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readdir.c revision 1.20 
      1 /*	$NetBSD: readdir.c,v 1.20 2005/09/13 01:44:09 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)readdir.c	8.3 (Berkeley) 9/29/94";
     36 #else
     37 __RCSID("$NetBSD: readdir.c,v 1.20 2005/09/13 01:44:09 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include "reentrant.h"
     43 #include <sys/param.h>
     44 
     45 #include <dirent.h>
     46 #include <errno.h>
     47 #include <string.h>
     48 #include <unistd.h>
     49 
     50 /*
     51  * get next entry in a directory.
     52  */
     53 static struct dirent *
     54 _readdir_unlocked(DIR *dirp)
     55 {
     56 	struct dirent *dp;
     57 
     58 
     59 	for (;;) {
     60 		if (dirp->dd_loc >= dirp->dd_size) {
     61 			if (dirp->dd_flags & __DTF_READALL)
     62 				return (NULL);
     63 			dirp->dd_loc = 0;
     64 		}
     65 		if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
     66 			dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
     67 			dirp->dd_size = getdents(dirp->dd_fd,
     68 			    dirp->dd_buf, (size_t)dirp->dd_len);
     69 			if (dirp->dd_size <= 0)
     70 				return (NULL);
     71 		}
     72 		dp = (struct dirent *)
     73 		    (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
     74 		if ((intptr_t)dp & _DIRENT_ALIGN(dp))/* bogus pointer check */
     75 			return (NULL);
     76 		/* d_reclen is unsigned; no need to compare it <= 0 */
     77 		if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
     78 			return (NULL);
     79 		dirp->dd_loc += dp->d_reclen;
     80 		if (dp->d_ino == 0)
     81 			continue;
     82 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
     83 			continue;
     84 		return (dp);
     85 	}
     86 }
     87 
     88 struct dirent *
     89 readdir(dirp)
     90 	DIR *dirp;
     91 {
     92 	struct dirent	*dp;
     93 
     94 #ifdef _REENTRANT
     95 	if (__isthreaded) {
     96 		mutex_lock((mutex_t *)dirp->dd_lock);
     97 		dp = _readdir_unlocked(dirp);
     98 		mutex_unlock((mutex_t *)dirp->dd_lock);
     99 	}
    100 	else
    101 #endif
    102 		dp = _readdir_unlocked(dirp);
    103 	return (dp);
    104 }
    105 
    106 int
    107 readdir_r(dirp, entry, result)
    108 	DIR *dirp;
    109 	struct dirent *entry;
    110 	struct dirent **result;
    111 {
    112 	struct dirent *dp;
    113 	int saved_errno;
    114 
    115 	saved_errno = errno;
    116 	errno = 0;
    117 #ifdef _REENTRANT
    118 	if (__isthreaded) {
    119 		mutex_lock((mutex_t *)dirp->dd_lock);
    120 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    121 			memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
    122 		mutex_unlock((mutex_t *)dirp->dd_lock);
    123 	}
    124 	else
    125 #endif
    126 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    127 			memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
    128 
    129 	if (errno != 0) {
    130 		if (dp == NULL)
    131 			return (errno);
    132 	} else
    133 		errno = saved_errno;
    134 
    135 	if (dp != NULL)
    136 		*result = entry;
    137 	else
    138 		*result = NULL;
    139 
    140 	return (0);
    141 }
    142