text: /*
   * Copyright (c) 1983 Regents of the University of California.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #if defined(LIBC_SCCS) && !defined(lint)
  static char sccsid[] = "@(#)closedir.c	5.9 (Berkeley) 2/23/91";
  #endif /* LIBC_SCCS and not lint */
  
  /*
   * One of these structures is malloced to describe the current directory
   * position each time telldir is called. It records the current magic 
   * cookie returned by getdirentries and the offset within the buffer
   * associated with that return value.
   */
  struct ddloc {
  	struct	ddloc *loc_next;/* next structure in list */
  	long	loc_index;	/* key associated with structure */
  	long	loc_seek;	/* magic cookie returned by getdirentries */
  	long	loc_loc;	/* offset of entry in buffer */
  };
  
  static long	dd_loccnt = 0;	/* Index of entry for sequential telldir's */
  
  #include <errno.h>
  #include <pthread.h>
  #include <sys/types.h>
  #include <sys/param.h>
  #include <dirent.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <fcntl.h>
  #include <string.h>
  
  
  /*
   * close a directory.
   */
  int closedir(DIR * dirp)
  {
  	void *ptr, *nextptr;
  	int fd;
  
  	pthread_mutex_lock (dirp->dd_lock);
  	fd = dirp->dd_fd;
  	dirp->dd_fd = -1;
  	dirp->dd_loc = 0;
  	for (ptr = (void *)dirp->dd_ddloc; ptr; ptr = nextptr) {
  		nextptr = (void *)(((struct ddloc *)ptr)->loc_next);
  		free(ptr);
  	}
  	for (ptr = (void *)dirp->dd_dp; ptr; ptr = nextptr) {
  		nextptr = (void *)(((struct __dirent *)ptr)->next);
  		free(ptr);
  	}
  	free((void *)dirp->dd_buf);
  	free (dirp->dd_lock);
  	free((void *)dirp);
  	return(machdep_sys_close(fd));
  }
  
  /*
   * open a directory.
   */
  DIR * opendir(const char * name)
  {
  	DIR *dirp;
  	int fd;
  
  	if ((fd = machdep_sys_open(name, 0)) < 0)
  		return NULL;
  	if (machdep_sys_fcntl(fd, F_SETFD, 1) < 0 ||
  	    (dirp = (DIR *)malloc(sizeof(DIR))) == NULL) {
  		machdep_sys_close (fd);
  		return NULL;
  	}
  	dirp->dd_lock = (pthread_mutex_t*) malloc (sizeof (pthread_mutex_t));
  	pthread_mutex_init (dirp->dd_lock, 0);
  	/*
  	 * If CLSIZE is an exact multiple of DIRBLKSIZ, use a CLSIZE
  	 * buffer that it cluster boundary aligned.
  	 * Hopefully this can be a big win someday by allowing page trades
  	 * to user space to be done by getdirentries()
  	 */
  #ifndef CLSIZE
  #define CLSIZE 1
  #endif
  	if ((CLSIZE % DIRBLKSIZ) == 0) {
  		dirp->dd_buf = malloc(CLSIZE);
  		dirp->dd_len = CLSIZE;
  	} else {
  		dirp->dd_buf = malloc(DIRBLKSIZ);
  		dirp->dd_len = DIRBLKSIZ;
  	}
  	if (dirp->dd_buf == NULL) {
  		machdep_sys_close (fd);
  		free((void *)dirp);
  		return NULL;
  	}
  
  	dirp->dd_ddloc = NULL;
  	dirp->dd_dp = NULL;
  	dirp->dd_seek = 0;
  	dirp->dd_loc = 0;
  	dirp->dd_fd = fd;
  	return(dirp);
  }
  
  /*
   * The real work in gettint the next entry in a directory.
   * Return
   * NULL on End of directory
   * &ERR	on Error
   * dp	on valid directory;
   */
  static struct dirent ERR;
  static struct dirent * readdir_basic(DIR * dirp)
  {
  	register struct dirent *dp;
  
  	for (;;) {
  		if (dirp->dd_loc == 0) {
  			dirp->dd_size = machdep_sys_getdirentries(dirp->dd_fd,
  			    dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
  			if (dirp->dd_size < 0)
  				return(&ERR);
  			if (dirp->dd_size == 0)
  				return(NULL);
  		}
  		if (dirp->dd_loc >= dirp->dd_size) {
  			dirp->dd_loc = 0;
  			continue;
  		}
  		dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
  		if ((long)dp & 03)	/* bogus pointer check */
  			return(&ERR);
  		if (dp->d_reclen <= 0 ||
  		    dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
  			return(&ERR);
  		dirp->dd_loc += dp->d_reclen;
  		if (dp->d_ino == 0)
  			continue;
  		return(dp);
  	}
  }
  
  /*
   * POSIX.1 version of getting the next entry in a directory.
   */
  struct dirent * readdir(DIR * dirp)
  {
  	register struct dirent * rp;
  	struct __dirent * my__dp;
  	pthread_t self;
  
  	pthread_mutex_lock (dirp->dd_lock);
  
  	self = pthread_self();
  	/* Allocate space and return */
  	for (my__dp = dirp->dd_dp; my__dp; my__dp = my__dp->next) {
  		if (pthread_equal(my__dp->owner, self)) {
  			break;
  		}
  	}
  	if (my__dp == NULL) {
  		if (my__dp = (struct __dirent *)(malloc(sizeof(struct __dirent)))) {
  			my__dp->next = dirp->dd_dp;
  			dirp->dd_dp = my__dp;
  			my__dp->owner = self;
  		} else {
  			pthread_mutex_unlock (dirp->dd_lock);
  			return(NULL);
  		}
  	}
  	if (rp = readdir_basic(dirp)) {
  		if (rp != &ERR) {
  			memcpy(& (my__dp->data), rp, sizeof(struct dirent));
  			rp = & (my__dp->data);
  		} else {
  			rp = NULL;
  		}
  	}
  	pthread_mutex_unlock (dirp->dd_lock);
  	return(rp);
  }
  
  /*
   * POSIX.4a version of getting the next entry in a directory.
   */
  int readdir_r(DIR * dirp, struct dirent * entry, struct dirent ** result)
  {
  	register struct dirent * rp;
  	int ret;
  
  	pthread_mutex_lock (dirp->dd_lock);
  	rp = readdir_basic(dirp);
  	if (rp != &ERR) {
  		if (rp) {
  			memcpy(entry, rp, sizeof(struct dirent));
  			*result = entry;
  			ret = 0;
  		} else {
  			*result = NULL;
  			ret = 0;
  		}
  	} else {
  		/* Should get it from errno */
  		ret = EBADF;
  	}
  	pthread_mutex_unlock (dirp->dd_lock);
  	return(ret);
  }
  
  void rewinddir(DIR * dirp)
  {
  	pthread_mutex_lock (dirp->dd_lock);
  	(void)machdep_sys_lseek(dirp->dd_fd, 0, 0);
  	dirp->dd_seek = 0;
  	dirp->dd_loc = 0;
  	pthread_mutex_unlock (dirp->dd_lock);
  }
  
  /*
   * Seek to an entry in a directory.
   * _seekdir is in telldir.c so that it can share opaque data structures.
   *
   * Use the POSIX reentrant safe readdir_r to simplify varifying POSIX
   * thread-safe compliance.
   */
  void seekdir(DIR * dirp, long loc)
  {
    register struct ddloc ** prevlp;
    register struct ddloc * lp;
    struct dirent * dp;
    struct dirent   de;
  
    pthread_mutex_lock (dirp->dd_lock);
    prevlp = (struct ddloc **)&(dirp->dd_ddloc);
    lp = *prevlp;
    while (lp != NULL) {
      if (lp->loc_index == loc)
        break;
      prevlp = &lp->loc_next;
      lp = lp->loc_next;
    }
    if (lp) {
      if (lp->loc_seek != dirp->dd_seek) {
        if (machdep_sys_lseek(dirp->dd_fd, lp->loc_seek, 0) < 0) {
  	*prevlp = lp->loc_next;
  	pthread_mutex_unlock (dirp->dd_lock);
  	return;
        }
        dirp->dd_seek = lp->loc_seek;
        dirp->dd_loc = 0;
        while (dirp->dd_loc < lp->loc_loc) {
  	if (readdir_r(dirp, &de, &dp)) {
  	  *prevlp = lp->loc_next;
  	  break;
  	}
        }
      }
    }
    pthread_mutex_unlock (dirp->dd_lock);
  }
  
  /*
   * return a pointer into a directory
   */
  long telldir(DIR *dirp)
  {
  	struct ddloc *lp, **fakeout;
  	int ret;
  
  	pthread_mutex_lock (dirp->dd_lock);
  	if (lp = (struct ddloc *)malloc(sizeof(struct ddloc))) {
  		lp->loc_index = dd_loccnt++;
  		lp->loc_seek = dirp->dd_seek;
  		lp->loc_loc = dirp->dd_loc;
  		lp->loc_next = dirp->dd_ddloc;
  
  		/* Compiler won't let us change anything pointed to by db directly */
  		/* So we fake to the left and do it anyway */
  		/* Wonder if the compile optomizes it to the correct solution */
  		fakeout = (struct ddloc **)&(dirp->dd_ddloc);
  		*fakeout = lp;
  
  		ret = lp->loc_index;
  	} else {
  		ret = -1;
  	}
  	pthread_mutex_unlock (dirp->dd_lock);
  	return(ret);
  }
  
  