/*
   =============================================================================
	dir.c - directory routines similar to unix 4.2 BSD
	Version 1 -- 1988-12-08 -- D.N. Lynx Crowe

	Modified versions of Usenet public domain source.
	Original author unknown.
   =============================================================================
*/

#include "errno.h"
#include "dir.h"

extern int errno;
extern char *calloc();

/* 
*/

/*
   =============================================================================
	opendir() - opens given directory and reads its contents into memory.
	Other functions use this data or the DIR structure to do their work.
   =============================================================================
*/

DIR *
opendir(dirname)
char *dirname;
{
	struct direct **namelist;
	DIR *dirptr;

	dirptr = (DIR *)calloc(1, sizeof(DIR));

	if(dirptr == (DIR *)0) {

		errno = ENOMEM;
		return((DIR *)0);
	}

	dirptr->d_magic = DMAGIC;
	dirptr->d_pos = 0;
	dirptr->d_length = scandir(dirname, &(dirptr->namelist),
		(int (*)())0, (int (*)())0);

	if(dirptr->d_length < 0) {

		free((char *)dirptr);
		return((DIR *)0);
	}

	return(dirptr);
}

/* 
*/

/*
   =============================================================================
	readdir - returns the next directory structure from the list and
	updates values in the DIR structure.
   =============================================================================
*/

struct direct *
readdir(dirptr)
DIR *dirptr;
{
	if(dirptr->d_magic != DMAGIC) {

		errno = ENOTDIR;
		return((struct direct *)0);
	}

	if(dirptr->d_pos >= dirptr->d_length) {

		errno = ENFILE;
		return((struct direct *)0);
	}

	return(dirptr->namelist[dirptr->d_pos++]);
}

/* 
*/

/*
   =============================================================================
	telldir - return the current position of the directory.
   =============================================================================
*/

long
telldir(dirptr)
DIR *dirptr;
{
	if(dirptr->d_magic != DMAGIC) {

		errno = ENOTDIR;
		return(-1L);
	}

	return((long)dirptr->d_pos);
}

/* 
*/

/*
   =============================================================================
	seekdir - position the given DIR stream to position given.
   =============================================================================
*/

seekdir(dirptr, loc)
DIR *dirptr;
long loc;
{
	if(dirptr->d_magic != DMAGIC) {

		errno = ENOTDIR;
		return(-1);
	}

	if(loc > (long)dirptr->d_length) {

		errno = EINVAL;
		return(-1);
	}

	dirptr->d_pos = (int)loc;
	return(0);
}

/* 
*/

/*
   =============================================================================
	rewinddir - rewind given DIR to beginning
   =============================================================================
*/

rewinddir(dirptr)
DIR *dirptr;
{
	if(dirptr->d_magic != DMAGIC) {

		errno = ENOTDIR;
		return(-1);
	}

	dirptr->d_pos = 0;
	return(0);
}

/* 
*/

/*
   =============================================================================
	closedir - close given directory. destroy given DIR struct so we
	know it is closed.
   =============================================================================
*/

closedir(dirptr)
DIR *dirptr;
{
	if(dirptr->d_magic != DMAGIC) {

		errno = ENOTDIR;
		return(-1);
	}

	dirptr->d_magic = ~DMAGIC;	/* mess it up a little */
	freedir(dirptr->namelist);
	free(dirptr);
	return(0);
}