xref: /illumos-gate/usr/src/lib/libc/port/gen/seekdir.c (revision 22028508fd28d36ff74dc02c5774a8ba1f0db045)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 /*
33  * seekdir -- C library extension routine
34  */
35 
36 #include	<sys/feature_tests.h>
37 
38 #if !defined(_LP64)
39 #pragma weak _seekdir64 = seekdir64
40 #endif
41 #pragma weak _seekdir = seekdir
42 
43 #include "lint.h"
44 #include "libc.h"
45 #include <mtlib.h>
46 #include <dirent.h>
47 #include <fcntl.h>
48 #include <unistd.h>
49 
50 #ifdef _LP64
51 
52 void
53 seekdir(DIR *dirp, long loc)
54 {
55 	private_DIR	*pdirp = (private_DIR *)dirp;
56 	dirent_t	*dp;
57 	off_t		off = 0;
58 
59 	lmutex_lock(&pdirp->dd_lock);
60 	if (lseek(dirp->dd_fd, 0, SEEK_CUR) != 0) {
61 		dp = (dirent_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc];
62 		off = dp->d_off;
63 	}
64 	if (off != loc) {
65 		dirp->dd_loc = 0;
66 		(void) lseek(dirp->dd_fd, loc, SEEK_SET);
67 		dirp->dd_size = 0;
68 
69 		/*
70 		 * Save seek offset in d_off field, in case telldir
71 		 * follows seekdir with no intervening call to readdir
72 		 */
73 		((dirent_t *)(uintptr_t)&dirp->dd_buf[0])->d_off = loc;
74 	}
75 	lmutex_unlock(&pdirp->dd_lock);
76 }
77 
78 #else	/* _LP64 */
79 
80 /*
81  * Note: Instead of making this function static, we reduce it to local
82  * scope in the mapfile. That allows the linker to prevent it from
83  * appearing in the .SUNW_dynsymsort section.
84  */
85 void
86 seekdir64(DIR *dirp, off64_t loc)
87 {
88 	private_DIR	*pdirp = (private_DIR *)(uintptr_t)dirp;
89 	dirent64_t	*dp64;
90 	off64_t		off = 0;
91 
92 	lmutex_lock(&pdirp->dd_lock);
93 	if (lseek64(dirp->dd_fd, 0, SEEK_CUR) != 0) {
94 		dp64 = (dirent64_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc];
95 		/* was converted by readdir and needs to be reversed */
96 		if (dp64->d_ino == (ino64_t)-1) {
97 			dirent_t *dp32;
98 
99 			dp32 = (dirent_t *)((uintptr_t)dp64 + sizeof (ino64_t));
100 			dp64->d_ino = (ino64_t)dp32->d_ino;
101 			dp64->d_off = (off64_t)dp32->d_off;
102 			dp64->d_reclen = (unsigned short)(dp32->d_reclen +
103 			    ((char *)&dp64->d_off - (char *)dp64));
104 		}
105 		off = dp64->d_off;
106 	}
107 	if (off != loc) {
108 		dirp->dd_loc = 0;
109 		(void) lseek64(dirp->dd_fd, loc, SEEK_SET);
110 		dirp->dd_size = 0;
111 
112 		/*
113 		 * Save seek offset in d_off field, in case telldir
114 		 * follows seekdir with no intervening call to readdir
115 		 */
116 		((dirent64_t *)(uintptr_t)&dirp->dd_buf[0])->d_off = loc;
117 	}
118 	lmutex_unlock(&pdirp->dd_lock);
119 }
120 
121 void
122 seekdir(DIR *dirp, long loc)
123 {
124 	seekdir64(dirp, (off64_t)(uint32_t)loc);
125 }
126 
127 #endif	/* _LP64 */
128