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readdir.c revision 1.24 
      1 /*	$NetBSD: readdir.c,v 1.24 2008/05/04 18:53:26 tonnerre 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 1.24 2008/05/04 18:53:26 tonnerre Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include "reentrant.h"
     43 #include "extern.h"
     44 #include <sys/param.h>
     45 
     46 #include <dirent.h>
     47 #include <errno.h>
     48 #include <string.h>
     49 #include <unistd.h>
     50 
     51 #include "dirent_private.h"
     52 
     53 /*
     54  * get next entry in a directory.
     55  */
     56 struct dirent *
     57 _readdir_unlocked(DIR *dirp, int skipdeleted)
     58 {
     59 	struct dirent *dp;
     60 
     61 
     62 	for (;;) {
     63 		if (dirp->dd_loc >= dirp->dd_size) {
     64 			if (dirp->dd_flags & __DTF_READALL)
     65 				return (NULL);
     66 			dirp->dd_loc = 0;
     67 		}
     68 		if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
     69 			dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
     70 			dirp->dd_size = getdents(dirp->dd_fd,
     71 			    dirp->dd_buf, (size_t)dirp->dd_len);
     72 			if (dirp->dd_size <= 0)
     73 				return (NULL);
     74 		}
     75 		dp = (struct dirent *)
     76 		    (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
     77 		if ((intptr_t)dp & _DIRENT_ALIGN(dp))/* bogus pointer check */
     78 			return (NULL);
     79 		/* d_reclen is unsigned; no need to compare it <= 0 */
     80 		if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
     81 			return (NULL);
     82 		dirp->dd_loc += dp->d_reclen;
     83 		if (dp->d_ino == 0 && skipdeleted)
     84 			continue;
     85 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
     86 			continue;
     87 		return (dp);
     88 	}
     89 }
     90 
     91 struct dirent *
     92 readdir(dirp)
     93 	DIR *dirp;
     94 {
     95 	struct dirent	*dp;
     96 
     97 #ifdef _REENTRANT
     98 	if (__isthreaded) {
     99 		mutex_lock((mutex_t *)dirp->dd_lock);
    100 		dp = _readdir_unlocked(dirp, 1);
    101 		mutex_unlock((mutex_t *)dirp->dd_lock);
    102 	}
    103 	else
    104 #endif
    105 		dp = _readdir_unlocked(dirp, 1);
    106 	return (dp);
    107 }
    108 
    109 int
    110 readdir_r(dirp, entry, result)
    111 	DIR *dirp;
    112 	struct dirent *entry;
    113 	struct dirent **result;
    114 {
    115 	struct dirent *dp;
    116 	int saved_errno;
    117 
    118 	saved_errno = errno;
    119 	errno = 0;
    120 #ifdef _REENTRANT
    121 	if (__isthreaded) {
    122 		mutex_lock((mutex_t *)dirp->dd_lock);
    123 		if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
    124 			memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
    125 		mutex_unlock((mutex_t *)dirp->dd_lock);
    126 	}
    127 	else
    128 #endif
    129 		if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
    130 			memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
    131 
    132 	if (errno != 0) {
    133 		if (dp == NULL)
    134 			return (errno);
    135 	} else
    136 		errno = saved_errno;
    137 
    138 	if (dp != NULL)
    139 		*result = entry;
    140 	else
    141 		*result = NULL;
    142 
    143 	return (0);
    144 }
    145