Trying to C a directory.

[Steve Manes]

>From article <236100013 at mirror>, by root at mirror.TMC.COM:
> I am having trouble trying to figure out how to read a directory in
> MS-DOS.  I would like to be able to read in the directory contents
> and then display them out onto the screen in a certain format.

Why I Like Turbo-C: it has the two functions you need, findfirst and
findnext, already in the libraries.  There's also an example.

Alternatively, you will essentially need to recreate these functions
(something I had to do recently for a partner who refuses to do any DOS
programming except under VP/ix and Xenix) with DOS service calls. You
will also need to create two functions to get/save the current DTA and
to set a new DTA because the DTA is where DOS will dump each directory
record as it reads the disk.

Here's what I did (and it ain't purty).  You may need to tweak this for
your compiler.

--------cut here-----cut here------cut here------cut here------
#include <stdio.h>
#include <dos.h>

#define	D_RDONLY	0x01
#define	D_HIDDEN	0x02
#define	D_SYSTEM	0x04
#define	D_LABEL		0x08
#define	D_DIREC		0x10
#define	D_ARCHIVE	0x20

struct DOSDIR {
	char	ff_reserved[21];	/* reserved for DOS */
	char	ff_attrib;		/* DOS file attributes */
	int	ff_ftime;		/* file time */
	int	ff_fdate;		/* file date */
	long	ff_fsize;		/* file size */
	char	ff_name[13];		/* file name */
};

struct	DOSDIR	fcb;		/* FCB -- must maintain between calls! */

/* declarations */
void	get_dta( int *, int * ), set_dta( int, int );
int     dirfirst( char *name, struct DOSDIR *, int),
	dirnext( struct DOSDIR * );
	
main()
{
	int	done;
		
	printf("\nDirectory:\n");
	done = dirfirst("*.*", &fcb, D_ARCHIVE);
	while ( !done ) {
		printf("%s\n", fcb.ff_name);
		done = dirnext(&fcb);
	}
}

int	dirfirst( name, rec, attrib )
char	*name;
struct	DOSDIR	*rec;
int	attrib;
{
	union	REGS	inregs, outregs;
	struct	SREGS	segregs;
	int	dtaseg_old, dtaoff_old;
	int	rc;
					
	get_dta(&dtaseg_old, &dtaoff_old);	/* get current DTA */

	set_dta( FP_SEG(rec), FP_OFF(rec) );	/* set new DTA */
	
	inregs.h.ah = 0x4E;			/* get first match */
	inregs.x.cx = attrib;
	segregs.ds = FP_SEG(name);
	inregs.x.dx = FP_OFF(name);
	rc = intdosx(&inregs, &outregs, &segregs);
					
	set_dta( dtaseg_old, dtaoff_old);	/* reset DTA */
	return (outregs.x.cflag ? rc : 0 );
}

int	dirnext( rec )
struct	DOSDIR *rec;
{
	union	REGS	inregs, outregs;
	struct	SREGS	segregs;
	int	dtaseg_old, dtaoff_old;
	int	rc;
					
	get_dta(&dtaseg_old, &dtaoff_old);	/* get current DTA */
	set_dta( FP_SEG(rec), FP_OFF(rec) );	/* set new DTA */
	
	inregs.h.ah = 0x4F;			/* get next match */
	rc = intdosx(&inregs, &outregs, &segregs);
		
	set_dta(dtaseg_old, dtaoff_old);	/* reset DTA */
	return (outregs.x.cflag ? rc : 0 );
}
	
void	get_dta(segment, offset)
int	*segment, *offset;
{
	union	REGS inregs, outregs;
	struct	SREGS	segregs;
			
	inregs.h.ah = 0x2F;
	intdosx(&inregs, &outregs, &segregs);
	*segment = segregs.es;
	*offset  = outregs.x.bx;
}
					
void	set_dta(segment, offset)
int	segment, offset;
{
	union	REGS inregs;
	struct	SREGS	segregs;

	inregs.h.ah = 0x1A;
	segregs.ds  = segment;
	inregs.x.dx = offset;
	intdosx(&inregs, &inregs, &segregs);
}

-- 
Steve Manes            Roxy Recorders, Inc.             Magpie-HQ BBS
UUCP : {rutgers|cmcl2}!hombre!magpie!manes              (212)420-0527
Smail: manes at MASA.COM