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readdir.c revision 1.18 
      1 /*	$NetBSD: readdir.c,v 1.18 2003/08/07 16:42:55 agc 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 1.18 2003/08/07 16:42:55 agc 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 #ifdef __weak_alias
     51 __weak_alias(readdir,_readdir)
     52 __weak_alias(readdir_r,_readdir_r)
     53 #endif
     54 
     55 /*
     56  * get next entry in a directory.
     57  */
     58 static struct dirent *
     59 _readdir_unlocked(DIR *dirp)
     60 {
     61 	struct dirent *dp;
     62 
     63 
     64 	for (;;) {
     65 		if (dirp->dd_loc >= dirp->dd_size) {
     66 			if (dirp->dd_flags & __DTF_READALL)
     67 				return (NULL);
     68 			dirp->dd_loc = 0;
     69 		}
     70 		if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
     71 			dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
     72 			dirp->dd_size = getdents(dirp->dd_fd,
     73 			    dirp->dd_buf, (size_t)dirp->dd_len);
     74 			if (dirp->dd_size <= 0)
     75 				return (NULL);
     76 		}
     77 		dp = (struct dirent *)
     78 		    (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
     79 		if ((long)dp & 03)	/* bogus pointer check */
     80 			return (NULL);
     81 		/* d_reclen is unsigned; no need to compare it <= 0 */
     82 		if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
     83 			return (NULL);
     84 		dirp->dd_loc += dp->d_reclen;
     85 		if (dp->d_ino == 0)
     86 			continue;
     87 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
     88 			continue;
     89 		return (dp);
     90 	}
     91 }
     92 
     93 struct dirent *
     94 readdir(dirp)
     95 	DIR *dirp;
     96 {
     97 	struct dirent	*dp;
     98 
     99 #ifdef _REENTRANT
    100 	if (__isthreaded) {
    101 		mutex_lock((mutex_t *)dirp->dd_lock);
    102 		dp = _readdir_unlocked(dirp);
    103 		mutex_unlock((mutex_t *)dirp->dd_lock);
    104 	}
    105 	else
    106 #endif
    107 		dp = _readdir_unlocked(dirp);
    108 	return (dp);
    109 }
    110 
    111 int
    112 readdir_r(dirp, entry, result)
    113 	DIR *dirp;
    114 	struct dirent *entry;
    115 	struct dirent **result;
    116 {
    117 	struct dirent *dp;
    118 	int saved_errno;
    119 
    120 	saved_errno = errno;
    121 	errno = 0;
    122 #ifdef _REENTRANT
    123 	if (__isthreaded) {
    124 		mutex_lock((mutex_t *)dirp->dd_lock);
    125 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    126 			memcpy(entry, dp, DIRENT_SIZE(dp));
    127 		mutex_unlock((mutex_t *)dirp->dd_lock);
    128 	}
    129 	else
    130 #endif
    131 		if ((dp = _readdir_unlocked(dirp)) != NULL)
    132 			memcpy(entry, dp, DIRENT_SIZE(dp));
    133 
    134 	if (errno != 0) {
    135 		if (dp == NULL)
    136 			return (errno);
    137 	} else
    138 		errno = saved_errno;
    139 
    140 	if (dp != NULL)
    141 		*result = entry;
    142 	else
    143 		*result = NULL;
    144 
    145 	return (0);
    146 }
    147