🚀 go-pugleaf

The following little program is derived from the material
in the Ralf Brown "interrupt list". It shows how to
prowl the Logical Drive Table and GetRedirList outputs.
Depending on your system and network, drives may show up
on either or both of these. Sorry about the cryptic
output: the "V" bit in the LDT means that the drive is valid.
Also, you MUST compile with /AL, or all of the pointer will be
screwed up. The code will adjust for DOS 3.x or 4.x correctly.

Enjoy

Geoff

----------------------------------------------------------------------
/*
 * SYS_SCAN.C
 * Compile with "cl /AL sys_scan.c". I use MSC5.0.
 */

#include <dos.h>
#include <io.h>
#include <stdio.h>

/* The following requires that we compile with /Zp for
 * packed structures, or use the pragmas
 */

#pragma pack(1)

struct dpb {
        unsigned                char            d_number;
        unsigned                char            d_unit;
        unsigned                int             d_secsize;
        unsigned                char            d_secpercl;
        unsigned                char            d_allocshf;
        unsigned                int             d_rsvsec;
        unsigned                char            d_fatnum;
        unsigned                int             d_roots;
        unsigned                int             d_data1;
        unsigned                int             d_lastcl;
        unsigned                char            d_fatsize;
        unsigned                int             d_root1;
        void                    far     *       d_blkdev_p;
        unsigned                char            d_mediad;
        unsigned                char            d_mediaf;
        struct dpb      far     *       d_next;
};

struct ldt3 {
        char                                            p_path[67];
        unsigned                int             p_flags;
        struct dpb      far     *       p_dpb_p;
        unsigned                int             p_seek;
        unsigned                int             p_unknown1;
        unsigned                int             p_unknown2;
        unsigned                int             p_substptr;
};


#define NETWORK_DRIVE   0x8000
#define VALID_DRIVE             0x4000
#define JOINED_DRIVE            0x2000
#define SUBST_DRIVE             0x1000

#define DRIVE_UNUSED		0
#define DRIVE_REDIRECTED	1
#define DRIVE_PERMANENT	2
#define DRIVE_INVALID	3

struct ldt4 {
        char                                            p_path[67];
        unsigned                int             p_flags;
        struct dpb      far     *       p_dpb_p;
        unsigned                int             p_seek;
        unsigned                int             p_unknown1;
        unsigned                int             p_unknown2;
        unsigned                int             p_substptr;
        unsigned                char            p_unknown3[7];
};


                

struct dbuf {
        struct dpb      far     *       s_dpb_p;
        void                    far     *       s_oft_p;
        void                    far     *       s_clkdev_p;
        void                    far     *       s_condev_p;
        unsigned                int             s_maxlogsec;
        void                    far     *       s_sbs_p;
        struct ldt3     far     *       s_ldt_p;
        void                    far     *       s_fcb_p;
        int                                             s_fcbs;
        unsigned                char            s_logdrv;
        unsigned                char            s_lastdrv;
};
        
        

static
struct dbuf     far     *       buf_p;

static
struct dpb      far     *       dpb_p;

static
struct ldt3     far     *       ldt_p;

static
int                                             onetime = 1;

static
int                                             lastdrive;

static
unsigned int                    dos_major_version;

/*
 * static prototypes
 */
static  void setup_pointers(void );
static  struct ldt3 far *find_drive(int n);

static
char	get_redir_device[128];

static
char	get_redir_info[128];

static void
display_redir_list()
{
	int	index;
   union           REGS                    inregs;
   union           REGS                    outregs;
   struct  SREGS                   segregs;
	char	far	*dev_p;
	char	far	*info_p;

	printf("\n\nGetRedirectionList output:\n\n");
	index = 0;
	dev_p = &get_redir_device[0];
	info_p = &get_redir_info[0];

	while(1) {
		inregs.h.ah = 0x5f;
		inregs.h.al = 2;
		segregs.ds = FP_SEG(dev_p);
		inregs.x.si = FP_OFF(dev_p);
		segregs.es = FP_SEG(info_p);
		inregs.x.di = FP_OFF(info_p);
		inregs.x.bx = index;
		intdosx(&inregs, &outregs, &segregs);
		if (outregs.x.cflag)
			break;
		if(outregs.h.bh & 1)
			printf("Entry %2d: (invalid)\n", index);
		else
			printf("Entry %2d: Type=%02X Status=%02X User=%04X Device=%s\n   Info=%s\n",
				index, outregs.h.bl, outregs.h.bh, outregs.x.cx,
				get_redir_device, get_redir_info);
		index++;
		}
	printf("GetRedirectionList terminated after %2d entries with Error=%04X\n",
		index, outregs.x.ax);
	if(outregs.x.ax == 1)
		printf(" (Network not installed)\n");
	if(outregs.x.ax == 18)
		printf(" (No more entries)\n");

}




/*
 * -- setup_pointers -- setup_pointers -- setup_pointers --
 *
 * setup_pointers()
 *
 */
static void
setup_pointers()
{
        union           REGS                    inregs;
        union           REGS                    outregs;
        struct  SREGS                   segregs;


        inregs.h.ah = 0x30;     /* get dos version */
        intdos(&inregs, &outregs);
        dos_major_version = outregs.h.al;


        inregs.h.ah = 0x52; /* get address of list of lists */
        intdosx(&inregs, &outregs, &segregs);
        FP_OFF(buf_p)   =       outregs.x.bx;
        FP_SEG(buf_p)   =       segregs.es;

        lastdrive = buf_p->s_lastdrv;
        dpb_p = buf_p->s_dpb_p;
        ldt_p = buf_p->s_ldt_p;

        onetime = 0;
}

/*
 * -- find_drive -- find_drive -- find_drive --
 *
 * find_drive(n)
 *
 */
static struct ldt3 far *
find_drive(n)
int n;
{
        struct ldt4 far *p4;


        if (dos_major_version == 3) 
                return(&ldt_p[n]);

        p4 = (struct ldt4 far *)ldt_p;
        p4 = &p4[n];
        return((struct ldt3 far *)p4);
}



main()
{
	int i;
	struct ldt3 far * lp;

	printf("SYS_SCAN 1.0 - display key device info\n\n");
	printf("Logical Drive Table\n\n");

	setup_pointers();
	printf("Home:%04X:%04X LDT:%04X:%04X DPB:%04X:%04X DosMaj=%d LastDrive=%d\n",
		FP_SEG(buf_p), FP_OFF(buf_p),
		FP_SEG(ldt_p), FP_OFF(ldt_p),
		FP_SEG(dpb_p), FP_OFF(dpb_p),
		dos_major_version,
		lastdrive);
	for(i = 0; i < lastdrive; i++) {
		lp = find_drive(i);
		printf("%04X:%04X %c: Flags=%04X=%c%c%c%c DPB:%04X:%04X Seek=%04X ?1=%04X ?2=%04X Subst=%04X\n",
			FP_SEG(lp), FP_OFF(lp), 'A'+i, lp->p_flags,
			(lp->p_flags & NETWORK_DRIVE ? 'N' : '-'),
			(lp->p_flags & VALID_DRIVE ? 'V' : '-'),
			(lp->p_flags & JOINED_DRIVE ? 'J' : '-'),
			(lp->p_flags & SUBST_DRIVE ? 'S' : '-'),
			FP_SEG(lp->p_dpb_p), FP_OFF(lp->p_dpb_p),
			lp->p_seek, lp->p_unknown1, lp->p_unknown2, lp->p_substptr);
		if(lp->p_flags & VALID_DRIVE)
			printf(".... Path=%s\n", lp->p_path);
	}
	display_redir_list();
}
----------------------------------------------------------------------
-- Geoff Arnold, PC-NFS architect, Sun Microsystems. (geoff@East.Sun.COM)   --
   *** "Now is no time to speculate or hypothecate, but rather a time ***
   *** for action, or at least not a time to rule it out, though not  ***
   *** necessarily a time to rule it in, either." - George Bush       ***