/* 
 * opendir.c --
 *
 *	This file provides dirent-style directory-reading procedures
 *	for V7 Unix systems that don't have such procedures.  The
 *	origin of this code is unclear, but it seems to have come
 *	originally from Larry Wall.
 *
 */

#include <tclint.h>
#include <tclunix.h>

#undef DIRSIZ
#define DIRSIZ(dp) \
    ((sizeof (struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))

/*
 * open a directory.
 */
DIR *
opendir(name)
char *name;
{
	register DIR *dirp;
	register int fd;
	char *myname;

	myname = ((*name == '\0') ? "." : name);
	if ((fd = open(myname, 0, 0)) == -1)
		return NULL;
	if ((dirp = (DIR *)ckalloc(sizeof(DIR))) == NULL) {
		close (fd);
		return NULL;
	}
	dirp->dd_fd = fd;
	dirp->dd_loc = 0;
	return dirp;
}

/*
 * read an old style directory entry and present it as a new one
 */
#ifndef pyr
#define	ODIRSIZ	14

struct	olddirect {
	ino_t	od_ino;
	char	od_name[ODIRSIZ];
};
#else	/* a Pyramid in the ATT universe */
#define	ODIRSIZ	248

struct	olddirect {
	long	od_ino;
	short	od_fill1, od_fill2;
	char	od_name[ODIRSIZ];
};
#endif

/*
 * get next entry in a directory.
 */
struct dirent *
readdir(dirp)
register DIR *dirp;
{
	register struct olddirect *dp;
	static struct dirent dir;

	for (;;) {
		if (dirp->dd_loc == 0) {
			dirp->dd_size = read(dirp->dd_fd, dirp->dd_buf,
			    DIRBLKSIZ);
			if (dirp->dd_size <= 0)
				return NULL;
		}
		if (dirp->dd_loc >= dirp->dd_size) {
			dirp->dd_loc = 0;
			continue;
		}
		dp = (struct olddirect *)(dirp->dd_buf + dirp->dd_loc);
		dirp->dd_loc += sizeof(struct olddirect);
		if (dp->od_ino == 0)
			continue;
		dir.d_ino = dp->od_ino;
		strncpy(dir.d_name, dp->od_name, ODIRSIZ);
		dir.d_name[ODIRSIZ] = '\0'; /* insure null termination */
		dir.d_namlen = strlen(dir.d_name);
		dir.d_reclen = DIRSIZ(&dir);
		return (&dir);
	}
}

/*
 * close a directory.
 */
void
closedir(dirp)
register DIR *dirp;
{
	close(dirp->dd_fd);
	dirp->dd_fd = -1;
	dirp->dd_loc = 0;
	ckfree((char *) dirp);
}
