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readdir.c revision 1.17 
      1 /*	$NetBSD: readdir.c,v 1.17 2003/05/28 21:08:23 kleink 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 1.17 2003/05/28 21:08:23 kleink 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 <string.h>
     52 #include <unistd.h>
     53 
     54 #ifdef __weak_alias
     55 __weak_alias(readdir,_readdir)
     56 __weak_alias(readdir_r,_readdir_r)
     57 #endif
     58 
     59 /*
     60  * get next entry in a directory.
     61  */
     62 static struct dirent *
     63 _readdir_unlocked(DIR *dirp)
     64 {
     65 	struct dirent *dp;
     66 
     67 
     68 	for (;;) {
     69 		if (dirp->dd_loc >= dirp->dd_size) {
     70 			if (dirp->dd_flags & __DTF_READALL)
     71 				return (NULL);
     72 			dirp->dd_loc = 0;
     73 		}
     74 		if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
     75 			dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
     76 			dirp->dd_size = getdents(dirp->dd_fd,
     77 			    dirp->dd_buf, (size_t)dirp->dd_len);
     78 			if (dirp->dd_size <= 0)
     79 				return (NULL);
     80 		}
     81 		dp = (struct dirent *)
     82 		    (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
     83 		if ((long)dp & 03)	/* bogus pointer check */
     84 			return (NULL);
     85 		/* d_reclen is unsigned; no need to compare it <= 0 */
     86 		if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
     87 			return (NULL);
     88 		dirp->dd_loc += dp->d_reclen;
     89 		if (dp->d_ino == 0)
     90 			continue;
     91 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
     92 			continue;
     93 		return (dp);
     94 	}
     95 }
     96 
     97 struct dirent *
     98 readdir(dirp)
     99 	DIR *dirp;
    100 {
    101 	struct dirent	*dp;
    102 
    103 #ifdef _REENTRANT
    104 	if (__isthreaded) {
    105 		mutex_lock((mutex_t *)dirp->dd_lock);
    106 		dp = _readdir_unlocked(dirp);
    107 		mutex_unlock((mutex_t *)dirp->dd_lock);
    108 	}
    109 	else
    110 #endif
    111 		dp = _readdir_unlocked(dirp);
    112 	return (dp);
    113 }
    114 
    115 int
    116 readdir_r(dirp, entry, result)
    117 	DIR *dirp;
    118 	struct dirent *entry;
    119 	struct dirent **result;
    120 {
    121 	struct dirent *dp;
    122 	int saved_errno;
    123 
    124 	saved_errno = errno;
    125 	errno = 0;
    126 #ifdef _REENTRANT
    127 	if (__isthreaded) {
    128 		mutex_lock((mutex_t *)dirp->dd_lock);
    129 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    130 			memcpy(entry, dp, DIRENT_SIZE(dp));
    131 		mutex_unlock((mutex_t *)dirp->dd_lock);
    132 	}
    133 	else
    134 #endif
    135 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    136 			memcpy(entry, dp, DIRENT_SIZE(dp));
    137 
    138 	if (errno != 0) {
    139 		if (dp == NULL)
    140 			return (errno);
    141 	} else
    142 		errno = saved_errno;
    143 
    144 	if (dp != NULL)
    145 		*result = entry;
    146 	else
    147 		*result = NULL;
    148 
    149 	return (0);
    150 }
    151