xref: /illumos-gate/usr/src/lib/libc/port/gen/seekdir.c (revision ddb365bfc9e868ad24ccdcb0dc91af18b10df082)
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 /*
31  * seekdir -- C library extension routine
32  */
33 
34 #include	<sys/feature_tests.h>
35 
36 #if !defined(_LP64)
37 #pragma weak _seekdir64 = seekdir64
38 #endif
39 #pragma weak _seekdir = seekdir
40 
41 #include "lint.h"
42 #include "libc.h"
43 #include <mtlib.h>
44 #include <dirent.h>
45 #include <fcntl.h>
46 #include <unistd.h>
47 
48 #ifdef _LP64
49 
50 void
51 seekdir(DIR *dirp, long loc)
52 {
53 	private_DIR	*pdirp = (private_DIR *)dirp;
54 	dirent_t	*dp;
55 	off_t		off = 0;
56 
57 	lmutex_lock(&pdirp->dd_lock);
58 	if (lseek(dirp->dd_fd, 0, SEEK_CUR) != 0) {
59 		dp = (dirent_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc];
60 		off = dp->d_off;
61 	}
62 	if (off != loc) {
63 		dirp->dd_loc = 0;
64 		(void) lseek(dirp->dd_fd, loc, SEEK_SET);
65 		dirp->dd_size = 0;
66 
67 		/*
68 		 * Save seek offset in d_off field, in case telldir
69 		 * follows seekdir with no intervening call to readdir
70 		 */
71 		((dirent_t *)(uintptr_t)&dirp->dd_buf[0])->d_off = loc;
72 	}
73 	lmutex_unlock(&pdirp->dd_lock);
74 }
75 
76 #else	/* _LP64 */
77 
78 /*
79  * Note: Instead of making this function static, we reduce it to local
80  * scope in the mapfile. That allows the linker to prevent it from
81  * appearing in the .SUNW_dynsymsort section.
82  */
83 void
84 seekdir64(DIR *dirp, off64_t loc)
85 {
86 	private_DIR	*pdirp = (private_DIR *)(uintptr_t)dirp;
87 	dirent64_t	*dp64;
88 	off64_t		off = 0;
89 
90 	lmutex_lock(&pdirp->dd_lock);
91 	if (lseek64(dirp->dd_fd, 0, SEEK_CUR) != 0) {
92 		dp64 = (dirent64_t *)(uintptr_t)&dirp->dd_buf[dirp->dd_loc];
93 		/* was converted by readdir and needs to be reversed */
94 		if (dp64->d_ino == (ino64_t)-1) {
95 			dirent_t *dp32;
96 
97 			dp32 = (dirent_t *)((uintptr_t)dp64 + sizeof (ino64_t));
98 			dp64->d_ino = (ino64_t)dp32->d_ino;
99 			dp64->d_off = (off64_t)dp32->d_off;
100 			dp64->d_reclen = (unsigned short)(dp32->d_reclen +
101 			    ((char *)&dp64->d_off - (char *)dp64));
102 		}
103 		off = dp64->d_off;
104 	}
105 	if (off != loc) {
106 		dirp->dd_loc = 0;
107 		(void) lseek64(dirp->dd_fd, loc, SEEK_SET);
108 		dirp->dd_size = 0;
109 
110 		/*
111 		 * Save seek offset in d_off field, in case telldir
112 		 * follows seekdir with no intervening call to readdir
113 		 */
114 		((dirent64_t *)(uintptr_t)&dirp->dd_buf[0])->d_off = loc;
115 	}
116 	lmutex_unlock(&pdirp->dd_lock);
117 }
118 
119 void
120 seekdir(DIR *dirp, long loc)
121 {
122 	seekdir64(dirp, (off64_t)(uint32_t)loc);
123 }
124 
125 #endif	/* _LP64 */
126