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readdir.c revision 1.16 
      1 /*	$NetBSD: readdir.c,v 1.16 2003/05/28 20:03:37 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)readdir.c	8.3 (Berkeley) 9/29/94";
     40 #else
     41 __RCSID("$NetBSD: readdir.c,v 1.16 2003/05/28 20:03:37 christos Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include "namespace.h"
     46 #include "reentrant.h"
     47 #include <sys/param.h>
     48 
     49 #include <dirent.h>
     50 #include <errno.h>
     51 #include <unistd.h>
     52 
     53 #ifdef __weak_alias
     54 __weak_alias(readdir,_readdir)
     55 __weak_alias(readdir_r,_readdir_r)
     56 #endif
     57 
     58 /*
     59  * get next entry in a directory.
     60  */
     61 static struct dirent *
     62 _readdir_unlocked(DIR *dirp)
     63 {
     64 	struct dirent *dp;
     65 
     66 
     67 	for (;;) {
     68 		if (dirp->dd_loc >= dirp->dd_size) {
     69 			if (dirp->dd_flags & __DTF_READALL)
     70 				return (NULL);
     71 			dirp->dd_loc = 0;
     72 		}
     73 		if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
     74 			dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
     75 			dirp->dd_size = getdents(dirp->dd_fd,
     76 			    dirp->dd_buf, (size_t)dirp->dd_len);
     77 			if (dirp->dd_size <= 0)
     78 				return (NULL);
     79 		}
     80 		dp = (struct dirent *)
     81 		    (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
     82 		if ((long)dp & 03)	/* bogus pointer check */
     83 			return (NULL);
     84 		/* d_reclen is unsigned; no need to compare it <= 0 */
     85 		if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
     86 			return (NULL);
     87 		dirp->dd_loc += dp->d_reclen;
     88 		if (dp->d_ino == 0)
     89 			continue;
     90 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
     91 			continue;
     92 		return (dp);
     93 	}
     94 }
     95 
     96 struct dirent *
     97 readdir(dirp)
     98 	DIR *dirp;
     99 {
    100 	struct dirent	*dp;
    101 
    102 #ifdef _REENTRANT
    103 	if (__isthreaded) {
    104 		mutex_lock((mutex_t *)dirp->dd_lock);
    105 		dp = _readdir_unlocked(dirp);
    106 		mutex_unlock((mutex_t *)dirp->dd_lock);
    107 	}
    108 	else
    109 #endif
    110 		dp = _readdir_unlocked(dirp);
    111 	return (dp);
    112 }
    113 
    114 int
    115 readdir_r(dirp, entry, result)
    116 	DIR *dirp;
    117 	struct dirent *entry;
    118 	struct dirent **result;
    119 {
    120 	struct dirent *dp;
    121 	int saved_errno;
    122 
    123 	saved_errno = errno;
    124 	errno = 0;
    125 #ifdef _REENTRANT
    126 	if (__isthreaded) {
    127 		mutex_lock((mutex_t *)dirp->dd_lock);
    128 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    129 			memcpy(entry, dp, DIRENT_SIZE(dp));
    130 		mutex_unlock((mutex_t *)dirp->dd_lock);
    131 	}
    132 	else
    133 #endif
    134 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    135 			memcpy(entry, dp, DIRENT_SIZE(dp));
    136 
    137 	if (errno != 0) {
    138 		if (dp == NULL)
    139 			return (errno);
    140 	} else
    141 		errno = saved_errno;
    142 
    143 	if (dp != NULL)
    144 		*result = entry;
    145 	else
    146 		*result = NULL;
    147 
    148 	return (0);
    149 }
    150