
union REGS regs;
struct SREGS segregs;
if(fd < 0 || _fd_type(fd) != _FL_FILE){
errno = EINVAL; /* Valid only on files */
return -1;
}
fd = _fd_seq(fd);
if(fd >= Nfiles || Refcnt[fd] == 0){
errno = EINVAL;
return -1;
}
regs.x.bx = fd;
regs.x.cx = cnt;
segregs.ds = FP_SEG(buf);
regs.x.dx = FP_OFF(buf);
regs.h.ah = 0x3f;
intdosx(®s,®s,&segregs);
if(regs.x.cflag){
if(regs.x.ax < NERROR)
errno = _ioerr[regs.x.ax];
return -1;
}
return regs.x.ax; /* Return count */
}
int
_write(fd,buf,cnt)
int fd;
const void *buf;
unsigned cnt;
{
union REGS regs;
struct SREGS segregs;
if(fd < 0 || _fd_type(fd) != _FL_FILE){
errno = EINVAL; /* Valid only on files */
return -1;
}
fd = _fd_seq(fd);
if(fd >= Nfiles || Refcnt[fd] == 0){
errno = EINVAL;
return -1;
}
regs.x.bx = fd;
regs.x.cx = cnt;
segregs.ds = FP_SEG(buf);
regs.x.dx = FP_OFF(buf);
regs.h.ah = 0x40;
intdosx(®s,®s,&segregs);
if(regs.x.cflag){
if(regs.x.ax < NERROR)
errno = _ioerr[regs.x.ax];
return -1;
}
cnt = regs.x.ax; /* Return count */
/* Not really necessary when share.exe is loaded, and it really slows down
* machines without disk write caches
*/
#ifdef notdef
/* Call the "commit file" command to flush it out (will fail for
* MS-DOS before 3.3)
*/
regs.x.bx = fd;
regs.h.ah = 0x68;
intdos(®s,®s);
#endif
return cnt;
}
long
_lseek(fd,offset,whence)
int fd;
long offset;
int whence;
{
union REGS regs;
if(fd < 0 || _fd_type(fd) != _FL_FILE){
errno = EINVAL; /* Valid only on files */
return -1;
}
fd = _fd_seq(fd);
if(fd >= Nfiles || Refcnt[fd] == 0){
errno = EINVAL;
return -1;
}
regs.x.bx = fd;
regs.x.cx = offset >> 16;
regs.x.dx = offset;
regs.h.al = whence;
regs.h.ah = 0x42;
intdos(®s,®s);
if(regs.x.cflag){
if(regs.x.ax < NERROR)
errno = _ioerr[regs.x.ax];
return -1;
}
/* Return new offset */
return ((long)regs.x.dx << 16) | regs.x.ax;
}
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